Detection Method of Focal Plane Arrays With Noise Suppression for Optical Communications

In many optical communication systems, in order to make the optical networking convenient and meet the application requirements, the optical terminals need to work in the same band and at the extremely closely adjacent working wavelengths. In practice, because of the light reflection and scattering of the wireless channels with the suspended particles, parts of the emitted optical signals will be reflected to the focal plane array (FPA). On the other hand, because the bandwidth of practical optical filters cannot be made narrow enough, or the sensitivity of FPAs is usually very high, the isolation between the transmitting and receiving optical paths in the terminal cannot be made high enough even if the optical filtering is used. Both the received optical signal from the remote terminal and the transmitted optical signal reflected by the terminal or wireless channels will be detected by the FPA at the same time. The reflected optical signal will interfere with the detection of the received optical signals from the far end, which seriously reduces the detection performance and the accuracy of the light spot centroid calculation. This paper proposes an integral control and increase-decrease counting statistical method for FPAs to eliminate the influence of the reflected optical signal on the signal detection and the noise mean value in the mean value of the total detection signal. The detection sensitivity of the received signal from the remote terminal, the isolation of the transmitting and receiving paths and the accuracy of the light spot centroid calculation are improved by this method. The Cramer-Rao lower bound is calculated and analyzed. In addition, the integral control and increase-decrease counting statistical algorithm is verified by the two software co-simulation, and the simulation results are given to illustrate the feasibility and performance of this method.