Dmitri Foursa

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 96×100G pre-filtered PDM-RZ-QPSK channels with 300% spectral efficiency over 10,608km and 400% spectral efficiency over 4,368km

We transmitted 96 × 100 G pre-filtered PDM-RZ-QPSK channels with 300% spectral efficiency over 10,608 km using 52 km spans of 150 μm2 fiber and simple single-stage EDFAs. We also achieved 400% spectral efficiency over 4,368 km using similar techniques.

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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We present an experimental investigation of 40 Gb/s transmission technology aimed at an aggregate capacity exceeding 1 Tb/s over multithousand kilometer transmission distances. These studies have been performed using a variety of dispersion management and modulation techniques. The transmission distances investigated range from a minimum of 2000 km, which is considered a regional undersea cable distance, up to a transatlantic distance of 6200 km. Our regional distance experiments were performed using both slope-matched and conventional dispersion maps where the accumulated dispersion becomes large for the edge channels. Dispersion map studies showed that slope-matched fiber performs better than nonslope-matched fiber (NZDSF) beyond 2000 km due to its larger effective area and lower accumulated dispersion slope. The demonstration of 38/spl times/40 Gb/s over 6200 km was the first transoceanic length experiment using 40 Gb/s DWDM channels. This was achieved with a relatively simple amplifier chain that uses only C-band EDFAs. Modulation format studies showed that RZ performs better over transoceanic distance, carrier-suppressed RZ performs better with nonslope-matched fiber at a distance of 2055 km, and prefiltered carrier-suppressed RZ is more suited for higher spectral efficiency. Experimental techniques for high bit-rate experiments are presented.

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

We present the first multi-terabit/s transoceanic length transmission demonstration using the RZ-DPSK format at a 10 Gb/s channel data rate. Error-free performance for 373-10 Gb/s RZ-DPSK channels after 11,000 km was demonstrated.

Long-haul 40 Gb/s DWDM transmission with aggregate capacities exceeding 1 Tb/s

We transmit 112×112 Gb/s pre-filtered PDM RZ-QPSK channels with 360% spectral efficiency over 9,360km with the channel spacing set to the baud rate. This results in a record spectral efficiency for transpacific distance.

A DWDM demonstration of 3.73 Tb/s over 11,000 km using 373 RZ-DPSK channels at 10 Gb/s

We demonstrate a pilot-symbol assisted joint polarization carrier phase estimation technique that detects cycle slip and avoid error propagation. Coherent detection without differential coding is feasible when the cycle slip probability is less than 10−3.

112×112 Gb/s transmission over 9,360 km with channel spacing set to the baud rate (360% spectral efficiency)

We transmit 106×200 Gb/s channels over 10,290 km at 6.0 b/s/Hz enabled by Nyquist spectral shaping and nonlinearity compensation. We also transmit 53×400 Gb/s channels over 9,200 km detecting two 200 Gb/s wavelengths simultaneously using a wideband receiver.

Cycle slip mitigation in POLMUX-QPSK modulation

We propose a high spectral efficiency transmission scheme employing tight pre-filtering and maximum-a-posteriori-probability (MAP) detection. We demonstrate that pre-filtering induced inter-symbol-interference can be effectively compensated with MAP detection after transoceanic transmission.

200 Gb/s and dual-wavelength 400 Gb/s transmission over transpacific distance at 6 b/s/Hz spectral efficiency

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.