op ti tools

OptiTools

Table of ContentsTable of Contents........................................................................................................1

OptiTools .....................................................................................................................9

Overlap Integral.........................................................................................................11

2D Overlap Integral ..................................................................................................14

3D Overlap Integral ..................................................................................................16

Gaussian Overlap Scanner ......................................................................................19

Overlap Integral Scanner..........................................................................................23

Overlap Integral 2D ..................................................................................................24

Overlap Integral 3D ..................................................................................................25

Multiple Fields ...........................................................................................................27

Multiple Fields (2D) dialog box.................................................................................28

Multiple Fields (3D) dialog box.................................................................................29

Multiple Fields—2D Mode Solver.............................................................................31

Notes ......................................................................................................................................32

Multiple Gaussians ...................................................................................................33

Notes ......................................................................................................................................36

Confinement Factor ..................................................................................................37

Notes ......................................................................................................................................42

Far Field .....................................................................................................................43

Fraunhofer approximation....................................................................................................43

Fresnel-Kirchhoff Diffraction Formula ................................................................................44

2D Far Field............................................................................................................................45

3D Far Field............................................................................................................................47

References.............................................................................................................................49

Mode 2D .....................................................................................................................51

Modes of Planar Waveguides...............................................................................................53

File menu................................................................................................................................54

Edit menu...............................................................................................................................54

View menu..............................................................................................................................55

Simulation menu ...................................................................................................................55

Window menu........................................................................................................................55

Simulation functions.............................................................................................................56

Global parameters....................................................................................................56

Edit Parameters .......................................................................................................57

Scan Parameters .....................................................................................................58

Which parameters can be scanned?........................................................................58

Output Data Files .....................................................................................................60

Calculate ..................................................................................................................61

Modes of Planar Waveguides—other functions .......................................................63

Correlation Function Method (CFM) ....................................................................................64

File menu................................................................................................................................65

Edit menu...............................................................................................................................65

View menu..............................................................................................................................66

Simulation menu ...................................................................................................................66

Window menu........................................................................................................................66

Simulation functions.............................................................................................................67

Global Parameters ...................................................................................................67

Edit Parameters .......................................................................................................71

Calculate ..................................................................................................................72

User Defined File ...................................................................................................................76

File menu................................................................................................................................77

Edit menu...............................................................................................................................78

View menu..............................................................................................................................78

Simulation menu ...................................................................................................................78

Window menu........................................................................................................................78

User Defined File dialog box ....................................................................................79

Notes: .....................................................................................................................................80

User Guide of View 2D..............................................................................................81

Graphic Engines....................................................................................................................82

User interface features .........................................................................................................83

Main menu bar .........................................................................................................84

Toolbars ...................................................................................................................85

Status bar.................................................................................................................85

Windows.................................................................................................................................86

Data browser............................................................................................................86

Info window ..............................................................................................................87

Edit data ...................................................................................................................88

Opti 2D Viewer menus and buttons.....................................................................................89

File menu .................................................................................................................89

Edit menu .................................................................................................................89

Curve menu..............................................................................................................90

View menu ...............................................................................................................90

Help menu................................................................................................................90

Opti 2D Viewer Graph toolbox .............................................................................................91

Opti 2D Viwer Graph toolbox ...................................................................................91

Graph tools...............................................................................................................92

Print and Export files ............................................................................................................94

Print..........................................................................................................................94

Export to EMF file.....................................................................................................95

Export to BMP file ....................................................................................................96

Copy.........................................................................................................................96

Mode 3D .....................................................................................................................97

File menu................................................................................................................................97

Edit menu...............................................................................................................................98

View menu..............................................................................................................................98

Operations menu.................................................................................................................100

Simulation menu .................................................................................................................100

Draw Tool menu ..................................................................................................................101

Preferences menu ...............................................................................................................101

Layout Designer Dialog boxes of Mode Solver 3D ..........................................................103

Initial Data layout dialog box ..................................................................................105

Waveguide Profile layout dialog box ......................................................................107

Device Info layout dialog box .................................................................................108

Move Selection layout dialog box...........................................................................109

Layers Structure layout dialog box.........................................................................110

Wafer Data layout dialog box .................................................................................111

Initial Data layout dialog box ..................................................................................112

Settings tab ............................................................................................................114

Global Data: CFM Method layout dialog box .........................................................116

Edit Parameters dialog box ....................................................................................119

Scan Parameters layout dialog box .......................................................................120

Layout Settings layout dialog box.....................................................................................122

Waveguide Colors layout dialog box ................................................................................123

Notes: ...................................................................................................................................124

User Guide of View 3D............................................................................................125

Commands of View 3D........................................................................................................125

File menu ...............................................................................................................125

Edit menu ...............................................................................................................126

View menu............................................................................................................................127

Toolbars menu.....................................................................................................................127

Status Bar menu..................................................................................................................128

Settings menu......................................................................................................................131

Dialog boxes of View 3D.....................................................................................................133

Topography Properties dialog box .........................................................................133

Surface Properties dialog box ................................................................................134

Print Preferences dialog box ..................................................................................135

Colors Selection dialog box....................................................................................136

Palette Selection dialog box...................................................................................137

X-Axis dialog box ...................................................................................................138

Y-Axis dialog box ...................................................................................................139

Z-Axis dialog box....................................................................................................141

Title dialog box .......................................................................................................143

View Point dialog box.............................................................................................144

X Cut and Y Cut dialog box....................................................................................145

Notes: ...................................................................................................................................146

Code V Converter....................................................................................................147

Data format ..........................................................................................................................149

EXFO OWA Converter.............................................................................................151

Region Selection and Expansion ...........................................................................152

Wavelength Extrapolation by Sellmeier formula ....................................................154

Sellmeier Extrapolation Technical Background......................................................155

Zemax Converter.....................................................................................................159

Conversion...........................................................................................................................159

Notes on Conversion ..........................................................................................................160

Data formats ........................................................................................................................161

ZEMAX Beam File (ZBF) binary format .............................................................................161

Appendix A: Opti2D Graph Control.......................................................................163

User interface features .......................................................................................................164

Information windows ..............................................................................................164

Info-window ............................................................................................................164

Legend ...................................................................................................................165

Graph toolbox.........................................................................................................166

Graph tools ..........................................................................................................................166

Graph menu ...........................................................................................................168

Graph Menu button ................................................................................................168

Tools ......................................................................................................................168

Windows.................................................................................................................169

Printing and exporting files.....................................................................................169

Utilities....................................................................................................................171

Help........................................................................................................................171

Displays..................................................................................................................172

Graph Properties dialog .....................................................................................................173

X-Axis.....................................................................................................................173

Y-Axis.....................................................................................................................175

Grid ........................................................................................................................177

Fonts ......................................................................................................................178

Legend ...................................................................................................................178

Graph .....................................................................................................................179

Label Management ................................................................................................180

Appendix B: File Formats.......................................................................................181

Generic file format...............................................................................................................181

Data file formats ..................................................................................................................181

Real Data 2D File Format: BCF2DPC....................................................................182

Real Data 3D File Format: BCF3DPC....................................................................183

Complex Data 2D File Format: BCF2DCX.............................................................185

Complex Data 3D File Format: BCF3DCX.............................................................186

User Refractive Index Distribution File Format ................................................................188

Reading User Refractive Index Files by BPM 2D and BPM 3D .......................................189

Complex Data 3D Vectorial File Format: BCF3DCXV ...........................................190

Path Monitoring File Format...............................................................................................191

BCF2DPM ..............................................................................................................191

Power In Output Waveguides File Format ........................................................................191

BCF2DMC..............................................................................................................191

Notes: ...................................................................................................................................192

9

OptiTools

OptiTools is a collection of programs that perform operations on fields used in OptiBPM and OptiFDTD.

The following tools are available:• Overlap Integral—Calculates power overlap integrals of fields. Can accept semi-

vector and full vector data. In full-vector data, the input field has both major and minor components.

• Gaussian Overlap Scanner—Calculates power overlap integrals with Gaussian fields for a range of offsets. Applies to the BPM 2D or 3D fields.

• Overlap Integral Scanner—Calculates the power overlap integrals for a range of field offsets.

• Multiple Fields—Creates a user field as a sum of given fields.• Multiple Gaussians—Creates a user field as a sum of Gaussian fields.• Confinement Factor—Calculates the portion of guided energy within an arbitrary

rectangular boundary. Can accept semi-vector and full vector data.• Far Field—Calculates the far-field radiation pattern from the near-field.• Mode 2D—Finds the effective refractive index and the modal field of any guided

mode in a two-dimensional (planar) structure.— Modes of Planar Waveguides

— Correlation Function Method (CFM)

— User Defined File

• Code V Converter—Converts Code V files to OptiBPM files and vice versa.• EXFO OWA Converter• Zemax Converter

To open the OptiBPM Utilities dialog box, from the Start menu, select Programs > Optiwave Software > OptiBPM 9.0 > OptiBPM Tools (see Figure 1). This opens the OptiBPM Utilities dialog box.

OPTITOOLS

10

Figure 1 OptiBPM Utilities dialog box

OPTITOOLS — OVERLAP INTEGRAL

11

Overlap Integral

Overlap Integral calculates power overlap integrals of fields. It can accept both full-vector data and semi-vector data. In full-vector data, the input field has both major and minor components.

The Overlap Integral tool can use input fields with different sizes and mesh configurations. The relative position of the two fields can be modified by specifying an Offset in X and Y coordinates. The integration range is a user-specified rectangle within the intersection of the two fields, not over the whole domain.

Note: It is E2 that moves, not E1. The user specified rectangle is on the same coordinate system as E1 (see Figure 2).

Figure 2 Two input fields, E1 and E2

E1 is defined on domain.

The offset is (-4, -4)—the user can specify a range of integration within the intersection.

The example shows a with

The power overlap integral in vector 3D is defined as:

Ω

x 1 7, and y 3 7, E2 on x 7 12, and y 7 13, .∈∈,∈∈

Ω

Ω

x 4 6, and y 4 6,∈∈


12

By the E1 and E2 in the integration limits, we mean the domain of the respective functions. The squared magnitudes are interpreted as:

The power is normalized so that any field, when overlapped with itself, will give a value of unity if the region of integration is the extent of the whole function (i.e. in the case is set to the domain of the function). Note that if a field is overlapped with itself, but integrated over an extent smaller than the domain, the result is the square of the confinement factor:

Power Overlap of with itself =

The Power Overlap Integral and Confinement factor are defined for scalar, semi vector, and 2D in a similar way.

(1)

(2)

(3)

POI

E1 x y,( ) E2∗ x y,( )⋅ xd yd

Ω∫

2

E1 x y,( )2 xd y E2 x y,( )

E2∫

2d xd yd

E1∫--------------------------------------------------------------------------------------=

E 2 E E∗ ExEx∗ EyEy∗ Ex2 Ey

2+=+=⋅=

ΩΩ

E x y,( )

E E⋅ ∗ xd ydΩ∫

2

E 2 xd y E 2 xd ydE∫d

E∫-------------------------------------------------

E 2 xd ydΩ∫

E 2 xd ydE∫-------------------------

2

(Confinement Factor)2= =


13

Overlap Integral calculates power overlap integrals of fields. To open the Overlap Integral, in the OptiBPM Utilities dialog box, click Overlap Integral (see Figure 3).

Figure 3 Overlap Integral dialog box

Select either a 2D or 3D Overlap Integral.

2D Overlap Integral

Integral of two one-dimensional fields *.f2d3D Overlap Integral

Integral of two-dimensional fields *.f3dClick Overlap Integral 2D to open the 2D Overlap Integral calculation dialog box, or click Overlap Integral 3D to open the 3D Integral Overlap calculation dialog box.


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2D Overlap IntegralThe 2D Overlap Integral dialog box allows you to calculate overlap integrals in 2D fields (see Figure 4).

Note: If you access the Overlap Integral tool via the 2D Mode Solver, the data file for Input Field 1 is already loaded.

Figure 4 2D Overlap Integral dialog box

Input Data

Specify the two 2D fields and the overlap regions.

Input Field 1 name of a .f2d file containing the first input field.

Input Field 2 name of a .f2d file containing the second input field.

Get Data

Once the two .f2d files have been selected, click Get Data to have the utility read the field data. Once the data is read, the following fields will be available (see Figure 4):

Offset—X field: This number indicates the distance the second field is moved before overlapping integral is done

Subdivisions—number of subdivisions of mesh intervals in overlap integral. The subdivisions option is related to the space discretization where the overlap integral will be solved.

The mesh of the two fields can be different, and the offset is arbitrary. We want to obtain an integral with an accuracy that is consistent with the mesh representation of


15

the functions in the integrand. This requires oversampling the integrand, which is achieved by subdividing the smaller mesh interval into the specified number of points. The accuracy improves with more subdivisions, but the execution time slows down. More accurate results can be obtained by using a number as large as 10 for subdivisions, but the accuracy is not likely to improve by further increasing the subdivisions.

Region of Integration—X Lower and X Upper: These numbers define, using the co-ordinate system of Input Field 1, the range of integration for the overlap integral (it is an integration over a single variable in the 2D Overlap Integral case).

Note: The following fields are never available in the 2D Overlap Integral dialog box:• Offset—Y field• Region—Y Upper and Y Lower

Statistics

The Power Overlap Integral.

Result of Overlap: The resulting overlap integral displays in percent and in decibels.

Status fields

The two small read-only windows display the current operation status (for example, Idle, Loading, or Calculating) and the completed percentage of the operation (progress bar).


16

3D Overlap IntegralThe 3D Overlap Integral dialog box allows you to calculate overlap integrals of 3D fields (see Figure 5).

Note: If you access the Overlap Integral tool via the 2D Mode Solver, the data file for Input Field 1 is already loaded.

Figure 5 3D Overlap Integral Calculation dialog box

Input Data

Specify the two 3D fields and the overlap regions.

Input Field 1 name of a .f3d file containing the first input field (see E1 in Figure 2).

Input Field 2 name of a .f3d file containing the second input field (see E2 in Figure 2).

Get Data

Once the two .f3d files have been selected, click Get Data to have the utility read the field data. Once the data is read, the following fields will be available (see Figure 5):

Offset—X and Y fields: specifies the translation of field E2 before the overlap integral is done.

Subdivisions—number of subdivisions of mesh intervals in overlap integral. The subdivisions option is related to the space discretization where the overlap integral will be solved.


17

The mesh of the two fields can be different, and the offset is arbitrary. We want to obtain an integral with an accuracy that is consistent with the mesh representation of the functions in the integrand. This requires oversampling the integrand, which is achieved by subdividing the smaller mesh interval into the specified number of points. The accuracy improves with more subdivisions, but the execution time slows down. More accurate results can be obtained by using a number as large as 10 for subdivisions, but the accuracy is not likely to improve by further increasing the subdivisions.

Region of Integration—X Lower, X Upper, Y Lower, and Y Upper: These coordinates define the Region of Integration in the coordinate system of Input Field 1 (see Figure 6).

Figure 6 3D Overlap Integral—available fields

Statistics

Result of Overlap: The resulting overlap is displayed in percent and in decibels.

Status fields

The two small read-only windows display the current operation status (for example, Idle, Loading, or Calculating) and the completed percentage of the operation (progress bar).

Ω


18

OPTITOOLS — GAUSSIAN OVERLAP SCANNER

19

Gaussian Overlap Scanner

The Gaussian Overlap Scanner applies to the OptiBPM/OptiFDTD 2D or 3D fields.

The program calculates the power overlap integral (POI) (see Equation 1) of a given complex field and a Gaussian field, where the Gaussian center position ( ) is varying or scanned within the mesh limits.

The Gaussian field is a Gaussian distribution defined from a center point and halfwidths and

In 2D, the function reduces to the case . The Gaussian field center is at coordinates , where has value of unity. At any point on a ellipse with semi axes and , the value is .

To open the Gaussian Overlap Scanner, in the OptiBPM Utilities dialog box, click Gaussian Overlap Scanner (see Figure 7).

Figure 7 Gaussian Overlap Integral Scanner dialog box

Select either 2D or 3D Overlap Integrals.

Overlap Integral 2D

Integral of two one-dimensional fields *.f2dOverlap Integral 3D

Integral of two-dimensional fields *.f3dWhen you select either integral, the Gaussian Overlap Field dialog box opens (see Figure 8). You can browse for and load an existing field.

(4)

xc yc,

xc yc,σx σy

G x y,( )x xc–σx

------------- –

2 y yc–σy

-------------

2 –exp=

y yc=xc yc, G

σx σy 1 e⁄


20

Note: If you access the Gaussian Overlap Scanner tool via the 2D Mode Solver, the Gaussian Overlap Field dialog box does not appear. The data file for Input Field is already loaded. The Overlap Integral dialog box opens.

Figure 8 Gaussian Overlap Field dialog box

After you select a file, click Load to open the Gaussian Overlap Integral (Scanner) dialog box (see Figure 9 for 2D, and Figure 10 for 3D).

2D Gaussian Overlap Integral dialog box

Figure 9 2D Gaussian Overlap Integral (Scanner) dialog box

Information

Input Field: name and location of the .f3d file.

Number of Points in Mesh: displays the number of discretization points of the Gaussian field.


21

Mesh Widths: displays the mesh width in microns.

Parameters

Gaussian Field Half Widths: enter X width of the current Gaussian field ( ).

X Limits of Gaussian Center Position: displays limits for X coordinates of the Gaussian center ( ).

Number of Calculation Points in X: specifys the number of calculation points for X.

Overlap Calculations: select the format of the overlap calculations, dB or Percentage.

Write 2D Output file: enable to provide a file name and path. For 2D calculations, use a .f2d file extension, so you can use Optiwave 2D viewers to view the scanned results.

Calculate: click to start the calculations. At the end of the calculation, a dialog box appears stating the maximum overlap integral and the displacement at which it was obtained. The results of all overlap integrals are sent to the file in the Write 2D Output File field.

3D Gaussian Overlap Integral dialog box

Figure 10 3D Gaussian Overlap Integral (Scanner) dialog box

σx

xc


22

Information

Input Field: name and location of the .f3d file.

Number of Points in Mesh (X/Y): displays the number of discretization points of the Gaussian field.

