Optical mixing in 23 liquids and 2 glasses is reported. Observations with a high-resolution grating spectrograph of the light from a giant-pulse ruby laser transmitted through the materials reveal the presence of more Stokes-shifted components than can be accounted for on the basis of amplification by the laser of Brillouin-shifted frequencies. In addition, anti-Stokes-shifted components are observed. The frequency shifts are shown to correspond to those expected for 180° Brillouin scattering. Sound speeds calculated agree in general with those from stimulated and spontaneous scattering experiments. Sound-speed measurements at different temperatures and for two-component liquids give results predictable from bulk properties of the liquids. A number of experiments showing the conditions and the parameters which affect the optical mixing are described.
T. A. WIGGINS, R. V. WICK, N. D. FOLTZ, C. W. CHO, and D. H. RANK, "Optical Mixing in Stimulated Brillouin Spectra," J. Opt. Soc. Am. 57, 661-664 (1967)