folded-resonator design of thin-disk laser with variable thermally-induced intra-cavity dioptric power

This paper presents the design procedure of folded-resonators for high-average power thin-disk lasers (tdls). because of the oblique angle of incidence in the laser path inside the resonator, folded resonators introduce astigmatism. additionally, the dependency of the dioptric power of the active medium on the pump power made the resonator design more complicated. in the first section of this work, the disk thermal lensing was measured using a wavefront sensor, and the measurement procedure was presented and thoroughly discussed. the disk radius of curvature varied between 4.3 m to 6.4 m depending on the pump power. the disk was considered a variable lens inside the resonator based on the measurement results. v-shaped and l-shaped configurations’ stability and m2 factor were predicted, optimized, and compared. astigmatism in the resonator parameters was considered and discussed. while the v-shaped cavity has better beam quality, the l-shaped cavity has less sensitivity to cavity misalignment. the primary approach of this paper was the resonator design of a cavity-dumped disk laser. however, the designed resonator configurations could be utilized in many laser resonators, such as industrial tdls (to reduce the overall length of the system) and second harmonic-generation in tdls.