为提高光隔离器在高功率激光条件下的工作性能，基于琼斯理论研究了隔离器的热致退偏效应，设计了一种外置补偿晶体的隔离器，着重分析了隔离器隔离度及热透镜效应随入射光功率的变化规律。结果表明：通过调整氟化钙晶体的晶轴方向和长度，隔离器的热致退偏和热透镜效应可以得到有效抑制。在100 W激光条件下，外置补偿晶体后隔离度提高了16.3 dB，功率损耗降低8%。研究结果可优化设计隔离器结构，有效提升高功率隔离器的隔离度并减小功率损耗。

In order to improve the performance of the operation of optical isolator at high power laser conditions, thermally induced depolarization effect in optical isolator was investigated with the use of Jones theory. An optical isolator system with external compensation crystal was proposed in this paper. Further the rules of the changes of both isolation degree and thermal lens effects with the increasing of input optical power were also analyzed. The results show that thermally induced depolarization and thermal lens in magneto-optic crystal can be effectively suppressed by regulating the crystal axis direction and changing length of CaF₂. Compared with traditional isolator, the isolation degree is increased by 16.3 dB and the power loss is reduced by 8% when the incident laser power is 100 W. Through the analysis result of this paper, the isolator structure can be optimized to both improve the isolation degree and reduce the power loss at high power laser conditions.