Impact of laser phase noise on the performance of a (3*3) phase and polarization diversity optical homodyne DPSK receiver

An analysis of the impact of laser phase noise on the performance of a (3*3) phase- and polarization-diversity differential phase-shift keying (DPSK) receiver is done for the phase and shot-noise limited case. The results show that, for zero laser linewidths, the maximal signal power penalty of the (3*3) phase- and polarization-diversity DPSK receiver with respect to the conventional heterodyne DPSK receiver is approximately 0.7 dB for P/sub e/=10/sup -9/. For nonzero laser linewidths, it appears that, depending on the laser linewidth, for large signal-to-noise ratios the performance of the analyzed (3*3) phase- and polarization-diversity DPSK receiver is close to that of the ideal conventional heterodyne DPSK receiver. For a rectangular intermediate-frequency filter, the maximum allowable normalized laser linewidth ( Delta upsilon *T) for the (3*3) phase and polarization diversity DPSK receiver is found to be approximately 0.46% for a power penalty of 1 dB.>