FOURIER-TRANSFORM RAMAN AND BRILLOUIN SPECTROSCOPY USING ATOMIC VAPORFILTERS

This paper presents Raman and Brillouin scattering measurements obtain ed with a Fourier transform interferometer, in which the laser light r ejection was provided by an alkali-metal vapor cell. The narrow absorp tion band of the vapor cell allowed for the detection of energy shifts as low as 0.85 cm-1 (approximately 26 GHz) while completely blocking scattered light at the laser frequency. Since, unlike a Fabry-Perot in terferometer, a Fourier transform interferometer does not have a free spectral range placing an upper bound on the energy shifts which it ca n detect without ambiguity, the energy regimes of both Brillouin and R aman scattering are for the first time accessible with a single instru ment.