Magnetic field sensor of enhanced sensitivity and temperature self-calibration based on silica fiber Fabry-Perot resonator with silicone cavity

In this paper, a magnetic field sensor with enhanced sensitivity based on a fiber Fabry-Perot (F-P) cavity formed by a pair of identical fiber Bragg gratings (FBGs) is demonstrated. The F-P cavity which was filled with silicone rubber was bonded to a magnetic alloy at two positions such that when longitudinal strain is applied, the cavity is lengthened while the FBGs was virtually strain-free, effectively magnified the magnetic-field induced strain of the magnetic alloy. The FBGs could also be used for temperature-compensation because the FBG spectrum change is negligible compared to the F-P spectrum.