Strong fluctuations of fields of optical beams in randomly inhomogeneous media

Asymptotic expressions are obtained for the characteristics of optical beams determined by the fourth moment of the field; this is done for an arbitrary spectrum of fluctuations of the permittivity of the medium. A study is made of the influence of the beam dimensions and of the inhomogeneity micro- and macroscales on the variance of the intensity fluctuations. A statistical far-field zone, where the beam characteristics cease to depend on the initial conditions, is described. An asymptotic expression is obtained for the intensity correlation function and this is used to investigate fluctuations of the power recieved by an aperture and wandering of the center of gravity of the beam in the region of strong intensity fluctuations. Numerical calculations are made of the beam characteristics and these are compared with experimental data.