optical mems in communication and sensing copyright o. solgaard, 2001. all federal and state...

Optical MEMS in communication

and sensing

Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course

O-MEMS Fiber SwitchesOlav Solgaard

Stanford University• Motivation• Fiber switch concepts

2x2 switch Matrix switch 3-D switch

Scaling Experimental demonstrations

Challenges Optical quality, large switches,

reliability, speed, fiber alignment, packaging…….

Network impact Packet switching?

• Conclusions


and sensing


Beam Steering Optical Switch

lkNs 2

I n p u tf i b e ra r r a y

O u t p u tf i b e ra r r a y

Analog mirrors 2N scaling Lucent, C-speed,

Xros(NT),.....


and sensing


Fresnel Zone Lens

Fresnel Zone plate on polysilicon plate, which is rotated out of the plane on microhinges. The fact that the lens is an amplitude grating limits its diffraction efficiency. Lin, Lee, Pister, Wu, UCLA, 1994.


and sensing


2 x 2 fiber-optic switch

Compact design One-mask fabrication

using DRIE on SOI Integration of fibers,

lenses, and micromirrors

2 by 1 operation By-pass switch AT&T, JDSU.......

In 1

In 2

Out 2

Out 1


and sensing


1 x 2 Matrix Switch


and sensing


2x2 switch – DRIE of SOI

manipulator

comb drives

Fiber grooves orchannels

Springs

Bryant Hichwa etal, OCLI/JDS Uniphase, “A Unique Latching 2x2 MEMS Fiber Optics Switch”, Optical MEMS 2000, Kauai, August 21-24 th, 2000.


and sensing


DRIE etched vertical micromirror

Pro: Simple fabrication (one

masking step) Simple packaging

Con: Scaling Large device count Immature fabrication

processes (reliability)

C. Marxer, N.F. de Rooij, Jrnl of Lightwave Tech., Vol. 17, No. 1, Jan 1999


and sensing


NxN Matrix OXC

Simple 1 by 2 cross-points

Digital mirrors N2 scaling Large motion Reliability?? OMM, Onix, AT&T,

Agilent.....


and sensing


Waveguide Cross Connects

TIR cell

Single mode optical waveguides

Champagne Switch (Agilent)

Input Straight through

Switched Output

Vertical directional coupler

Vertical Directional Coupler

S. Yu, M. Owen, R. Varrazza, R.V. Plenty, I.H. White, “High speed optical packet routing demonstration of a vertical coupler cross point switch array”, Proceedings of the Conference on Lasers and Electro-optics(CLEO), San Francisco, May 7-12, 2000, pp. 256-257


and sensing


AGILENT’s NxN OXC based on InkJet Technology


and sensing


Micromachined tilt-up mirrors

TORSIONALHINGE

100 m

COMB DRIVE

TORSIONALHINGES

100 m

COMB DRIVES

Fast-mirror design Slow-mirror design

For 15 degrees optical deflection:Fast mirror: 36.1 Vrms at 4.6 kHzSlow mirror: 60 Vpp below resonance


and sensing


Coupling chip


and sensing


Diode-laser display

CCD camera

Laser-diodearray

Scanningmicromirror


and sensing


Video Display System Based on Microscanners (TV on a chip)

Computer controls the laser diode and both scanning mirrors

The laser beam hits the fast scanning mirror,

... is imaged onto the slow scanning mirror,

…and the image is projected onto the screen

Surface micromachined,

flip-up scanning mirror

1f

1f

2f


and sensing


Single-chip scanner layout

633nmHeNe Laser

Mirror Curvature Compensation Optics

Output Optics

Camera

Spatial Filter

Acousto-Optic Modulator

Fast mirror

Output mirror Slow mirror Single-Chip

Raster-Scanner

MechanicalShutter


and sensing


Micromachined raster-scanner


and sensing


Two-chip scanner images

a d

e

c

f

b

g h

Resolution: 62 by 66 pixels, optical scanning angles 5.3 and 5.7 degrees Acousto-optic modulator switches the laser light off during mirror wobble.


