Influence of anisotropic factor fluctuations on the scintillation index in optical turbulence

Abstract

Atmospheric turbulence results in the degradation of performance in optical communications, with the scintillation phenomenon significantly influencing the optical link performance. Various physical parameters influence optical scintillation, such as the atmospheric refractive index structure constant, optical transmission distance, turbulence intensity, and anisotropy. In classical theoretical predictions, the anisotropic factor is often assumed to be constant over the long term. Nevertheless, anisotropic factors in real turbulence undergo temporal fluctuations, manifesting as a distribution. Consequently, it is imperative to examine the correlation between the distribution of anisotropic factors and the outcomes of scintillation. This study utilizes a semi-Gaussian distribution for sampling anisotropic factors and employs the non-Kolmogorov spectrum to develop scintillation theory for Gaussian beams in the transition region from weak to strong turbulence. The results indicate that the scintillation index may be higher than the theoretical prediction when considering the distribution of anisotropic factors in weak turbulence. Conversely, in strong turbulence, the scintillation index may be lower than the theoretical prediction, necessitating further judgment for moderate to strong turbulence.