Applications of optical phase conjugation in robust optical transmission systems

In this paper, WDM transmission experiments are discussed showing simultaneous compensation of nonlinear effects and chromatic dispersion through optical phase conjugation (OPC). The performance of OPC and DCF for chromatic dispersion compensation are compared in a wavelength division multiplexed (WDM) transmission link with 50-GHz spaced 42.8-Gb/s RZ-DQPSK modulated channels. The feasible transmission distance for a Q-factor ∼10 dB is limited to approximately 5,000 km and 3,000 km for the OPC and the DCF based configuration, respectively. When the Q-factor as a function of the transmission distance is observed, at shorter distances, the Q-factor of the OPC based configuration is about 1.5 dB higher than that of the DCF based transmission system. Up to 2,500-km transmission a linear decrease in Q is observed for both configurations. After 2,500-km transmission, the Q-factor of the DCF based configuration deviates from the linear decrease whereas the OPC based performance is virtually unaffected.