Fiber Optic Communication in Practice · Fiber Optic Communication in Practice RAD Seminar Stanford University 4 October 2012 Chris Cole . 4 October 2012 2 Outline Fiber Optic Communication

Fiber Optic Communication

in Practice

RAD Seminar

Stanford University

4 October 2012

Chris Cole

4 October 2012 2

Outline

Fiber Optic Communication (Optics) Inside the Internet

■ Optics Areas: Datacom & Telecom

■ Non-optical Communication: Voiceband, Wireline, Wireless

■ Mainstream Datacom & Client Optics: 1Gb/s & 10Gb/s

■ Next Gen Datacom & Client Optics: 40Gb/s & 100Gb/s

■ Future Datacom & Client Optics: 400Gb/s & 1.6Tb/s

■ Next Gen Telecom Transport Example: 100Gb/s

4 October 2012 3

Internet Ecosystem

4 October 2012 4

Internet Bandwidth Growth

100

1,000

10,000

100,000

1,000,000

1995 2000 2005 2010 2015 2020

Date

Ra

te M

b/s

Core

Networking

Doubling

≈18 mos

Server

I/O

Doubling

≈24 mos

Gigabit Ethernet

10 Gigabit Ethernet

100 Gigabit Ethernet

40 Gigabit Ethernet

4 October 2012 5

Optics Areas

Transport

300-2000km

Metro Core

80-300km

Metro

Access

2-80km

Access

1-20km

SW & LW Datacom Client & Transport Telecom

Typical

Datacenter

<100m

Intra and

Inter-Office

500m-20km

Enterprise

Datacenter

<300m

4 October 2012 6

Optics Hierarchy

Devices:

ICs, lasers,

photo-detectors

Components:

optical

sub-assemblies

Sub-systems:

pluggable transceiver

modules

Systems:

routers / switch

chassis and boxes

4 October 2012 7

Outline

■ Fiber Optic Communication (Optics) Inside the Internet

Optics Areas: Datacom & Telecom






4 October 2012 8

SW (Short Wave) Datacom Optics

■ Multi Mode Fiber (MMF) point to point interconnect

■ 10m, 100m, 300m, intra-rack, inter-rack, data-center

interconnect applications

■ Interoperable pluggable transceiver modules

■ Ethernet (IEEE) primary standards

■ FibreChannel (storage) other standards

■ 850nm Vertical Cavity Surface Emitting Laser (VCSEL)

■ High volume (100ks to 1Ms / year)

■ Very stringent cost requirements

4 October 2012 9

LW (Long Wave) Datacom Optics

■ Single Mode Fiber (SMF) point to point interconnect

■ 2km, 10km, 40km inter-rack, data-center, central office,

campus and inter-office interconnect applications


■ Ethernet (IEEE) primary standards

■ FibreChannel (storage) other standards

■ 1310nm Distributed Feedback (DFB) Laser

■ Few 1550nm Electro-absorption Modulator Laser (EML)

■ High volume (100ks to 1Ms / year)

■ Stringent cost requirements

4 October 2012 10

Client Telecom Optics

■ Single Mode Fiber (SMF) point to point interconnect

between transport and switching equipment

■ 2km central office applications


■ ITU primary standards

■ IEEE (Ethernet) other standards

■ 1310nm Distributed Feedback (DFB) Laser

■ Few 1550nm Electro-absorption Modulator Laser (EML)

■ Moderate volume (1ks to 10ks / year)

■ Similar to and often same as LW Datacom Optics

4 October 2012 11

Transport Telecom Optics

■ Single Mode Fiber (SMF) DWDM multi-channel

■ 100km, 500km, 2000km enterprise, metro, long haul

transmission applications

■ ITU (International Tele-communications Union) standards

■ OIF (Optical Interface Forum) other standards

■ 1550nm tunable CW laser with MZ Modulator per lambda

■ Optical Amplifiers and Dispersion Compensation

■ Moderate volume (1ks to 10ks / year)

■ Stringent performance requirements

■ Only briefly discussed in this presentation

4 October 2012 12

Outline



Non-optical Communication: Voiceband, Wireline, Wireless





4 October 2012 13

Voiceband Datacom Examples

ITU standard V.22 (1980) V.32 (1984)

bit rate (b/s) 1200 9600

Baud (Bd) 600 2400

bits/symbol 2

(4 state QPSK)

4

(16 state QAM)

physical channels

1

(wire pair)

1

(wire pair)

frequencies 1

(unidirectional, half-band)

1

(bi-directional, full-band)

DSP none Echo cancellation, adaptive equalization and forward error correction (FEC)

