Wavefront reproduction by stimulated Brillouin and Raman scattering

Experimental investigations were made of the wavefront reproduction process (WFR) by backward stimulated Brillouin scattering (SBS) and backward stimulated Raman scattering (SRS)in CS2 with a linearly polarized ruby pump beam. The experimental studies were carried out as a function of the power pump into the cell, the diameter of the optical waveguide, the length of the optical waveguide, and the frequency shift, between the pump and backscattered beams for both CS2 and C7H6O. Photographic records comparing the pump beam with the backscattered SBS and SRS beams were obtained over several orders of magnitude of exposure and quantitative measurements of percentage of nonreproduced radiation in the backscattered beams were made. In all of the cases studied there was a high degree of replication observed between the SBS and pump beams using both non-Gaussian and near-Gaussian incident laser profiles. In all of the cases studied the efficiency of the WFR process by backward SBS was better than 85% and it improved as the pump intensity was increased and the frequency shift was decreased. Neither the diameter nor the length of the optical waveguides utilized in these experiments appeared to significantly influence the efficiency of the WFR process by backward SBS.