Long-haul coherent QPSK transmission of 40G channels with 120% - - PowerPoint PPT Presentation

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Long-haul coherent QPSK transmission of 40G channels with 120% - - PowerPoint PPT Presentation

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conference & convention enabling the next generation of networks & services Long-haul coherent QPSK transmission of 40G channels with 120% spectral efficiency using increased linearity dispersion map with 100km spans and EDFAs EDFAs

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SLIDE 1 enabling the next generation of networks & services

conference & convention

Long-haul coherent QPSK transmission

  • f 40G channels with 120% spectral

efficiency using increased linearity dispersion map with 100km spans and EDFAs EDFAs

  • D. G. Foursa, Y. Cai, C. R. Davidson, A. Lucero,
  • M. Mazurczyk, W. Patterson, O. Sinkin, W. Anderson,
  • J. X. Cai, G. Redington, M. Nissov, A. Pilipetskii and

N.S Bergano

Tyco Electronics Subsea Communication

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Presenter Profile

Alexei Pilipetskii received his M.S degree in physics from Moscow State University in 1985. From 1985 to 1994 he worked at the General Physics Institute in Russia. He received his Ph.D. in 1990 for research in nonlinear fiber optics. From 1994 to 1997 he was with the University

  • f Maryland Baltimore County, where his

Alexei Pilipetskii Director - System Modeling & Signal Processing Research mail: apilipetskii@subcom.com Tel: 732-578-7533

  • f Maryland Baltimore County, where his

interest shifted to fiber optic data

  • transmission. Since 1997 he has been

with SubCom, where he works on a number of research and development

  • projects. He is currently the director of a

research group focusing on next generation technologies for undersea transmission systems.

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Introduction

  • Recent transmission demonstrations showed feasibility of achieving

transoceanic transmission distance with spectral efficiencies > 100%

– coherent detection – PDM-QPSK or PDM-OFDM-QPSK – distributed Raman amplification – low loss transmission path with large effective area fibers – low loss transmission path with large effective area fibers

  • In this presentation we will review our latest experimental results for:

– 40G using dispersion managed system with 100 km spacing and dual stage EDFAs only (120% SE over 7200 km, OFC 2010-OtuD2) – 100G using optimized for coherent detection testbed with 50 km spacing and simple single stage EDFAs (300% SE over 10600 km, OFC2010-PDPB10)

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Experimental Setup: Transmitter 1

Single polarization RZ-QPSK transmitter at 23 Gbaud

Interleav Delay QPSK RZ ODD measured λ λ λ λ CW loading

  • Modulation paths are operated with 223-1 data and inverted

data patterns at 23 Gbaud accounting for 15% FEC rate

  • Transmission bandwidth loading: 8 wavelength tunable data

channels substitute uniformly spaced CW DFB tones

  • Performance is measured for 4 center channels

aver QPSK RZ EVEN 11.5GHz 23Gb/s CW Signals CW

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Experimental Setup: Transmitter 2

PDM RZ-QPSK transmitter at 11.5 Gbaud

QPSK QPSK PBC RZ RZ Delay ODD CW loading measured λ λ λ λ Inter

  • Each channel is generated by splitting a single wavelength into two

modulation paths driven at a symbol rate of 11.5 Gbaud with a quarter word shift in the 223-1 PRBS patterns and subsequent orthogonal optical combining

QPSK QPSK PBC RZ RZ EVEN 5.8GHz 11.5Gb/s λ λ λ λ CW Signals CW terleaver

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40G Experimental Setup: testbed and amplifiers

  • Loop testbed: 6 x 100 km spans and 7 EDFAs

– periodic dispersion management with dispersion compensated to 0 after 600 km (optimized for direct detection)

  • Each span: 50 km large effective area fiber ~135 µm2 followed by 50 km

pure silica core fiber

– provides reduced transmission nonlinearity and loss

  • Dual stage EDFA: 28 nm BW and 20.5 dBm output
  • Dispersion compensation: intra stage DCM (~9 km; -2300 ps/nm)
  • Dispersion compensation: intra stage DCM (~9 km; -2300 ps/nm)

– provides ~1 dB OSNR advantage compared to 100 km DFF spans

TAP WDM1 980 nm LD1 EDF1 ISO GFF EDF2 ISO TAP TAP ISO WDM2 980 nm LD2 DCM

Stage1 Stage2

Amplifier schematics

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Performance of PDM-QPSK 40Gb/s at 7200 km

