Thermal effects and their mitigation in end-pumped solid-state lasers

Degradation in beam quality due to aberrated thermal lensing and depolariza tion loss due to stress induced birefringence in end-pumped edge-cooled sol id-state lasers are investigated. A simple model for the dependence of ther mal lensing and degradation in beam quality on the transverse intensity pro file of the pump beam is presented. Experimental measurements of thermal le nsing, degradation in beam quality and depolarization loss in a diode-bar-e nd-pumped Nd:YAG rod support the main predictions of the model and, in addi tion, show that there can be significant extra heating under non-lasing con ditions compared to lasing conditions. The role of energy transfer upconver sion as a mechanism for additional heat loading under non-lasing conditions is considered. Finally, various strategies for limiting the impact of ther mal lensing and thermally induced birefringence on laser performance in sim ple end-pumped cavity configurations are reviewed.