Study of scintillation for a Gaussian beam propagating in atmospheric turbulence on Earth-space paths

On Earth-space paths, by applying a modification of the Rytov method that incorporates a spatial frequency filter function under strong fluctuation conditions, a model for the scintillation index of a Gaussian laser beam wave that is valid under moderate-to-strong irradiance fluctuations is developed. The scintillation indexes for a collimation Gaussian beam are predicted by using this analytic model, based on the ITU-R C_n² model. The results agree with theoretic expected scintillation. This scintillation model can be converted into a plane or a sphere wave scintillation index model on Earth-space paths, and also reduced to a Gaussian beam wave model on horizontal sight paths of invariable C_n².