A phase-space approach for propagating field-field correlation functions near stochastic sources

Radiation from complex and inherently random but correlated wave sources can be modelled by exploiting the connection between correlation functions and the Wigner function. Wave propagation can then be directly linked to the evolution of ray densities in phase space. We discuss here in particular the role of evanescent waves in the near-field of non-paraxial sources. We give explicit expressions for the growth rate of the correlation length as function of the distance from the source.