Nonlinear backscattering from opaque media

The angular distribution of light scattered from an opaque medium is considered in the case in which the medium is both nonlinear and disordered. It is shown that at the top of the linear backscattering peak there should be a narrow dip in the scattered intensity due to the simultaneous effects of nonlinearity and weak localization. The relative depth of this dip is proportional to the imaginary part of the nonlinear constant ${\mathrm{\chi }}^{\mathrm{}\left(3\right)\mathrm{}}$ and the intensity of the incident light.