Polarization-dependent gain due to signal-signal Raman interaction in low-PMD fiber

We study polarization-dependent gain (PDG) due to signal-signal Raman interaction (SSRI). We find that SSRI-induced PDG can be significant when the fiber polarization-mode dispersion (PMD) is low. If the PMD from the discrete optical components is also small, the accumulated PDG grows almost linearly with the number of the span.