Stimulated Brillouin scattering of spatially inhomogeneous pump radiation with a small number of nonaxial modes

It is shown that in the case of stimulated Brillouin scattering pumped by a small number of nonaxial (transverse) modes there is practically no wavefront reversal. In a theoretical analysis of this situation one has to allow for the non-Bragg terms in the equations for the interaction between the waves which show no oscillations along the longitudinal coordinate.