Spatial dynamics of laser-induced fluorescence in an intense laser beam: An experimental and theoretical study with alkali-metal atoms

摘要

We show that it is possible to model accurately optical phenomena in intense laser fields by taking into account the intensity distribution over the laser beam. We present an extension of an earlier theoretical model that divides an intense laser beam into concentric regions, each with a Rabi frequency that corresponds to the intensity in that region, and solve a set of coupled optical Bloch equations for the density matrix in each region. Experimentally obtained magneto-optical resonance curves for the F-g = 2 -> F-e = 1 transition of the D-1 line of Rb-87 agree very well with the theoretical model up to a laser intensity of around 200 mW/cm(2) for a transition whose saturation intensity is around 4.5 mW/cm(2). We examine the spatial dependence of the fluorescence intensity in an intense laser beam experimentally and theoretically. We present and discuss the results of an experiment in which a broad, intense pump laser excites the F-g = 4 -> F-e = 4 transition of the D-2 line of cesium while a narrow probe beam scans the atoms within the pump beam and excites the D-1 line of cesium, whose fluorescence is recorded as a function of probe beam position. Experimentally obtained spatial profiles of the fluorescence intensity agree qualitatively with the predictions of the model.