Thermal distortions in high-power end-pumped Nd:YVO4 crystals

A high-resolution infrared thermal imager is employed to measure temperature and fit the thermal conductivity of Nd:YVO 4 crystal. A theoretical model to analyze the thermal distortion of end-pumped Nd:YVO 4 crystals is established. Both simulations and experiments reveal that with high-power pumping, the thermal effects of Nd:YVO 4 crystal cause spherical aberration as well as astigmatism. It is identified that the major cause of astigmatism is the anisotropy of the Nd:YVO 4 crystals’ thermal conductivity. The influence of astigmatism on the ellipticity of the output beam is investigated, and the significance of astigmatism compensation is demonstrated. The experimental results agree well with the simulation results.