Stimulated Brillouin Scattering (SBS) is one of the most common nonlinear optical processes for achieving Phase Conjugating Mirror (PCM). Phase conjugating SBS mirrors are simple self-pumped devices that can easily be applied in double-pass amplifier configurations as high-reflecting mirrors. 

The wavefront inversion with respect to the propagation direction of the light, the phase conjugation, allows for the compensation of phase distortions from, for example, the active material in solid-state lasers in the second pass. As result, almost ideal wavefronts can be obtained at the output of such lasers. 

The beam quality of such laser systems containing phase conjugating SBS mirrors can be diffraction-limited, although the phase distortions from the highly pumped and thus strongly thermally stressed active material would not allow beam propagation factors better than 10. 

Besides phase conjugation mirror the SBS cells can be applicable for another important phenomenon called SBS pulse compression. The SBS pulse compression is based on the ability of an SBS-active material to amplify the leading edge of a backward Stokes pulse in the field of forward-propagating pump beam.

For more information follow the link: https://www.geola.com/product/sbs-phase-conjugating-cells/