and sensing


Large Arrays

Texas Instrument’s DMD

NASA's Next Generation Space Telescope (2008) with 4M micromirrors by Sandia NL

Lucent’s Optical X-Connect


and sensing


System on a chip

Laser-to-fiber coupling

Micropositioners of mirrors

and gratings

High-resolution raster scanner


and sensing


Grating Light Valve

1991 Polysilicon hinge (Pister, Judy, Burgett, Fearing)

1992 Grating light modulator (Solgaard, Sandejas, Bloom)


and sensing


UNIQUE FUNCTIONALITY

Silicon Dioxide

Silicon Nitride

Silicon Substrate

25 to 100 µm

Top electrode• Diffractive micro optics• Adaptive micro optics• Configurable holograms• Photonic Crystals• Applications:

1-D and 2-D spatial light modulators (Projection displays - Silicon Light Machines)

Displacement sensors (AFM arrays - C. Quate)

IR sensors Sensor integration, free-space

communication Diffractive lenses and holograms

(Fresnel zone plates - M. Wu, UCLA)

Spectroscopy


and sensing


Grating Light Modulator

Silicon Dioxide

Silicon Nitride

Silicon Substrate

Individual ribbons are from 1 to 2 µm wide and from 25 to 100 µm long.Top electrode

Substrate electrode

Beams up, reflection

Beams down, diffraction

Cross section


and sensing


High-contrast GLM

Dark State Bright State

sinon sinoff


and sensing


High Speed Switching

•L

ight

Out

put

20 nsec Switching Speed

time

down

up

GLV devices switch in as little as 20 nsec (~1,000 times faster than TI DMD)


and sensing


Grating Light Valve Technology

GLV

Basic Projection System

• Advantages:

• Traditional light source and projection system

• Disadvantages:

• 2-D Addressing

• Large Array =>Low yield


and sensing


SEMs of Grating Light Valve

1-D Grating Light Valve with Silicon nitride ribbons. The detailed picture shows the termination of the ribbons and the addressing lines. Courtesy Silicon Light Machines.


and sensing


GLV Device Reliability

• Ribbon material is Silicon Nitride — a stable ceramic material

• Device operates at small fraction of material’s tensile breaking stress

• Ratio of [ribbon length]:[max deflection] is about 800:1• No contact between ribbon and substrate

2

2.25

2.5

2.75

3

0 1 2 3 4 5 6

1012 Ribbon Cycles

Nat

ura

l F

req

uen

cy (

MH

z)

• Negligible change in natural frequency after equivalent of 10,000 hours of television use

Courtesy of Silicon Light Machines


and sensing


GLV Pixel Fundamental Contrast

Applied Potential (v)

0.3 1 2 3 4 5 6 7 8 1012 15

Opt

ical

Det

ecto

r Res

pons

e (V

)

0.0001

0.001

0.01

0.1

1

~0.125 mV

~325 mV

~ 2600:1 Contrast>2000:1 contrast at the GLV device



and sensing


The Scanned GLV Architecture

Relative to Scanned Beam (CRT)

1,000X lower channel bandwidth

Natural gamma, smoothly blended images

Variable aspect ratios without light loss

Relative to 2-D Panel

2,000X fewer pixels, smaller silicon die size

Retains high optical MTF

No “screen door” effect



and sensing


GLM Characteristics

• Small (/4) required deflectionHigh SpeedGood heat dissipation

=> high power-handling capability1-D implementation & simple structure

=> High YieldCMOS “compatible”

=> Inexpensive, flexible fabrication “On-chip” interferometer Good reliability


and sensing


MEMS Phased Arrays

Linear array of piston-motion mirrors for beam steering. Each micromirror is 110 m long and 27 m wide. D.M. Burns and V.M. Bright 1997.


and sensing


Variable Blaze Grating

Variable Blaze grating with torsional hinges for tilting of each element in the array. Burns, Bright, and Gustavson 1997.

optical mems in communication and sensing copyright o. solgaard, 2001. all federal and state...

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