Symmetry Enhancement Through Advanced Dispersion Mapping in OPC-Aided Transmission

In this work, we present a novel strategy to satisfy the nonlinearity compensation criteria by optical-phase-conjugation (OPC). Contrary to the most common approach, which relies on tailoring power profiles using distributed Raman-amplification, we achieve the required OPC propagation symmetry through optimized dispersion management across the link. The method is applied to transmission systems with periodic lumped amplification, and the symmetry enhancement is directly translated into a substantial increase in the OPC compensation gains. This study is based on a numerical analysis combined with experimental validation of the findings. The numerical part provides a comprehensive overview of different dispersion management techniques, and compares them against the symmetric schemes we propose. It is consistently shown that the symmetry-optimized systems provide the best performance when OPC is included, with the signal-to-noise ratio (SNR) gains reaching up to 6.6 and 5.2 dB for transmission of a single and seven wavelength channels, respectively. These results are verified in an experimental investigation, where we implemented and compared a standard dispersion mapping scheme to the optimized design. For all distances considered, the optimized link is demonstrated superior once OPC is included, leading up to 1.9 dB improvement in SNR for seven-channel transmission.