High-sensitivity vector magnetic field and temperature sensor based on side-polished GPCF

We experimentally demonstrate a vector magnetic field sensor based on a grapefruit-type photonic crystal fiber (GPCF). The sensor utilizes the unique air-hole structure of the GPCF, which is further enhanced by side-polishing to enable direct interaction between the magnetic fluid (MF) sensing medium and the fiber core. This structural optimization significantly improves both sensitivity and response speed, leading to high-performance vector magnetic field detection. Experimental results indicate a linear magnetic field sensitivity of 1.296 dB/mT within the 5-15 mT range and an orientation sensitivity of 0.260 dB/° under a fixed 10 mT field. Furthermore, the sensor exhibits a temperature sensitivity of 0.586 dB/°C in the 24-34°C range. Benefiting from its compact structure, high sensitivity, and rapid response, the proposed sensor shows strong potential for real-time magnetic field monitoring in complex environments, such as industrial automation and biomedical applications.