采用保偏光纤耦合器等保偏器件,搭建了马赫-曾德尔型保偏光纤干涉仪,在干涉臂中接入磁致伸缩材料粘附光纤结构的保偏光纤磁传感探头,通过磁致伸缩效应探测地磁场引起的光纤中的相位变化,建立了保偏光纤地磁场传感器实验系统,实现了稳定的磁场检测。实验分析了系统相位信号随磁场变化的特性以及频率响应特性,为系统选择适当的交流磁场进行直流磁场检测提供了依据,结果表明该系统最小可检测到1 nT量级的磁场。实验测量了地磁场矢量在水平面各方向上的分量大小,得到的实验结果与理论值吻合得较好,证明该系统能够用于基于地磁场测量的定向导航。

A polarization-maintaing fiber Mach-Zehnder interferometer is made from polarization-maintaing fiber couplers and other polarization-maintaing fiber components. In the sensing arm, a transducer made by polarization-maintaining fiber bonded on a magnetostrictive material is joined. Because of magnetostriction effect, the phase variation in the fiber caused by earth magnetic field is detected. At last, a stable polarization-maintaing fiber earth magnetic field sensing system is set up. The phase response of the system to the varying magnetic field is measured and analyzed, and the frequency response is obtained too, from which an appropriate AC magnetic field used in the next DC magnetic field sensing experiment has been selected. The magnetic field at level of 1 nT can be measured in the experimental system, and the measured results for the earth magnetic fields in different directions agree with the theoretic prediction, which proves that the system can be used in the navigation and orientation fields.