Research on isolation ratio limit induced by depolarization in Shenguang-Ⅲ laser facility

Laser depolarization induced by the propagation-rotation structure would greatly affect the isolation ratio of the Shenguang-Ⅲ laser facility. We build a simulation model on the reflectance coefficient of the propagation-rotation structure based on the film system theory, and point out that the depolarization origins from the reflective film thickness error. Through comparison between the simulation result and the off-line experimental result, we obtain the reflectance coefficient of each reflective film inside the propagation-rotation structure. Furthermore, we obtain the total reflectance coefficient of the propagation-rotation structure and then the system isolation ratio limit.