4 October 2012 14

Wireline Datacom Examples

IEEE standard 100BASE-TX (1995) 1000BASE-T (1999)

bit rate (Mb/s) 100 1000

Baud (MBd) 125 125

bits/symbol 1

(3 state PAM)

~2

(5 state PAM)

physical channels

1

(2 wire pairs)

4

(4 parallel wire pairs)

frequencies 1

(unidirectional, baseband)

1

(bi-directional, baseband)

DSP 4B/5B encoding Echo cancellation and trellis coding across all channels

4 October 2012 15

Wireless Datacom Examples

IEEE standard 802.11b (WiFi) 1999 802.11a (WiFi) 1999

bit rate (Mb/s) 11 (simplex) 54 (simplex)

Baud (KBd) 1400 208

bits/symbol

8

(64 state QPSK x 4 state DQPSK CDMA)

6

(64 state QAM)

spatial channels

1 1

frequencies

1

(unidirectional, CCK, CSMA/CA full-band

48

(unidirectional, OFDM, CSMA/CA full-band)

DSP Walsh/Hadamard coding, adaptive rate selection

FFT coding, adaptive rate selection

4 October 2012 16

Outline




Mainstream Datacom & Client Optics: 1Gb/s & 10Gb/s




4 October 2012 17

1G Datacom

IEEE standard 1000BASE-SX (SW) 1998 1000BASE-LX (LW) 1998

Source 850nm VCSEL 1310nm DFB laser

bit rate (Gb/s) 1 1

Baud (GBd) 1.25 1.25

bits/symbol 1

(2 state NRZ)

1

(2 state NRZ)

physical channels

1

(2 simplex MMFs)

1

(2 simplex SMFs)

wavelengths 1


1


DSP 8B/10B coding 8B/10B coding

4 October 2012 18

10G Datacom

IEEE standard 10GBASE-SR (SW) 2002 10GBASE-LR (LW) 2002

Source 850nm VCSEL 1310nm DFB laser

bit rate (Gb/s) 10 10

Baud (GBd) 10.3 10.3

bits/symbol 1

(2 state NRZ)

1

(2 state NRZ)

physical channels

1

(2 simplex MMFs)

1

(2 simplex SMFs)

wavelengths 1


1



4 October 2012 19

Electric

I/O

Optical

I/O

pin

pair

Gb

/s

fiber

pair λ

Gb

/s

1 10 1 1 10

10G SW Transceiver

4 October 2012 20

Electric

I/O

Optical

I/O

pin

pair

Gb

/s

fiber

pair λ

Gb

/s

1 10 1 1 10

10G LW Transceiver

4 October 2012 21

Why is Optical vs. Non-optical Com. so Simple?

■ Possible reasons:

● Optics engineers are lazy and/or stupid

● Fiber channel is far below Nyquist and Shannon limits

■ Voice band channel: BW = ~4kHz

■ Shielded twisted wire pair channel: BW = ~100MHz/50m

■ SMF channel:

● 1310nm window ~100nm wide → BW = ~15THz:

Nyquist limit = ~ 30TBaud

● 1550nm window ~200nm wide → BW = ~25THz:

Nyquist limit = ~ 50TBaud

● 1550nm window Mitra & Stark (Bell Labs) capacity:

Shannon limit = ~150Tbps

4 October 2012 22

Optics Architecture Design

■ Data Rate = channels * bits/symbol * baud (symbols/sec)

■ Minimum channel count is simplest and cheapest (ex. 1)

■ Minimum bits/symbol is simplest and cheapest (ex. 1, NRZ)

■ Maximum baud is simplest and cheapest if feasible

● Datacom

○ Channel bandwidth is not a limit

○ TX and RX device (IC and Laser) limits dominate

● Telecom

○ DWDM channel bandwidth (50GHz)

○ Fiber impairments over 100kms to 1000kms distance: chromatic & polarization mode dispersion (CD & PMD)

○ TX and RX device limits also important

4 October 2012 23

Baud from SiGe Limits

■ Bipolar IC process figure of merit:

fT = unity magnitude short circuit current gain

■ Reference: Paul Gray & Robert Meyer, “Analysis and Design of Analog Integrated Circuits”, ©1977

■ Based on fT of mainstream SiGe production processes:

Max Baud ≈ fT/10

■ Why fT/10?