Mesh Widths (X/Y): displays the mesh width in microns. This specifies the XY domain.

Parameters

Gaussian Field Half Widths: enter X and Y widths of the current Gaussian field ( .

X Limits of Gaussian Center Position: displays limits for X coordinates of the Gaussian center ( ).

Number of Calculation Points in X: specifys the number of calculation points for X.

Y Limits of Gaussian Center Position: displays limits for Y coordinates of the Gaussian center ( ).

Number of Calculation Points in Y: specifys the number of calculation points for Y.


Write 3D Output file: enable to provide a file name and path. For 3D calculations, use a .f3d file extension, so you can use Optiwave 3D viewers to view the scanned results.

Calculate: click to start the calculations. At the end of the calculation, a dialog box appears stating the maximum overlap integral and the displacement at which it was obtained. The results of all overlap integrals are sent to the file in the Write 3D Output File field.

At the end of the calculations, you are asked about your normalization choice (see Figure 18).

Figure 11 Normalization dialog box

σx σy,

xc

yc

OPTITOOLS — OVERLAP INTEGRAL SCANNER

23

Overlap Integral Scanner

The Overlap Integral Scanner calculates the overlap integral of two given fields scanning the position of the second field. This feature works in a similar manner to the Gaussian Overlap Scanner. The number of calculation points is fixed, but you can change the limits of the second field position.

To open the Overlap Integral Scanner, in the OptiBPM Utilities dialog box, click Overlap Integral Scanner (see Figure 12).

Figure 12 Overlap Integral Scanner dialog box

Type of Overlap

Select either 2D or 3D Overlap Integral to control the scanning parameters.

Overlap Integral 2D: Integral of two one-dimensional fields *.f2dOverlap Integral 3D: Integral of two-dimensional fields *.f3dWhen you select either integral, the Input Fields dialog box opens (see Figure 13).

Note: If you access the Overlap Integral Scanner tool via the 2D Mode Solver, the data file for First Field is already loaded.

Figure 13 Input Fields dialog box


24

First Field

Select the first file (.f2d or .f3d)

Second Field

Select the second file (.f2d or .f3d)

Note: You must select a file for each field.

Click OK to open the Overlap Integral dialog box.

The Overlap Integral Scanner involves the repeated application of the Overlap Integral for various displacements of the second field (E2 of Figure 2).

Overlap Integral 2D

Figure 14 Overlap Integral dialog box—2D

Parameters

X Limits of Second Field Movement: controls the range of X displacement of second field.


Write 2D file: enable to provide a file name and path. For 2D calculations, use a .f2d file extension, so you can use Optiwave 2D viewers to view the scanned results.


25

Region of Integration

Specifies region of integration where the overlap integration is performed.

X Lower: bottom left corner of the rectangle

X Upper: top right corner of the rectangle

Status fields: two small read-only windows display the current operation status (Idle, Loading, or Calculating) and the completed percentage of the operation (progress bar).

Calculate: click to start the calculations. At the end of the calculation, a dialog box appears stating the maximum overlap integral and the displacement at which it was obtained. The results of all overlap integrals are sent to the file in the Output File field.

Overlap Integral 3D

Figure 15 Overlap Integral dialog box—3D case

Parameters

X Limits of Second Field Movement: controls the range of X displacement of second field

Y Limits of Second Field Movement: controls the range of Y displacement of second field

The number of points in the scan is taken from the mesh size of the first or second field (the smaller of the two mesh sizes is used).

Ω

Ω

Ω


26

Example

In the example shown in Figure 15, the Y displacement of the second field will be set at -1.25, and then the X displacement of the second field will range from -1.2 to -1.0. Next, the Y displacement will be scanned up to -1.0, with the X scan repeated for each new Y displacement. In 2D, only the X displacement is scanned.


Write 3D file: enable to provide a file name and path. For 3D calculations, use a .f3d file extension, so you can use Optiwave 3D viewers to view the scanned results. In 2D, use .f2d.

Region of Integration

Specifies the rectangular region of integration , as in Equation 1 where the overlap integration is performed, . The numbers in the fields are coordinates in the system of field E1.

X Lower: bottom left corner of the rectangle

Y Lower: bottom left corner of the rectangle

X Upper: top right corner of the rectangle

Y Upper: top right corner of the rectangle

Status fields: two small read-only windows display the current operation status (Idle, Loading, or Calculating) and the completed percentage of the operation (progress bar).

Calculate: click to start the calculations. At the end of the calculation, a dialog box appears stating the maximum overlap integral and the displacement at which it was obtained. The results of all overlap integrals are sent to the file in the Output File field.

Ω

Ω

Ω

Ω

Ω

OPTITOOLS — MULTIPLE FIELDS

27

Multiple Fields

The Multiple Fields utility enables you to create a user field E as a sum of given fields E1, E2.....EN with custom weights and phase changes.

To open the Multiple Fields, in the OptiBPM Utilities dialog box, click Multiple Fields (see Figure 16).

Figure 16 Multiple Fields

Select 2D or 3D Multiple Field to perform additions of 2D or 3D fields.

Multiple Field 2D: addition of two-dimensional fields *.f2dMultiple Field 3D: addition of three-dimensional fields *.f3d


28

Multiple Fields (2D) dialog boxTo open the Multiple Fields dialog box (2D), click Multiple Field 2D (see Figure 17).

Note: If you access the Multiple Fields tool via the 2D Mode Solver, the data file for Field to add is already loaded. The dialog box is also different (see Figure 21).

Figure 17 Multiple Fields 2D dialog box

Field Data

Field to add: browse to an existing field file.

Weight Factor

Amplitude: enter the coefficient that multiplies the amplitude of the original field.

Power: enter the coefficient that multiplies the power of the original field.

Phase Change:

[deg]: enter the phase factor that changes the phase of the original field.

Fields already added: lists fields added to the existing field file

Browse: click to open the Open window dialog box and select the field file

Add Field: click to add the current field to the list.

Finish: click to perform the summation of all fields in the list.


29



Multiple Fields (3D) dialog boxTo open the Multiple Fields dialog box (3D), click Multiple Field 3D (see Figure 19).

Note: If you access the Multiple Fields tool via the 2D Mode Solver, the data file for Field to add is already loaded (see Figure 21).

Figure 19 Multiple Fields 3D dialog box

Field Data

Field to add: browse to an existing field file.

Weight Factor




30

Phase Change:


Fields already added

Lists fields added to the existing field file

Browse: click to open the Open window dialog box, where you can choose which file to select.






31

Multiple Fields—2D Mode Solver

Figure 21 2D Mode Solver Multiple Fields dialog box

Available Fields

Lists fields available to add to the field file.

Fields already added

Lists fields added to the existing field file.

Field Data

Weight Factor



Phase Change:





32

Notes

OPTITOOLS — MULTIPLE GAUSSIANS

33

Multiple Gaussians

The Gaussian field is a Gaussian distribution defined from a center point ( and halfwidths and

In 2D, the function reduces to the case . The Gaussian field center is at coordinates , where has value of unity. At any point on an ellipse with semi axes and , the value is .

In Multiple Gaussians, you can create a sum of Gaussian fields G1, G2, G3... each with different centers and halfwidths. The Gaussian fields can be added with different amplitudes and phases. The phases are specified in units of , as shown in Equation 6.

The Multiple Gaussians feature creates a user field as a sum of Gaussian fields.

To open the Multiple Gaussian dialog box, in the OptiBPM Utilities dialog box, click Multiple Gaussians (see Figure 22).

(5)

(6)

xc yc,σx σy

G x y,( )x xc–σx

------------- –

2 y yc–σy

-------------

2–exp=

y yc–xc yc, G

σx σy 1 e⁄

π

E x y,( ) A1 jπp1[ ]G1 x y,( ) A2 jπp2[ ]G2 x y,( ) ... AN jπpN[ ]GN x y,( )exp+ +exp+exp=


34

Figure 22 Multiple Gaussian dialog box

Parameters of Gaussian

Number of Points in Mesh: enter the number of discretization points of the Gaussian field. After the first entry, followed by Add, the Number of Points in Mesh cannot be changed for subsequent fields.

Mesh Width: enter the mesh width in microns. This specifies the XY domain. After the first entry, followed by Add, the Mesh Width cannot be changed for subsequent fields.

Gaussian Field Center: enter X and Y coordinates of the Gaussian center ( ).

Gaussian Half Width: enter X and Y widths of the current Gaussian field ( .

Amplitude Weight Factor: enter the coefficient that multiplies the amplitude of the current Gaussian field ( ).

Phase Change [deg]: enter the phase factor that changes the phase of the current Gaussian field ( ).

Add: click to add the current field to the list.


xc yc,

σx σy,

A1 A2...,

P1 P2...,


35




36

Notes

OPTITOOLS — CONFINEMENT FACTOR

37

Confinement Factor

Figure 24 Definition of Confinement Factor

The confinement factor field is defined over the rectangle bounded on the lower left corner by (Xmin, Ymin) and on the upper right by (Xmax, Ymax). The confinement factor is the fraction of power to be found in the smaller rectangular region bounded by (xmin, ymin), (xmax, ymax).

The squared magnitude is interpreted as

In the case of scalar fields and 2D fields, similar definitions are used.

Confinement Factor calculates a portion of guided energy within waveguide boundaries. To open the Confinement Factor dialog box, in the OptiBPM Utilities dialog box, click Confinement Factor (see Figure 25).

(7)

(8)

Confinement Factor =

E x y,( )2 xd yd

xmin

xmax

∫ ymin

ymax

∫

E x y,( )2 xd yd

Xmin

Xmax

∫ Ymin

Ymax

∫

------------------------------------------------------------

E 2 E E∗ ExEx∗ EyEy∗ Ex2 Ey

2+=+=⋅=


38

Figure 25 Confinement Factor dialog box

Type of Confinement Factor

2D Confinement: are for *.f2d fields

3D Confinement: are for *.f3d fields

Click 2D Confinement or 3D Confinement to open the Open dialog box. Select a file, and click Open to open the Confinement Factor - 2D dialog box (see Figure 26), or the Confinement Factor - 3D dialog box (see Figure 27).

Figure 26 Confinement Factor - 2D dialog box

Data File

Field: displays the path to the current data file.


39

Data Coordinates

Xmin: displays the minimum value of the data domain

Xmax: displays the maximum value of the data domain

Confinement Data

xmin: defines the minimum value of the boundaries confining the field

xmax: defines the maximum value of the boundaries confining the field

Note: An alternative is to use the Use Mesh Points option.

Number of mesh points: displays the number of mesh points in the data field

Use Mesh Points

min pt: defines the minimum value of the field boundaries in mesh points

max pt: defines the maximum value of the field boundaries in mesh points

Note: An alternative is to use the Confinement Data option.

Statistics

Confinement Factor: displays the calculated confinement factor in percent

Compute: starts the confinement factor calculation


40

Figure 27 Confinement Factor - 3D dialog box

Data File

Field: displays the path to the current data file.

Data Coordinates

Xmin: displays the minimum value of the data domain

Ymin: displays the minimum value of the data domain

Xmax: displays the maximum value of the data domain

Ymax: displays the maximum value of the data domain

Number of mesh points

XNo: displays the number of mesh points in the X-data field

YNo: displays the number of mesh points in the Y-data field


41

Confinement Data

xmin: defines the minimum value of the X-boundaries confining the field

xmax: defines the maximum value of the X-boundaries confining the field

ymin: defines the minimum value of the Y-boundaries confining the field

ymax: defines the maximum value of the Y-boundaries confining the field

Note: An alternative is to use the Use Mesh Points option.

Use Mesh Points

xmin pt: defines the minimum value of the field X-boundary in mesh points

xmax pt: defines the maximum value of the field X-boundary in mesh points

ymin pt: defines the minimum value of the field Y-boundary in mesh points

ymax pt: defines the maximum value of the field Y-boundary in mesh points

Note: An alternative is to use the Confinement Data option.

Statistics

Confinement Factor: displays the calculated confinement factor in percent

Compute: starts the confinement factor calculation


42

Notes

OPTITOOLS — FAR FIELD

43

Far Field

Far Field calculates a far field distribution from a near-field one.

Fraunhofer approximationNarrow angle far field transform being used in OptiBPM is based on the Fraunhofer approximation [1]:

At a large distance d, the far field position can be expressed by the far field angle,

Where the x-directional angle is the angle between the orginal yz-plane and the shortest straight line connecting the point and the Y axis, and the y-directional angle

is the angle between the orginal xz-plane and the shortest straight line connecting the point and the x axis. the far field is also shown in Equation 11.

Associated with the angle where to observe the far field, far field formula now can be simplified as

Please note that the above formula assumed far field is far away from the near field. OptiBPM uses Equation 13 to calculate the narrow angle far field transform.

(9)

(10)

(11)

E x( y z, , d ) ieikdeik

2d------ x2 y2+( )

λd---------------------------- E x′ y′ 0 )e i–

kd--- xx′ yy′+( )

,,( x′d y′d∫∫–≅=

θx( )tan xd--- θy( )tan; y

d---= =

θx( )

θy( )

E θx θy,( )α E x( ′ y′ 0 ) i– n2πλ

------ x′ θx y′ θytan+tan( )exp,, x′d y′d∫∫


44

Figure 28 Far field angle (the red region is the near field)

Fresnel-Kirchhoff Diffraction FormulaWide angle far field transform is based on the Fresnel-Kirchhoff diffraction formula [1].

where R is the vector from near-field to far-field.

The far-field position can be expressed with far field angle the far field distance z=d. Therefore, in the wide angle far field transform, user needs to specify the far field distance.

In the wide angle Far Field dialog boxes, a field is provided to input the distance.

(12)E x( y z, , d ) iλ--- E x( ′ y′ 0 )e

ikR

R----------,, 1 R z,( )cos+

2-------------------------------- x′d y′d∫∫–= =


45

2D Far FieldThe far field pattern in 2D is calculated using a discrete Fourier transform based on the formula in Equation 13:

where is the position coordinate in the near field plane, is the coordinate in the observation plane, and is the distance between the near field plane and the observation plane. is the wavelength of the field. is refractive index of the medium.

To open the Far-Field Calculation 2D dialog box, in the OptiBPM Utilities dialog box, click Far-Field (see Figure 29).

Note: If you access the Far Field tool via the 2D Mode Solver, the data file for Input Field is already loaded.

Figure 29 Far-Field Calculation 2D dialog box

Data File

Input Field:

enter the input field for calculations

Load:

click to load the selected input field.

(13)Fx0z0----- α f x( ) jn2π

λ------

x0z0-----x–exp xd

Xmin

Xmax

∫

x x0z0

λ n


46

Parameters

Wavelength:

enter the wavelength in microns

Refractive Index:

enter the refractive index of the medium

Result

Select Amplitude or Intensity for display of results.

Angle

Initial:

initial angle parameter

Final:

final angle parameter

Number of steps:

number of steps to be calculated

Calculate

Click to start the calculations.

Save As

Click to save the results of the calculations in a user-defined file.

Close

Click to close the dialog box.


47

3D Far FieldThe far field distribution can be observed and measured, thereby providing an important tool for estimating the characteristics of a given waveguide. The far field distribution can be derived from the Fraunhofer diffraction pattern of its near field. To calculate the far-field intensity pattern in 3D, first, the fast Fourier transform is used to calculate the Fraunhofer integral, and then, the result is re-sampled in order to have uniform angular sampling.

The fast Fourier transform estimates the value of the formula:

where and are the coordinates in the near field plane, and are the coordinates in the observation plane, is the distance between the near field plane and the observation plane. is the wavelength of the field. is the refractive index of the medium.

After performing the Fourier transform above, the modulus squared of the result:

(the optical intensity) is normalized such that the maximum value is 1.0.

In addition, the independent variables are presented as angles in degrees:

so that in the output, the optical normalized intensity will be plotted as a function of angle of deviation fro the z-axis in degrees.

To open the Far-Field Calculation 3D dialog box, in the OptiBPM Utilities dialog box, click Far-Field (see Figure 29).

(14)

F x0z0-----

y0z0----- ,

α f x y,( ) ej n 2π

λ------

x0

z0---- x

y0

z0---- y⋅+⋅

⋅⋅–⋅ xd yd∫∫

x y x0 y0z0

λ n

Fx0z0-----

y0z0-----,

2

θtan x x0z0----- =

θtan y y0z0----- =


48

Note: If you access the Far Field tool via the 2D Mode Solver, the data file for Input Field is already loaded.

Figure 30 Far Field Calculation 3D dialog box

Data File

Input Field:

enter the input field for calculations

Load:

click to load the selected input field.

Parameters

Wavelength:

enter the wavelength in microns

Refractive Index:

enter the refractive index of the medium

Angle

X direction:

angle in the XZ plane

Y direction:

angle in the YZ plane

Number of steps:

number of steps to be calculated


49

References[1] Justin Peatros and Harold Stokes, “Physics of Light and Optics”


50

OPTITOOLS — MODE 2D

51

Mode 2D

The Mode Solver 2D finds the effective refractive index and the modal field of any guided mode in a two-dimensional structure.

Two methods for mode solving are available:• Modes of Planar Waveguides (MPW)• Correlation Function Method (CFM)

For the MPW simulations, you can automatically scan modal solutions using the Scan Parameters option. Thickness, refractive index of layers, and other parameters can be scanned individually or in combinations defined using a programmable spreadsheet.

Using the solvers, you may find effective refractive indices that are needed to convert a 3D problem to a 2D problem by the Effective Index Method.

To open the 2D Mode Solver dialog box, in the OptiBPM Utilities dialog box, click Mode 2D (see Figure 31).

Figure 31 2D Mode Solver dialog box


52

To open the New dialog box, from the File menu, select New (see Figure 32).

Select one of the mode solving options:• Modes of Planar Waveguides• Correlation Function Method (CFM)• User Defined File (CFM)

Figure 32 New dialog box


53

Modes of Planar WaveguidesThe Modes of Planar Waveguides option allows you to configure the two-dimensional structure of planar waveguides (see Figure 33).

Figure 33 2D Mode Solver

You design the 2D structure by adding layers, in which we assume real refractive indices. There is no limitation on the number of layers you can add. You can also enter parameters for the cladding and substrate (see Figure 34).

