Modeling of picosecond pump and probe photobleaching experiments on fast saturable absorbers

A model is developed for the time evolution of the transmission of a dye during and after photobleaching by an intense pulse of light. The model is used to calculate the effects, which can be considerable, of the characteristics of the probe pulse used to measure the transmission of the sample, and criteria are established for the accurate determination of ground state recovery times from such observations. The saturation behavior of the dye is also modeled, and it is shown that saturation curves are of almost no value in deducing GSR times. The calculations are compared with results of experiments on Kodak Dye 9860 with excellent agreement.