Scintillation Index of a Gaussian Schell-Model Beam on Slant Atmospheric Turbulence

Based on the altitude-dependent model of the ITU-R slant atmospheric turbulence structure constant model, we present scintillation index calculations for a partially coherent Gaussian Schell-model (GSM) beam under all irradiance fluctuation conditions. The longitudinal and radial components of the scintillation index are treated separately. Our results correctly reduce to the result of the horizontal path with atmospheric structure constant fixed; and simplify to a fully coherent Gaussian beam with source coherence parameter ζ representing unit. The numerical conclusions indicate that within specific source and parameter ranges, a partially coherent GSM beam is capable of offering less scintillation in comparison with the full coherent Gaussian beam. Before the maximum value of the scintillation, the scintillation index of the partially coherent GSM beam will decrease with the increased altitude. However the off axis radial scintillation index will vanish when the Rytov variance is infinity.