Self-phase modulation in high-power stimulated Brillouin compression

The spectrum of the stimulated Brillouin-compressed subnanosecond laser radiation is studied experimentally in a wide range of pump intensities up to the eightfold threshold value. It is found that at intensities increasing four times the threshold, the spectrum splits and acquires a two-humped shape, which is explained by the phase modulation near the Brillouin resonance. Analytical model of self-phase modulation in stimulated Brillouin compression is developed, which describes the observed spectral splitting and formation of the frequency chirp. (C) 2011 American Institute of Physics. [doi:10.1063/1.3559624]