A Proposed Receiver Structure for Optical Communication Systems that Employ Heterodyne Detection and a Semiconductor Laser as a Local Oscillator

Abstract
Coherent heterodyne detection in optical communication is degraded by phase instabilities present when a semiconductor laser is used as a local oscillator. Postdetection processing that accounts for these instabilities is suggested, based on a diffusion-process model for oscillator instabilities and a maximum-likelihood sequence-estimator of information symbols modulating the received light.