A Magnetic Sensor Based on a Hybrid Long-Period Fiber Grating and a Magnetic Fluid

A magnetic sensor based on a hybrid long-period fiber grating (HLPFG) and an ester-based Fe₃O₄ magnetic fluid (MF) has been proposed and experimentally investigated. The Fe₃O₄ MF and HLPFG are encapsulated in a capillary tube using paraffin. The sensor is sensitive to a vertical magnetic field and environmental temperature, while it is not very sensitive to an axial magnetic field. Due to the hybrid structure of HLPFG, the transmission spectrum of the sensor has two groups of resonance dips that have different sensitivities to vertical magnetic field intensity and temperature. This sensor can be used for the simultaneous measurement of temperature and vertical magnetic field intensity, which is desirable to resolve the temperature cross sensitivity issue. The sensor is also advantageous in its ease of fabrication, compactness, and wide linear measurement range.