Comparison of Performance of SSB-AMI-RZ Formats in Long-Haul 40 Gbit/s/channel UDWDM Transmission Systems

The transmission performance of single-sideband alternate mark inversion return-to-zero (SSB-AMI-RZ) formats, with duty-cycles of 15%, 30% and 50%, in long-haul 40 Gbit/s/channel ultra dense WDM systems with 50 GHz of channel spacing is assessed through systematic numerical simulation. After optimizing the bandwidths and detuning of optical multiplexer and demultiplexer, the dispersion maps are optimized for each duty-cycle. From these, the tolerances to the in-line residual dispersion (IRD) and total residual dispersion (TRD), and the nonlinear thresholds (NLT) are assessed. It is shown that the different SSB-AMI-RZ formats have high tolerance to linear crosstalk, due to a - 20 dB bandwidth much smaller than the channel spacing, and similar tolerance to IRD. Numerical results indicate that the format with duty-cycle of 15% outperform the others because of its better tolerance to TRD and higher NLT.