We have begun a study of stimulated scattering processes in critical mixtures, both single component systems near the gas-liquid critical temperature and two-component liquid mixtures near the consolute temperature. These systems have the potential to exhibit large steady state gain factors for stimulated Rayleigh processes, i.e., essentially elastic pump scattering resulting from nonpropagating index modulations in the scattering medium. To date, we have observed stimulated Brillouin scattering in such systems.1 In particular, one of these systems, pure CF3CI near the gas-liquid critical point, exhibits an unusually small, temperature tunable, frequency shift (Fig. 1). The phase conjugate reflectivity in this system exceeds 60%. These experiments were performed with a Nd:YAG laser (Laser Applications, Inc.) with 20-mJ pulses of ~10-ns duration.
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