Mitigation of polarization-mode dispersion in optical multichannel systems

Simulations of first-order polarization-mode dispersion (PMD) mitigation, based on the electrical power spectrum has been performed. We show that, although first-order compensation significantly improves the signal quality for PMD values of a few tenths of the bit-slot, the improvement still is deficient for telecom purposes when the PMD value neighbors a third of the bit-slot. We, therefore, propose and analyze a novel concept for PMD mitigation in optical multichannel systems, which increases the systems reliability at the expense of the total capacity for the same system. With the proposed method, which uses switching to redundant channels based on measurements of signal quality of all channels in the actual system, the PMD value can be increased to a half of the bit-slot while still keeping the probability for signal outage at acceptable low levels. In the appendixes we simulate the statistical impact of different PMD-emulator models and we show that static bit sequences may induce notches in the electrical power spectrum. These notches may obstruct the extraction of feedback signals for PMD-mitigator schemes based on electrical power spectrum.