Investigation of the dynamic Stark effect in a J=0-->1-->0 three-level system. III. The "strong-probe" case.

Abstract

We have investigated the dynamic Stark effect in a J=0\ensuremath{\rightarrow}1\ensuremath{\rightarrow}0 three-level ladder system in an atomic beam of natural barium. An intense, actively stabilized cw dye laser was tuned to resonance between the upper two levels, and a similar laser was scanned through resonance with the transition connecting the lower two levels. Fluorescence arising from transitions out of the middle and upper levels was separately recorded as a function of probe laser frequency. This is the third and final paper in a series, of which the first two papers investigated theoretically and experimentally the ``weak-probe'' case, where the intensity of the probe laser was sufficiently low for the interaction between the atoms and the probe laser to be linear. In this paper we present an experimental investigation of the ``strong-probe'' case, where both lasers interact nonlinearly with the atoms, and we compare the results with the predictions of a theoretical model based on the optical Bloch equations.