建立了基于单模多模单模光纤结构和磁流体的全光纤电流传感器，此传感器能够通过检测透射光谱的特征波长漂移和传输损耗变化两种方法来探测电流。对于第一种方法，得到电流灵敏度为1243.7 pm/A[77.9 pm/Oe,1 Oe=1/(4π)×103 A/m]；对于第二种方法，传感特性依赖于波长的选择，分析了不同波长条件下传感器传输损耗的变化特性。结果表明：选择单波长时，传感特性受波长的影响，且传输损耗变化小，从而灵敏度小；使用宽波长范围内的总传输损耗时，传输损耗变化大，电流检测灵敏度大大加强，所得灵敏度为506.2 dB/A(31.7 dB/Oe)，分别是单波长1529 nm和1611 nm下灵敏度的337倍和723倍。在自发辐射宽带光源入射条件下，利用探测器直接检测传感器输出光强的变化，得到26.8 V/A(1.7 V/Oe)的电流灵敏度。

A single mode-multimode-single mode fiber optic structure and magnetic fluid based all-fiber optic current sensor, which can be interrogated by monitoring the dip wavelength shift or transmission loss of the transmission spectrum, is designed. For the first interrogation method, the current sensitivity of 1243.7 pm/A [77.9 pm/Oe, 1 Oe=1/(4π)×103 A/m] is obtained. For the second way, the sensing property depends on wavelength. By analyzing the rule of the change of transmission loss under different wavelengths, it is found that when a specified wavelength is used, the sensing property is influenced by different wavelengths and the variation of transmission loss is little, leading to a small sensitivity. When the all transmission loss during broad wavelength range of source is employed, the change of transmission loss is obvious, and hence the current sensitivity is greatly enhanced. The obtained sensitivity of 506.2 dB/A (31.7 dB/Oe) is 337 times and 723 times larger than those under 1529 nm and 1611 nm, respectively. Furthermore, the sensitivity of 26.8 V/A (1.7 V/Oe) is achieved by detecting the output intensity using detector with amplified spontaneous emission broadband light source inputting.