Modeling of scaling of a diode longitudinally pumped metastable rare gas with a master oscillator power amplifier

There has been recent interest in diode pumped metastable rare gas lasers (DPRGLs) and their scaling to higher powers, due to the advantages of excellent beam quality and high quantum efficiency. In this paper, a cw diode pumped rare gas amplifier (DPRGA) with single-pass longitudinally pumped configuration is studied theoretically based on master oscillator and power amplifier (MOPA). A five-level kinetic model of DPRGAs is first established. Then, the influences of gain medium density, pump and seed laser intensities and gain length on DPRGA performance are simulated and analyzed. The results of numerical simulation agree well with those of Rawlins et al.'s experiment. With the best set of working parameters, the amplification factor reaches 22.18 dB, at pump intensity of 50 kW/cm² and seed laser intensity of 100 W/cm². Parameter optimization is helpful for design of a relatively high-power DPRGL system.