Orbital angular momentum of a laser beam in a turbulent medium: preservation of the average value and variance of fluctuations

The process of the propagation of vortex laser beams in a turbulent atmosphere with recording of the total orbital angular momentum (OAM) and determination of the beam's statistical characteristics, such as the average over realizations of the turbulent medium and the variance of fluctuations, has been simulated numerically. The dependences of OAM fluctuations on the turbulence intensity and the initial topological charge of the beam have been obtained. Numerical results are compared with the earlier asymptotic estimates.