Dynamical thermal lensing of high-power solid-state lasers

Based on a graded-refractive-index lens model, the effects of thermal lensing on the overlap integrals, diffraction loss, pump threshold, and laser efficiency of the TEM 00 mode for uniformly pumped solid-state lasers with a flat-flat symmetrical cavity are analyzed. Unlike the end-pumped system, the overlap integral V th related to the threshold pump power will not change with pump power, due to the uniform pumping. We link the thermal lensing with the laser output power. A dramatic increase of the laser mode radius at the crystal caused by the thermal lensing reduces the Fresnel number and raises the diffraction loss so that the laser output power drops at one value of the pump power.