Localization of Stimulated Brillouin Scattering in Random Phase Plate Speckles

This paper presents the first experimental evidence of the transverse localization of stimulated Brillouin scattering (SBS) emission to the laser beam axis, demonstrating that only a few small regions of plasma contribute to the emission. As a consequence, SBS reflectivity of these regions is much higher than the average SBS reflectivity, by a factor of ~50--100. These observations are consistent with the recent concept of SBS growing mainly in ``active'' speckles, having an intensity higher than the average laser intensity.