Impact of PMD on four-wave-mixing-induced crosstalk in WDM systems

The impact of polarization-mode dispersion (PMD) on four-wave mixing crosst alk in wavelength division-multiplexed (WDM) fiber systems is quantified On a commercial system. It is found that even a small amount of PMD reduces t he benefit of using polarization-multiplexed channels for suppression of cr osstalk, As a rule of thumb, it is suggested that polarization-multiplexed schemes are of significant interest only when system differential group-del ay (DGD) is smaller than DGD < 1/(4 Delta f), where Delta f is the channel- spacing.