Experimental study on SBS-PCM at 200 Hz repetition rate pumped with joule-level energy

Abstract In this paper, an experiment is designed to research the properties of the stimulated Brillouin scattering phase conjugation mirror (SBS-PCM) working under joule-level pump energy and 200 Hz repetition rate. The nonlinear medium FC-770 is chosen as the SBS medium working in high-power condition. Due to the excellent preparation process and ultra-filtration technology for SBS-PCM, there is no optical breakdown phenomenon under the reflectivity maintained at 98% under 200 Hz and pump energy from 500 mJ to 1100 mJ. Under 800 mJ pump energy, the diffraction fringes of the near-field pattern are reduced and the beam quality of the laser beam has been improved to 1.42 times diffraction limited after the double-pass amplification from the single-pass 2.01 times diffraction limited. The incident and reflected pulse width are becoming wider with pump energy increasing. When the pump energy reaches a certain extent, the reflected pulse width will become nearly approximate to the incident pulse width. When the pump energy is 800 mJ, the pump pulse width is 40.3 ns and the output pulse width is 38.8 ns.