Determination of the parameters of rotational and translational diffusion of a resonant medium by nonlinear polarization spectroscopy

A complete theoretical interpretation of the experimental data on the transformation of the polarization state of a weak wave in a layer of resonant medium (methane) depending on the intensity of high-power counterpropagating wave is presented in terms of the vector theory of radiation-matter interaction. A method for the experimental determination of the coefficients of rotational and translational gas diffusion is developed based on the theoretical calculation of two types of dichroism and birefringence and the use of experimental data on the change in the probe wave polarization at saturation of the resonant transition by the intensity of a counterpropagating wave with two different (linear and circular) field polarizations. This method also takes into account low backscattering of the strong wave field from optical path inhomogeneities.