Magnetic field sensor based on optical fiber Fabry–Pérot interferometer with V-shaped hinge structure

Abstract Magnetic field measurement holds significant application value in fields such as disaster prevention, mitigation, work safety, and resource exploration. However, existing optical fiber Fabry–Pérot interferometer (FPI) magnetic field sensors generally suffer from low sensitivity, which limits their practical engineering applications. To address this issue, this paper proposes a high-sensitivity optical fiber FPI magnetic field sensor based on a V-shaped hinge structure. The sensor employs Terfenol-D as the magnetostrictive sensing element and utilizes a single-mode fiber combined with a quartz glass tube to construct an FPI cavity in the configuration of ‘single-mode fiber-air cavity-single-mode fiber.’ Through the mechanical amplification effect of the V-shaped hinge structure, the magnetostrictive strain of Terfenol-D under the influence of a magnetic field is amplified, thereby enhancing the response sensitivity of the FPI cavity length to magnetic field variations. Experimental results demonstrate that the sensor achieves a sensitivity of 187.13 nm mT −1 under a 35 mT bias magnetic field, with a magnetic field resolution of 267.2 nT, and its directionality conforms to the cosine law. The research findings provide a reference for the development of high-sensitivity optical fiber magnetic field sensors.