Figure 34 Layers between the cladding and the substrate


54

The Modes of Planar Waveguides main menu bar contains menus that are available in the Modes of Planar Waveguides dialog box (see Figure 35).

Figure 35 Main menu bar

File menu

Edit menu

File menu item Toolbar button

Description

New (Ctrl+N)

Opens the New dialog box. Create a new 2D Mode Solver file:• Modes of Planar Waveguides• Correlation Function Method (CFM)• User DefinedFile

Open (Ctrl+O)Opens the Open dialog box. Select an existing 2D Mode Solver *.m2d file.

Close — Closes the active file.

Save (Ctrl+S) Saves the active file under the current name in the default location.

Save As — Saves the current project with a different name and in a location that you select.

Recent file — Lists the most recent files that you worked on.

Exit — Closes the 2D Mode Solver dialog box.

Edit menu item Toolbar button

Description

Undo (Ctrl+Z) — Allows you to undo the last change made in the file. You can undo all actions until the last saved operation.

Cut (Ctrl+X) Removes all selected items and places them on the clipboard.

Copy (Ctrl+C) Allows you to copy selected items to the clipboard. The selected items remain in the active file.

Paste (Ctrl+V) Copies devices from the clipboard and pastes them in a user-defined location.

Delete — Allows you to delete all selected items.


55

View menu

Simulation menu

For more information on the Simulation functions, see “Simulation functions” on page 56.

Window menu

View menu item Toolbar button

Description

Toolbar — Select to display the main Toolbar.

Status Bar — Select to display the Status Bar.

Simulation menu item

Toolbar button

Description

Global Parameters — Set up data for the mode solver.

Edit Parameters — Add new parameters or change values of existing parameters.

Scan Parameters — Define how to automatically repeat simulations in a loop-like manner.

Output Data Files — If you use the loop-like simulations from the Scan Parameters option, the resulting output files are additionally numbered according to the loop iteration numbers.

Calculate — Run the 2D Mode Solver to find modes.


Description

New Window — If this function is selected, a duplicate window will be reproduced.

Cascade — Arranges all open windows in a cascading format.

Tile — Arranges all open windows in a tile format.

Arrange Icons — Arranges the icons of windows you have minimized, neatly at the bottom left of the window.

Open files — List of all files that are currently open.


56

Simulation functionsThis section describes the following functions that are available from the Simulation menu:• Global parameters• Edit Parameters• Scan Parameters• Output Data Files• Calculate

Global parametersEnables you to set up data for the mode solver. To open the Global Parameters dialog box, from the Simulation menu, select Global Parameters (see Figure 36).

Figure 36 Global Parameters dialog box

General

Wavelength [µm]: enter the vacuum wavelength

Wafer Thickness: Reference display—the wafer thickness is determined by the substrate, layers, and cladding.

Number of points in mesh: number of points in the mesh

Polarization

TE: Transverse electric (TE) polarization

TM: Transverse magnetic (TM) polarization


57

Edit ParametersEnables you to add new parameters or change values of existing parameters. To open the Edit Parameters dialog box, from the Simulation menu, select Edit Parameters (see Figure 37).

Figure 37 Edit Parameters dialog box

Parameter

Name: Name for the variable—must be unique

Value: Value assigned to the parameter name

The existing parameters are displayed on the list. To edit a parameter and assign a new value to it, click Add/Apply. To add a new parameter to the list, enter its name and value and click Add/Apply. Click Clear All to remove all parameters.


58

Scan Parameters Enables you to define how to automatically repeat simulations in a loop-like manner. Since a number of parameters can be changed simultaneously in each loop iteration, these parameters are called scan parameters.

To open the Scan Parameters dialog box, from the Simulation menu, select Scan Parameters (see Figure 38).

Figure 38 Scan Parameters dialog box

Which parameters can be scanned?As scan parameters, you can use any of the symbolic parameters from the list of symbolic parameters. The list may contain parameters that are not directly related to waveguides and the design parameters (for example, the wavelength, waveguide refractive index, and start and end waveguide width). Among the design parameters, there is a group of parameters that can be used for scanning. The scannable parameters are marked by a star symbol on the data entry dialog boxes. For example, in the Global Data dialog box, the Wavelength data entry is marked by the star symbol. Assume that you do not have a parameter Lambda on your list of variables. If you type Lambda as the Global Data entry, instead of providing a number, the program prompts you to accept Lambda as a new parameter that can vary and adds its name and value to the list of symbolic parameters. All existing scannable parameters are listed as unassigned parameters in the Scan Parameters dialog box.


59

The Scan Parameters dialog box consists of two main sections: in the upper section, you configure the iterations; in the lower section, you work with a spreadsheet for establishing what values of the parameters are used in each iteration.

Unassigned Parameters

Lists the parameters that can be used for the scan calculations.

Number of iterations

Displays the number of iterations in the loop. The iteration number defines the number of spreadsheet rows.

Ask for end values: when enabled, prompts for end values of scanned parameters in the spreadsheet.

Scanned parameters

Allows you to add a parameter from the Unassigned Parameters list or remove parameter column from the spreadsheet. Adding a parameter creates a corresponding column in the spreadsheet.

Leading parameter

Allows you to assign a leading parameter among the scanned parameters that will be displayed in the Report dialog box during the simulations.

In Between

Fills in blank rows between selected start and end rows by using a linear, logarithm, or (1-log) function. The start and end rows must not be blank.

Copy

Copies a first value from spreadsheet selection to the entire selection.

Delete

Deletes a selection.

Fill Down

Fills down the column linearly using the linear step taken from first two values.

Expressions

Recalc: recalculates mathematical expressions used in the spreadsheet. For example, you can simultaneously change the wavelength, width, or refractive index of a waveguide. The resulting data will be identified by the corresponding iteration number. You designate a parameter as the leading parameter. The resulting data will be identified by the iterated values of that leading parameter. The Recalc option is useful for the displaying of results.


60

Output Data FilesThe simulation output data is saved in selected files in the Output Data Files dialog box. If you use the loop-like simulations from the Scan Parameters option, the resulting output files are additionally numbered according to the loop iteration numbers.

To open the Output Data Files dialog box, from the Simulation menu, select Output Data Files (see Figure 39).

Figure 39 Output Data Files dialog box

Modal Fields check box

Modal fields are numbered by the loop number and by the mode order.

Start Mode: first mode to store

End Mode: last mode to store

Output Data file name

Name of the Output Data file.

Modal Indices:

Select to store modal indices.

Modal Indices Data file name:

Name of the Output Data file.

Log File:

Select to generate log files.

Log file name: name of the Log file.


61

Auto Generate File Names

Select this check box to automatically generate the file names. For modal fields, the file names will be of the form Mode2d1_M2D_XX_Mode_XXX.f2d where XX is the iteration and XXX is the mode number. The modal indices will have the form Mode2D1_m2d.mi. For the log file, the automatic file name will be Mode2D1_M2D.log.

CalculateRun the mode solver to find modes. To open the Global Parameters dialog box and run the simulation, from the Simulation menu, select Calculate (see Figure 40).

Figure 40 Global Parameters dialog box—Calculate

General

Wavelength [µm]: enter the vacuum wavelength

Wafer Thickness: reference display—the wafer thickness is determined by the substrate, layers and cladding.

Number of points in mesh: number of points in the mesh

Polarization


TM: Transverse magnetic (TM) polarization

Run

Runs the mode solver.

As the calculation runs, the Modes Found dialog box opens and displays a list of the found modes (see Figure 41).


62

Figure 41 Modes Found dialog box

Figure 42 2D Mode Solver (PLW)


63

Modes of Planar Waveguides—other functionsThis section describes other functions available in the Modes of Planar Waveguides dialog box.

Layers

The layers are listed in order. Layers are numbered from 0 to n, from bottom to top. The Layer list allows for the multiple selection of layers (hold down SHIFT or CTRL key as you select layers). You can also draw a marquee box around desired items to select them. Any changes made to the layer properties will be registered after clicking Apply.

Layer data

These variables are common to all selected elements in the list:

Thickness: Thickness of the selected layer(s).

Refractive Index: Refractive index of the selected layer(s). The index is a real number.

Apply Thickness

Click to apply thickness changes made to the selected layer(s).

Apply Index

Click to apply refractive index changes made to the selected layer(s).

Apply

Click to apply thickness and refractive index changes made to the selected layer(s).

Note: You must click Apply for the changes to take effect. If you click OK without clicking Apply first, the changes will not be saved.

Remove

Removes the selected layer(s).

Add

Adds the selected layer(s).

Cladding

You can add a cladding on top of the device:

Thickness: Enter the cladding thickness in microns. The thickness is perpendicular to the propagation direction along the Y axis.

Refractive Index: Enter the cladding refractive index. The index is a real number.

Substrate

You design a device on a substrate:


64

Thickness: Enter the substrate thickness.

Refractive Index: Enter the substrate refractive index. The index is a real number.

Correlation Function Method (CFM)To open the Correlation Function Method dialog box, in the New dialog box (see Figure 43), select Correlation Function Method (CFM) and click OK (see Figure 44).

Figure 43 New dialog box—Correlation Function Method (CFM)

Figure 44 2D Mode Solver—Correlation Function Method dialog box


65

The Correlation Function Method main menu bar contains menus that are available in the Correlation Function Method dialog box (see Figure 45).


File menu

Edit menu


Description

New (Ctrl+N)

Opens the New dialog box. Create a new 2D Mode Solver file:• Modes of Planar Waveguides• Correlation Function Method (CFM)• User Defined File








Description




Paste (Ctrl+V) Copies devices from the clipboard and pastes them in a user-defined location.


66

View menu

Simulation menu

For more information on the Simulation functions, see “Simulation functions” on page 67.

Window menu


Description




Toolbar button

Description


Edit Parameters — Add new parameters or change values of existing parameters.



Description



Tile — Arranges all open windows in a tile format.

Arrange Icons — Arranges the icons of windows you have minimized, neatly at the bottom left of the window.

Open files — List of all files that are currently open.


67

Simulation functionsThis section describes the following functions that are available from the Simulation menu:• Global parameters• Edit Parameters• Calculate

Global ParametersEnables you to set up data for the mode solver. To open the Global Data dialog box, from the Simulation menu, select Global Parameters (see Figure 46).

Figure 46 Global Data dialog box

In the Global Data dialog box, you to configure the Correlation Function Method simulations. The solver needs to propagate a starting field to find waveguide modes. Depending on the starting field, you can excite different modes. For a complete solution, the solver runs the propagation twice – first time to find modal propagation constants, and the second time to calculate modal fields. You set up parameters for the BPM propagation and for the correlation function calculations.


68

Starting Field

The starting field is the field distribution at the start of propagation. There are four choices of the starting field amplitude:

Gaussian: Initializes a Gaussian starting field and allows you to select the distribution parameters.

File: Initializes a field from a user file in the *.f2d format.

Polarization

Two field polarization options are possible:


TM: Transverse magnetic (TM) polarization.

The field polarization is properly taken into account in the treatment of the dielectric interfaces in BPM2D algorithms.

BPM Solver

There are three solver options:

Paraxial: Paraxial solver

Padé (1,1): Wide-angle solver based on the Padé (1,1) approximant


The simplest and fastest solver is based on the paraxial method. The results are accurate for propagation cone angles not exceeding 15-20 degrees. The wide-angle solvers are more precise than the paraxial solver for layer angles but are also more time-consuming. Solvers based on higher Padé approximants also allow for simulations of structures with a larger refractive index contrast.

Boundary conditions

An important problem in waveguide modeling is the treatment of radiation waves since the radiation tends to reflect from the problem boundaries back into the solution region where it causes unwanted interference. A common way to prevent boundary reflection is through the insertion of artificial absorption regions that are close to the boundaries. Unfortunately, this method cannot be implemented in BPM2D because its application is problem-dependent. The absorption method requires an adjustment of the absorption parameters which is not appropriate for a general purpose software. Consequently, the most natural way to escape unwanted reflections from the boundaries is to introduce transparent boundary conditions (TBC) that are not problem-dependent.

BPM2D uses the transparent boundary condition called TBC, which allows the optical field to flow out through the boundaries.


69

Reference index

The reference index is a constant refractive index used as a reference in the BPM2D calculations. There are two options available:

Auto: Average refractive index over the starting index distribution in the transverse mesh. The average index is recommended for general use.

User: Allows you to define your own reference index.

Conformal mapping

You can activate the conformal mapping simulation for finding modes of bend waveguides. We assume the upward direction of the bend radius.

Correlation function

The correlation between the starting field and the propagating field is the basis for determining waveguide modes. Peaks of the correlation function correspond to excited modes:

Nr of points: Must be a power of 2; adjusts the precision of modal indices; more points means better precision.

Nr of steps per point: Number of propagation steps per a correlation function point; adjusts index limits where the solver search looks for modes; more steps expands the searching limits.

Wavelength [µm]

The wavelength button allows you to define the wavelength value used in propagation simulations. The wavelength value is assumed to be the vacuum wavelength.

Number of Points in Mesh

The simulation results could be very sensitive to the number of mesh points. In general, the usage of more mesh points results in better precision. In the simulation of multimode waveguides, it is suggested that you use at least several points per eigenmode. For example, for a ten-mode waveguide, the number of points within the waveguide boundaries should be twenty or more. The minimum number of mesh points is 19. The maximum number of mesh points is not limited in BPM2D and depends solely on the computer memory available. However, too large a number of mesh points may lead to long computations and round-off errors.

Nr of Displays

This is the number of layout cross-sections that are displayed and saved to output data files. The Number of Displays parameter is usually much less than the number of propagation steps. While the propagation step is a numerical parameter, the number of displays is not and does not affect the simulation accuracy. The number of displays is limited by how many display points your computer can handle in the memory. Usually, 50 displays is sufficient for simple devices.


70

Propagation Step

The options in the Propagation Step section allow you to define the number of propagation steps and to do calculations. The program suggests the step size that results in good precision. However, the numerical method used in BPM2D is unconditionally stable, and you can enter a step size larger than the suggested one. The suggested value is usually smaller than the precision-safe value.

The propagation step can have different values in different layout regions. This is possible to be done using Calculation Zones, where you define custom calculation parameters.


71

Edit ParametersEnables you to add new parameters or change values of existing parameters. To open the Edit Parameters dialog box, from the Simulation menu, select Edit Parameters (see Figure 47).


Parameter

Name: Name for the variable—must be unique.

Value: Value assigned to the parameter name.

The existing parameters are displayed on the list. To edit a parameter and assign a new value to it, click Add/Apply. To add a new parameter to the list, enter its name and value and click Add/Apply. Click Clear All to remove all parameters.


72

CalculateTo open the Global Data dialog box and run the Mode 2D calculations, from the Simulation menu, select Calculate (see Figure 48).

Figure 48 Global Data dialog box—Calculate


73

Starting Field

The starting field is the field distribution at the start of propagation. There are four choices of the starting field amplitude:

Gaussian: Initializes a Gaussian starting field and allows you to select the distribution parameters.

File: Initializes a field from a user file in the *.f2d format.

Polarization

Two field polarization options are possible:


TM: Transverse magnetic (TM) polarization.

The field polarization is properly taken into account in the treatment of the dielectric interfaces in BPM2D algorithms.

BPM Solver

There are three solver options:

Paraxial: Paraxial solver



The simplest and fastest solver is based on the paraxial method. The results are accurate for propagation cone angles not exceeding 15-20 degrees. The wide-angle solvers are more precise than the paraxial solver for layer angles but are also more time-consuming. Solvers based on higher Padé approximants also allow for simulations of structures with a larger refractive index contrast.

Boundary conditions

There are two options available:

Simple TBC: Recommended for most cases

Full TBC: Recommended for very irregular boundary fields

An important problem in waveguide modeling is the treatment of radiation waves since the radiation tends to reflect from the problem boundaries back into the solution region where it causes unwanted interference. A common way to prevent boundary reflection is through the insertion of artificial absorption regions that are close to the boundaries. Unfortunately, this method cannot be implemented in BPM2D because its application is problem-dependent. The absorption method requires an adjustment of the absorption parameters which is not appropriate for a general purpose software. Consequently, the most natural way to escape unwanted reflections from the boundaries is to introduce transparent boundary conditions (TBC) that are not problem-dependent. Recent publications indicate important advantages of the TBC [4].


74

BPM2D uses the transparent boundary condition called TBC, which allows the optical field to flow out through the boundaries.

Reference index

The reference index is a constant refractive index used as a reference in the BPM2D calculations. There are two options available:

Auto: Average refractive index over the starting index distribution in the transverse mesh. The average index is recommended for general use.

User: Allows you to define your own reference index.

Conformal mapping

You can activate the conformal mapping simulation for finding modes of bend waveguides. We assume the upward direction of the bend radius.

Correlation function

The correlation between the starting field and the propagating field is the basis for determining waveguide modes. Peaks of the correlation function correspond to excited modes:

Nr of points: Must be a power of 2; adjusts the precision of modal indices; more points means better precision.

Nr of steps per point: Number of propagation steps per a correlation function point; adjusts index limits where the solver search looks for modes; more steps expands the searching limits.

Wavelength [µm]

The wavelength button allows you to define the wavelength value used in propagation simulations. The wavelength value is assumed to be the vacuum wavelength.


The simulation results could be very sensitive to the number of mesh points. In general, the usage of more mesh points results in better precision. In the simulation of multimode waveguides, it is suggested that you use at least several points per eigenmode. For example, for a ten-mode waveguide, the number of points within the waveguide boundaries should be twenty or more. The minimum number of mesh points is 19. The maximum number of mesh points is not limited in BPM2D and depends solely on the computer memory available. However, too large a number of mesh points may lead to long computations and round-off errors.

Nr of Displays

This is the number of layout cross-sections that are displayed and saved to output data files. The Number of Displays parameter is usually much less than the number of propagation steps. While the propagation step is a numerical parameter, the number of displays is not and does not affect the simulation accuracy. The number of displays is limited by how many display points your computer can handle in the memory. Usually, 50 displays is sufficient for simple devices.


