Coherent optical focal plane array receiver for PPM signals: investigation and applications

The performance of a coherent optical focal plane array receiver for PPM signals under atmospheric turbulence is investigated and applications of this system are addressed. The experimental demonstration of this project has already been explained in previous publications. This article shows a more exhaustive analysis of the expressions needed to obtain the Bit Error Rate (BER) for the real system under study in the laboratory, specifically an approach using the Saddle-Point approximation of the Marcum-Q function. Selected experimental results of this system are described and compared with theoretical BER expressions, and array combining gains are presented. Receiver sensitivity in terms of photons per bit (PPB) is examined; BER results are shown as a function of signal to noise ratios (SNR) as well as a function of photons per bit.