Comprehensive analysis of kinetic and fluid dynamic processes in flowing-gas diode-pumped alkali vapor amplifiers is reported. Taking into account effects of the temperature, the amplified spontaneous emission, the saturation power, the excitation of the alkali atoms to high electronic levels and the ionization, a detailed physical model is established to simulate the output performance of flowing-gas diode-pumped alkali vapor amplifiers. Influences of the flow velocity and the pump power on the amplified power are calculated and analyzed. Comparisons between single and double amplifier, longitudinal and transverse flow are made. Results show that end-pumped cascaded amplifier can provide higher output power under the same total pump power and the cell length, while output powers achieved by single- and double-end pumped, double-side pumped amplifiers with longitudinal or transverse flow have a complicated but valuable relation. Thus the model is extremely helpful for designing high-power flowing-gas diode-pumped alkali vapor amplifiers.

Considering the effects of higher excited and ion energy states and utilizing the methodology in the fluid mechanics, a modified model of exciplex pumped alkali vapor lasers with sonic-level flowing gas is established. A comparison of output characters between subsonic flow and supersonic flow is made. In this model, higher excited and ion energy states are included as well, which modifies the analysis of the kinetic process and introduces larger heat loading in an operating CW exciplex-pumped alkali vapor laser. The results of our calculations predict that subsonic flow has an advantage over supersonic flow under the same fluid parameters, and stimulated emission in the supersonic flow would be quenched while the pump power reaching a threshold value of the fluid choking effect. However, by eliminating the influence of fluid characters, better thermal management and higher optical conversion efficiency can be obtained in supersonic flow. In addition, we make use of the “nozzle-diffuser” to build up the closed-circle flowing experimental device and gather some useful simulated results.

A theoretical model is established to describe the thermal dynamics and laser kinetics in a static pulsed exciplex pumped Cs–Ar laser (XPAL). The temporal behaviors of both the laser output power and temperature rise in XPALs with a long-time pulse and multi-pulse operation modes are calculated and analyzed. In the case of long-time pulse pumping, the results show that the initial laser power increases with a rise in the initial operating temperature, but the laser power decreases quickly due to heat accumulation. In the case of multi-pulse operation, simulation results show that the optimal laser output power can be obtained by appropriately increasing the initial temperature and reducing the thermal relaxation time.

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Multiple deleterious processes occurring in alkali vapor laser amplifiers can significantly degrade their performance. To study that, a theoretical model of a side-pumped flowing-gas alkali vapor amplifier is set up, which mainly takes into account the effect of saturation, amplified spontaneous emission, quenching, energy pooling, photoexcitation, Penning ionization, photo-ionization, and ion recombination. Influences of powers of the pump and seed laser, the velocity of gas mixture flow, and the cell length on the deleterious processes are also simulated. The results show that the influence of deleterious processes can be increased when pump power enhances. But it can be effectively restrained with relatively strong seed laser power and optimized operating parameters. The total percent drop in amplified laser power is about 19.95% at a pump power of 500 W, a seed laser power of 5 W, a saturated flowing velocity of 40 m/s, and an optimized cell length of 7 cm.