75

Propagation Step

The options in the Propagation Step section allow you to define the number of propagation steps and to do calculations. The program suggests the step size that results in good precision. However, the numerical method used in BPM2D is unconditionally stable, and you can enter a step size larger than the suggested one. The suggested value is usually smaller than the precision-safe value.

The propagation step can have different values in different layout regions. This is possible to be done using Calculation Zones, where you define custom calculation parameters.

Run

Click Run to start the calculation.


76

User Defined FileTo open the User Defined File dialog box, in the New dialog box (see Figure 43), select User Defined File (CFM) and click OK (see Figure 44).

Figure 49 New dialog box—User Defined File

Figure 50 2D Mode Solver [Mode2D2]


77

The User Defined File main menu bar contains menus that are available in the User Defined File dialog box (see Figure 51).


File menu


Description

New (Ctrl+N)

Opens the New dialog box. Create a new 2D Mode Solver file:• Modes of Planar Waveguides• Correlation Function Method (CFM)• User Defined File








78

Edit menu

View menu

Simulation menu

Window menu


Description




Paste (Ctrl+V)Copies devices from the clipboard and pastes them in a user-defined location.


Description




Toolbar button

Description




Description




79

User Defined File dialog box

Refractive Index file

Data file with 2D refractive index distribution.

Browse

Click Browse to open the Browse dialog box and select the refractive index distribution file.

Wafer

Width: Dimension of the wafer.


80

Notes:

OPTITOOLS — USER GUIDE OF VIEW 2D

81

User Guide of View 2D

The Opti 2D Viewer is intended for the display and examination of 2D data cuts. The 2D data are displayed as points in the X-Y plane. It supports files with the following extensions: *.rpd, *.fld, *.rid, *.mon, *.piw, *.poi.

Figure 52 2D Viewer


82

Graphic EnginesThe ActiveX control in Opti 2D Viewer supports three graphic engines:

• DirectX• OpenGL• GDI

Three engines have been provided in order to support a maximum number of hardware-software configurations, and controls are tested to work without problems on all Windows operating systems from Windows 98.

The DirectX and OpenGL engines use standard libraries for hardware accelerated rendering (if supported by your computer configuration). Rendering speeds differ between the engines— DirectX engine is normally the fastest, and GDI the slowest. The GDI graphical engine only uses standard Windows API calls, and all rendering is done within the software.

All three graphic engines are contained in separate DLLs. If they are all installed, it is possible to switch between them while data is displayed. The display configuration is the same for all three.


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User interface featuresThe Opti 2D Viewer offers many useful features. These include:

To open Opti 2D Viewer, from the Start menu, select Programs > Optiwave Software > OptiBPM > Opti 2D Viewer

Feature Description

Large data handling capabilities Opti 2D Viewer is capable of handling millions of points.

Optimized drawing Even with a large number of data points, Opti 2D Viewer is optimized to allow for smooth tracing and panning of graphs

Moveable information windows Moveable information windows allows for place-ment of windows in the most convenient location in the graph window.

Graph Toolbox The popup Graph toolbox allows easier access to the viewing/organizing/editing capabilities of the GraphWave graph tools.


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Figure 53 Viewer -new

Main menu barThe main menu bar contains the menus that are available in Opti 2DViewer. Many of these menu items are also available as buttons on the toolbars.

Figure 54 Main Menu Bar


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ToolbarsYou select the toolbars that you want to have available in the main layout window.

Status barDisplays the number of curves in the active file and the number of curves that have been loaded.


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Windows

Data browserThe Data browser lists all loaded graphs . To select a graph in the Data Browser, click in the selection box next to the graph icon or name in the list. The graph appears in the Opti 2D Viewer window. To remove the view, deselect the check box.

You can also open the Graph properties dialog box for the active graph if you double-click on the graph icon or name in the Data browser.

The Data browser has two states:

Icon view small thumbnails represent the loaded graphs

Report view graph names represent the loaded graphs

Note: The Report view is useful when there is a large number of graphs loaded, or when a graph has a long name that cannot be displayed in the Icon view.

To switch between Report view and Icon view, select or clear the check box in the top right corner of the Data browser dialog box.

To open the Data browser, click the Graph menu button, and select View > Data browser.

To have the Data browser open automatically when you open GraphWave, click Properties to open the GraphWave Properties dialog box, click the General tab, click Windows, and select Data browser. To save this change, click Apply.

Figure 55 Icon view


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Figure 56 Report view

Info windowThe Info window displays measurement data about the tools displayed in the Opti 2D Viewer window . To enable or disable any of the displayed data, double-click on the Info window to open the InfoView Properties dialog box, or select Edit > Graph properties > InfoView tab.

The data displayed in the Info window consists of:

• Current tool position: displays the point where the minimum X-Y plane intersects the cursor with an imaginary line (in 3D mode).

• Axis scaling factor: displays the zoom scale. Default scaling factor is 100%.

• Active tool data: displays the corresponding data in the Opti 2D Viewer window.

Figure 57 Info window


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Edit dataTo view the data points in a graph file, select Edit > Edit Data. The Data Editor dialog box opens. Values can be displayed in scientific notation by selecting the Scientific checkbox. Click Apply to change the Data Editor values in the graph view for the selected data point.

Figure 58 Data editor


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Opti 2D Viewer menus and buttons

File menu

Edit menu


Description

Open (ctrl+O) Opens an existing graph data file. Select the file from the Open dialog box.

Add Opens the Opti 2DViewer dialog box. Add existing graphs to the graph layout.

Export to BPM - Export a file from Opti 2DViewer in *bpm format.

Export to EMF - Export a file from Opti 2DViewer in *emf format.

Print (ctrl+P) Prints the active project.

Recent file - Lists the most recent files that you worked on.

Exit - Closes Opti 2DViewer.


Description

Copy (ctrl-C) Copies selected devices and places them on the clipboard. The selected devices remain in the active file.

Axix Color - Opens the Color dialog box. You can change the axix color in the layout window.

Graph properties

Opens the Graph Wave Properties dialog box. You can change property settings for the graph window.


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Curve menu

View menu

Help menu

Edit menu item

Toolbar button

Description

Set Visible - Hides/displays curve in graph view.

Edit Data Opens Data Editor dialog box that displays curve data.

Save Curve To - Opens the Save As dialog box to save the 2D graph file as a *2dg file.

Properties Opens the Graph Properties dialog box. You can change the settings for the curve in the graph and select curves to display/hide in the graph view.

Edit menu item

Toolbar button

Description

Main Toolbar - Select to hide/display the Main toolbar.

Curves Toolbar - Select to hide/display the Curves toolbar.

Status Toolbar - Select to hide/display the Status toolbar.

Edit menu item

Toolbar button

Description

Help Topic - Opens Help dialog box for Opti 2D Viewer.

Help Index - Opens Help dialog box with Index listing for Opti 2D Viewer.

About Select to open the About Opti 2D Viewer dialog box. Displays version number, modules, copyright information, and contact information.


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Opti 2D Viewer Graph toolbox

Opti 2D Viwer Graph toolboxTools can be separated into three groups:

Positioning tools: Select, Pan, and Zoom

Measurement tools: Tracer, Difference Tracer

Marker tools: Label, Marker, and Region

To access the Graph toolbox, right-click in the graph view. Most graph editing/viewing/organizing capabilities are accessible using the toolbox.

Figure 59 Graph toolbox - without graphs loaded

Figure 60 Graph toolbox - with graphs loaded

To access the Graph toolbox, right-click inside the Opti 2D Viewer graph window.

Note: If there are no graphs loaded, several items are disabled.

The first two rows in the Graph toolbox are tools used for precise data examination. The third row contains items for showing or hiding grid and mesh, and for displaying/hiding the Info window and Data browser window.

To enter specifications for a Label, Marker, Tracer, Difference Tracer, or Region before creating them in the Opti 2D Viewer window, press Ctrl and click on the tool. The properties dialog box for the tool appears, where you can change the specifications.

Note: To close the properties dialog box without making the changes, click Cancel.

To select labels, markers, regions and axes in the current graph view:

• use the Select tool and click on the item in the graph view, or;


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• use the Select tool, click on an item in the graph view and press the Tab key to scroll through other items. If no object is selected, the X-axis is highlighted.

When an object in the graph view is selected, it is highlighted in the color specified in the properties dialog box of the object.

To delete an object from the current graph view, select the object and press Del.

Graph tools

Tool Toolbar button

Description

Select Allows you to manipulate and move most of the objects on the graph.

Note: To edit the properties of an object, double click the object in the graph view.

Pan Allows you to pan from side to side in the graph display to see parts of the graph that may not be visible at the existing Zoom level or resolution.

To pan, click to grab the display, and move the cursor from side to side.

Extra Features:

• If you press Ctrl while panning the graph display, accelerated pan is engaged, which makes the pan much faster. This feature is useful when you work under a high zoom factor.

Zoom Zoom in: You can select a rectangular region or click the graph view for a proportional zoom in.

Extra Features:

Zoom out: Hold Ctrl and click to perform a zoom out.

Reset Zoom Level: Double click in the graph view to return to the defaul Zoom level.

Label Allows you to place customized labels in the active graph view.

Marker Allows you to place markers in the active graph view. The markers can be horizontal, vertical or both. The position of the markers is displayed in the Info Window.


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Tracer Allows you to select a curve and trace over it while viewing the exact positional values on the curve in the Info Window. To select a differenct curve, double click in the graph view.

Extra Features:

• You can freeze the tracer by pressing Ctrl. click to place a marker on the curve at that position.

• Press Shift and drag the cursor to put the tracer itno a high-resolution trace that iterates through each element in the source data array. This allows fora very detailed scan of the data and to find peaks that the standard trace may omit.

Trace Allows you to select a curve and trace over it while viewing the exact positional values on the curve in the Info-Window. The Difference Tracer differs from the Tracer tool because it allows you to create a second tracer to compare values on either the same curve or on different curves. To select the next curve, double click on the curve in the graph view.

Extra features:

• By pressing the Ctrl key, the tracer will freeze in its present position. Then by pressing the left mouse button a marker will be placed on that position on the curve.

• By pressing the Shift key, and dragging the mouse, the tracer jumps into a high-resolution trace that iterates through each element in the source data array. This allows for a very detailed scan of the data and to find peaks that the standard trace may omit.

Region Allows you to select a horizontl, vertical or rectangular region in the active graph view. The coordinates of the selection are displayed in the Info-Window.

Grid Displays/hides the grid lines within the active graph view.

Mesh Activates the Mesh tool within the active graph view.

Info Displays/hides the Info-Window within the active graph view.

Browse Displays/hides the Data browser within the active graph view.

Tool Toolbar button

Description


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Print and Export files

PrintOpens the Print dialog box and allows you to print an image of the active graph view.

Figure 61 Print dialog box


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Export to EMF fileExports an image of the active graph view to a file in .emf format using the Save As dialog box.

Figure 62 Print to EMF file


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Export to BMP fileExports an image of the active graph view to a file in .bmp format using the Save As dialog box.

Figure 63 Print to BMP file

CopyCopies an image of the active graph view to the clipboard.


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Mode 3D

File menu


Description

New (Ctrl+N)Opens the New dialog box. Create a new 3D Mode Solver file:• Channel Waveguides Profile Designer• User Defined File

Open (Ctrl+O) Opens the Open dialog box. Select an existing 3D Mode Solver *.m3d file.


Save (Ctrl+S)Saves the active file under the current name in the default location.


Print — Prints the active project. Define printing options by using the Print Setup command.

Print Preview — Generates a print preview of the active project.

Print Setup — Allows you to define the printer, set page size and orientation, and other print options.



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Edit menu

View menu


Description

Undo Allows you to undo the last change made in the file. You can undo all actions until the last saved operation.

Redo Cancels the last undo operation. Use the Redo command immediately after the Undo command.

Cut (Ctrl+X)Removes all selected components and places them on the clipboard.

Delete — Deletes all the selected components in the project layout.

Copy (Ctrl+C) Allows you to copy selected components to the clipboard. The selected components remain in the active file.

Paste (Ctrl+V) Copies components from the clipboard and pastes them in a user-defined location.

Duplicate — Duplicates the selected component in the project layout.

Select All — Selects all components in the active project layout.

Properties — Displays the properties dialog box for the selected component in the project layout.


Description

Select Activates the Select tool when the Zoom In/Out tool is disabled. Enabled by default.

Zoom

Activates the Zoom In/Out tool. Allows you to increase or decrease the magnification of the current layout view. To zoom in, click in the area you wish to magnify, and to zoom out, click the right mouse button in the area you want to reduce in size. You can also zoom in on a specific area of a component by selecting the area with the mouse (click and drag to make the selection).

Restore Zoom Cancels the last Zoom command.

Grid — Displays/hides the grid in the layout.

Device Info — Displays/hides the component information window.


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Toolbars

Toggles the display of the following toolbars:

Main toolbar

View Tools toolbar

Profile toolbar

Transformations toolbar

Mirror toolbar

Object Level toolbar

Draw Options toolbar

Status Bar — Displays/hides the Status Bar. When the Status Bar is displayed, there is a check mark next to the Status Bar command in the View menu.

Set Toolbars Default

— Applies default toolbar screen arrangement.

Refresh Window — Refreshes the screen display.


Description


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Operations menu

Simulation menu

Operations menu item

Toolbar button

Description

Move Selection Opens the Move dialog box. Allows you to move selected component(s) to another position in the layout.

Mirror Horizontally to Left

Generates a left-mirrored version of the selected component(s).

Mirror Horizontally to Right

Generates a right-mirrored version of the selected component(s).

Flip Horizontally Flips the selected component(s) symmetrically along the horizontal axis.

Flip Vertically Flips the selected component(s) symmetrically along the vertical axis.

Move to FrontRearranges the stacking order by moving the selected object to the front of the screen. The top-most object will mask the area underneath if it overlaps with other objects in your device. This means that the Refractive Index used by BPM 2D for calculation is that of the top-most element.

Move to BackRearranges the stacking order by moving the selected object to the back of the screen. Areas of the object overlapped by other objects will be masked out. This means that the Refractive Index used by BPM 3D for calculation is that of the top-most element.

Move Forward Rearranges the drawing order by moving the selected component(s) one position upward.

Move Backward Rearranges the drawing order by moving the selected component(s) one position backward.

View Layers — Allows you to manage the properties of layers in your project. For each layer, you can change its name, thickness, and refractive index.

Wafer Data — Allows you to modify the thickness and refractive index of the substrate and the cladding, as well as the length and width of the wafer.


Toolbar button

Description

Global Data ADI Method

Allows you to configure Alternating Direction Implicit (ADI) method simulations by specifying polarization, boundary conditions, the complex acceleration parameter, maximum error, and other parameters.

Global Data CFM Method

Allows you to configure Correlation Function Method (CFM) simulations by specifying the starting field, polarization, reference refractive index, and other parameters concerning BPM propagation and run time data display.

Edit Parameters Allows you to add new design parameters, change the values of existing parameters, and delete parameters.


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Draw Tool menu

Preferences menu

Layout Options layout command

The Layout Options layout command allows you to control settings of the layout such as the grid, layout axes, and display ratio.

This command can be accessed from:

· Preferences menu

Waveguide Colors layout command

The Waveguide Colors layout command allows you to control the colors of waveguide frame, path line, and fill.

Scan ParametersAllows you to define how to repeat automatically simulations in a loop-like manner. Because a number of parameters can be changed simultaneously in each loop iteration, these parameters are called scan parameters.

Calculate ADI Allows you to launch the Alternating Direction Implicit (ADI) method simulations. Before starting the calculations, you can verify the global simulation data.

Calculate CFMAllows you to launch the Correlation Function Method (CFM) simulation. Before starting the calculations, you can verify the global simulation data. The Calculate command also gives you access to the BPM 3D Simulator, a numerical application within Mode Solver 3D.

Draw Tool menu item

Toolbar button

Description

Waveguide Profile Allows you to draw a waveguide profile in the active layout.


Toolbar button

Description

Layout Options


Toolbar button

Description


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· Preferences menu

Snap to Grid layout command

The Snap to Grid layout command activates automatic connection between a newly-drawn waveguide and a nearest grid point. With the command enabled, the start position of the new waveguide is identical with the nearest grid point.


· Preferences menu

· Snap to Grid button

Layout Settings layout dialog box

Auto Scroll layout command

The Auto Scroll layout command activates automatic scrolling of the layout screen while you draw a waveguide beyond the current view area.


· Preferences menu

Device Info layout dialog box

Duplicate on Mirror layout command

The Duplicate on Mirror layout command activates duplication of mirrored object. If the Duplicate On Mirror button is enabled the Mirror command leaves the selected object(s) intact and creates a mirror copy of the object(s) at the new position.


· Preferences menu

· Duplicate on Mirror button

Save Settings Now layout command

The Save Settings Now layout command saves current layout settings to an initialization file right when the command is selected. These data will appear as defaults when you open a new project.


· Preferences menu

Save Settings on Exit layout command

The Save Settings on Exit layout command saves current layout settings to an initialization file upon exiting the layout environment.



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· Preferences menu

Layout Designer Dialog boxes of Mode Solver 3D

Figure 64 New layout dialog box

The New layout dialog box allows you to choose between Channel Waveguides Profile Designer or Refractive Index Distribution File as the new document type.

There are two options to choose from:

· Channel Waveguide Profile Designer

· Refractive Index File

Channel Waveguide Profile Designer

When you select this option, then you must fill the Initial Data layout dialog box.

The multilayer waveguide structure lies in the plane X-Z, Z being the propagation axis. There is no limitation on the number of layers you can add. You enter also parameters for the cladding and substrate. The layers lies between the cladding and the substrate. They are numbered from zero to 'n', from bottom to top.

The Layer list allows for the multiple selection of layers (hold down SHIFT or CTRL key as you select layers). You can also draw a marquee box around desired items to select them. Any changes made to the layer properties will be registered after clicking the Apply button.

You can use the Profile Drawing Tool to design the cross section of your device. The waveguides profile lies in the plane X-Y, Z being the propagation axis. There is no limitation on the number of waveguide profile you can add.

Refractive Index File

When you select this option, then you must supply a user Refractive Index Distribution File to feed the Mode 3D simulator. The file format should follow the *.rid format that is described in the Appendix of the manual. The origin of the axis is located at the center of the index data file as shown on the drawing at the bottom.


