自由空间旋光器是利用磁光材料的法拉第效应，即它可以将同一波长的正向入射光及反向入射光的偏振面都向同一个方向旋转同一个角度，而与光束传播方向无关。高功率自由空间旋光器广泛应用于各种高功率激光系统中，如超快光纤激光器、固体激光器、多级激光放大器、光参量振荡器、环形激光器、掺铒光纤放大器、种子注入型激光器等。

A Faraday rotator is an optical device that rotates the polarization of light due to the Faraday effect, Faraday Rotators rotate the plane of polarized light 45° in the forward direction and an additional 45° of non-reciprocal rotation in the reverse direction while maintaining the light’s linear polarization. It is ideal forultrafast fiber laser、solid-state laser, multi-level laser amplifier、 Optical parametric oscillator Ring laser、Erbium-doped fiber amplifier、or seed injecting laser and etc.