Quasi-Distributed Magnetic Field Fiber Sensors Integrated with Magnetostrictive Rod in OFDR System

Abstract

We have proposed and designed a fiber-optic magnetic field sensors based on magnetostriction, of which the magnetostrictive induced strain of magnetostrictive rod attached to an optical fiber can be measured by optical frequency-domain reflectometry (OFDR). By analyzing the stress transfer process at the interface between the magnetostrictive rod and the sensing optical fiber, we find that the sensor sensitivity is mainly related to the magnetostrictive material and bond width. The experimental results show the sensor performance under different magnetostrictive rods and radiuses. The sensitivity of the Fe-Ga-based sensor is up to 5.05 με/mT, while the sensitivity of the Tb-Dy-Fe-based sensor is up to 3.42 με/mT. The proposed sensor can easily construct a sensor network for quasi-distributed fiber-optic magnetic field sensing, which can be used to monitor magnetic fields at more than one point.