Broadening of the stimulated Brillouin spectrum in wavefront reversal

An experimental investigation was made of the behavior of the spectral width (integrated during a laser pulse) of a stimulated Brillouin scattering line excited with and without wavefront reversal. Anomalous broadening of the stimulated Brillouin spectrum was attributed to phase modulation of the scattered and exciting radiation pulses because of thermal absorption. Quantitative theoretical estimates ensured a satisfactory agreement with the experimental results.