Small-scale distortions in wavefront reversal of a beam with incomplete spatial modulation (stimulated Brillouin backscattering, theory)

A theoretical analysis is made of small-scale distortions of the scattered wave formed during wavefront reversal in stimulated Brillouin backscattering of a pump beam consisting of a strong plane wave and interfering components with an extended angular spectrum. The relative value of the distortions is mainly determined by the small parameter $g/k\theta^2$ ($g$ is the gain in reciprocal centimeters, $k$ is the wave number, and $\theta$ is the angular divergence). An investigation is made of the conditions when the addition of a plane wave to the wave with an extended angular spectrum improves and causes a deterioration in the quality of the small-scale wavefront reversal.