Impact of Signal Waveform Distortion on the System Performance of Optical Costas Type PLL Receivers

Abstract

The receiver performance of optical Costas PLL's is evaluated accounting for the effects of laser phase noise, shot noise and the data-to-phaselock crosstalk induced by signal waveform distortion. In contrast to the conventional discussion in which the received signal data is a sequence of square pulses, this paper for the first time investigates the problem encountered in BPSK homodyne communication systems with Costas PLL's as the received signal data is not a sequence of square pulses but is a sequence of distorted pulses. The signal waveform distortion induces additional amount of phase error variance and henceforth an incresae in bit-error rate, resulting in a more stringent laser linewidth requirement. The laser linewidth requirement is evaluated here taking into account such an effect of signal waveform distortion.