Laser-beam scintillations for weak and moderate turbulence

TL;DR

This paper derives a quantum optics-based model to accurately calculate laser-beam scintillations in weak to moderate atmospheric turbulence, revealing higher scintillation indices than traditional approximations.

Contribution

It introduces a first-principles kinetic equation approach for laser scintillation in turbulence, improving accuracy over existing models.

Findings

Scintillation index is higher than Rytov approximation predicts.

Analytical solutions for photon distribution function are obtained.

The model explains the increased scintillation in moderate turbulence.

Abstract

The scintillation index is obtained for the practically important range of weak and moderate atmospheric turbulence. To study this challenging range, the Boltzman-Langevin kinetic equation, describing light propagation, is derived from first principles of quantum optics based on the technique of the photon distribution function (PDF) [G. P. Berman et al., Phys. Rev. A 74, 013805 (2006)]. The paraxial approximation for laser beams reduces the collision integral for the PDF to a two-dimensional operator in the momentum space. Analytical solutions for the average value of PDF as well as for its fluctuating constituent are obtained using an iterative procedure. The calculated scintillation index is considerably greater than that obtained within the Rytov approximation even at moderate turbulence strength. The relevant explanation is proposed.