the next generation multimode fiber: wide bandwidth mmf

The Next Generation Multimode Fiber: Wide Band MMF (WBMMF)

Paul Kolesar

Engineering Fellow

Chair TIA TR-42.11

CommScopeAugust 20, 2015

TIA Fiber Optics Technology Consortium 1

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Outline

• Application drivers

• Multiplexing technology overview

• Trends in time division multiplexing

• Trends in space division multiplexing (a.k.a. parallel fibers)

• Trends in short-wavelength division multiplexing

• Benefits of SWDM and WBMMF

• Cabling evolution roadmap examples

• Bandwidth-wavelength relationships

• Wavelength usage refinement

• Bandwidth and transmission performance data

• OFC 2015 demo

• Standardization


Applications Drivers

• continues to evolve– Existing:

10M, 100M, 1G, 10G40G, 100G

– Developing:2.5G, 5G, 25G, 400G

– Near future interest:50G, 200G

– On and over the horizon:800G, 1.6T

• and thrive– due to unrelenting

demand for services needing faster data rates:video streaming, on-line gaming, smart phone apps, music streaming, photo messaging, …

Ethernet Roadmap 2015 – courtesy of Ethernet Alliance

Ethernet


Multiplexing Technology Overview

Wavelength Division Multiplexing

(WDM)MU

X

44

33

22

11

Single Fiber (e.g. WBMMF) DE

MU

X

Space Division Multiplexing (SDM)

(a.k.a. parallel fiber, parallel optics)

Four Conductors

e4

e3

e2

e1

e4

e3

e2

e1

MU

X

DE

MU

X

Time Division Multiplexing (TDM)Single Conductor

e4

e3

e2

e1

e4

e3

e2

e1

Ord

er of d

eplo

ymen

t in sh

ort-reach

op

tical com

mu

nicatio

ns system

s


Trends in TDM

• Higher data rates typically defined using– Parallel electrical sub-rate, sometimes serialized via SERDES (TDM

mux/demux) for delivery over fiber

– Serialize the electrical rate as technology permits

– Example: 10G has 4-lane (quarter rate)and serial electrical rates defined

• Today’s datacom max serial rates– Ethernet = ~25 Gb/s

– Fibre Channel = ~28 Gb/s

• Emerging datacom max serial rates – Ethernet = ~50 Gb/s

– Fibre Channel = ~56 Gb/s

MU

X

DE

MU

X

Single Conductor

(e.g. fiber, circuit board)e4

e3

e2

e1

e4

e3

e2

e1


Trends in SDM

• Data rates above 28Gb/s (32GFC) employ parallel fibers– 40GBASE-SR4

– 100GBASE-SR10 100GBASE-SR4

– 128GFC (will be like 100G-SR4)

– 400GBASE-SR16

• Transmission via parallel fibers has pragmatic limits– 100GBASE-SR4 more practical than -SR10

– Diminished appeal above -SR16

– A better approach is needed to keep MMF solutions optimized

– Enter SWDM

Rx Rx Rx Rx Rx Rx Rx Rx Rx Rx Rx Rx Rx Rx Rx Rx

Tx Tx Tx Tx Tx Tx Tx Tx Tx Tx Tx Tx Tx Tx Tx Tx

400GE Optical Lanes in MPO-16

Four Fibers

e4

e3

e2

e1

e4

e3

e2

e1


Trends in Short-Wave WDM (SWDM)

• Example - Cisco’s 40G-SR-BD– 40G transmission on one pair of MMF

– Uses two wavelengths in opposite directions per fiber, each at 20G

– Wavelength discrimination supports bi-directional operation

– Nominal wavelengths of 850 nm and 900 nm

– Four wavelengthsillustrated

WDM also supports uni-directional transmission per fiber

MU

X

44

33

22

11

Single Fiber (e.g. WBMMF) DE

MU

X


Mu’xed Multiplexing

• Example – TDM + WDM– Can also replicate over parallel fibers to combine TDM + WDM + SDM