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Figure 65 Refractive Index file dialog box

· Refractive Index File - Enter the location and filename of the refractive index distribution data file or click the browse button to locate it.

· Wafer - Used to define the wafer data. It's size is the maximum size of the device.

· Width - enter the wafer width in the transverse mesh direction.

· Thickness - enter the wafer thickness in micron.


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Initial Data layout dialog boxThe Initial Data layout dialog box allows you to enter initial data for drawing and simulation.

Figure 66 Initial Data dialog box

You can change these values later. Data entry boxes that are marked by the star symbol can accept symbolic names. When you enter a symbolic parameter name instead of numeric data, the program looks for known names. If the parameter is not recognized, the program considers it as a new parameter and prompts for its value.

The wafer width is along the discretization mesh in the X direction. Its thickness is along the discretization mesh in the Y direction. The wafer has three elements: substrate, cladding and layers. The layers contain waveguides. All refractive indices can be complex numbers. On the screen you see an XY cross-section of the wafer box. The X-axis is horizontal on the screen and the Y-axis is vertical on the screen.


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Figure 67 Waveguide layers

The default waveguide set up is used in drawing waveguides from the library.

The number of points in mesh determines the discretization in X and Y directions.

The wavelength is the vacuum wavelength of the light signal.

The wafer width is the mesh width in the X direction. The wafer thickness is the mesh size in the Y direction, determined by the total thickness of the substrate, cladding and layers. Initially, you only enter the thickness of substrate and cladding, the layers thickness is determined later and depends on the layers structure.

substrate

Layer 0

Layer 1

Layer 2

cladding

Y

X0


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Waveguide Profile layout dialog boxAn assignment for the waveguide exist across all layers. You can customize the waveguide profile by changing its width and refractive index in selected layers.

Figure 68 Waveguide Profile dialog box

Width - enter the waveguide width for the selected layers. To make changes effective, press Apply Width.

Refractive index - enter the waveguide index for the selected layers. The index is a complex number. To make changes effective, press Apply Index.

Apply - press this to apply width and index changes simultaneously.

Apply to All - press this to apply width and index changes to all layers.

Delete - press this to make a part of the profile non-existent for simulations (make its width=0). For example, in a three-layer structure you can delete the waveguide in the middle layer and keep it in other layers.

Waveguide center coordinate - waveguide position in the X-direction of the mesh (horizontal on the screen).


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Figure 69 Waveguide center coordinates

Device Info layout dialog boxThe Device Info layout dialog box shows an overall view of the Wafer.

Figure 70 Device Info dialog box

You can switch between the three different options of the Device Info window by clicking the appropriate tab.

Default Waveguide

The Default Waveguide tab has entries for the default waveguide width and refractive index. These parameters are common to all layout elements for which the Global option is enabled.

Work Area

It is assumed that the device layout is generated on a base substrate or Wafer. The Wafer can be large enough to accommodate complicated layouts. However, the whole Wafer may be too large to be displayed in one window. If this is the case, then the editing window displays a part of the Wafer which we will refer as the Work Area. The Work Area tab displays information about the work area size and position. The

substrate

Layer 0

Layer 1

Layer 2

cladding

w2, r2

w1, r1

w0, r0


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size is controlled by the zoom value and is adjusted automatically. To change the position, you enter the horizontal and vertical coordinates of the lower left corner of the work area rectangle. The size of Work Area is adjusted automatically by the program. The view area may not cover the whole Work Area. You can use the scrollbars to move the display within the limits of the Work Area. You can use the jump buttons to move the Work Area within the limits of the Wafer.

Device View

Device View tab displays the entire device and allows you to move the work area. The work area is marked by a rectangle. Press and hold the left mouse button to position the rectangle. After dragging the rectangle to the desired position, pressing the Apply button will properly position the work area.

Move Selection layout dialog boxIn the Move Selection layout dialog box, you specify where to move the selected element on the wafer.

Figure 71 Move Selection dialog box

You can change the position of a selected element by using the following buttons:

· To Right--moves a selected element to the wafer right

· To Left--moves a selected element to the wafer left

· Center--moves a selected element to the center

The wafer and selection sizes are provided for your convenience.


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Layers Structure layout dialog boxThe Layers Structure layout dialog box allows you to modify the name, thickness, and refractive index of each layer.

Figure 72 Layers Structure dialog box

The layers' structure is set up upon creation of the new designing file, when you can add layers to form the structure. However, once the structure has been established, you can only modify its selected properties, that is, the refractive index and thickness of layers.

Thickness

The thickness of each layer can vary linearly along the propagation. Therefore, you can enter the start and end thickness separately.

Refractive Index

The layer refractive index is a complex number.

The overall thickness of the wafer is conserved and space above the layers is filled by the cladding material.


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Wafer Data layout dialog boxIn the Wafer Data layout dialog box, you can change wafer specific data.

Figure 73 Wafer Data dialog box

The wafer has three elements: substrate, cladding and layers. In this dialog box, you only enter data concerning the substrate and the cladding.

Thickness

The thickness is along the discretization mesh in the Y direction

Refractive Index

Refractive indices can be complex numbers.

Width

The width is measured horizontally, along the X-axis on the layout screen.


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Initial Data layout dialog boxThe Global Data: ADI Method dialog box displays parameters used in the Alternate Direction Implicit (ADI) simulation method.

Figure 74 Global Data: ADI Method dialog box

Solver

The ADI Solver can be real or complex. The real solver deals with the real refractive indices, while the complex solver deals with the complex indices.

Real: Use this option when you want to find an ideal lossless guided mode. The modal index will be a real number.

Complex: Use this option when you expect the mode will have losses. The loss could result either from lossy materials in the waveguide or from a leaky waveguide.

Waveguide

The waveguide can be assumed to be straight or bent over a radius. If the Bent option is selected, then the solver automatically becomes complex. The conformal mapping method is used to calculate modes for the Bent case.

Straight: Usual mode solving case.

Bent: This option will simulate a bent waveguide by a perturbation in the refractive index profiles.


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Mode

Scalar: The solver works in the simplest scalar mode.

Semi-Vector TE: The solver finds transverse electric modes.

Semi-Vector TM: The solver finds transverse magnetic modes.

Full Vector

For this option, you are able to select the initial excitation field: along the X- or Y- direction.

Initial Excitation

Along X: If the initial field is parallel to the x axis, you can expect to find a quasi-TE mode.

Along Y: If the initial field is parallel to the y axis, you can expect to find a quasi-TM mode this way.


Enter the number of points along X and Y mesh directions.

X: The width of the calculation window will have a mesh with this number of points.

Y: The height of the calculation window will be meshed with number of points.

Wavelength [µm]

Enter the wavelength in microns.

Number of Modes

Maximum number of guided modes to be found.

Run button

Click Run to open the 3D Simulator.


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Settings tab

Figure 75 Global Data: ADI Method dialog box—Settings tab

Starting Field

The starting field is for initial excitation of the waveguide. By default, the Gaussian option is selected. You can modify the Gaussian field by clicking Properties and entering your data in the Gaussian Starting field dialog box. You can select a Gaussian field or supply a user-defined field from file.

Gaussian: In the Gaussian Starting Field, you can set up the Gaussian starting field for the BPM simulation.

The Gaussian field is defined by

where x is the transverse layout coordinate, x0 is the center position, and is the field halfwidth.

File: Use this option if you want to supply your own starting field from a file.

Properties button: Click Properties to open the Gauss Field Parameters dialog box (see Figure 76).

E x( ) x x0–σ

-------------

2–exp=

σ


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Figure 76 Gauss Field Parameters dialog box

Complex Acceleration Parameter (CAP)

This is an important parameter which controls the convergence and duration of the iteration process. The parameter can vary from one iteration step to another. The range of values of is between -2 and -200. If is close to -2, the convergence is fast, but this might affect the stability. If is closer to -200, then the iteration process is very stable, however, the convergence is slow. We have implemented a procedure with two acceleration parameters. This means that at each odd step and at each step . By default and

which ensures a very stable and fast iteration. You can change only the value of if any symptoms of instability appear. It could happen in some cases where a small number of mesh points are chosen in the region with the highest refractive index.

Wafer Data

Wafer Thickness: Total thickness of the wafer in µm (substrate + all layers + cladding). Since it is the sum of multiple entities, this field is Read-only.

Wafer Width: Wafer width. Read-only.

Boundary Condition

The program can use three kind of boundary conditions. The first kind is the homogeneous boundary conditions (Dirichlet), where the dependent variable vanishes on all the boundaries. The second kind is the Neumann boundary conditions, where all the normal derivatives of the dependent variable vanishes on the boundaries. By default, Neumann boundary conditions are applied. The Transparent boundary condition is the third option and is similar to the OptiBPM 3D method.

Homogeneous: Homogeneous boundary conditions.

Neumann: Neumann boundary conditions.

TBC: Transparent Boundary conditions.

Accuracy

Index Tolerance: The solver checks whether the mode index converges slower than this tolerance number.

Field Tolerance: The solver checks a current mode field integral expression.

CAP CAPCAP

CAP W1= CAP W2= W1 200–=W2 2–=

W2


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Enter the number of points along X and Y mesh directions.

X: Number of points in the mesh in X-direction.

Y: Number of points in the mesh in Y-direction.

Wavelength [µm]

Enter the number in microns.

Number of Modes

Maximum number of modes you want to search for.

Gaussian Starting Field layout dialog box

In the Gaussian Starting Field layout dialog box, you set up the Gaussian starting field for the BPM simulation.

The Gaussian field is defined by E(X)=exp[-((X-X0)/S)**2], where X is the transverse layout coordinate, X0 is the center position, and S is the field halfwidth.

Positioning

Choose the automatic or user defined position of the field center X0. The Automatic option puts the field center in the middle of a waveguide that is closest to the mesh center. Only waveguides that are present at Z=0 are considered. The automatic field halfwidth is equal to half of the waveguide width.

Coordinates in Mesh

Enter the center position X0 and the field halfwidth S.

In the Global Data layout dialog box, you configure the numerical simulations.

Global Data: CFM Method layout dialog box In the Global Data dialog box, you can define the following:

· Starting Field

· Polarization

· Boundary Condition

· Reference Index

· Tilt At Start

· Wavelength

· Number Of Points In Mesh

· Mesh Cut Point Number


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· Propagation Step

· Number Of Displays

Starting Field

The starting field is the field distribution at the start of propagation. There are two choices of the starting field amplitude:

· Gaussian--initializes a Gaussian starting field and allows you to select the distribution parameters.

· File--initializes a field from a user file in the *.f2d format.

Reference Refractive Index

The reference index is a constant refractive index used as a reference in the BPM 2D calculations. There are two options available:

· Auto--is an average refractive index over the starting index distribution in the transverse mesh. The average index is recommended for general use.

· User--allows you to define your own reference index.

Conformal mapping

This option is available for correlation function method when only one waveguide is defined.

· Activate - activate the conformal mapping mode.

· Radius - enter the bend radius in microns.

Correlation Function

· Nr of points - defines the number of times the correlation function between the input and propagating field is calculated. The number of points in the correlation function must be a power of two.

· Nr of steps per point - number of propagation steps made for each calculation of the correlation function

Wavelength

Enter the wavelength in microns.

Wafer Thickness

This is only a reference display for choosing discretization. To change the thickness value, select the Wafer Data option from the Wafer menu.

Polarization

Three polarization options are available:

· None (scalar) - use no polarization in simulation.


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· TE - transverse electric polarization.

· TM - transverse magnetic polarization.

Propagation Step

Enter the BPM propagation step size in microns.

Calculate - this option provides an automatic step size.


Enter a number greater than 18. The upper number of mesh points is not limited in BPM_CAD and depends solely on the computer memory available. However, too large a number of mesh points may lead to long computations and round-off errors.

Propagation Step

Enter the BPM propagation step size in microns.

· Calculate - this option provides an automatic step size.

Display and storage

Enter the number of propagation locations used for display in run-time graphics and for storage in output files. The actual number is increased by 1, because the starting location is added.

· Mesh cut point nr - you can select two cross-sections (one in XZ plane, one in the YZ plane) to be displayed when calculations are running.

· Nr of displays - number of displays and stored cross-sections

Note: The Global Data dialog box also opens when you select the Calculate command from the Simulation menu.


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Edit Parameters dialog boxThe Edit Parameters dialog box helps you to manage symbolic variables that can be used in calculations and design.


The symbolic variables are on the list of variables that is kept by the program. You can modify the list of variables by changing their values, adding variables, or deleting variables.

Name

Enter the name of the variable.

Value

Enter the value of the variable.

You can edit an existing variable from the list by clicking it.

Add/Apply

The selected variable is added to the list.

Delete

The selected variable is deleted from the list.

Clear All

Delete all variable from the list.


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Scan Parameters layout dialog boxThe Scan Parameters command opens the Scan Parameters dialog box which allows you to define how to repeat automatically simulations in a loop-like manner. Since in each loop iteration, a number of parameters can be changed simultaneously, these parameters are called scan parameters.

Figure 78 Scan Parameters dialog box

Which parameters can be scanned

As scan parameters, you can use any of the symbolic parameters from the list of symbolic parameters. The list may contain parameters that are not directly related to waveguides and the design parameters (for example, the wavelength, waveguide refractive index, start and end waveguide width etc). Among the design parameters, there is a group of parameters that can be used for scanning. The scanable parameters are marked by a star symbol on the data entry dialog boxes. For example, in the Global Data dialog box, the Wavelength data entry is marked by the star symbol. Assume that you do not have a parameter Lambda on your list of variables. If you type Lambda as the Global Data entry, instead of providing a number, the program prompts you to accept Lambda as a new parameter that can vary and adds its name and value to the list of symbolic parameters. All existing scanable parameters are listed as unassigned parameters in the Scan Parameters dialog box.

The Scan Parameters dialog box consists of two main sections: in the upper section, you configure the iterations; in the lower section, you work with a spreadsheet for establishing what values of the parameters are used in each iteration.


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Unassigned Parameters

Lists the parameters that can be used for the scan calculations.

Number Of Iterations

Displays the number of iterations in the loop. The iteration number defines the number of spreadsheet rows.

Ask For End Values

When enabled, prompts for end values of scanned parameters in the spreadsheet.

Scanned Parameters

Allows you to add a parameter from the Unassigned Parameters list or remove parameter column from the spreadsheet. Adding a parameter creates a corresponding column in the spreadsheet.

Leading Parameter

Allows you to assign a leading parameter among the scanned parameters that will be displayed in the Report dialog box during the simulations.

In Between

Fills in blank rows between selected start and end rows by using a linear, logarithm, or (1-log) function. The start and end rows must not be blank.

Copy

Copies a first value from spreadsheet selection to the entire selection.

Delete

Deletes a selection.

Fill Down

Fills down the column linearly using the linear step taken from first two values.

Recalc

Recalculates mathematical expressions used in the spreadsheet. For example, you can simultaneously change the wavelength, width, or refractive index of a waveguide. The resulting data will be identified by the corresponding iteration number. You designate a parameter as the leading parameter. The resulting data will be identified by the iterated values of that leading parameter. The Recalc option is useful for the displaying of results.


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Layout Settings layout dialog boxThe Layout Options layout dialog box allows you to set parameters of the device layout.

Figure 79 Layout Settings dialog box

The Layout Settings dialog box controls settings affecting the way BPM_CAD displays objects on the screen. The grid and coordinate axes can be displayed with diverse line styles and colors. You can adjust the grid spacing in both directions. The coordinate axes can be shown or hidden. Other options are for layout background (paper) color and the display ratio.

Grid

The grid helps to position layout elements. You customize its type, line style, color, and spacing.

· Type - four options are available: no grid, dot grid, X lines, Z lines, and XZ lines. The X lines are vertical on the screen and the Z lines are horizontal.

· Line style - changes the line style: solid, dash, dot, dash-dot, and dash-dot-dot

· Color - color of the grid

· Print - show the grid in printed output

· Spacing - grid spacing in the Z and X direction. The spacing is measured in units of [0.01um].

Layout axes

The Z-axis is the propagation axis and is horizontal on the screen. The X-axis is the transverse mesh axis and is vertical on the screen. The axes are shown on the layout: the vertical X-axis is on the left-most position of the wafer while the horizontal Z-axis is shown in the center of the wafer.


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· Line width: between 1 and 10 in arbitrary units. The default value is 1.

· Line style - the same options as for the grid line style

· Color - axes color

· Print - show the layout axes in printed output

· Show - show the layout axes

· Background color: color for the wafer background

Display ratio

It is sometimes convenient to display the axes with different scales. Distances involved in BPM simulations are usually long compared to transverse waveguide variations. The program checks whether the user-defined display ratio is not in conflict with the given mesh density. In the case of conflict, the program automatically resizes the grid.

Waveguide Colors layout dialog boxThe Waveguide Colors layout dialog box allows you to customize waveguide colors displayed on screen.

Figure 80 Waveguide Colors dialog box

Frame color

Defines the color of waveguide boundaries.

Path color

Defines the color of the waveguide path line.

Fill color

Defines the waveguide color.

Fill waveguide

Enables or disables the filling of waveguides with the fill color.


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Notes:


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User Guide of View 3D

Commands of View 3D

File menuOpen

The Open command opens an existing data file.


Export Data in View 3D Format

The Export Data in View 3D Format command exports the display data in the View 3D file format.

Export Data in Generic Format

The Export Data in Generic Format command exports the display data in the generic file format that is a three-column text data format.

Print

The Print command prints the screen.


Print Setup

The Print Setup command allows you to define the printer, to set the page size and orientation, and to choose other printing options.

Print Preference

The Print Preferences command allows you to chose graphics options in printing from the screen.

Print to EMF

The Print To EMF command allows you to print the screen to an enhanced metafile (EMF).

Print to BMP

The Print To BMP command allows you to print the screen to a bitmap (BMP) file.

Exit

The Exit command allows you to exit the program. The program prompts for confirmation.


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Edit menuCopy

The Copy command copies the selected graph to the clipboard.


· Edit menu

· Copy button

Properties

The Properties command allows you to define the display of the contour lines, the color gradation, the axes, etc.


