On the speckle correlation in nonlinear random media

We calculate the intensity-intensity correlation functions for the light tr ansmitted through a slab made of a nonlinear and random medium at the lowes t order of the nonlinear interaction. We obtain the short-range correlation function as a function of the intensity and angles: it depends on a charac teristic length of the nonlinear system. This characteristic length decribe s the loss of correlation due to the phase shift through the change of the refractive index inside the nonlinear random medium.