Magneto-Optical Sensor Based on Fiber Bragg Gratings and a Magnetostrictive Material

We have designed a magneto-optical sensor based on fiber Bragg grating (FBG) and Metglas 2605CO (Fe67Co18B14Si1) material with magnetostriction coefficient of 35ppm. The FBG sensor is glued between two sheets of Metglas. FBG-based detectors are sensitive to both temperature changes (approximately 10pm/°C) and mechanical stress (approx. 1.15pm). Also due to the thermal expansion of Metglas, it becomes imperative to isolate the joint effects of thermal expansion of Metglas and the FBG temperature drifts. This is achieved by introducing an additional FBG used as a temperature sensor. We have characterized the responses of the sensor in two directions simultaneously: parallel and perpendicular to the direction of the applied magnetic field.