Fiber Optic Magnetic Field Sensor Utilizing DFB Fiber Laser and Terfenol-D Material

We present a novel distributed feedback fiber laser (DFB-FL) fiber laser sensor, which can measure static magnetic field through sweep acoustic wave. A fiber laser is bonded on the giant magnetostrictive material Terfenol-D (Tb
_0.3
Dy
_0.7
Fe
_1.92
) tube oriented along the longitudinal direction. When acoustic wave of different frequency is added to the fiber laser, it has the maximum response at its resonant frequency, which will vary with the external magnetic field. The measurement sensitivity of the sensor is 0.39 Hz/mT to the magnetic field. The experimental results also show that the sensor exhibits excellent linearity and directivity in response to static magnetic field.