COMPUTATION OF NONLINEAR RADIATION TRAPPING IN A SATURATED CESIUM VAPOR

We analyze the temporal evolution of the excited-state distribution in a cesium vapor excited by a strong laser pulse of arbitrary duration. We model this situation with equations that include radiation trappin g, saturation, and optical pumping. Both the strength and the temporal behavior of the emergent radiation after the laser is switched off de pend on the duration of the laser pulse and on the diameter of the las er beam. The decay time constant of the emergent radiation varies from less than the natural lifetime to several hundred times the natural l ifetime for cesium densities varying in the range 20-100 degrees C.