A novel fiber-optic vector magnetic field sensor and its sensing quality dependent of fabrication method has been proposed and investigated. The proposed sensor has two surfaces on the tip of a multimode fiber, which is used as the sensing probe. By plating different thickness of gold film on the surfaces, surface plasmon resonance (SPR) can be generated and the signal can be reflected by the surfaces as well. Meanwhile, magnetic fluid (MF) as the magnetic field sensitive material is packed around the sensing probe. The experimental results prove that the response of MF to external magnetic field can be used to sense magnetic field intensity and direction via monitoring the dip wavelength of SPR. The obtained refractive index (RI) sensitivities are 2105 nm/RIU (RI range: 1.332–1.365) and 6692 nm/RIU (RI range: 1.372–1.411), magnetic field intensity sensitivities are 11.67 nm/mT (0°), and −0.47 nm/mT (90°). Besides, the proposed sensing probe is ultracompact and the footprint is extremely small (the length of sensing part is only 615 μm), which is very helpful for magnetic field detection in narrow space and gradient field.

中文翻译：

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基于表面等离子体共振和磁流体的楔形纤维尖端超高性能矢量磁场传感器

提出并研究了一种新型光纤矢量磁场传感器及其与制造方法相关的传感质量。所提出的传感器在多模光纤的尖端有两个表面，用作传感探头。通过在表面镀上不同厚度的金膜，可以产生表面等离子共振（SPR），信号也可以被表面反射。同时，作为磁场敏感材料的磁流体（MF）包裹在传感探头周围。实验结果证明，MF对外部磁场的响应可以通过监测SPR的倾角波长来感知磁场强度和方向。获得的折射率 (RI) 灵敏度为 2105 nm/RIU（RI 范围：1.332–1.365）和 6692 nm/RIU（RI 范围：1.372–1.411），磁场强度灵敏度为 11.67 nm/mT (0°) 和 -0.47 nm/mT (90°)。此外，所提出的传感探头超紧凑，占地面积极小（传感部分的长度仅为615μm），对于狭窄空间和梯度场的磁场检测非常有帮助。