Mach–Zehnder Interferometric Switch Utilizing Faraday Rotation

An all-fiber interferometric switch based on Faraday rotation exhibited by magneto-optic materials in the presence of an external magnetic field is reported. The interferometer is Mach-Zehnder type and the related phase shift was obtained by the rotation of the state of polarization of a linearly polarized optical signal. The operation of the switch is demonstrated experimentally. The effect of the optical beam size on the achievable Faraday rotation is also investigated. Hysteresis is avoided as the magnetic field required for switching is much lower than the saturation field