Analysis of EEPN-Induced Phase and Amplitude Distortions in Coherent Optical QPSK Systems

We thoroughly examine intra- and inter-symbol EEPN and calculate the variances of EEPN-induced phase, amplitude noise, and their ratio for coherent QPSK signals. We also provide the phase-compensated EEPN following blind phase search (BPS). All theoretical proofs are validated through simulation.