Magnetic field sensor based on a microsphere attached to a side-polished fiber

Abstract

Magnetic field sensors have important application values in the fields of geophysical surveying and navigation, military equipment applications, biomedical sensing, and aerospace field. This paper proposes a magnetic field sensor based on side-polished fiber and microsphere. The sensor uses optical fiber microspheres as the light sensing platform and magnetic fluid as the magnetic field response and sensitizing material. The magnetic field sensor is made of a multi-mode side-polished optical fiber and SiO2 microspheres, which are put into a capillary package, and Fe3O4 magnetic fluid is injected into the capillary.We used COMSOL Multiphysics 5.4 based on finite element analysis to simulate the proposed sensor structure. Simulation results show that the magnetic field sensor has a maximum intensity sensitivity of 0.75dB / Oe, a refractive index sensitivity of 125nm / RIU, a Q-factor of 2.5x104, and the FOM of 2.5x103. Compared with the traditional magnetic fluid magnetic field sensor, the proposed sensor has a simple structure, low production cost, high Q-factor and high FOM. It has potential application prospects in developing magnetic field sensors compatible with high-sensitivity sensing and high-precision detection.