Investigation on Back-Reflected Pumping Light in High-Power Quasi-End-Pumped Yb:YAG Thin-Disk Lasers

An innovative investigation was theoretically and experimentally carried out on a back-reflected pumping power (BRP) in the Yb:YAG thin-disk laser. Based on the Monte Carlo ray tracing method and laser rate equations, the pumping and absorption processes of a thin-disk laser are simulated in the lasing condition. The effects of pumping diameter, disk specifications, and cooling temperature on the BRP and laser efficiency are investigated. Also, an experimental method is suggested and applied to the measurement of BRP. The results show good consistency between simulations and experimental measurements. In addition, the theoretical calculations reveal that BRP is strongly dependent on the thin-disk specifications and pumping parameters.