基于Sagnac干涉仪的光纤直流磁场传感研究

Study of Fiber DC Magnetic Sensor Based on Sagnac Interferometer

将磁致伸缩材料粘贴单模光纤构成的光纤磁传感探头接入Sagnac光纤环的一端,外加交流磁场将探头周围的直流磁场加载到4.9 kHz的高频信号上,建立了基于Sagnac干涉仪的光纤直流磁场传感实验系统。采用锯齿波相位调制的方法,将干涉仪系统相位偏置在π/2附近,通过测量所加高频信号的幅度,实现了对直流磁场的测量。实验得到系统信号稳定性为0.4%,磁场分辨率为4.3 nT,并给出36.75 g铁块经过磁传感探头时系统的响应信号。

A fiber DC magnetic sensor based on Sagnac interferometer is proposed and experimentally demonstrated. The magnetic transducer made by SM fiber bonded on a magnetostrictive material is joined at one end of the Sagnac fiber loop. A stable quadrature phase is obtained by using a saw-tooth phase modulation method. The DC magnetic field signal around the magnetic transducer is carried by a 4.9 kHz magnetic dither, and the DC magnetic field signal can be achieved by measuring the amplitude of the 4. 9 kHz in the output of the Sagnac interferometer. The results show the signal stability is less than 0. 4%, and the magnetic field resolution is 4.3 nT. When a 36.75 g iron is passing by, the response of the sensor is presented.