A Vector Magnetic Field Sensor Based on MF-Coated HCF-PMF-HCF Fiber Structure

This paper presents an optical fiber vector magnetic field sensor based on magnetic fluid (MF) and a hollow-core fiber (HCF)-polarization-maintaining fiber (PMF)-HCF fiber structure sandwiched with single-mode fibers (SMF). The HCF-PMF-HCF fiber structure is obtained by sandwiching a segment of panda-type PMF between two segments of HCF. Therein, one end of the PMF is core-offset spliced with HCF, thus an L-shaped optical fiber sensing structure is formed. The core-offset splicing destroys the fiber's circular symmetry, therefore it enables measurement of the magnetic field direction surrounding the fiber element. Experimental results reveal that the sensor exhibits a magnetic field intensity sensitivity of 470 pm/mT within the field intensity range of 40–54 mT, with a maximum magnetic field direction sensitivity of 214 pm/
^○
. The proposed magnetic field sensor is fabricated using an all-optical fiber structure, offering benefits including cost-effectiveness, simple manufacturing.