Investigation of thermal induced depolarization in high-power Faraday isolator and its compensation design

For the use of the magneto-optic crystal in a high-power optical isolator, the relationship between the isolation and the incident light power is analyzed with Jones matrix using the parameters of actual optical elements. A compensation scheme for thermal induced depolarization in magneto-optic crystal is proposed, which is based on external material. The design method of the compensation scheme for two different materials is given. The result shows that at the power of 50 W, by using CaF₂ crystal and SiO₂, the isolation can be increased by 15 dB and 4 dB respectively.