Cesium diode pumped alkali lasers (DPALs) have been operated using various hydrocarbons (methane, ethane, and propane) and helium as a buffer gas. We find that the optimum partial pressure of hydrocarbons depends on the cross sections of the upper-state mixing reaction, while the maximum output power does not depend on the hydrocarbon species. Because the cross section of the quenching reaction between cesium and these hydrocarbons is significantly smaller than that for the upper-state mixing reaction, no direct measurement of such cross sections has been attempted to date. In this study, we attempted to determine the cross sections with the aid of DPAL simulation. Output power calculations were repeated by varying the quenching cross sections until a reasonable agreement with the experiments was met. The results indicated that the quenching cross sections of methane, ethane, and propane were 0.05 ± 0.03, 0.14 ± 0.04, and 0.23 ± 0.07 Å2, respectively. The validity of the results is supported by the fact that the cross section of methane obtained is consistent with that suggested by Yacoby et al. [Opt. Express 26, 17814 (2018)].
We have developed a small-scale, diode-pumped alkali laser with a closed-loop gas circulation device and investigated the effect of gas circulation on the laser output power. The gain cell, with a 5 cm active length, is fitted with antireflection windows, and a cross-flow fan is incorporated inside it. The active medium is composed of cesium, hydrocarbon, and a buffer gas whose total pressure is approximately 2 atmospheres. The laser output power was measured as a function of the gas flow velocity for different buffer gases. In the case of argon, the laser power was strongly dependent on the gas flow velocity, whereas it was almost independent of the gas flow in the case of helium. The maximum output power of the argon buffer was close to that of the helium buffer when the gas velocity exceeded 6 m/s. The experimental results were in good agreement with the numerical simulations.