Optimization of Yb:YAG thin-disk-laser design parameters considering the pumping-light back-reflection

• Underlines back-reflection of pump power (BRP) in thin-disk-laser (TDL) optimization.
• Minimum BRP with acceptable optical efficiency obtainable simultaneously.
• In a typical TDL, BRP decreases from 300 to 40 W while increasing optical efficiency.
• BRP controlled without any change in beam-shaping or pumping-system configuration.

A new approach for optimization of thin-disk laser design parameters is introduced in this paper. The back-reflected pumping power (BRP) is considered as one of the design parameters; for this reason optimization is conducted based on minimum pumping light back-reflection and acceptable optical efficiency. The effects of laser parameters on the laser efficiency and back-reflected pumping power are evaluated using analytical and numerical models. The agreement between the numerical results and experimental data verifies the validity of the numerical method. Based on the simulation results, the design procedure of Yb:YAG laser with maximum efficiency and minimum BRP is explained. Using the presented method for a typical Yb:YAG thin-disk-laser, it is possible to decrease the BRP from 300 W to 40 W while increasing laser efficiency from 49% to 54% for a disk of 190 μm thickness and 14% doping concentration. In this condition the BRP is just 40 W which is acceptable from view point of damage problems. The study reveals a pattern of results which shows that the detrimental back-reflection of pumping power could be controlled only by modifying active medium parameters without any change in beam-shaping or pumping-system configurations.