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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 × 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 × 40 Gb/s) propagated with > 3-dB FEC margin. Moreover, it was shown that parallel launch only suffered a penalty of ∼ 0.2 and ∼ 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. [ABSTRACT FROM PUBLISHER]

This work presents the first field trial using the return-to-zero differential-phase-shift-keying (RZ-DPSK) modulation format. A 96×10-Gb/s RZ-DPSK field trial was conducted over a 13 100-km optical undersea path by double passing the installed 6550-km underwater link which was deployed with non-slope-matched submarine fibers. All channels performed with more than a 3-dB forward-error correction margin, including channels that accumulated over ±13 000ps/nm of dispersion. It is also shown that the RZ-DPSK format has similar residual dispersion and channel power tolerance for both slope-matched and non-slope-matched fibers. Furthermore, it is demonstrated that the chirped RZ-DPSK format could further improve system performance by 1-2 dB. [ABSTRACT FROM PUBLISHER]

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 38×40 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. [ABSTRACT FROM PUBLISHER]