A Polarization Control Method for Intra-Cavity Frequency Doubling of Q-switch Nd:YAG Lasers with KTP Crystals

摘要

In effcient frequency doubling (SHG) of the Q-switch Nd:YAG laser，a biaxial nonlinearcrystal like KTP(Potassium Titanyl Phosphate) is mostly used inside the lasercavity with the quarter wave plate to adjust the laser beam polarization angle. In thispaper，a new technique has been developed for controlling the laser beam polarizationwithout the wave plate by adjusting the angles of the biaxial KTP crysta1. The refractiveindex of the biaxial nonlinear crystal was analyzed using the Jones Matrix. This methodwas testedusing the Q-switch Nd: YAG laser and a good agreement was obtained betweentheoretical and experimental polarization data. A high effective conversion efficiency of84% was realized from 1064 nm to 532 nm beam at 1 kHz pulse repetition frequency.