Stimulated Brillouin scattering dependence on polarization state, speckle shape, and polarization smoothing implementation

Abstract

Laser beam smoothing is a key element to enhance laser plasma hydrodynamic coupling in the context of high energy density physics experiments carried out in Inertial Confinement Fusion Facilities. Here, we experimentally study the effects of different polarization smoothing implementations on the Stimulated Brillouin Backscattering (B-SBS) and the transmission of a laser beam using the LULI2000 laser facility. First, we show that the polarization state (linear or circular) has no effect on B-SBS and transmission. We also show that under our experimental conditions, both the statistical average laser power carried by the speckle spots and their statistical average shape provide information on the effectiveness of the laser beam smoothing configuration. These findings open new paths for the optimization of high-power laser beam smoothing techniques on existing and future laser facilities.