Researching pointing error effect on laser linewidth tolerance in space coherent optical communication systems

Abstract

In order to evaluate the pointing error effect on laser linewidth tolerance in a space coherent optical communication system, we derive a closed-form bit error rate (BER) model for binary phase-shift-keying (BPSK) modulation and heterodyne detection, under atmospheric turbulence, pointing error and laser phase noise. Based on the BER model, the linewidth tolerance is given, and numerical simulation is conducted. We find that laser linewidth tolerance decreases greatly with the increase of pointing error. Considering that pointing error consists of jitter and boresight, the effect of jitter and boresight are discussed separately and jointly in detail. Our results show that laser linewidth tolerance is more sensitive to the jitter variation than the boresight variation. In addition, with the increasing of the pointing error, the linewidth tolerance decreases faster under the large pointing error as compared to the case under the small pointing error. This paper is a good reference for designing space coherent optical communication systems.