Influence of Phase Noise and Interchannel Interference on the Performance of Optical Heterodyne FSK Receiver

The moments approach is generally considered a systematic way to perform the analysis of coherent optical systems. Exact moments of the filtered signal corrupted by phase noise enable the construction of the Gaussian quadrature rule, which may be used to calculate the system error probability. In this paper, we extend the method to a wider class of systems to include the cases where the interchannel interference may be significant. We derive the essential equations in the matrix form and compare the moments approach with numerical simulation and Fokker-Planck approach. To illustrate the results, we apply the moment's method to two-channel optical heterodyne FSK system with dual-filter receiver structure, and evaluate the required channel spacing to have less than 1 dB penalty due to crosstalk.