Correlations of photon trajectories in the problem of light scintillations

TL;DR

This paper develops a kinetic equation approach to analyze photon trajectory correlations in laser beam scintillations through Earth's atmosphere, revealing how trajectory correlations significantly influence scintillation index growth.

Contribution

It introduces an iterative scheme based on photon trajectory correlations to calculate the scintillation index, bridging theoretical and computational methods.

Findings

Trajectory correlations cause significant growth in scintillation index.

The approach applies to both coherent and partially coherent light.

Criteria for the method's applicability are established.

Abstract

A distribution function approach is applied to describe the dynamics of the laser beam in the Earth atmosphere. Using a formal solution of the kinetic equation for the distribution function, we have developed an iterative scheme for calculation of the scintillation index ($\sigma^2$). The problem reduces to obtaining the photon trajectories and their correlations. Bringing together theoretical calculations and many-fold computer integrations, the value of $\sigma^2$ is obtained. It is shown that a considerable growth of $\sigma^2$ in the range of a moderate turbulence is due to the correlations of different trajectories. The criteria of applicability of our approach for both the coherent and partially coherent light are derived.