MU

X

Single Fiber

e1d

e1c

e1b

e1a

MU

X

e2d

e2c

e2b

e2a

MU

X

e3d

e3c

e3b

e3a

MU

X

e4d

e4c

e4b

e4a

MU

X

DE

MU

XD

EM

UX

DE

MU

XD

EM

UX

DE

MU

X

e1 e1

e2

e3

e3

e2

e4e4

e1d

e1c

e1b

e1a

e2d

e2c

e2b

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e3d

e3c

e3b

e3a

e4d

e4c

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1 1

22

33

44

ASIC ASICOptical Tx Optical Rx


Benefits of SWDM & WBMMF

• Wavelengths used to reduce number of fibers– Good trend for improving MMF utility

– SWDM utility is more limited on OM3 or OM4 at high lane rates

• Deliver sufficient bandwidth over wavelength spectrum – to support > 100G / fiber to at least 100 m

Goals and benefits:

retain legacy application support of OM4

increase capacity to > 100G per fiber

reduce parallel fiber count by factor of 4

enable Ethernet:

40G-SR, 100G-SR, 400G-SR4

enable Fibre Channel:

128GFC-SWDM4, 256GFC-SWDM4

extend MMF utility as universal medium


Application Evolution Map –Ethernet Examples

parallel fiber transmission

WDM transmission

WDM + parallel transmission

Legend

Data Rate 10G

ParallelTX RX

25G

ParallelTX RX

10G, 25G

WDM &

ParallelTX RX

N/A

N/A

40G

100G

400G

SWDM enablingfactor of 4 fiber count

reduction

Imagine running 10G, 40G and 100G

over the same WBMMF cable plant using duplex LC connections *


*Parallel fibers remain essential to support break-out functionality

FC Rate 32GFC

ParallelTX RX

64GFC

ParallelTX RX

32G, 64G

WDMTX RX

128GFC

256GFC

N/A

N/A

Application Evolution Map –Fibre Channel Examples

Legend

SWDM enablingfactor of 4 fiber count

reduction

Imagine running 32G, 64G, 128G and 256G

over the same WBMMF cable plant using duplex LC connections *

parallel fiber transmission

WDM transmission


*Parallel fibers remain essential to support break-out functionality

WBMMF Specification Framework

• Wavelength range is central to WBMMF specification– although WBMMF standard will not specifically set WDM plan

• What is clear from the outset:– Legacy application support dictates inclusion of 850 nm wavelength

– Move towards longer wavelengths to gain improvements from lower chromatic dispersion, lower attenuation, faster VCSELs

– Four wavelength bands are ideal complement to four-lane parallel

• Transceiver vendors say low-cost WDM needs ≥ 30 nm pitch– Accommodates low-cost manufacturing tolerances, temperature variation,

spectral width, low-complexity filters

• The following analysis puts this all together– to determine shortest wavelength and wavelength range


0

1,000

2,000

3,000

4,000

5,000

750 775 800 825 850 875 900 925 950

Ban

dw

idth

(M

Hz·k

m)

Wavelength (nm)

Worst-case OM4 total bandwidth analysis

Modal BW

Chromatic BW (0.6nm)

Total Bandwidth

Bandwidth-Wavelength Relationships

Basic Requirements & Indications

Must retain legacy 850 nm application

support.

Wavelengths > 850 nm benefit from

increasing chromatic bandwidth and

improving VCSEL capability.

Must support at least 4 wavelengths.

Low-cost WDM needs ~30 nm spacing.

Resulting target wavelength region:

~840 nm to ~950 nm

Bandwidth improvement is needed to

raise total bandwidth to that at ~840 nm

over target wavelength region.


