Nd∶YAG固体激光器的偏振特性在许多实际应用中非常重要。特别是在非线性光学频率变换中, 无论是实现Ⅰ类相位匹配还是Ⅱ类相位匹配的非线性光学晶体, 对基频光的偏振特性都有一定的要求。研究了半导体激光侧向泵浦固体Nd∶YAG激光器的偏振特性。实验测量了腔内镀膜偏振片和它们在腔内不同位置时对激光偏振特性的影响。消光比测量表明, 热致退偏效应影响激光的偏振特性。合理选择腔内偏振片的位置和在腔内插入1/4波片补偿热致退偏效应, 能够获得较好的偏振激光, 可提高和频紫外激光功率。

The polarization of solid state Nd∶YAG laser are important in many applications, especially for the nonlinear optical frequency conversion. The polarization of a diode-side-pumped solid state Nd∶YAG laser is investigated, the influence of the coating and position of the polarizer in the cavity on the polarization characteristics of the laser is experimentally studied. The measurements of extinction ratio show that the effect of thermally induced depolarization deteriorates the polarization properties of the laser. A better polarized laser is obtained by rational placing the polarizer and inserting a 1/4 wave plate in the cavity to compensate the depolarization effect. Therefore, the sum-frequency ultraviolet laser power is enhanced.