Influence of thermal lens effect on second harmonic process in semi-monolithic cavity scheme

Second harmonic generation (SHG) is an effective way to generate short wavelength laser with high power. The SHG accompanied the absorptions of fundamental waves and waves, which converts a fraction two deposit energy into heat, causing temperature gradient along radial direction periodically poled potassium titanyl phosphate (PPKTP) crystal. inhomogeneous distribution causes thermal lensing in effect will deform spatial mode cavity result mode-mismatching wave cavity, therefore conversion efficiency process reduced. Moreover, increase injected power, influence caused by lens becomes more serious. In order obtain high-efficiency frequency conversion, it necessary take measure minimize lensing. this paper, we report on green at 532 nm external semi-monolithic standing cavity. influences optimal different cavities are theoretically analyzed. variations pump power “plane-concave” based parallel crystal also “concave-concave” concave quantitatively experiments, types structures built variation doubling For maximum 747 mW obtained corresponding reaches 93.4%±3%, 800 infrared injected. 529 88.2% ± 3%, 600 results show that affects seriously than Furthermore, turns higher loss It obvious suitable for has many potential applications quantum optics cold atom physics provides guidance future research process.