  • Carrier phase recovery is impacted by nonlinear transmission effects

– Differential (D)QPSK scheme provided similar performance compared to

Differential Coding (DC)-QPSK – Differential QPSK scheme does not use carrier phase estimation (similar to direct detection) – QPSK scheme (absolute phase) suffers from loss of phase tracking (phase slips) 2 4 6 8 10

  • 16
  • 14
  • 12
  • 10
  • 8
  • 6
  • 4

Signal Pre-emphasis [dB] Q [dB]

Coherent QPSK (absolute phase) Coherent DC-QPSK Coherent DQPSK

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Performance vs. Distance

  • For 23 Gbaud signal, coherent detection has 2 dB advantage relative

to direct detection near 3500 km distance

  • Phase wandering effect (OFC 2010 – OTuL2) increases with distance

and the benefit of coherent detection reduces

13 15 5 7 9 11 13 2 4 6 8 10 12 Distance x1000 [km] Q [dB] 23G DC-QPSK 23G direct detection DQPSK

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Performance vs. Distance

  • PDM DC-QPSK performs better than single polarization DC-QPSK
  • At 7200 km, performance was above FEC threshold for PDM DC-QPSK

13 15 B] 23G DC-QPSK 5 7 9 11 2 4 6 8 10 12 Distance x1000 [km] Q [dB] 23G DC-QPSK 11.5G PDM DC-QPSK

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RZ 14G PPG 2:1 Mux

I Q Q I

48 DFBs 4 ECLs Coupler Tx Out Interleaver Filter

1x2

96 x 112Gb/s Transmitter Setup

  • 112 Gb/s: 7% FEC overhead, ETDM, true PRBS (223-1)
  • Pre-filtered RZ- QPSK
  • De-correlated 4-rails
  • Measurements at ECL channels

RZ

Q

48 DFBs 4 ECLs Coupler Interleaver Filter

1x2

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624 km Circulating Loop

GEF LSPC 12x 52 km IO Span

  • 26 nm BW single-stage EDFAs
  • 12 x 52 km spans: Aeff ~ 150 µm2, Loss ~ 0.183 dB/km, Dispersion ~ 20.6

ps/nm/km – The new fiber provides one of the highest Figures Of Merit (FOM)

52 km

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300% Spectral Efficiency over 10600 km

9 10 11 12 Q-factor [dB] Better polarization Worse polarization

  • 112Gb/s on 33 GHz channel spacing
  • Average Q-factor 10.7 dB

– 22.4 Mbs decoded for each channel (2150 Mbs total)

7 8 1535 1545 1555 1565 Wavelength [nm] Q- 7% continuously-interleaving BCH Hard Decision FEC Threshold [10]

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400% Spectral Efficiency over 4360 km

6 8 10 12 Q-factor [dB]

  • 112 Gb/s on 25 GHz
  • Average Q-factor 10.2 dB

– 5-tap maximum aposteriori algorithm (MAP) provides 3.5 dB average benefit

2 4 1535 1545 1555 1565 Wavelength [nm] Q

CMA + 5-tap MAP CMA only

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100G Performance vs. Transmission Distance

Measured at 1550 nm with optimum power

10 11 12

  • factor [dB]
  • For Q-factor >10 dB

– 300% SE, ~14000 km (dispersion ~300 000 ps/nm) – 400% SE, ~5000 km

8 9 5,000 10,000 15,000 20,000 Transmission Distance [km] Q-f 400% SE 300% SE

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Conclusions: 40G

  • We show 40 Gb/s transmission over 7200 km with 120%

spectral efficiency using 100 km EDFA repeater spacing

– In-line dispersion management optimized for direct detection

  • Advantage of coherent over direct detection diminishes

with distance in the case of dispersion managed system

  • Polarization multiplexed DC-QPSK has better

performance than single polarization DC-QPSK

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Conclusions: 100G

  • Key technologies in improving SE and system reach with

coherent detection

– Simple single stage EDFAs – Large effective area fiber, non-dispersion compensated line – Pre-filtered PDM RZ-QPSK – Pre-filtered PDM RZ-QPSK – MAP detection algorithm reduces inter symbol interference

  • 3.5 (2.0) dB MAP benefit at 400% (300%) spectral efficiency
  • We demonstrated record transmission distances:

– 96 x 100G over 10600 km with 300% spectral efficiency – 400% spectral efficiency over 4360 km

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SLIDE 17

2010

enabling the next generation of networks & services

conference & convention

Pacifico Convention Plaza Yokohama & InterContinental The Grand Yokohama 11 ~ 14 May 2010 www.suboptic.org The 7th International Conference & Convention

  • n Undersea Telecommunications