Optical beams traveling in a single mode fiber experience random birefringence, which could make it difficult or impossible for fiberoptic Michelson interferometer to function properly. Faraday rotator mirrors take the output beam from a single mode fiber and rotate the polarization by 90 degrees before sending it back through the same fiber. By doing so, a Faraday mirror functions as a phase conjugate mirror and cancels out any birefringent effects the beam experienced along the forward path.

Princetel’s FRM series Faraday rotator mirrors offer strong suppression against secondary reflections (-55 dB), a feature critical to most interferometer applications.