Formation of high-quality XeCl laser radiation in a cavity with an SBS mirror

An experimental investigation was made of a XeCl laser with a cavity formed by a semitransparent plane mirror and a stimulated-Brillouin-scattering (SBS) medium. Spatial and spectral selection by the SBS mirror resulted in the formation of narrow-band highly directional radiation representing a superposition of converging and diverging beams. Each beam was amplitude-modulated at intervals of time corresponding to two round trips through the cavity and it consisted of a set of spectral lines 0.3 cm^-1 wide, distributed over an interval of two SBS frequency shifts. About 30% of the energy of each beam was within the diffraction angle. The total output energy was 10 mJ when the pulse duration was 120 ns.