Stimulated Rayleigh-Brillouin gain spectroscopy

Steady-state stimulated Rayleigh-Brillouin gain spectroscopy and its application are reported. The stimulated gain, which is derived in terms of the spectral function of density fluctuations, is shown to approach, in the limit of zero density, the gain derived from the individual-particle picture of Rayleigh scattering. Using a pulsed pump laser, experimental gain spectra of pure SF₆, pure Ar, and a SF₆- and He-gas mixture are obtained and explained. Other associated coherent Rayleigh-Brillouin spectroscopies and the possibility of using a cw pump laser for higher spectral resolution are discussed.