Analysis of Phase Recovery Algorithms for DP-QPSK Optical Receivers

This paper compares the performance of phase re- covery techniques for optical dual-polarization quadrature phase- shift keying (DP-QPSK) coherent receivers, using simulated and experimental data. In particular, we investigate the following phase recovery techniques: the Viterbi & Viterbi feedforward (V&V) algorithm; the decision-directed (DD) algorithm; and a hardware efficient feedforward algorithm. We find that 10 tap filters are sufficient for a satisfactory performance of both DD and V&V algorithms, and that the hardware efficient algorithm presents a minimum penalty, com- pared to the V&V algorithm, for a 5 tap filter size. The problem of obtaining the SNR at the receiver from a set of noise corrupted samples is also addressed.