Kinetic and fluid dynamic modeling, numerical approaches of flowing-gas diode-pumped alkali vapor amplifiers

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.