Optimal signal receiving technology based on APD in atmospheric laser communications

Abstract

Abstract The intensity fluctuation of atmospheric turbulence significantly affects the performance of the laser communication system. To suppress the turbulence effect, we propose an avalanche photodiode (APD) optimal gain formula under the turbulence channel, taking the real-time received signal-to-noise ratio (SNR) as the evaluation parameter of the turbulence channel’s state. Based on this formula, we design a model of the optimal optical signal receiver in the atmospheric channel, utilizing the Fuzzy-Pi control mechanism to adapt to the nonlinear properties caused by turbulence. The experimental results show the feasibility and advantages of the control mechanism. In addition, when turbulence is weak, as Rytov variance is equal to 0.145, the variance of light intensity flicker is lowered from 0.1353 to 0.103. As Rytov variance rise to 1.068, the variance of light intensity flicker decreased from 0.6547 to 0.32.