Spectroscopy of Atoms Dressed by Optical Photons in Nearly Degenerate Four-Wave Mixing

Abstract

The concept of dressed-atom [1] is often useful when an atom interacts with an intense electromagnetic field. In the case of degenerate four-wave mixing in Doppler-broadened systems, it has been shown that the saturation effects can be clarified using the dressed-atom approach [2]. In the case of nearly degenerate four-wave mixing, we show thereafter that narrow natural-width limited resonances are observed which correspond to an enhancement of the four-wave mixing process due to transitions between energy levels of the dressed-atom. The fact that Rabi sidebands could be observed in nearly degenerate four-wave mixing was first pointed out by Harter and Boyd [3] who use a model of homogeneous broadened medium. Later on, Steel and Lind [4] show that the lineshape in nearly degenerate four-wave mixing is strongly modified by a saturating beam and that some indication of Rabi sidebands is observed experimentally. The understanding of the effect of an inhomogeneous broadening has permitted to improve the experimental conditions and to obtain clearer results.