用激光原理和晶体光学原理分析了腔内加旋光晶体的激光器输出光的偏振特性。实验和分析表明：激光器输出两束不同频率的垂直线偏振光；激光器两端输出光的偏振面有一夹角α，且此夹角与晶轴和传光方向的夹角θ有关。理论计算结果与在双折射双频激光器的实验结果符合很好。

The polarization characteristic of a He Ne laser with an activity in its cavity (LAPC) is studied with laser physics and crystal optics. The experiments show that two modes of the laser are orthogonal linear polarized. There is an angle between the polarization orientation of the front beam and the of the back beam. Moreover, this angle is related to the angle θ, which is the angle between the optical axis and k. The experiment results can be explained by the analysis. The theoretic calculation matchs the experiment well.