Bit-rate dependent performance degradation of the long-haul RZ-DPSK system using block type dispersion map.

Bit-rate dependent performance degradation was observed in the long-haul RZ-DPSK system using the block type dispersion map. The performance was degraded near the system zero dispersion wavelength, and it showed a spectral performance hole near the zero dispersion wavelength. The existence of the hole did not depend on the spectral efficiency of the system, but it depended on the bit-rate. The hole existed for lower bit-rate up to 5 Gbit/s, but disappeared more than about 15 Gbit/s.