Modeling and Analysis of the Pumping Threshold Characteristics in One-Color Two-Photon Excited Cs Vapor

The pumping threshold is an important parameter for laser sources. Limited by the intricate transition mechanism of the one-color two-photon excitation, there has been a shortage of theoretical studies on the pumping threshold characteristics of alkali vapors. Thus, we propose a physical model of the pumping threshold by innovatively combining the coupled wave equation and the rate equation for one-color two-photon excited Cs vapor. To verify the validity of the model, we compare our simulation results with the available experimental data and show that they agree well with each other. By analyzing the main factors influencing the pumping threshold, we find that the cell temperature and frequency detuning of the pumping laser have a decisive impact on the pumping threshold. These results can provide a valuable reference for the selection of appropriate pumping parameters in further experiments.