Transformation of the spatial statistics of a partially coherent beam under conditions of transient thermal self-interaction

The Monte Carlo method and analytic techniques are used to investigate thermal self-interaction of multimode pulsed optical radiation. The transformation of the intensity profile, the spatial coherence radius, and the variance of the beam intensity fluctuations are studied. It is found that as the spatial coherence of the beam deteriorates, the influence of the nonlinearity of the medium on the intensity fluctuations and the coherence of the radiation decreases. The range of validity of the analytic expressions is determined by comparing the numerical and analytic results.