Small angles vector magnetometer based on anisotropic ferromagnetic nanofluid functionalized fiber interferometer

Abstract As factories and vehicles become more automated, accurate and low-latency sensing of motor shaft speed and position is critical for process control, system reliability, and safety. To address these needs, a highly precise and fast vector magnetometer is required that has the capability to detect magnetic field variations also at tiny angles. We present the development of an ultrathin tapered fiber interferometer-based highly accurate sensor suspended in a magnetorheological fluid film, which holds the capability of simultaneously detecting magnetic field intensity and its direction in three-dimensional space. The sensing mechanism counts on the magnetism-regulatable effective index amendment of exciting asymmetric cladding modes in a nonadiabatic biconical tapered fiber interferometer. Based on the azimuth-dependent anisotropic distribution of nanoparticles surrounding the fiber, such a magnetometer has achieved the maximum magnetic field sensitivity of ∼16.4 pm mT −1 at 0° whereas at small angles of ±1° and ±2° the sensitivities are observed of ∼ ±14.6 pm mT −1 and ∼ ±11.7 pm mT −1 , respectively over a larger span of 0–567 mT.