High performance configuration of all-raman N × 40 Gbit/s RZ-DPSK systems over ultrawave<sup>TM</sup> maps

In order to explore the impact of the DPSK format on best system configuration, and to cross-check the simulation tools, transmission experiments involving 16 × 40 Gbit/s WDM channels on a recirculating loop including a symmetric UltrawaveTM fiber dispersion map are performed. In these experiments the RZ-DPSK format is used, and each 100 km span is brought to optical transparency with 75%(25%) of backward (forward) Raman gain. The pre-compensation is experimentally varied, and a significant transmission improvement after 4000 km for the pre-compensation of -350 ps/nm is observed.