Fiber-Based Magneto-Optic Sagnac Optical Modulator

In this paper, a fiber-based, magneto-optic (MO) optical modulator based on Sagnac interferometry is proposed. The system uses a Faraday rotator to produce optical modulation with low magnetic fields. The Sagnac geometry allows for increased modulation at lower fields than traditional MO modulators. A formulation of the system is provided using Jones calculus. Experimental results at 1550 nm using single mode fiber are reported, including a discussion of dynamic range and effect of magnetic field strength. Theoretical and practical advantages and limitations are discussed. Methods for improving modulation speed, dynamic range, and performance are presented.