An Intensity-Modulated Magnetic Field Sensor Based on Magnetic Fluid and HCF-SMF-HCF Fiber Sensing Structure

In this paper, an all-optical fiber magnetic field sensor is proposed and developed. The sensor head is fabricated by using magnetic fluid (MF) encapsulating a hollow core fiber (HCF)-single-mode fiber (SMF)-HCF structure. The two segments of HCF serve as beam splitters and couplers of sensor. Three different parametric sensors were fabricated to evaluate the magnetic field sensing properties. In the experiments, the maximum intensity sensitivity of the magnetic field was -0.587 dB/mT in the range of 40–54 mT. The sensors have the advantages of simple structure, easy fabrication, anti-electromagnetic interference, low cost and high sensitivity.