· Edit menu

· Right mouse button on the graph

Display Data as Amplitude

The Display Data As Amplitude command displays the propagating signal as field amplitude. This command is not available during simulations.


· Edit menu


Display Data as Intensity

The Display Data As Intensity command displays the propagating signal as Intensity. This command is not available during simulations.


· Edit menu


Display Data as dB

The Display Data As dB command displays the propagating signal in the decibel scale. This command is not available during simulations.


· Edit menu


Restore Defaults


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The Restore Defaults command allows you to restore the default settings of the simulator.


· Edit menu

View menuSingle Quadrant

The Single Quadrant command expands the view of a selected quadrant to the full screen view.


· View menu

· F2 key

View Point

The View Point command allows you to make changes of the point of view of a three dimensional graphics.


· View menu

Toolbars menuThe Toolbars command allows you to toggle the display of the following toolbars:

Main toolbar:

The Main toolbar commands are: Copy, Print, About, and Help.

3D Tools toolbar:

The 3D Tools toolbar commands are: Turn Left, Turn Right, Turn Down, Turn Up, Zoom In, and Zoom Out.

Axes Tools toolbar:


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The toolbar commands are: X-Axis, Y-Axis, and Z-Axis.

Display Tools toolbar:

The Display Tools toolbar commands are: Show Surface, Show Topography, and Show Cube.

Ratio Tools toolbar:

The toolbar commands are: Increase Height, Decrease Height, Increase Depth, and Decrease Depth. The Decrease/Increase commands can only be accessed from the toolbar.

The Toolbars command can be accessed from:

· View menu, after pausing the simulation

Status Bar menuThe Status Bar command toggles the display of the Status Bar.


· View menu, after pausing the simulation

Refresh Window command

Refresh Window refreshes the display window.


· View menu

Change X and Y Cut

The Change X and Y Cut command is for selecting the X and Y cuts for display and export.


· View menu

· XY Cuts Tools toolbar


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Complex Field

The 3D Complex Field command is used to select what part of a complex field is to be displayed.

You may select between the real part, imaginary part, amplitude, or phase of the complex field.


· View menu

3D Tools

Turn Left command: Turns left a 3D display.


· View menu, View Point command

· Turn Left button

Turn Right command: Turns right a 3D display.



· Turn Right button

Turn Down command: Turns down a 3D display.



· Turn Down button

Turn Up command: Turns up a 3D display.


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· Turn Up button

Zoom In and Zoom Out commands: Zoom the selected display.



· Zoom In button and Zoom Out button

Tip: Turning and moving a 3D display using the mouse

You can turn a 3D display by pressing the Ctrl key on the keyboard and simultaneously clicking-and-dragging with the left mouse button.

You can move a 3D display by pressing the Shift key on the keyboard and simultaneously clicking-and dragging with the left mouse button.

For the above mouse-controlled operations, the display turns automatically into a 3D cube. After finishing the operations you can revert to a 3D surface display, or topography display by using the display tools commands.

Display Tools

The Display Tools commands allow you to see 3D data in surface and topographic views, as well as to turn the display into a 3D cube for manipulations.

Show Surface command: displays a 3D surface plot



· Show Surface button:

Show Topography command: displays a 2D, topographic plot of 3D data



· Show Topography button:

Show Cube command: displays a 3D cube contouring 3D data surface



· Show Cube button:

Ratio Tools


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The Ratio Tools commands allow you to manipulate 3D displays by changing the height and depth scales.

Increase Height command: increases the scale of the Z-axis of the display


· Increase Height button

Decrease Height command: decreases the scale of the Z-axis of the display


· Decrease Height button

Increase Depth command: increases the scale of the Y-axis of the display


· Increase Depth button

Decrease Depth command: decreases the scale of the Y-axis of the display


· Decrease Depth button

Note that the X,Y, and Z axes of a 3D display do not correspond to the layout coordinates. For example, the Y-axis is usually the distance coordinate (Z-axis in the layout coordinates).

Settings menuBuffered Drawing

The Buffered Drawing command activates redrawing or modifying of the display during the simulation. When the command is enabled, the program adds only the last step to the graph. When the command is disabled, the program redraws the display at every run. By default, the command is enabled.


· Settings menu

Colors

The Colors command allows you to select colors of the display.


· Settings menu

Palette

The Palette command allows you to choose the color options.


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· Settings menu

X-Axis

The X-Axis command allows you to define settings of the X-axis.


· Settings menu

Y-Axis

The Y-Axis command allows you to define settings of the Y-axis.


· Settings menu

Z-Axis command

The Z-Axis simulator command allows you to define settings of the Z-axis.


· Settings menu

Title

The Title command allows you to define the display title.


· Settings menu

Save Settings Now

The Save Settings Now layout command saves current layout settings to an initialization file right when the command is selected. These data will be used as defaults when you open a new project.


· Settings menu


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Dialog boxes of View 3D

Topography Properties dialog boxThe Topography Properties dialog box is used for selecting topographic display options.

Figure 81 Topography Properties dialog box

Contour Lines Only

Enables the displaying of contours of the graph.

Number of Levels

Enter the number of contour lines between 1 and 99.

Show color gradation

Displays the color scale on the graph.

Show Axes

Displays the graph axes.

The following options are available when the Contour Lines Only option is not checked:

Use Fast Drawing

Disables high resolution drawing for the topographic view.

Use Inverse Color Mapping

Enables the option of using inverted color mapping.


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Surface Properties dialog boxThe Surface Properties dialog box is used for setting options of three dimensional surfaces.

Figure 82 Surface Properties dialog box

Surface Type

One of the following seven types of 3D surfaces can be chosen:

Points - Display only data points.

Wire Frames - Display data points connected by lines.

Hidden Lines - Display data points, connected by lines. Overlapping surface parts are not shown.

Fast Hidden lines - Display as Hidden Lines. Less options are available.

Height Color Coding - Display surface with color-coded height The coding is from minimum to maximum values of the color palette.

Gouraud Shading - Display surface with shading and light source effects. Solid modeling of the surface.

Fast Gouraud Shading - Display as Gouraud shading. Less options are available.

Surface Options

You can display the upper or lower surface.

Topographic Contour Lines


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Options for displaying the contour lines: None, On Top, At Bottom. The contour lines are displayed in addition to the three dimensional graphs.

Display Options

Options for displaying axes and graph lines.

Print Preferences dialog boxThe Print Preferences dialog box allows you to configure the printing of the graphics.

Figure 83 Print Preferences dialog box

Print Background as White

Enables printing of the graphic background. By default, the background is not printed, that is, it is printed as white.

Line Thickness Factor

The line thickness factor can vary between 1 and 20. The default value is 1.

Text Thickness Factor

The outline text thickness factor can vary between 1 and 20. The default value is 2.


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Colors Selection dialog boxThe Colors Selection dialog box enables you to customize the colors of graphics displayed on the screen. Custom colors are available.

Figure 84 Colors Selection dialog box

Press the corresponding button to select the color. The various options for color selection are:

Background

Selects the background color for the quadrant.

Text

Selects the title color of the graph.

Axes

Selects the color for the axes and their captions.

Graph Lines

Selects the color for the graph lines (for surface, topography or cube). Lines colors are displayed only for one of the following surface types: Points, wire frame, fast hidden lines and hidden lines.

Lower Surface

Selects the color of the lower surface of a graph (for surface, topography or cube). This option is available only for one of the following surface types: hidden lines, fast Gouraud shading and Gouraud shading.

E Field

Selects the color of the Electric Field (for 2D cut quadrant).

Neff

Selects the color of the Effective Index (for 2D cut quadrant).


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Palette Selection dialog boxThe Palette Selection dialog box allows you to select a color palette used in the display of graphics. The Palette is used only for the topographic view and in one of the following surface types: height colors coding, fast Gouraud shading and Gouraud shading.

Figure 85 Palette Selection dialog box

Palette Choice

Selects one of the following predefined color palettes: Gray scale, Dark Red, Light Red, Dark Green, Light Green, Dark Blue, Light Blue, Cyan, Yellow, Spectrum, Rainbow, and Custom.

Custom Palette Settings

For defining a custom palette you specify starting and ending RGB colors. The color values are between 0 and 255.

Preview

Enables previewing of the custom palette before applying it.


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X-Axis dialog box

Figure 86 X-Axis dialog box

The X-Axis dialog box displays settings for the range, ticks, labels, and captions of coordinate axes.

Minimum and Maximum Values

Sets the upper and lower limits for the X-axis.

Major and Minor Tics

Displays tick marks at major and minor intervals.

Labels

The number format for axis number labels offers the following options:

· Exponent (example 1.2E02)

· Floating (example 120.00; never displays exponents)

· General (example 120.00; this format differs from Floating for numbers with many digits. In such cases, the General format becomes the Exponent format)


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· Power (example 1.2x102)

Note: The default number format is Floating.

The number of displayed digits is from 1 to 15.

The Orientation option selects the orientation of labels as perpendicular or parallel to the axis.

Captions

Allows the selection of text, orientation, and scale factor.

· Text: Enter the axis title.

· Symbol: Press this button to see the list of available symbols. For introducing symbols into the text, a TEX-like convention is applied.

· Orientation: The caption orientation can be set parallel or perpendicular to the axis.

· Scale Factor: Enter the scale factor for the caption. The factor may vary between 0.1 and 0.4.

Y-Axis dialog boxThe Y-Axis dialog box displays settings for the range, ticks, labels, and captions of coordinate axes.


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Figure 87 Y-axis dialog box


Sets the upper and lower limits for the Y-axis.



Labels









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Captions






Z-Axis dialog boxThe Z-Axis dialog box displays settings for the range, ticks, labels, and captions of coordinate axes.

Figure 88 Z-Axis dialog box


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Sets the upper and lower limits for the Z-axis.



Enable Z Clipping

Enables clipping of those parts of the graph that are out of range in the Z-direction.

Labels









Captions







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Title dialog boxThe Title dialog box allows you to set the title text, position, and scale factor of the graph title.

Figure 89 Title dialog box

Caption

Enter the graph title.

Symbol

Press this button to see the list of available symbols. For introducing symbols into the text, a TEX-like convention is applied.

X Position

Horizontal position of the graph title. The range is between 0 and 1000 in normalized units.

Y Position

Vertical position of the graph title. The range is between 0 and 1000 in normalized units.

Scale Factor

Arbitrary scaling size factor for the graph title. The factor can be from 0.1 to 4. The default value is 1.


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View Point dialog boxThe View Point dialog box allows you to set the angles, distance, zoom, and ratio values in 3D viewing.

Figure 90 View Point dialog box

Camera Settings

The camera position is the position of the observer. It is assumed that the camera position is determined in spherical coordinates, where you supply two angles and a radius to calculate its position.

Theta

Angle measured from the x-z plane of the graph. It varies from 0 to 360 degrees.

Phi

Angle measured from the x-y plane of the graph. It varies from -90 to 90 degrees.

Rho

Distance measured from the origin of the graph. It varies from 0 to 60 in arbitrary units.

Zoom

The zoom factor in camera settings ranges from 0.1 to 8 in arbitrary units.

Ratio

You can change the height ratio and the depth ratio of the display. Both ratio values are referred to a non-deformed graph.

Height Ratio


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Ratio of the vertical axis to the horizontal axes. Enter a value between 0.1 and 3.0.

Depth Ratio

Ratio of the Z-axis to the other axes. Enter a value between 0.1 and 3.0.

X Cut and Y Cut dialog boxThe X Cut and Y Cut dialog box is used to control the cuts of a selected 3D display.

Figure 91 X Cut and Y Cut dialog box

You can select a cross-section of the three-dimensional graph to be displayed in two dimensions. An X-cut refers to two-dimensional slices that are perpendicular to the x-axis. A Y-cut refers to two-dimensional slices that are perpendicular to the y-axis.

Type of List

Select X- or Y-cut data for listing in the dialog box. You can scroll the list and select the cut position.

Export selection

Save selected cut data to a file. The exported file is automatically named including the mesh number position. For example, an X-cut at the Xmin position is numbered 0, next x-position is numbered 1, etc. The same number naming extension rule applies to Y-cuts.


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Notes:

OPTITOOLS — CODE V CONVERTER

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Code V Converter

OptiBPM is a software for waveguide optics, and is optimized for analysis of structures that are of size (in the transverse plane) comparable to an optical wavelength. Although it is theoretically possible to analyze free space or bulk optical components such as lenses and mirrors by the solution of Maxwell's equations, generally it is more practical to make use of approximations commonly used in ray optics. Optiwave does not supply ray optics software, but OptiBPM Tools has a utility to convert the data of another software, Code V ™ of Optical Research Associates. In Code V, you can analyze bulk optics such as mirrors and lenses using ray tracing techniques. If at some part of the system, the rays converge to a focus and the light enters an optical waveguide, Code V can be used together with OptiBPM to analyze the whole system. Code V can use ray tracing to determine the optical field distribution at the focal point, and the information can be sent to a file. The Code V Converter Utility in OptiBPM Tools can be used to convert the output file from Code V to another format that OptiBPM can read as input to the beginning of a waveguide. OptiBPM can analyze the subsequent waveguide part of the system, and estimate the coupling loss on input. If the light needs to leave the waveguide and reenter a lens system, the Code V converter can convert the output near-field-pattern to a form that Code V can accept as input to a ray tracing problem.

You can access the Code V converter by clicking Tools > Code V Converter (see Figure 92).

Figure 92 Code V Converter dialog box


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Conversion

CODE V ==> OptiBPM: specifies conversion from CODE V format to OptiBPM.

OptiBPM ==> CODE V: specifies conversion from OptiBPM format to CODE V.

Note: Code V keeps wavelength information, but OptiBPM does not. Therefore, on converting from OptiBPM to Code V it is necessary to supply this information in the enabled Wavelength field.

Wavelength (nm): wavelength parameter stored in the CODE V file.

Input File: (CODE V format expected): displays the name of input file. Click Browse to load a file from a folder.

Output file: displays the name of the output file. Click Browse to load a file from a folder.

Progress bar: displays the percentage of operation completed.

Convert: click to start file conversion.

Help: click to open on-line help.

Close: click to close the dialog box.

After you enter the filenames that hold the input and output data, click Convert. If the conversion is successful, the message shown in appears.

Figure 93 Successful conversion dialog box


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Data formatThe data format for the OptiBPM compatible file is the standard Optiwave .f3d file format (see “Data file formats” on page 181 for file definitions).

The information from Code V is contained in a text file with the default file extension .dat. Any line starting with an exclamation (!) is a comment.

Note: The file may start with any number of comments.

The next several lines contain information about the data. Each of these lines begins with a label describing the information on the line. The label ends with a colon (:). The information pertaining to the label follows the colon. White space (at least two spaces) will appear between the colon and the following data item and between the data items on the line. These may appear in any order. It is assumed that the first row that is not a comment (starts with a !) or a label (contains a colon) is the first row of data.

The labels found in Table 1 are currently defined.

Table 1 Data formats - Defined labels

Datatype may be Complex or Real.

Units are specified as two-character mnemonics, as shown in the following table:

Coordinates are the (x,y,z) coordinates of the center of the grid with respect to a reference surface. The direction is the set of direction cosines (l,m,n) defining the direction of the beam with respect to the reference surface. Both of these are optional and would normally be (0,0,0) and (0,0,1).

Label Definition

Datatype Type of data

Wavelength Wavelength units

Grid spacing x-spacing, y-spacing units

Array size x-size, y-size

Coordinates x, y, z units

Direction l m n

nm nanometers

mm millimeters

cm centimeters

in inches


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An example illustrating the file format of Code V output is shown in Table 2.

Table 2 Code V optical field distribution.

The optical field data follows the header information. All the optical field data is assumed to lie on a regular grid specified by the grid spacing and grid size. Many of the calculations in CODE V assume that the grid is square and the grid size is a power of 2 (for example, 32, 64, 128,). However, this is not universal, so both the X and Y grid spacings and sizes are specified. All of the data is in a spreadsheet type of format and may be space delimited (single space) or tab delimited (it is designed to be imported/exported into Microsoft Excel). Therefore, all the values for a single row must be on the same line. The data may be in integer, fixed-decimal, or floating-point format.

In the example shown in Table 2, the first line is a comment. The second line specifies that this is real data (e.g., field intensity), so there is one value per grid point. The third line gives the wavelength and the units. The example in Table 2 uses nanometers for the units, but other units may be used as long as they are specified. The fourth line gives the X and Y grid spacings and the units. The fifth line gives the X and Y arrays sizes. Note that numbers may be integer, fixed-decimal, or floating-point notation, and they may be mixed. Spaces or tabs are used to separate adjacent numbers. The data starts on the line following the last label. If M and N are the X and Y array sizes, there must be M numbers in each row and N rows of data. The coordinate convention used is that the origin is in the center of the grid and the upper right hand quadrant is (+X,+Y). The optical axis is the Z axis, and the light travels in the +Z direction. The observer is looking towards the source of the light (the opposite direction of the light propagation).

The data for a complex array looks very similar, except that two adjacent numbers, real and imaginary, are included for each grid point. Thus, for a 4 x 4 grid, there are 4 rows each containing 8 numbers.

! CODE V Real optical field data

Datatype Real

Wavelength 1550.0 nm

Grid spacing .00013; .00013 mm

Array size 4 x 4

.27 .36e0 .39 2.1e-1

.45 .76 .78 .59

.35 .49 .55 .46

.12 .34 .67 .45

OPTITOOLS — EXFO OWA CONVERTER

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EXFO OWA Converter

The OWA converter is a software module used to convert files created by the EXFO OWA 9500 Optical Waveguide Analyser into Optiwave file format. The EXFO instrument is used to scan the refractive index of a waveguide facet at a specific wavelength, 656nm. The results of the scan are stored in an EXFO proprietary format within a file. The OWA Converter translates the data into an Optiwave refractive index data file so that the waveguide can be numerically analyzed within the Optiwave mode solver. Apart from the data format transformation, the converter has two additional functions • The OWA converter enables approximation of the refractive index distribution at

a user specified wavelength, which may be different from the wavelength the OWA instrument uses for index profile scanning.

