Thermo-Optical Distortions in Nd:YAG Crystals under Longitudinal Pumping with Divergence Taken into Account

We report numerical analysis of the effect of pump divergence on thermo-optical distortions in an Nd:YAG crystal. Thermally induced distortions are shown to depend on the focusing depth, power, and divergence of the pump beam under longitudinal diode pumping. The focal length of a thermally induced lens increases by ∼36% when the pump beam divergence is taken into account. Increasing the pump focusing depth by 1–2 mm into the crystal leads to an increase in the optical power of the thermal lens by approximately 12%. The obtained results can be used in laser development.