840 850 860 870 880 890 900 910 920 930 940 950 960

λ1

λ2

λ3

λ4

guard guard guardpass pass pass pass

WavelengthRefinement

• Calculate pass-band & guard-band allocations– Support 4 WDM operating wavelengths

• Set λL1 (longest wavelength of first pass-band) = 860 nm, the legacy upper limit for best performance and to allow λ1 VCSEL use for legacy applications

• move towards longer wavelengths for other bands

– Account for spectral width & temperature shift in pass-band calculation• λw allowance

0.6 nm rms (widest in recent standards)

• VCSEL temperature coefficient and temperature range 0.065 nm/⁰C coefficient account for 100 ⁰C variation

(supports -5 to 85 ⁰C ambient temperature range)

– Apply calculations as a function of wavelength• VCSEL λc manufacturing tolerance allowance

Percentage of nominal wavelength Trades-off with temp. coefficient, temp. range and spectral width

to fit within pass-band

• Filter pass-bands and guard-bands scaled with wavelength As requested by transceiver makers, provide ≥ 30 nm spacing

temp.

λw

pass-band allocations

λc


Results

• Highlights– Spectrum used equitably for all bands due to wavelength scaling– Nominal wavelengths shifted up slightly from basic concepts– Pitch between all nominal wavelengths > 30 nm– Longest wavelength = 953.0 nm– Shortest wavelength = 846.0 nm 107 nm range

840 850 860 870 880 890 900 910 920 930 940 950 960

Possible 4 λ Plan

λ1

λ2

λ3

λ4

guard guard guardpass pass pass pass

name nominal VCSEL range pass-band guard-band

λ1 853.0 846.0 - 860.0 14.0

16.2

λ2 883.4 876.2 - 890.5 14.3

16.5

λ3 914.3 907.0 - 921.5 14.5

16.8

λ4 945.7 938.3 - 953.0 14.7


Samples of Standard OM4 and Wide-Band MMFs

Fiber and measurements courtesy of OFS


Transmission Test Configuration

BERT

FUTFUTFUT

VOA

RX

limiting amp

VCSELs:

λ A, λB, …


http://www.teamwavelength.com/info/laserdiodedrivers.php

http://www.teamwavelength.com/info/laserdiodedrivers.php

*

Transmission Performance at 100 m

* 980nm VCSELs readily available for transmission tests and extract near-worst-case bandwidth effects.

Compare the left plot at 850 nm to the right plot at 980 nm, noting their different x-axis scales. Notice how the lines for the two OM4 fibers move significantly up and to the right, indicating that transmission impairments have substantially increased at 980 nm for OM4. But the two WBMMFs plotted in red remain comparatively similar at 980 nm to their 850 nm performance showing their ability to well support a very useful range of wavelengths.


Demo at OFC 2015

• 4λ, each at 25.78 Gb/s– Finisar SWDM concept transceiver (4 SFPs mu’xed together)– OFS fiber meeting CommScope WBMMF specification– > 100 Gb/s over single-fiber channel– 225 m reach (50 m + 75 m + 100 m spools) – Error-free without FEC assistance– Enabling FEC would have permitted longer reach


WBMMF Standardization

• Initial presentations to TIA TR-42 October 2014

– Coauthored and supported by fiber, transceiver and system companies

• TIA TR-42 approved project

– October 2014, without dissent

– International participation from IEC 86A members

– Monthly meetings with several contributors, > 40 contributions

– First ballot authorized June 2015

– TIA-492AAAE anticipated 2016

• For Fibre Channel & Ethernet

– 128GFC Gen 2, 256GFC, …

– 100GE Gen 3, 200GE Gen 1, 400GE Gen 2, …


Summary• The industry is moving to utilize SWDM

– Transceivers, fibers, cabling

• WBMMF will optimize the reach of SWDM solutions– While retaining support for 850 nm legacy applications at OM4 reaches

• Applications provide opportunities to seed these technologies– Ethernet and Fibre Channel

• SWDM & WB technologies extend the utility of MMF– Continuing legacy of delivering lowest-cost optical solutions

over the universal data-comm transmission medium that is MMF

Thank You


Q&A

Thank you for your time

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Important Notice

Any product(s) identified or identifiable via a trade name or otherwise in this presentation as a product(s) supplied by a

particular supplier(s) is provided for the convenience of users of this presentation and does not constitute an endorsement of any

kind by TIA of the product(s) named. This information may be provided as an example of suitable product(s) available

commercially. Equivalent product(s) may be used if they can be shown to lead to the same results.
