Calculation of the spatial characteristics of radiation emitted by a laser with an unstable resonator containing random small-scale phase inhomogeneities

A numerical study is made of the influence of random small-scale phase inhomogeneities on the angular divergence of the radiation and the structure of the field of the lowest mode emitted by a laser with an unstable resonator. It is shown that the scattering of laser radiation on such inhomogeneities gives rise to a small-scale jaggedness of the intensity and field of the lowest mode, accompanied by the appearance of strong wings in the angular distribution. It is also demonstrated that for certain parameters of the resonator and small-scale inhomogeneities the angular divergence can increase by an order of magnitude compared with the diffraction limit when rms fluctuations of the optical path amount to just λ /20.