The fiber Faraday rotator is used to change the polarization state of the input light, so that the direction of the polarized light after passing through the Faraday rotator and the reflector rotates 90 degrees. It is perpendicular to the input polarized light and has the opposite polarization direction. The fiber Faraday rotator adopts a micro-optical structure inside, which is suitable for various optical fibers, and the input and output optical fibers can have different choices.