Effects of spatial and temporal smoothing on stimulated Brillouin scattering in the independent-hot-spot model limit

The influence of laser beam smoothing on stimulated Brillouin backscatterin g (SBBS) is studied analytically in the limit of the independent hot spot m odel. It is shown that the temporal beam smoothing can reduce the SBBS refl ectivity significantly even though the laser bandwidth is smaller than the growth rate for the average intensity. The explanation of this reduction ef fect is given in terms of SBBS growth in the statistically significant hot spots. The minimum laser bandwidth corresponding to an important reduction of the reflectivity is thus determined properly. The dependence of this red uction effect on the acoustic damping for a given laser bandwidth is discus sed.