Ultra-high sensitivity weak magnetic field detecting magnetic fluid surface plasmon resonance sensor based on a single-hole fiber

An ultra-high sensitivity weak magnetic field detecting magnetic fluid surface plasmon resonance (SPR) sensor based on a single-hole fiber (SHF) is proposed for detecting weak magnetic fields. The sensor is constructed with a single-hole fiber in which an exclusive air hole in the cladding is embedded with a metal wire and filled with a magnetic fluid (MF) to enhance the magnetic field sensitivity. The effects of the structural parameters, embedded metals, and refractive index difference between the core and cladding on the magnetic field sensitivity and peak loss are investigated and optimized. The sensitivity, resolution, figure of merit (FOM), and other characteristics of the sensor are analyzed systematically. The numerical results reveal a maximum magnetic field sensitivity of 451,000 pm/mT and FOM of 15.03 mT