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 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
conference & convention enabling the next generation of networks & services 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 of Maryland Baltimore County, where his of 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 Alexei Pilipetskii research group focusing on next generation technologies for undersea Director - System Modeling & transmission systems. Signal Processing Research mail: apilipetskii@subcom.com Tel: 732-578-7533
conference & convention enabling the next generation of networks & services 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)
conference & convention enabling the next generation of networks & services Experimental Setup: Transmitter 1 Single polarization RZ-QPSK transmitter at 23 Gbaud CW measured loading Delay RZ QPSK Interleav ODD λ λ λ λ aver RZ QPSK EVEN CW Signals CW 11.5GHz 23Gb/s • Modulation paths are operated with 2 23 -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
conference & convention enabling the next generation of networks & services Experimental Setup: Transmitter 2 PDM RZ-QPSK transmitter at 11.5 Gbaud RZ QPSK CW measured PBC ODD loading RZ QPSK Delay Inter terleaver λ λ λ λ λ λ λ λ RZ QPSK EVEN QPSK RZ CW Signals CW PBC 5.8GHz 11.5Gb/s • 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 2 23 -1 PRBS patterns and subsequent orthogonal optical combining
conference & convention enabling the next generation of networks & services 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 µ m 2 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 Amplifier schematics Stage2 Stage1 EDF1 EDF2 ISO ISO ISO WDM1 WDM2 GFF DCM TAP TAP TAP 980 nm 980 nm LD1 LD2
conference & convention enabling the next generation of networks & services 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) 10 8 Q [dB] 6 Coherent QPSK (absolute phase) Coherent DC-QPSK 4 Coherent DQPSK 2 -16 -14 -12 -10 -8 -6 -4 Signal Pre-emphasis [dB]
conference & convention enabling the next generation of networks & services 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 15 13 13 23G DC-QPSK Q [dB] 11 23G direct detection DQPSK 9 7 5 0 2 4 6 8 10 12 Distance x1000 [km]
conference & convention enabling the next generation of networks & services 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 15 13 23G DC-QPSK 23G DC-QPSK B] Q [dB] 11 11.5G PDM DC-QPSK 9 7 5 0 2 4 6 8 10 12 Distance x1000 [km]
conference & convention enabling the next generation of networks & services 96 x 112Gb/s Transmitter Setup 48 DFBs Interleaver Coupler RZ Filter 1x2 4 ECLs I PPG Tx Mux 14G I 2:1 Q Out Q Q 48 DFBs Coupler RZ 1x2 Interleaver Filter 4 ECLs 112 Gb/s: 7% FEC overhead, ETDM, true PRBS (2 23 -1) • • Pre-filtered RZ- QPSK • De-correlated 4-rails • Measurements at ECL channels
conference & convention enabling the next generation of networks & services 624 km Circulating Loop LSPC GEF IO Span 12x 52 km 52 km • 26 nm BW single-stage EDFAs 12 x 52 km spans: Aeff ~ 150 µ m 2 , Loss ~ 0.183 dB/km, Dispersion ~ 20.6 • ps/nm/km – The new fiber provides one of the highest Figures Of Merit (FOM)
conference & convention enabling the next generation of networks & services 300% Spectral Efficiency over 10600 km 12 Better polarization 11 Q-factor [dB] 10 Worse polarization 9 Q- 8 7% continuously-interleaving BCH Hard Decision FEC Threshold [10] 7 1535 1545 1555 1565 Wavelength [nm] • 112Gb/s on 33 GHz channel spacing • Average Q-factor 10.7 dB – 22.4 Mbs decoded for each channel (2150 Mbs total)
conference & convention enabling the next generation of networks & services 400% Spectral Efficiency over 4360 km 12 10 Q-factor [dB] 8 6 Q CMA + 5-tap MAP 4 CMA only 2 1535 1545 1555 1565 Wavelength [nm] • 112 Gb/s on 25 GHz • Average Q-factor 10.2 dB – 5-tap maximum aposteriori algorithm (MAP) provides 3.5 dB average benefit
conference & convention enabling the next generation of networks & services 100G Performance vs. Transmission Distance 12 11 -factor [dB] Measured at 1550 nm with optimum power 10 Q-f 9 400% SE 300% SE 8 0 5,000 10,000 15,000 20,000 Transmission Distance [km] • For Q-factor >10 dB – 300% SE, ~14000 km (dispersion ~300 000 ps/nm) – 400% SE, ~5000 km
conference & convention enabling the next generation of networks & services 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
conference & convention enabling the next generation of networks & services 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
2010 conference & convention enabling the next generation of networks & services The 7th International Conference & Convention on Undersea Telecommunications Pacifico Convention Plaza Yokohama & InterContinental The Grand Yokohama 11 ~ 14 May 2010 www.suboptic.org
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