Optimized filtering for AMI-RZ and DCS-RZ SSB signals in 40-Gb/s/ch-based UDWDM systems

Optical sideband suppression. filtering is proposed for alternate-mark-inversion return-to-zero (AMI-RZ) and duobinary-carrier-suppressed-RZ (DCS-RZ) coding formats as a solution for improving the performance of 40-Gb/s/channel with 50-GHz channel spacing wavelength-division-multiplexing systems. A suppressed sideband power ratio exceeding 20 dB is achieved by both formats; hence, these filtered signals are single-sideband (SSB) signals. Simulation results reveal that AMI-RZ-SSB and DCS-RZ-SSB signals exhibit similar nonlinear transmission performance and better dispersion-compensation-ratio tolerance relative to the duobinary signal. After 8 x 80 km of low-cost transmission spans and considering easy configurations at the transmitter and receiver, a Q factor around six remains attainable by both SSB signals.