Alan J. Lucero

20 Tbit/s Transmission Over 6860 km With Sub-Nyquist Channel Spacing

We demonstrate that channel spacing can be reduced to values smaller than the Nyquist channel spacing over transoceanic distance. Modulation memory induced by constrained transmitter bandwidth together with multisymbol detection can reduce intersymbol interference for systems with sub-Nyquist channel spacing. We transmit 198 × 100 G bandwidth constrained polarization-division-multiplexed return-to-zero quaternary phase shift keying channels with 400% spectral efficiency over 6860 km using 52 km spans of 150 μ m2 fiber and simple single-stage erbium-doped fiber amplifiers without any Raman amplification. We also show that 100 G coherent nonlinear performance scales differently with distance on uncompensated dispersion maps compared with direct detection transmission.

Transmission of 96

We demonstrated that simple pre-filtering at the transmitter to constrain the channel bandwidth together with a maximum a posteriori probability (MAP) detection algorithm can significantly improve spectral efficiency (SE). 96 × 100-Gb/s bandwidth-constrained polarization-division-multiplexing return- to-zero-QPSK channels were transmitted with 300% SE over 10 610 km using 52-km spans of 150-μ m 2 fiber and simple single-stage erbium-doped fiber amplifiers without any Raman amplification. We also achieved 400% SE over 4370 km using similar techniques.

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The 8991-km-long transpacific segment of the Tyco Global Network (TGN) [TGN is a trademark of Tyco Telecommunications, Eatontown, NJ 07724 USA], connecting Hillsboro, Oregon, USA to Toyohashi, Japan, is the first installed dispersion-flattened dense wavelength division multiplexed (DWDM) system. In this paper, we describe the development path bringing this system from the computer design stage to a field trial, which confirms that the installed segment can support the design capacity of 96/spl times/10 Gb/s customer channels per fiber pair. Commercial channels have been provisioned on this segment with satisfactory system margins. Exploratory transmission results at 128/spl times/12.3 Gb/s over this segment are also reported here. The experimental results agree well with our expectations based on the results from our system design simulator.

100-Gb/s Bandwidth-Constrained PDM-RZ-QPSK Channels With 300% Spectral Efficiency Over 10610 km and 400% Spectral Efficiency Over 4370 km

This paper investigated the impact of receiver dispersion slope compensation for 40-Gb/s transoceanic transmission over conventional nonzero dispersion shifted fibers. Various differential phase-shift keying (DPSK) modulation formats were experimentally compared at 42.8 Gb/s [to account for forwarded error correction (FEC) overhead] with dispersion slope compensators at the receiver. These transmission measurements were performed in a circulating loop over a transatlantic distance of 6250 km using a variety of channel spacings, relative polarizations, and synchronous modulation techniques. All formats benefited from receiver dispersion slope compensation. For orthogonally polarized channels on 133-GHz spacing, the return-to-zero DPSK (RZ-DPSK) format performed the best; all channels (18 /spl times/ 40 Gb/s) propagated with > 13.5-dB Q-factor and with > 4-dB FEC margin. Whereas for copolarized channels on 100-GHz spacing, carrier-suppressed return-to-zero (CSRZ)-DPSK performed the best; all channels (25 /spl times/ 40 Gb/s) propagated with > 3-dB FEC margin. Moreover, it was shown that parallel launch only suffered a penalty of /spl sim/ 0.2 and /spl sim/ 0.5 dB relative to the orthogonal launch for 133and 100-GHz channel spacing, respectively. Finally, it was demonstrated that copolarized 40 Gb/s RZ-DPSK worked as well as 10 Gb/s RZ-ON-OFF keying (RZ-OOK) for the same spectral efficiency (30%) over the 6250 km of conventional nonzero dispersion shifted fibers (NZ-DSF) originally designed for 10 Gb/s transmission.

First dispersion-flattened transpacific undersea system: from design to terabit/s field trial

We transmit 198x100G pre-filtered PDM-RZ-QPSK channels with 400% spectral efficiency over 6,860 km. We also show that 100G coherent nonlinear performance scales differently with distance on uncompensated dispersion maps than expected from direct-detection transmission.

Transmission of 40-Gb/s WDM signals over transoceanic distance using conventional NZ-DSF with receiver dispersion slope compensation

40 Gb/s RZ-DPSK signals were successfully transmitted over 4,920 km with 110 km repeater spacing using only single stage C-band EDFAs. The performance of 40 Gb/s and 10 Gb/s RZ-DPSK was compared. Q-factor fluctuations are an issue for 40 Gb/s systems.

20 Tbit/s capacity transmission over 6,860 km

We present a methodology to optimize a Raman assisted EDFA transmission system. We analyzed span lengths from 120 km to 210 km and then give in-depth numerical and experimental results for 150 km spans.

Long-haul 40 Gb/s RZ-DPSK transmission with long repeater spacing

Our simulations demonstrate that in wavelength-division multiplexing systems where cross phase modulation is the dominant nonlinear impairment, performance penalties depend weakly on dispersion statistical variations and have a strong bit pattern dependence.

Long-Haul Raman-Assisted EDFA Systems with Ultra-Long Spans

40Gb/s RZ-DPSK signals were successfully transmitted over 4450km with 150km repeater spacing (33dB span loss) using Raman assisted EDFAs. The performance was compared with EDFA only amplification and 110km repeater spacing. Long-term Q-factor fluctuations were also quantified for Raman-assisted amplification.

Impact of bit pattern and dispersion variation on cross-phase modulation penalty

We have presented a comparison of orthogonal and parallel polarization launch in a straight-line transatlantic DWDM transmission experiment. We observed more than 1 dB of Q-factor improvement when employing orthogonal launch. Our experimental results agree well with our simulator predictions.