Experimental investigations of stimulated Brillouin scattering beam combination

We conducted an experimental investigation of beam combination of two beams by stimulated Brillouin scattering (SBS) to determine the conditions under which good phase locking, piston conjugation, and aberration correction could be achieved. Test parameters that were varied included bandwidth, f-number, near- and far-field separation between beams, power ratio between beams, beam aberrations, and polarization mismatch between the beams. The experiments were performed at 532 nm with n-hexane as the SBS medium. Piston-conjugation accuracy was measured by using fringe stability with conventional interferometry and by using extinction in a wave-front-reversing interferometer. The best piston conjugation was obtained when we maximized the overlap of the SBS interaction volumes of the two beams by minimizing the beam separation in the near and the far fields.