An insight into the magneto-refractive effects of terbium-doped silica optical fibers used in magnetic field sensors

In this study, the magneto-refractive effect (MRE) of a terbium-doped fiber (TDF) that can be employed for magnetic field sensing was investigated. A microscopic model of a terbium doped magneto-refractive silica fiber was proposed, and the relationship between the refractive index (RI) of the fiber and its magnetic field was numerically studied. The MRE of the TDF was then characterized using an electronic holographic magneto-refractive measuring system. The characterization results showed that the RI of the TDF increased linearly at a rate of 2.13 × 10−5 RIU/mT as the magnetic field intensity increased from 0 to 10 mT. An all-solid-state magneto-refractive measurement system based on a fiber-optic Sagnac interferometer was designed for magnetic field sensing, which linearly responded to the applied magnetic field. The relationship between the dielectric tensor and magnetic moment of the fiber was analyzed. Based on the finite difference algorithm, the change in the RI and dielectric tensor of the optical fiber under a magnetic field was simulated. Results indicated that the proposed fiber has potential use in high-sensitive magnetic field sensing applications.