Fluorescence monitoring of laser induced population changes of 6P and 6D levels in cesium vapor

Abstract

Observations of enhancement and reduction of the fluorescence intensity in the continuous-wave excitation of Cs atomic vapor is reported. The reduction is due to a depopulation of the 6 2P o 3/2 state upon illumination of a Cs vapor cell with light corresponding to the 6 2P o 3/2→6 2D 5/2 transition (917.23 nm). Collisional relaxation of the 6 2D 5/2 atoms to the 6 2D 3/2 state, followed by radiative decay to the 6 2P o 1/2 state (876.14 nm), creates an increase in the population of the 6 2P o 1/2 state. The increase in the excited state population results in an increase in the fluorescence intensity of the 6 2P o 1/2→6 2S 1/2 transition (894.35 nm). These laser induced population changes, monitored by the decrease or increase of the corresponding fluorescence signals, were modeled using a simplified density matrix formalism, which allowed an order of magnitude estimate of the rates of level mixing between 6 2D states and 6 2P states.