Optimum dispersion mapping of single-channel 40 Gbit/s return-to-zero differential phase-shift keying transmission systems.

We present a numerical study of the performance of 40 Gbit/s return-to-zero differential phase-shift keying (RZ-DPSK) transmission with different dispersion maps. The optimum dispersion mapping for RZ-DPSK format are discussed and compared with those for on-off keying (OOK). Two pseudo-linear transmission systems, one using standard single-mode fiber and the other nonzero dispersion-shifted fiber, are investigated, respectively. In principle, the optimum dispersion mapping for RZ-DPSK format is different from that for OOK and depends on intra-channel four-wave mixing and nonlinear phase noise.