提出一种使用磁性液体的新型光纤Sagnac磁场传感器。磁性液体具有磁致可变双折射效应和二向色性,在外加磁场作用下,液体中的磁性纳米粒子沿磁场方向结链规则排列,形成各向异性。将其制成液体薄膜,放入具有一段保偏光纤的Sagnac环中,使光纤Saganc干涉仪的正弦形状干涉光谱可随外磁场变化。光纤中传输光垂直经过磁性液体薄膜,在外加磁场与磁性液体薄膜平面平行时,传输光产生双折射现象,干涉光谱的峰值波长随着外加磁场的变化而变化。传感器灵敏度与磁性液体薄膜厚度有关,对于60μm的磁性液体薄膜,灵敏度为16.7pm/Oe(1Oe≈79.578A/m),分辨率为0.60Oe。而在外加磁场与磁性液体平面垂直时,干涉光谱的峰值波长几乎不随外加磁场的变化而变化。 A new type of optical fiber Sagnac magnetic sensor using magnetic fluid is proposed. Magnetic fluid has a magnetically-variable birefringence effect and a dichroism. Under the action of an applied magnetic field, the magnetic nanoparticles in the liquid are regularly arranged along the direction of the magnetic field to form an anisotropy. The liquid film is made into a Sagnac ring with a polarization maintaining fiber so that the sinusoidal interference spectrum of the fiber Saganc interferometer can vary with the external magnetic field. Optical fiber transmission perpendicular to the magnetic liquid film through the magnetic field in the external magnetic field parallel to the plane of the liquid film, the transmission of light birefringence occurs, the interference peak wavelength of the spectrum with the change in the external magnetic field changes. The sensitivity of the sensor is related to the thickness of the magnetic liquid film. For a 60μm magnetic liquid film, the sensitivity is 16.7pm / Oe (1Oe≈79.578A / m) and the resolution is 0.60Oe. When the applied magnetic field is perpendicular to the plane of the magnetic liquid, the peak wavelength of the interference spectrum hardly changes with the change of the applied magnetic field.