Performance Analysis of Acousto Optical Modulator-Free Space Optical System Over Gamma-Gamma Turbulent Channel

Acousto optical modulator (AOM) is proposed recently to externally modulate the laser beam in free space optical (FSO) system. The idea is to control the laser beam diffraction angle by a sequence of incoming bits, which controls the frequency of the acoustic wave propagating inside the Bragg cell. At the receiver, multiple photo diodes (PDs) are installed, where each is aligned to one of the pre-designed diffracted angles [1]. Superior performance are already reported over lognormal and negative exponential fading channels. In this study, the performance of AOM-FSO system is analyzed over Gamma-Gamma (GG) turbulent channel. Closed form expression of the average bit error rate is obtained in terms of Meijer's G function and analytical results are corroborated through Monte Carlo simulation results. In addition, the impact of atmospheric turbulence, separation distance between PDs and link range are studied.