• The OWA converter allows the original index scan mesh and window to be changed. This function is necessary because the observation window and mesh used in the measurement is often not convenient for calculation. To perform successful modal analysis, the waveguide facet observation window may need to be clipped or extended, and the mesh may need to be adjusted to a finer or more coarse level.

Typical workflow in using the OWA Converter1 User performs measurements on EXFO OWA 9500 and obtains refractive

index data.

2 User converts the obtained data file into a refractive index file readable by Optiwave applications.

a. Launch Component Utilities.

b. Launch the OWA Converter.

c. Specify input EXFO OWA data file (.rri) and the output Optiwave (.rid) file name.

d. Load the EXFO OWA data file

e. View the refractive index distribution. If the OWA observation window is too big or too small, clip or extend the region to a size appropriate for holding the optical field. Change discretization of mesh if necessary.

f. If extrapolation to another wavelength is desired, select Sellmeier's approximation parameters and extrapolation wavelength.

g. Convert and save the data.

3 Launch Optiwave application (i.e. mode solver) and use the file containing the refractive index distribution as needed.


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Region Selection and Expansion

Selected Region panel

The grey rectangle in the centre of the viewing region will be exported. Use the mouse to move or extend the rectangle, or enter the coordinates directly into the fields in the Selected Region panel. Choosing an area smaller than the view display will clip the measured data out of the calculation.

Data Points In Selected Region panel

The integers in the read only fields in this panel indicate the number of data points of the original data set that are enclosed by the selected rectangle. This number will give some idea regarding the accuracy of the interpolation.

Final Mesh Size panel

Use these fields for adjusting the mesh of the new file to the desired level. Since the new mesh does not coincide with the old one, the new mesh points are assigned on a nearest-to-original-mesh-point basis. In this simple algorithm depicted in the figure below, the closest original mesh point defines the refractive index on the new mesh.


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Figure 94 Original mesh (black) is different from the new mesh (red). The values on the red mesh are defined by the closest 'black' mesh point.

Region Expansion panel

If the original refractive index measurement was done over a region too small to hold the optical field, it will be necessary to extend the data beyond the original boundaries. This situation might occur in a waveguide measurement with low index contrast. The measurement is concentrated in the area of the waveguide, but the field extends far into the cladding. Some simple form of extrapolation is desirable. The OWA Converter uses the following rule:

Figure 95 Expansion of the region. The inner grey rectangle is exported on a larger domain (outer rectangle on the left). The unknown values outside the measured boundary are filled up with the boundary values as shown. B1, B2, B3 and B4 are value arrays of the refractive index on the horizontal and vertical boundaries, C1…C4 are single values of the refractive index in the corners of the the scanned domain. An example of the expansion is shown on the right. The Grey shaded region is the last boundary layer of the original scanned

data.


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In the Region Expansion panel, specify the number of mesh points to extend on the top, bottom, left, and right sides.

Wavelength Extrapolation by Sellmeier formulaThis is an optional step. To perform the extrapolation from the measurement wavelength to another working wavelength, go to the OWA Converter dialog box. In this dialog, select the Sellmeier Extrapolation check box. Then click on Parameters, to open the Sellmeier Parameters dialog box.


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Host Panel

Select a material (e.g. Silica) in the library list in the window on the left. Click on Load to load the Silica parameters into the Host Panel. Alternatively, this panel can be used to create a new material in the library. To do this, enter the appropriate numbers in the fields, enter a new (unique) name, and click Save. Once created, these parameters can be later recalled as described above, by selecting the library name and clicking on Load.

Doped Panel

This panel works the same way as the Host Panel, but it enters the algorithm in a different place. See the discussion below for the details.

Output Wavelength

The wavelength at which the waveguide will be used. In general, this is different from the wavelength used by the OWA 9500 instrument when it makes the measurement. See the following discussion for details on how this number is used in the algorithm.

Sellmeier Extrapolation Technical BackgroundThe terminology used in the dialog boxes (namely host, doped) is taken from the optical telecommunication fibers. The fibres are often made from silica glasses. The high purity glass is called the host material or substrate. Its bulk refractive index is usually the fiber cladding refractive index. To change the refractive index of a material, the material can have dopants added to it. For example, adding germanium to pure silica can result in an increase in the refractive index, while adding fluorine reduces it. The refractive index of doped material can be determined by the linear relationship between the doped material's mole percentage and permittivity.

Assume that is the refractive index of the host material and is the refractive index of mole-percentage doped material. Then, the refractive index of mole-percentage doped material can be interpolated as:

The square of the index and not the index itself is linearly interpolated. The model assumes that the dopants contribute to the electric displacement in response to an applied field in proportion to the mole fraction of the dopant. The coefficient of proportion of to is the permittivity, proportional to . Note that this formula can also extrapolate (the case where ).

When the refractive index at a central wavelength , , and the host and dopant material dispersion curves, and are defined, the dependence of the refractive index with wavelength, , is calculated based on the following equation:

(1)

n0 n1m1 n m

n2 n02 m

m1------ n1

2 n02–( )+=

DED E n2

m m1>

λ0 n λ0( )nhost λ( ) ndopant λ( )

n λ( )


156

This equation is the same as Equation 1, with the fraction estimated by comparing, at the centre wavelength , the refractive index of the given material with the index of a doped material with known Sellmeier coefficients ( ). OWA Convertor uses Equation 2 to handle the case where the Sellmeier coefficients are known for material of just one doping concentration. If the material in question has the same dopant, but with an unknown concentration, the fraction in Equation 2 will estimate the concentration by comparing the given index with the reference index . With the doping concentration estimated this way, the refractive index at other wavelengths is accurately estimated by Equation 2.

The functions and are often one of the Sellmeier's formulas. For example, the following 3 term formula is suitable for fused silica throughout the wavelength range 0.21 to 3.71 microns:

where

= 0.6961663

= 0.4079426

= 0.897479

= 0.0684043

= 0.1162414

= 9.896161

Wavelength dependent measurements on a sample of silica with some fixed level of doping can be used to fit to an equation of form [3], to get slightly different values of the and . These 12 values are used to define the functions and in Equation 2. You can create named entries with 6 parameters associated with each name. Use the Save and Load buttons to build a library containing parameters suitable for your material system. The values are remembered the next time the

(2)

(3)

n2 λ( ) nhost λ( )n2 λ0( ) nhost

2 λ0( )–

ndopant2 λ0( ) nhost

2 λ0( )–-------------------------------------------------------- ndopant

2 λ( ) nhost2 λ( )–[ ]⋅+=

m m1⁄λ0

ndopant

n λ0( )ndopant λ0( )

nhost λ( ) ndopant λ( )

n2 1–A1λ

2

λ2 λ12–

-----------------A2λ

2

λ2 λ22–

-----------------A3λ

2

λ2 λ32–

----------------- ,+ +=

A1

A2

A3

λ1

λ2

λ3

As λs nhost ndopant


157

application is called. Typical library entries for various silica materials are supplied by Optiwave in the initial installation.

In the operation of the EXFO OWA-9500, the measurement wavelength is . The refractive index measured at this wavelength at a given point is

squared and it takes the place of in Equation 2. The desired wavelength (the contents of the Output Wavelength Field) is set to in Equation 2, and the index of the material at the output wavelength is evaluated from the formula. The same process is repeated at each point in the raster scan to develop a refractive index profile as would be seen by the long wavelength.

λ0 656nm=n2 λ0( )

λ


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OPTITOOLS — ZEMAX CONVERTER

159

Zemax Converter

OptiBPM is a software for waveguide optics, and is optimized for analysis of structures that are of size (in the transverse plane) comparable to an optical wavelength. Although it is theoretically possible to analyze free space or bulk optical components such as lenses and mirrors by the solution of Maxwell’s equations, generally it is more practical to make use of approximations commonly used in ray optics. Optiwave does not supply ray optics software, but OptiBPM Tools has a utility to convert the data of another software, Zemax. With Zemax, you can analyze bulk optics such as mirrors and lenses using ray tracin waveguide, Zemax can be used together with OptiBPM to analyze the whole system. Zemax can use ray tracing to determine the optical field distribution at the focal point, and the information can be sent to a file. The Zemax Converter Utility in OptiBPM Tools can be used to convert the output file from Zemax to another format that OptiBPM can read as input to the beginning of a waveguide. OptiBPM can analyze the subsequent wabeguide part of the system, and estimate the coupling loss on input. If the light needs to leave the waveguide and reenter a lens system, the Zemax converter can convert the output near-field-patter to a form that Zemax can accept as input to a ray tracing problem.

You can access the Zemax converter by clicking Tools > Zemax Converter

Figure 96 Zemax Converter dialog box

ConversionZEMAX ==> OptiBPM: specifies conversion from ZEMAX format to OptiBPM. These are mutually exclusive options. Specify the direction of the conversion. ‘ZEMAX -> OptiBPM’ is checked by default.

OptiBPM ==> ZEMAX: specifies conversion from OptiBPM format to ZEMAX.


160

Input File: (ZEMAX format expected): displays the name of input file. Editable text field. Empty by default. Specifies the path and name of the input file. May be filled in through the browser button located to the right of it, which displays a Windows standard file open dialog. In this dialog the user will be able to filter filenames according totypical extensions for the file formats (*.f3d for OptiBPM and *.zbf for ZEMAX). Click Browse to load a file from a folder.

Output file: displays the name of the output file. Editable text field. Empty by default. Specifies the path and name of the output file. May be filled in through the broser button located to the right of it, which displays a Windows standard file save dialog. In this dialog the user will be able to filter filenames acording to typical extensions for the file formats (*f3d for OptiBPM and *.zbf for ZEMAX). Click Browse to load a file from a folder.

Progress bar: The progress bar above the row of push-buttons will give feedback about the progression of the conversion. The user will be informed about success of failure through a message box containing an appropriate message.

Convert: Push buttton. Starts the conversion. If the output file exists, the user will receive a warning and will be able to abort the conversion if he wants.

Help: Push button. Displays a help page explaining the use of the controls in this dialog.

Close: Push button. Closes the dialog and the converter with it.

After you enter the filenames that hold the input and output data, click Convert. If the conversion is successful, the message shown.

Figure 97 Successful conversion dialog box

Notes on ConversionThe ZEMAX file has Nx powers of two only, and OptiBPM can have any integer. The difference is made up by using the next power of two in the ZEMAX file, and adding zeros in the new space in the ZEMAX file to keep the data of OptiBPM in the middle of mesh. When converting back from ZEMAX to OptiBPM, the added zero points are not removed.

The OptiBPM file can have Nx and Ny either even or odd. in the case of odd number, the mesh of ZEMAX and OptiBPM cannot be made to overlap exactly. The zero padding on the plus side of the axix will have one more point in it than on the minus side. This changes the position of the centre of the field by half a mesh point.


161

The unit in OptiBPM is always microns, but the unit of microns is not a possible unit in the ZEMAX file. Therefore, on conversion to ZEMAX file, distances in microns are converted to mm, and the units are set to mm. In converting the other way, distances are converted into microns. This means that applying the conversion twice (there and back again) could generate a result in different units from the original.

There are several parameters defined in the ZEMAX file that don’t exist in the OptiBPM file. These are zx, Rx, zy, Ry, wy, lambda, index, re, and se. On converting from OptiBPM to ZEMAX, all these parameters are set to zero. The settings of these variables in the global scope will be used in the ZEMAX project.

On converting from OptiBPM to ZEMAX, Dx=(Xmax-Xmin)/Nx-1, Dy=(Ymax-Ymin)/Nx-1. On converting from ZEMAX to OptiBPM, Xmax=Dx*(Nx-1)/2, Xmin=-Xmax, Ymax=Dy*(Ny-1)/2, Ymin=-Ymas. so when we convert back and forth, the Ymin/Ymax and Xmin/Xmax may be changed.

Data formatsThis converter can read the OptiBPM file in the format BCF3DPC, BCF3DCX, BCF3DCX 3.0 and BCF3DCX, and convert it to the ZEMAX file in binary format propertly. If the OptiBPM file is in BCF3DCXV format, then the target ZEMAX file will be set to “polarized”. These data formats for the OptiBPM compatible file have extension .f3d (see “Data file formats” on page 181 for definitions). The information from Zemax is contained in a binary file. This converter can only read the ZEMAX file in binary format. We don’t support the ASCII format ZEMAX file. If the “is polarized” is set (1), then we will create an OptiBPM file in BCF3DCXV format, otherwise it always creates the OptiBPM file in BCF3DCX 3.0 format.

ZEMAX Beam File (ZBF) binary formatBeams in ZEMAX are always contered on the chief ray for the selected field and wavelength. Therefore, the data in the beam file should be positioned relative to the chief ray that will be used to align the beam. The center point in the beam file is at the coordinate (nx/2+1, ny/2+1). ZEMAX requires the values of nx and ny to be an integral power of 2; for example, 32, 64, 128, 256, etc. The minimum sampling is 32 and the current maximum sampling is 8192. Fiber coupling data is ignored when reading beams, and will be zero if fiber coupling is not computed on output. Note the total fiber coupling is the product of the receiver and systems efficiency. The first data point is at the -x, -y corner, and the data proceeds across the x rows first. The Rayleigh distance is ignored on input and is automatically recomputed by ZEMAX. The wavelength value stored in ZBF file is scaled by index of the media the beam is curently in.

The ZBF binary file format is defined as follows. All integers are 4 bytes, all doubles are 8 bytes.

1 integer: The format version number, currently 1.

1 integer: The number of x samples (nx).

1 integer: The number of y samples (ny).

1 integer: The “is polarized” flag; 0 for unpolarized, 1 for polarized.


162

1 integer: Units, 0 for mm, 1 for cm, 2 for in, 3 for meters.

4 integers: Currently unused, may be any value.

1 double: The x direction spacing between points.

1 double:The y direction spacing between points.

1 double: The z position relative to the pilot beam waist, x direction.

1 double: The Rayleigh distance for the pilot beam, x direction.

1 double: The waist in lens units of the pilot beam, x direction.

1 double: The z position relative to the pilot beam waist, y direction.

1 double: The Rayleigh distance for teh pilot beam, y direction.

1 double: The waist in lens units of the pilot beam, y direction.

1 double: The wavelength in lens units of the beam in the current medium.

1 double: The index of refraction in the current medium.

1 double: The receiver efficiency. Zero if fiber coupling is not computed.

1 double: The system efficiency. Zero if fiber coupling is not computed.

8 doubles: Currently unused, may be any value.

2*nx*ny double: Ex values.

163

Appendix A: Opti2D Graph Control

The Graph control is a versatile, powerful easy-to-use tool for observing data (see Figure 98). This section gives a brief description of some of the 2D graph control features and an explanation of how to use them.

Figure 98 Opti2D Graph Control

APPENDIX A: OPTI2D GRAPH CONTROL

164

User interface features

Information windowsThere are two main windows visible on the main display:• Info-window• Info-Window settings dialog box

Both can be launched using the Graph menu or Graph tools.

Info-window

Figure 99 Info-window

Feature Description

Large data handling capabilities

Opti2D Graph control is capable of handling millions of points.

Optimized drawing Even with a large number of data points, Opti2D Graph Control is optimized to allow for smooth tracing and panning of graphs.

Moveable information windows Moveable information windows allows for placement of the windows in the most convenient location in the graph window.

Crosshair Visible cross to make seeing trace points easier.

Graph toolbox The popup Graph toolbox allows easier access to the viewing/organizing/editing capabilities of the Opti2D Graph tool.

Graph Menu button The Graph menu button allows you to access a full list of functionality associated with the graphs and their data.


165

When you access the Info-window, it displays in the work area of the graph view. By default, it displays the current position (in data-base coordinates) of the cursor. When you add marker, tracers, and regions, the Info-Window expands to show the details of these components.

When you use the Select tool, if you double click in the window, the Info-Window properties dialog displays (see Figure 100).

Figure 100 Info-Window settings dialog box

LegendYou can switch the Legend on and off using the Legend tool in the Graph toolbox, or the Graph menu. The Legend displays a list of all the curves displayed in the graph with the corresponding line color that is used to display those curves (see Figure 101). Use the Minimize/Maximize button to change the display of the Legend, or close the Legend by using the Close button.

Figure 101 Legend


166

Graph toolboxTo access the Graph toolbox, right-click in the graph view. Most graph editing/viewing/organizing capabilities are accessible using the toolbox (see Figure 102).

Figure 102 Popup Graph Toolbox

Graph tools


Description

SelectAllows you to manipulate and move most of the objects on the Graph.

Note: To edit the properties of an object, double-click the object in the graph view.

Zoom

Zoom in: You can select a rectangular region, or click in the graph view for proportional zoom in.

Extra features:• Zoom out: Hold Ctrl and click to perform a zoom out.• Reset Zoom Level: Double-click in the graph view to return to the default Zoom

level.

Pan

Allows you to pan from side to side in the graph display to see parts of the graph that may not be visible at the existing Zoom level or resolution.

To pan, click to grab the display, and move the cursor from side to side.

Extra features:• If you press Ctrl while panning the graph display, accelerated pan is engaged,

which makes the pan much faster. This feature is useful when you work under a high zoom factor.

GridAllows you to turn the grid lines on/off. Click on the Grid tool to toggle the grid lines.

Tracer

Allows you to select a curve and trace over it while viewing the exact positional values on the curve in the Info Window. To select a different curve, double click in the graph view.

Extra features:• You can freeze the tracer by pressing Ctrl. Click to place a marker on the curve

at that position.• Press Shift and drag the cursor to put the tracer into a high-resolution trace that

iterates through each element in the source data array. This allows for a very detailed scan of the data and to find peaks that the standard trace may omit.


167

Trace

Allows you to select a curve and trace over it while viewing the exact positional values on the curve in the Info Window. The Difference Tracer differs from the Tracer tool because it allows you to create a second tracer to compare values on either the same curve or on different curves. To select the next curve, double click on the curve in the graph view.

Extra features:• By Pressing the Control Key the tracer will freeze in its present position. Then by

pressing the left mouse button a marker will be placed on that position on the curve.

• By Pressing the shift key and dragging the mouse the tracer jumps into a high-resolution trace that iterates through each element in the source data array. This allows for a very detailed scan of the data and to find peaks that the standard trace may omit.

MarkerAllows you to place markers in the active graph view. The markers can be horizontal, vertical or both. The position of the markers is displayed in the Info Window.

