Dynamics of power and coherence characteristics for partially coherent beams in nonlinear media

Abstract

The beam dynamics for equal power ray tubes and equal coherence ray tubes is investigated for the partially coherent radiation propagating in non-linear media. The Gaussian beam propagation through media with Kerr non- linearity and thermal blooming is considered on the basis of the solution of the equation for coherence function of the second order. Calculations are adduced for the two- dimensional beam. The dimension of a coherence function decreases from five down to three for this case. Consequently, the numerical solution of this equation is possible by means of the method of a separation on physical factors, widely using for a solution of the parabolic wave equation, with using the algorithm of fast Fourier transformation. The comparable analysis of the equal power and equal coherence ray tubes behavior is carried out. The same analysis is carried out for solutions of the equation for coherence function obtaining by the ray-tracing technique allowing to create effective numerical algorithms for the three dimensional problem. The technique is asymptotically exact since it gives exact solutions at limiting cases when the coherence length tends to zero or when the distribution of complex dielectric constant of medium has the parabolic form.