<title>Carrier recovery and filtering in optical BPSK systems using external cavity semiconductor lasers</title>

Abstract

An optical binary phase-shift keying (BPSK) heterodyne receiver using synchronous demodulation by means of a squaring loop carrier synchronizer is analysed.A detailed modelling of the phase error is performed taking into account the influence of additive noise and non-Lorentzian laser phase noise from external cavity semiconductor lasers.The effect of filtering on the baseband signal is also examined. It is found that the filter decreases the impact of laser phase noise, namely by reducing the degradation due to relaxation oscillations.