Two-photon spectroscopy of cold cesium atoms

This thesis describes two different experiments involving two-photon spectroscopy of cold cesium atoms. The first experiment consisted of using an independent probe laser to investigate the absorption lineshapes of a doubly-resonant, "cascade" two-photon transition of cesium atoms in a magneto-optical trap. A five-level, density matrix model which included many properties of the trapping environment was developed to compare to the experimental Rabi-split absorption lineshapes. This model was successful in predicting many of the properties of these lineshapes for various trap parameters. The system was also used to probe the collective effects of the trapped atoms resulting from specific trapping laser configurations. By comparing the results of this model to the experimental lineshapes insight was gained into the dominant aspects of the trapping and cooling process.; To further study the advantages cold atoms bring to high-resolution spectroscopy, the second experiment investigated a degenerate two-photon transition in both warm and cold atoms. In order to drive this nonlinear transition, a new type of semiconductor laser technology was used to generate high power, optically narrow radiation. This technology provided enough optical power to drive this transition, allowing comparison between the fluorescence signals from samples of both warm and cold atoms to be made. These comparisons emphasized the benefits of using cold atom samples for high-resolution spectroscopy. Since cold atom samples provide freedom from many of the broadening mechanisms of warm atoms, a narrow ({dollar}sim{dollar}250 kHz) transition was observed and studied. Cold atoms also provided the ability to observe rarely seen transitions involving the velocity-sensitive absorption of copropagating two-photon transitions.