Characterizing Filtered Light Waves Corrupted by Phase Noise

The phase noise associated with single mode semiconductor lasers must be accounted for in performance studies of lightwave communication systems. The standard phase noise model is a Brownian motion stochastic process. Although many analyses of lightwave communication systems have been published, none, to our knowledge, has fully adhered to the standard model. The reason is that a proper characterization of a filtered lightwave signal had not been achieved. Such a characterization, along with theoretical approaches to obtaining it, are detailed here. We shoe, for example, how to generate probability distribution functions (pdf's) of the magnitude of a filtered laser tone (with special attention to the tail region) and how to analytically represent the characteristic function of the pds in closed form in the small-phase-noise realm. With the characterization in place, the stage is now set for determining the BER performance of advanced detection techniques which seek to mitigate the phase noise impairment.