Adaptive phase correction of vortex lasers beams in a turbulent atmosphere

A theoretical possibility of correcting amplitude--phase distortions of Laguerre–Gaussian (LG) laser beams on atmospheric paths is studied by computer simulation. Use is made of a dynamic adaptive correction scheme based on the principle of phase conjugation of the reference wave from an auxiliary coherent source. By numerically solving the inhomogeneous parabolic wave equation, the propagation of beams in a randomly inhomogeneous medium with a power-law spatial spectrum, characteristic of atmospheric turbulence, is simulated. The scalar wave equation is solved by the split-step method with 2D fast Fourier transform algorithm using parallel architecture. The effect of atmospheric turbulence on fluctuations of the orbital angular momentum (OAM) of the vortex LG beam is considered, and its possibility is theoretically demonstrated. The efficiency of minimising the fluctuations using an adaptive optical system of phase conjugation of the reference wave is estimated. The paper notes the role of Academician N.G. Basov on organising systematic studies of the propagation of coherent optical waves in the atmosphere as a randomly inhomogeneous medium.