Research on Magnetic Field Sensor Based on Magnetic Fluid and L-shaped Dislocation Fusion Fiber Devices
Citation
徐奕斐 (Xu Yifei). (2024). 基于磁流体和 L 型错位熔接光纤器件的磁场传感器研究 (Research on Magnetic Field Sensor Based on Magnetic Fluid and L-shaped Dislocation Fusion Fiber Devices) [Master's thesis, discipline: 光学工程 (Optical Engineering)].
Keywords
- Optical fiber sensor
- Fiber optic vector magnetic field sensing
- Magnetic fluid
- L-shaped dislocation fused optical fiber devices
- Magnetic field sensor
- Vector magnetic field sensor
- Polarization-maintaining fiber (PMF)
- Hollow-core fiber (HCF)
- Core-offset mode
- Mode interference
- Refractive index
- Sensitivity
Brief
This master's thesis proposes and experimentally investigates a novel high-sensitivity optical fiber vector magnetic field sensor utilizing magnetic fluid and an L-shaped dislocated fusion spliced structure of polarization-maintaining fiber (PMF) and hollow-core fiber (HCF).
Summary
This master's thesis addresses the limitations of traditional electromagnetic field sensors by proposing a novel optical fiber vector magnetic field sensor. The sensor utilizes magnetic fluid and an L-shaped dislocated fusion spliced structure composed of a polarization-maintaining fiber (PMF) and a hollow-core fiber (HCF). This design, with the offset fusion disrupting circular symmetry, enhances sensitivity to environmental refractive index changes and enables vector magnetic field measurements through the anisotropic properties of the magnetic fluid. Experimental results demonstrate the sensor's sensitivity to both refractive index and vector magnetic fields, with higher sensitivity observed for sensors displaced along the slow axis of the PMF. Specifically, a sensor with a 6 µm offset along the slow axis achieved a refractive index sensitivity of 319.17 nm/RIU, a magnetic field intensity sensitivity of -813 pm/mT (in the 39-55 mT range), and a maximum magnetic field direction sensitivity of 245 pm/°. The thesis also investigates the impact of HCF length and offset on sensor performance, finding that sensitivity to the vector magnetic field decreases with increasing HCF length, and that the offset amount influences sensitivity and temperature cross-sensitivity.
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