Statistical Investigation of Polarization Dependent Loss for Coherent Polmux QPSK Transmission

Coherently detected polarization-multiplexed (CP) division multiplexing of quadrature phase shift keying (QPSK) modulation format (CP-QPSK) together with DSP has been considered as a very promising technique for next generation optical networks. However, CP-QPSK suffers the penalty from polarization dependent loss (PDL), which result in polarization dependent power fluctuations and hence degrade the system performance as well as the stability. In this work, based on intensive simulations and experiments, the impact of PDL on 40G CP-QPSK is investigated theoretically and statistically.