Low power field generation for magneto-optic fiber-based interferometric switches

A new fiber-based, magneto-optic switch is proposed with a novel approach for low power and efficient operation. The switch, with reasonable switching speed compared to competitive designs, operates at considerably reduced power levels, which makes it a practical deployable solution. The basic switch setup consists of a Faraday rotator in a Sagnac fiber-optic interferometer in which optical switching is controlled by an electronic driving circuit. The electronic system generates a magnetic field through the Faraday rotator by driving current through a specially designed two-coil system. The new coil system allows for sufficient field generation at low quiescent power levels while maintaining very short optical rise and fall times. The design and considerations as well as the effect of mutual inductance between the two coils and its influence on switching times are investigated. The optical system consists of a Sagnac interferometer with a Faraday rotator within the Sagnac loop. Appropriate phase shift for interference is achieved by the proposed field generating system designed for the magneto-optical element. The theory of operation, design, experimental results, and optical and electronic setup are presented and analyzed.