■ All optical IC communication building blocks require gain

■ 10x gain at baud gives efficient, low power circuits

■ 3x gain is difficult; requires cascading gain stages

■ 1x gain is not usable

■ Assumes electrical signal integrity is not a limitation

4 October 2012 24

10GBaud from SiGe Limits

2002 – 2006

fT ≈ 110GHz (mainstream 250nm SiGe production processes)

■ 10GHz < fT/10

10Gbaud SiGe ICs were efficiently implemented

■ 40GHz ≈ fT/3

40Gbaud SiGE ICs were implemented but with great difficulty

4 October 2012 25

Baud from CMOS Limits

■ CMOS IC process figure of merit:

fT = unity magnitude short circuit current gain

[ fMax (unity magnitude power gain) is better but not general]

■ Reference: Thomas Lee, “The Design of CMOS Radio-Frequency Integrated Circuits”, ©1998

■ Based on fT of mainstream CMOS production processes:

Max Baud ≈ fT/10

■ Why fT/10?

■ All optical IC communication building blocks require gain

■ 10x gain at baud gives efficient, low power circuits

■ 3x gain is not usable; low CMOS gm makes cascading gain stages impractical

4 October 2012 26

10GBaud from CMOS Limits

2004 - 2006

fT ≈ 120GHz (mainstream 90nm CMOS production processes)

■ 10GHz < fT/10

10Gbaud CMOS ICs were efficiently implemented

■ 40GHz ≈ fT/3

40Gbaud CMOS ICs were not possible

4 October 2012 27

Why Pluggable Transceiver Modules?

■ the good (il buono)

● multiple applications supported

● pay as you go

● confined, replaceable failures

● common market

● specialized R&D & production

■ the bad (il cattivo)

● increased component count

● SI complicated by I/O connector

● power increased by I/O SerDes

● density limited by SFP+ size

■ & the ugly (il brutto)

● poor thermal interface

● heat localized at host front

4 October 2012 28

Outline





Next Gen Datacom & Client Optics: 40Gb/s & 100Gb/s



4 October 2012 29

40G Telecom Client

Standard ITU-T G.693 40G 2000 IEEE 40GBASE-FR 2011

Source 1550nm EML 1550nm EML


Baud (GBd) 40 40

bits/symbol 1

(2 state NRZ)

1

(2 state NRZ)

physical channels

1

(2 simplex SMFs)

1

(2 simplex SMFs)

wavelengths 1


1


DSP SDH or OTN framing 64B/66B coding

4 October 2012 30

40G LW Transceiver

Electric

I/O

Optical

I/O

pin

pair

Gb

/s

fiber

pair λ

Gb

/s

10 1 1

4 40

40 40

4 October 2012 31

40G λ Typical Measurements

1.E-13

1.E-12

1.E-11

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

-14.00 -12.00 -10.00 -8.00 -6.00 -4.00 -2.00

BE

R

Average Power dBm

■ Test Conditions:

1550nm λ, 75oC, 39.81312Gb/s PRBS 2^31 -1 pattern

■ TX Eye Mask Margin: 23%

■ RX Average Sensitivity: -10.3dBm AOP

4 October 2012 32

40G Datacom

IEEE standard 40GBASE-SR4 (SW) 2010 40GBASE-LR4 (LW) 2010

Source 850nm VCSEL Array 1310nm DFB laser PIC


Baud (GBd) 10.3 10.3

bits/symbol 1

(2 state NRZ)

1

(2 state NRZ)

physical channels

4

(8 simplex SMFs)

1

(2 simplex SMFs)

wavelengths 1


4



4 October 2012 33

40G SW Transceiver

Electric

I/O

Optical

I/O

pin

pair

Gb

/s

fiber

pair λ

Gb

/s

10 1 10

4 4

40 40

4 October 2012 34

40G LW Transceiver

Electric

I/O

Optical

I/O

pin

pair

Gb

/s

fiber

pair λ

Gb

/s

10 1 10

4 4

40 40

4 October 2012 35

10G λ Typical Measurements

1.E-13

1.E-12

1.E-11

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

-18 -16 -14 -12 -10 -8

BE

R

OMA dBm

■ Test Conditions:

1310nm λ, 55oC, 10.3125Gb/s PRBS 2^31 -1 pattern

■ TX Eye Mask Margin: 37%

■ RX Average Sensitivity: -15.6dBm OMA

4 October 2012 36

100G Datacom

IEEE standard 100GBASE-SR4 2013(?) 100GBASE-LR4 2010

Source 850nm VCSEL Array 1310nm DFB laser PIC


Baud (GBd) 25.8 25.8

bits/symbol 1

(2 state NRZ)

1

(2 state NRZ)

physical channels

4

(8 simplex SMFs)

