Fiber-optic magnetic field sensor based on curved Terfenol-D rod combined with FBG

A kind of magnetic field sensor with enhanced sensitivity was designed by integrating the fiber Bragg gratings (FBGs) with the curved terbium-dysprosium-iron alloy (Terfenol-D) rods. Seven magnetic field sensors with Terfenol-D rods of different curvatures were fabricated and tested. The highest enhancement in magnetic field sensitivity is observed for sensors equipped with Terfenol-D rods having a curvature of 50 m ^-1 . In addition, the designed sensor demonstrated directional sensitivity to the magnetic field, which was obtained to be 3.5 pm/deg at 10 mT. The utilization of magnetostrictive materials in unconventional shapes (magnetostrictive rods in curved shapes) in this study not only enhances magnetic field sensitivity but also opens up a world of possibilities for future specific applications.