Analysis of BPSK homodyne receivers based on modified dither optical phase-locked loop

Abstract

Optical homodyne receivers based on modified Dither Optical Phase-Locked Loop is analyzed taking into account the laser phase noise, photo detectors shot noise and the dither signal. This modified loop contains all the components of a standard Dither OPLL in conjunction of an additional phase modulator. This modified loop considerably improves the performance of the homodyne reception technique over the earlier technique with the help of commercially available external cavity lasers with line-width of about few hundred kHz. This modified dither OPLL seems a realistic approach for receiving modulated signal for inter-satellite communication systems. This modified technique provides the advantage of low weight, small size and above low cost because the proposed technique significantly reduces the requirement of very narrow line-width lasers. This modified dither loop shows good improvements in the reduction performance over previously reported methods, like, less system power penalty, relaxed line-width requirement.