Passive interferometric interrogation of a magnetic field sensor using an erbium doped fiber optic laser with magnetostrictive transducer

An erbium doped (Er3+) fiber optic laser is proposed for magnetic field measurement. A pair of FBGsglued onto a magnetostrictive material (Terfenol-D rod) modulates the laser wavelength operation whensubject to a static or a time dependent magnetic field. A passive interferometer is employed to measure thelaser wavelength changes due to the applied magnetic field. A data acquisition hardware and a LabVIEWsoftware measure three phase-shifted signals at the output coupler of the interferometer and processthem using two distinct demodulation algorithms. Results show that sensitivity to varying magneticfields can be tuned by introducing a biasing magnetic field. A maximum error of 0.79% was found, formagnetic fields higher than 2.26 mT-RMS