Physical Review Letters
Recoil-induced resonances in cesium: An atomic analog to the free-electron laser
J.-Y. Courtois, G. Grynberg, Brahim Lounis, Philippe Verkerk
Abstract
We report on the first expeimental observation of recoil-induced resonances. These resonances, which can be considered as the atomic analog of the grain mechanism of the free-electron laser, are observed on the transmission spectrum of a probe beam making a small angle with a one-dimensional lin\ensuremath{\perp}lin cesium optical molasses. They are interpreted either as stimulated Raman transitions between differently populated velocity groups (the internal atomic state being unchanged), or as stimulated Rayleigh resonances originating from a bunching of the atomic density. Their shape provides information about the transverse velocity distribution of the atoms.