Investigating the Probability Density Function of the Detected Intensity of Overlapping Laser Sources in an FSO Turbulent Environment

Free space optical (FSO) communication systems are an attractive alternative for wireless communication links. A turbulent FSO channel can be modeled by a gamma-gamma probability density function (pdf. However, when two or more overlapping lasers that have the same central frequency but have random polarization and phase angles, the gamma-gamma pdf cannot represent the intensity In this paper we investigate via Monte Carlo Simulation the effect of both the beat noise and turbulence on the detected pdf when a FSO system uses a number of overlapping lasers. Results show that the beat noise is the dominant source of noise, while a turbulent channel A gamma pdf can give a good approximation of the intensity when the number of overlapping lasers is greater than sixteen, otherwise, the empirical pdf is provides a better estimate.