1

(2 simplex SMFs)

wavelengths 1


4



4 October 2012 37

100G SW Transceiver

Electric

I/O

Optical

I/O

pin

pair

Gb

/s

fiber

pair λ

Gb

/s

1

4 4

25 25

100 100

4 October 2012 38

100G LW Transceiver

Electric

I/O

Optical

I/O

pin

pair

Gb

/s

fiber

pair λ

Gb

/s

1

4 4

25 25

100 100

4 October 2012 39

25GBaud from SiGe Limits

2008 - 2012

fT = ~220GHz (mainstream 130nm SiGe production processes)

■ 25GHz ≈ fT/10

25Gbaud SiGe ICs were/are efficiently implemented

■ 40GHz ≈ fT/6

40Gbaud SiGe ICs are feasible

4 October 2012 40

25GBaud from CMOS Limits

2010 - 2012

fT = ~240GHz (mainstream 40nm CMOS production processes)

■ 25GHz ≈ fT/10

25Gbaud CMOS ICs were/are efficiently implemented

■ 40GHz ≈ fT/6

40Gbaud CMOS ICs are feasible with difficult

4 October 2012 41

Key GaAs Technology for 40G and 100G SW

■ Photonic Integrated Circuit (PIC*) parallel quad VCSEL array

■ Ex. monolithic GaAs quad 850nm VCSEL array, 0.25mm x 1.0mm PIC, Finisar Corp.

* The “C” in PIC is a stretch since there are no optical connections

4 October 2012 42

Key InP Technology for 40G and 100G LW

■ Photonic Integrated Circuit (PIC) WDM quad DFB array

■ Ex. monolithic InP quad 1310nm band DFB laser array with AWG, 1.1mm x 2.4mm PIC, CyOptics Inc.

4 October 2012 43

Key Si Technology for 40G and 100G LW

■ Photonic Integrated Circuit (PIC) Transceiver Chips

■ Ex. Hybrid Si Photonics quad 1550nm band PICs, Kotura

4 October 2012 44

Outline






Future Datacom & Client Optics: 400Gb/s & 1.6Tb/s


4 October 2012 45

Electric

I/O

Optical

I/O

pin

pair

Gb

/s

fiber

pair λ

Gb

/s

1

25 25

16 16

400 400

2x16 MPO

plug connector

400G SW Transceiver

4 October 2012 46

Electric

I/O

Optical

I/O

pin

pair

Gb

/s

fiber

pair λ

Gb

/s

1

8

8

50 50

400 400

400G LW Transceiver

4 October 2012 47

1.6T Transceiver Alternatives

■ 64x25Gb/s or 32x50Gb/s NRZ lasers

● Too many channels

● Not practical

■ Complex (amplitude and phase) modulation is only feasible alternative to control channel count

● PAM-N

● PSK-N

● QAM-N

● DMT-N

● Requires complex CMOS DSP and PICs

● No technology exits that can be commercialized

■ Excellent area for academic research

■ May be first used in late generation 400G Transceivers

4 October 2012 48

1.6T Transceiver Parameter Alternatives

Electrical

I/O

Optical

I/O

pin pair Gb /s Bits /

Symbol fiber pair λ Gb /s

Bits /

Symbol

1 10 1 1 1 10 1

4 12.5 2 4 4 12.5 2

8 25 3 8 8 25 3

16 50 4 16 16 50 4 = 50T

= 10G

(SFP+)

4 October 2012 49

Outline







Next Gen Telecom Transport Example: 100Gb/s

4 October 2012 50

100G Coherent Transport PM-QPSK TX

Precoding MZM

MZM

I

Q

X-pol

Y-pol

PBC Laser PM-QPSK Soft

Decision

FEC

Encoder

Re

Im

Precoding

I

Q

Re

Im

4 October 2012 51

100G Coherent Transport PM-QPSK RX

Hard

Decision

Decoding

Hard

Decision

Decoding

Soft

Decision

FEC

Decoder

SP

M C

om

p.

4 October 2012 52

100G Coherent Transport OSNR Limited BER

T. Mizuochi, “Next Generation FEC for Optical Communications,” OFC’08, Tutorial, San Diego, CA, 24-28 Feb. 2008

4 October 2012 53

Coherent Transport Trends

P. J. Winzer, “Coherent Optical Communications,” IEEE Photonics

Conference, Tutorial, San Francisco, Sep. 2012

4 October 2012 54

Fiber Optic Communication in Practice

Thank you

Documents

Fiber Optic Communication in Practice · Fiber Optic Communication in Practice RAD Seminar Stanford University 4 October 2012 Chris Cole . 4 October 2012 2 Outline Fiber Optic Communication