Polarization control in two-pass anisotropic optical systems with a new Faraday mirror

The new Faraday mirror for compensation of parasitic optical anisotropy in two pass single mode fiber optic systems, is proposed and experimentally tested. Proposed Faraday mirror is based on ring polarization Sagnac interferometer with Faraday cell placed on the way of counterrunning waves. Unlike conventional Faraday mirrors, where precise compensation is achieved only when Faraday rotation angle is exactly equal to 45 degrees, proposed ring interferometer based Faraday mirror is not sensitive to deviations of Faraday rotation angle from 45 degrees. In the experiment, where the quality of polarization restoration by both conventional and new Faraday mirrors have been compared good compensation by new Faraday mirror has been observed in wide range of Faraday rotation angles. As the experiment shows new Faraday mirror has the better performance then conventional one even at the angles of Faraday rotation close to 45 degrees. New FM may be applied in the fiber optic interferometric sensors, where high polarization stability is needed.