Magnetic Field Measurement Using Surface Plasmon Resonance Sensing Technology Combined With Magnetic Fluid Photonic Crystal

Magnetic fluid is a new type of functional material. In a certain magnetic field, it can aggregate to form a magnetic fluid photonic crystal owing to a two-phase separation. When the material is used in surface plasmon resonance sensing technology, surface plasma waves can be influenced by the presence of the formed structure. In this paper, a novel magnetic field sensor is described. The modulatory effect of the surface plasma wave was analyzed when the magnetic fluid photonic crystal was formed near the Au film, and the shift of resonance angle with an increasing magnetic field was computed. The simulation results showed that when the magnetic fluid photonic crystal was formed, an evanescent wave would resonate with a surface plasma wave at a wavelength of 1.8 μm. The resonance angle shifts from 79.2° to 85.1° when the applied magnetic field is increased from 15 to 25 mT. The obtainable sensitivity was 0.612°/mT.