RegionAllows you to select a horizontal, vertical or rectangular region in the active graph view. The coordinates of the selection are displayed in the Info Window.

LabelAllows you to place customized labels in the active graph view.

LegendAllows you to toggle the Legend on and off within the active graph view.

InfoAllows you to toggle the Info-Window on and off within the active graph view.

LayoutAllows you to reset the layout and place all windows in their default positions.


Description


168

Graph menuTo open the Graph menu, click the blue icon at the top left corner of the Graph view (see Figure 103).

Figure 103 Graph Menu

Graph Menu buttonThe Graph Menu button is in the top left corner of the graph view.

ToolsThe tools available from the Graph menu include:• Select• Zoom• Pan• Grid• Tracer• Difference Tracer• Marker• Region• Label


169

WindowsThe information windows available in the Graph Menu include:• Legend• Info Window• Reset Layout

Printing and exporting files

Print

Opens the Print dialog box and allows you to print an image of the active graph view (see Figure 104).

Figure 104 Print dialog box

Print to BMP file

Exports an image of the active graph view to a file in .bmp format using the Save As dialog box (see Figure 105).


170

Figure 105 Print to BMP File

Print to EMF file

Exports an image of the active graph view to a file in .emf format using the Save As dialog box (see Figure 106).

Figure 106 Print to EMF File

Copy image to clipboard

Copies an image of the active graph view to the clipboard.


171

Utilities

Tool setup

Allows you to modify the properties of some of the tools.

Note: The tool property dialog only launches if the active tool allows settings to be changed.

Set Active Display

Allows you to select the active display. For more information, see “Displays” on page 172.

Properties

Allows you to launch the Graph Properties dialog. For more information, see “Graph display” on page 173.

Table of Points

Launches a dialog box that displays a list of all the curves on the graph control and displays the data coordinates of those curves. It also allows you to export the data points to a text file (see Figure 107).

Figure 107 Data Table dialog box

HelpLaunches a help dialog box specifically related to the Opti2D Graph Control.


172

Import Curve

Allows you to import a curve from a text file. The file must be in the format below.

X1 (tab) Y1

X2 (tab) Y2

Etc…

Ex:

// (Beginning of file) (this line should not be in the file)

123.23 123.45

123.24 124.55

123.25 555.5

123.26 222.22

//(End of file) (this line should not be in the file)

DisplaysThe graph is made up of layered displays. Each display has a pair of axes. By default, the control contains one display with Axis X on the bottom of the display and Axis Y on the left. In the case of complex graphs that require more than one pair of axes, more than one display exists (see Figure 108).

Figure 108 Active Display dialog box

Any objects that you place on the graph are placed on the active graph view. Therefore, if you place a marker on the graph and Display 1 is active, the new marker


173

is based on the coordinate system of Display 1. If you want to add a marker on Display 2, you must select the main menu in the Graph menu. This launches the Graph Display dialog, which permits you to select a different display. In complex graphs, the displays are layered one on top of the other (see Figure 109).

Figure 109 Graph display

Graph Properties dialogThe Graph Properties dialog allows you to manage properties of the graph.

The Graph Properties dialog tabs include:• X-Axis• Y-Axis• Properties dialog box—Y-Axis tab• Grid• Fonts• Legend• Properties dialog box—Legend Tab• Label Management

X-AxisThe X-Axis Tab allows you to set properties of the X-axis (see Figure 110).


174

Figure 110 Properties dialog box—X-Axis tab

The values in Scale Type can be:• Linear• Logarithmic • DB


175

The values in Format Value can be:• Decimal: simple decimal values (1000.0, 2000.0, 3000.0)• Exponential: exponential notation (1.0-e3, 2.0-e3, 3.0-e3)• Engineering: engineering notation (1k, 2k, 3k)• Scientific: scientific notation (1.0 x 103,2.0 x 103, 3.0 x 103)

Prefix: You can place a prefix string before each of the scale values.

Suffix: You can place a suffix string after each of the scale values (e.g. 1000.0 nm)

Automatic Range, Min Value, Max Value: You can check Automatic Range, which sets the range according to the curves in the displays, or force the axis range to certain values.

Tickmarks: You can set the number of major and minor tick marks on the Axis.

Y-AxisThe Y-Axis Tab allows you to set properties of the Y-axis (see Figure 111).

To see descriptions of the Y-Axis dialog fields, see “X-Axis” on page 173.

Figure 111 Properties dialog box—Y-Axis tab


176

Curve

The Curve tab allows you to set various properties of the curves that are added to the control (see Figure 112).

Figure 112 Properties dialog box—Curves tab

Curve List: Displays all of the curves on the active display.

Curve Properties

Color: Allows you to choose the color of the selected curve.

Line Style: Allows you to select the line style of the selected curve.

Plot Style: Allows you to select the plot style.

The values in Plot Style can be:• Point• Line• Segment Left• Segment Right• Segment Center• Step Left• Step Right• Drop Line


177

Line Thickness: Allows you to select the thickness of the currently plotted curve line. Values range from 1 to 8.

Point Style: Allows you to select the style in which each point on the curve will be drawn.

The values in Point Style can be:• None• Circle• Square• Diamond• Cross• X• Trangle• Star

GridThe Grid tab allows you to select which of the grid lines on the display are visible, and what color they are to be displayed in (see Figure 113).

Figure 113 Properties dialog box—Grid tab


178

FontsThe Font Tab allows you to select the fonts used for displaying titles and axis values. (see Figure 114).

Figure 114 Properties dialog box—Fonts tab

LegendLegend tab simply has a toggle for the Legend Visible/Invisible. More features will become available in the future (see Figure 115).


179

Figure 115 Properties dialog box—Legend Tab

GraphThe Graph tab is used for editing the titles of any axis as well as the graph title itself (see Figure 116).

Figure 116 Properties dialog box—Graph tab


180

Label ManagementThe Label Management tab allows you to remove and edit labels on the graph. You can also access the Label Management function using the Label tool in the Graph toolbox (refer to Figure 117).

Note: For removing a large number of labels or labels that may have been positioned at coordinates that are not in the viewable area, it is easier to remove or edit them using the Label Management tab, because of the multiple selection feature.

Figure 117 Properties dialog box—Label Management tab

Use the Label Properties dialog box to edit the name or coordinates of the selected label (see Figure 118).

Figure 118 Label Properties dialog box

181

Appendix B: File Formats

Generic file formatThe Generic file format is a text format that consists of three data columns, X, Y, and Z, separated by space (see Table 3).

Note: This format is one of the export formats. It is not supported by any of the viewers.

Table 3 Generic file format

Data file formatsOptiBPM uses the text data format for saving the simulation results and reading user defined fields and index of refraction distributions:

• Real Data 2D File Format: BCF2DPC• Real Data 3D File Format: BCF3DPC• Complex Data 2D File Format: BCF2DCX• Complex Data 3D File Format: BCF3DCX• User Refractive Index Distribution File Format

X1

Y1

Z1

X2

Y2

Z2

X3

Y3

Z3

..

....

..

.

XN

YN

ZN

APPENDIX B: FILE FORMATS

182

OptiBPM uses several different formatted text files for reading and saving optical fields and index of refraction distributions.

Real Data 2D File Format: BCF2DPCApplies to input and output files that contain real data as text. The file contains the file header, number of data points, and the real x and y data points:

Files that follow the BCF2DPC format• Output files in BPM 2D: [*.rpd], [*.poi]• Output files in BPM 3D: [*.rpd], [*.poi]

Example: Power overlap integral output file in BPM 2D [*.poi]

In this example, a Gaussian input field is propagated in a Linear Waveguide from the starting distance 0.000000E+000 to the end distance 1.000000E-001. The propagating field is overlapped with the starting field, giving the power overlap value 1.000000E+000 at the start and the value 4.034535E-001 at the end of propagation. The number of displays in the Global Data dialog box is 30, while the actual number of saved data points is 31. This is, because the file contains also the power overlap value at the start of propagation in addition to 30 values from the propagation.

BCF2DPC file header (this string is used to identify the file type)

N number of data points

X1 Y1 first x and y data separated by space

X2 Y2 second x and y data point

.

.

.

XN YN last x and y data point

BCF2DPC file header

31 number of data points

0.000000E+000 1.000000E+000

start distance and power overlap at start

3.330000E-003 3.558430E-001 distance and power overlap


.

.

.


183

Real Data 3D File Format: BCF3DPCThis format applies to input and output files that contain real data as text. The file contains the file header, number of x and y data points, minimum and maximum values of x, y and z, and the real z(x,y) data points. The data points are presented in one column with the order determined by scanning the x and y coordinates.

where dx = (xmax-xmin)/(nx-1) and dy = (ymax-ymin)/(ny-1).

Files that follow the BCF3DPC format• Output files in BPM 2D: [*.amp], [*.pha], [*.rri]• Output files in BPM 3D: [*-x.amp], [*-y.amp], [*-x.pha], [*-y.pha], [*-x.rri], [*-y.rri]

For more information, see “Data file formats” on page 181.



1.000000E-001 4.034535E-001 end distance and power overlap

BCF3DPC file header

NX NY number of x and y data points

XMIN XMAX minimum and maximum x values

YMIN YMAX minimum and maximum y values

ZMIN ZMAX minimum and maximum z values

Z1 real z data point with coordinates (xmin, ymin)

Z2 real z data point with coordinates (xmin+dx, ymin)

Z3 real z data point with coordinates (xmin+2dx, ymin)

.

ZNX real z data point with coordinates (xmax, ymin)

ZNX+1 real z data point with coordinates (xmin, ymin+dy)

.

.

ZN last real z data point with coordinates (xmax, ymax), where N=NXxNY


184

Example: Real refractive index in BPM 2D [*.rri]

In this example, the transverse mesh extends from -5.000000E+000 to 5.000000E+000 microns. The propagation distance extends from 0.000000E+000 to 1.000000E-001 millimeters. A Linear Waveguide with refractive index 1.5 is laid out on a wafer with the index 1.3. The number of mesh points is 100 and the number of displays in the Global Data dialog box is 30. The actual y number of saved index x distributions is 31. This is, because the file contains also the index distribution at the start of propagation in addition to 30 values from the propagation.

BCF3DPC file header

100 31 number of x and y data points

-5.000000E+000 5.000000E+000 minimum and maximum transverse mesh values

0.000000E+000 1.000000E-001 minimum and maximum distance

0.000000E+000 1.000000E+000 unused values added by BPM 2D to conform to the format

Note: OptiBPM adds a line of default values 0 and 1 to conform this format.

1.300000E+000 real z data point with coordinates (xmin, ymin)

1.300000E+000

1.300000E+000

.

.

.

1.300000E+000

1.300000E+000

1.300000E+000


185

Complex Data 2D File Format: BCF2DCXThis format applies to input and output files that contain complex number data as text. The file contains the file header, number of data points, mesh width, and the complex z data points:

New format

Files that follow the BCF2DCX format• Output files in BPM 2D: [*.f2d]


Example: Complex field (end of propagation) in BPM 2D [*.f2d]

In this example, the number of data points, that is, the number of mesh points is 100. The transverse mesh extends from -5.000000E+000 to 5.000000E+000 microns giving the mesh width 1.000000E+001 microns.

BCF2DCX 3.0 file header

N number of data points

Xmin Xmax minimum and maximum x values

Z1 first complex data point

Z2 second complex data point

.

.

.

ZN last complex data point

BCF2DCX 3.0

100

1.000000E+001 3.000000 E+001

-1.625361825110615E-003, -4.389245939619818E-004

-1.509141347436203E-003, -5.157781413025380E-004

-1.396612427100470E-003, -5.882450646580990E-004

.

.

.

-1.396612427102228E-003, -5.882450646589938E-004


186

Complex Data 3D File Format: BCF3DCXThis format applies to input and output files that contain complex data as text. The file contains the file header, number of x and y data points, mesh widths in x and y, and the complex z(x,y) data points. The data points are presented in one column with the order determined by scanning the x and y coordinates.

New format

where dx = (xmax-xmin)/(nx-1) and dy = (ymax-ymin)/(ny-1).

-1.509141347437384E-003, -5.157781413024150E-004

-1.625361825110870E-003, -4.389245939610474E-004

BCF3DCX 3.0 file header

NX NY number of x and y data points

Xmin Xmax Ymin Ymax minimum and maximum x and y values

Z1 complex number z data point with coordinates (xmin, ymin)

Z2 complex number z data point with coordinates (xmin+dx, ymin)

Z3 complex number z data point with coordinates (xmin+2dx, ymin)

.

ZNX complex number z data point with coordinates (xmax, ymin)

ZNX+1 complex number z data point with coordinates (xmin, ymin+dy)

.

.

ZN last complex number z data point with coordinates (xmax, ymax), N=NXxNY


187

Example: Complex field (end of propagation) in BPM 3D [*.f3d]

In this example, the number of data points is 100 and equals to the number of mesh points. The transverse mesh extends from -5.000000E+000 to 5.000000E+000 microns giving the mesh width 1.000000E+001 microns.

Files that follow the BCF3DCX format• Output files in BPM 3D: [*.f3d]


BCF3DCX 3.0

100 100

1.000000E+001 1.100000E+001 2.000000 E+001 3.000000 E+001

-4.582487025358980E-004, -2.411965546811583E-002

1.813879122411751E-004, -2.322439514101689E-002

8.864140535377826E-004, -2.245463661588051E-002

.

.

.

-1.004141897700716E-002, 7.709994296904761E-003

-9.736326254112302E-003, 8.732395427319460E-003

-9.270032367315658E-003, 9.686774052240091E-003


188

User Refractive Index Distribution File Format

UPI2DRI 3.0 file header

NPM number of points in mesh

XMIN XMAX min and max mesh points

Z1 first complex number data point

Z2 second complex number data point

.

.

.

ZN last complex number data point

Example

UPI2DRI 3.0

500

-50 50

1.491000000000000E+000, 0.000000000000000E+000

1.491000000000000E+000, 0.000000000000000E+000

.

.

.

1.491000000000000E+000, 0.000000000000000E+000

Default format for 3D Refractive Index Distribution

UPI3DRI 3.0 file header

NPMX NPMY number of points in mesh in X and Y

Xmin Xmax Ymin Ymax min and max mesh points in X and Y

Z1 first complex number data point

Z2 second complex number data point

.

.

.

ZN last complex number data point


189

Reading User Refractive Index Files by BPM 2D and BPM 3DDuring the propagation, the BPM simulator reads the index distribution file in a step by step manner. The information for reading the user data file is provided by the Device Layout Designer of OptiBPM and it concerns the number of mesh points and the extent of the User Defined File Region.

If the refractive index distribution as defined by the properties of the region is independent of the propagation distance (i.e. constant), then the simulator reads the index data only once, for the first step of propagation in the region and uses the same data for every step in that region.

If the refractive index distribution is defined as propagation dependent, then the BPM propagation enters the User Defined File Region, the program reads index of refraction data for each propagation step. The number of lines that is read at one step is equal to the number of transverse mesh points.


Example

UPI3DRI 3.0

151 121

-7.5 7.5 -3 3

3.300000000000000E+000, 0.000000000000000E+000

3.300000000000000E+000, 0.000000000000000E+000

.

.

.

3.250000000000000E+000, 0.000000000000000E+000


190

Complex Data 3D Vectorial File Format: BCF3DCXVThis format applies to input and output files that contain vectorial complex data. The file contains the file header, number of x and y data points, mesh widths in x and y, and the complex z(x,y) data points both for Ex and Ey field components. The data points are presented in one column with the order determined by scanning the x and y coordinates.

BCF3DCXV file header

Nx Ny number of x and y mesh points

Xmin Xmax Ymin Ymax minimum and maximum X and Y coordinates

Za1 complex field (Ex field component) at point with coordinates (xmin, ymin)

Za2 complex field (Ex field component) at point with coordinates (xmin+dx, ymin)

Za3 complex field (Ex field component) at point with coordinates (xmin+2dx, ymin)

.

ZaNX complex field (Ex field component) at point with coordinates (xmax, ymin)

ZaNX+1 complex field (Ex field component) at point with coordinates (xmin, ymin+dy)

.

.

ZaN (N=Nx*Ny) complex field (Ex field component) at point with coordinates (xmax, ymax)

Zb1 complex field (Ey field component) at point with coordinates (xmin, ymin)

Zb2 complex field (Ey field component) at point with coordinates (xmin+dx, ymin)

Zb3 complex field (Ey field component) at point with coordinates (xmin+2dx, ymin)

.

ZbNX complex field (Ey field component) at point with coordinates (xmax, ymin)

ZbNX+1 complex field (Ey field component) at point with coordinates (xmin, ymin+dy)

.


191

where N=Nx*Ny, dx=(xmax-xmin)/(Nx-1), and dy=(ymax-ymin)/(Ny-1).

Note: The total number of data points is twice the number of the total mesh points Nt=2*N.

Path Monitoring File FormatThe sample is provided (*.mon):

BCF2DPM

Power In Output Waveguides File FormatThe sample is provided (*.piw)

BCF2DMC

.

ZbN (N=Nx*Ny) complex field (Ey field component) at point with coordinates (xmax, ymax)

NPts NPath Number of data points (lines) and number of paths

[Distance] [Path 1] [Path 2] [Path 3] …. [Path NPath] text descriptor

XCoord1 P1val1 P2val1 P3val1 …. PNPathval1

XCoord2 P1val2 P2val2 P3val2 …. PNPathval2

...

XCoord NPts P1valNPts P2valNPts P3valNPts …. PNvalNPts

NPts WGN Number of data points (lines) and number of waveguides

[Wavelen] [ WG1 ] [ WG2 ] [ WG3 ] …. [ WGWGN] text descriptor

XCoord1 P1val1 P2val1 P3val1 …. PWGNval1

XCoord2 P1val2 P2val2 P3val2 …. PWGNval2

...

XCoordNPts P1valNPts P2valNPts P3valNPts …. PWGNvalNPts


192

Notes:

Optiwave7 Capella CourtOttawa, Ontario, K2E 8A7, Canada

Tel.: 1.613.224.4700Fax: 1.613.224.4706

E-mail: [email protected]: www.optiwave.com

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