Magnetic Field Sensor Based on Magnetic Fluid Selectively Infilling Photonic Crystal Fibers

Magnetic field sensor based on magnetic fluid selectively infilling photonic crystal fibers is designed and analyzed by the finite-element method. One cladding air hole is infiltrated with magnetic fluid and works as a defect core. As the phase matched condition is satisfied, the lights in transferring core couple to the defect core and the confinement losses of core modes experience an abrupt increase. The sensitivity and figure of merit can reach to 456.1 pm/Oe, 0.408 Oe^-1 for $x$ -polarized direction and 542.9 pm/Oe, 0.169 Oe^-1 for $y$ -polarized direction, respectively. The designed magnetic fluid selectively infilling photonic crystal fibers which show small volume, high sensitivity, and figure of merit are suitable for magnetic field sensor.