A novel detection strategy for optical receivers with focal plane array

In this paper, the problem of optimizing the performance of a free-space optical system with large field of view (FOV) focal plane array is addressed. A large FVO detector is desired when beam tilt, large pointing inaccuracies, or other impairments leading to uncertainties in the angle of arrival of the beam are present. For such an arrangement, when we consider a large aperture size, which results in a small diffraction-limited FOV, a large number of photo-detectors in the array are exposed to background radiation only. In addition, in adaptive optics system without a wave-front sensor (WFS), one has to contend with the same issue when large FOV system with small diffraction-limited FOV is considered. Hence, detection strategies to deal with the excess background noise in this scenario is of interest in this paper. We assume here that the receiver is utilizing a recently proposed technique to identify the presence and the location of the beam footprint in the focal plane, thereby reducing the “area” of consideration in the focal plane to a subset of the total photodetectors. It is shown here that, when the proposed receiver is utilized, one can expect an improvement in the overall bit error rate of several orders of magnitude as compared with the standard array detector.