Stimulated scattering with distributed feedback in a scattering medium

The effect of a distributed feedback on stimulated Brillouin scattering (SBS) is considered. The feedback is due to linear scattering by random inhomogeneities or microinclusions in the medium. A theoretical analysis is made taking account of focusing, in this medium, of laser pump radiation with different degrees of spatial coherence. It is shown that, in spite of the beam attenuation on increase in the scatterer concentration, the SBS threshold may decrease because of the distributed feedback. The range of conditions under which this effect can appear is determined. A well-defined maximum of the SBS efficiency, considered as a function of the scatterer concentration, can be used to obtain information on the scattering inhomogeneities.