Impact of PDL-induced crosstalk on 100-Gb/s polarization-multiplexed RZ-DQPSK in PMD-affected metro networks

The impact of PDL-induced crosstalk on 100-Gb/s polarization-multiplexed RZ-DQPSK performance in direct detection systems is experimentally assessed in presence of a moderate amount of PMD. In particular, RZ-interleaving and RZ-overlapping schemes have shown opposite behaviours towards PMD and PDL. Measurements carried out confirm the less robustness of RZ-interleaving than RZ-overlapping towards PMD, but highlight a much stronger tolerance of RZ-interleaving to PDL with respect to RZ-overlapping. When PDL combines with moderate PMD, as in metro networks, it is shown that RZ-overlapping high tolerance to PMD drastically fails, RZ-interleaving proving more efficient to deal with polarization issues in case of direct detection of polarization-multiplexed signals.