设计并制作了一种马赫-曾德尔干涉仪(Mach-Zehnder Interferometer, MZI)与光纤布喇格光栅级联的光纤磁场传感器, 其中MZI由相当于分光器的锥结构和相当于耦合器的花生锥结构级联组成, 封装在填充了磁流体的毛细管中.由于磁流体的有效折射率会随着外界磁场强度的改变而变化, 故可通过观察干涉谱的特征波长的变化来测量外界磁场强度, 而光纤布喇格光栅透射峰对磁场强度不敏感.当磁场强度由0 mT变化到20 mT时, 马赫-曾德尔干涉峰的灵敏度为0.11 nm/mT.温度特性实验测得马赫-曾德尔干涉峰和光纤布喇格光栅透射峰的温度灵敏度分别为0.401 5 nm/℃和0.011 4 nm/℃.因此, 可利用敏感矩阵实现双参量同时测量.

An optical fiber magnetic field sensor was proposed and demonstrated. The sensor head is composed of a Mach-Zehnder Interferometer (MZI) cascading with a Fiber Bragg grating (FBG). The MZI consists of a taper structure and a peanut-shape structure, which are encapsulated in capillary with Magnetic Fluid (MF) . The taper structure and peanut-shape structure is equivalent to an optical splitter and a coupler respectively. The external magnetic field intensity can be measured by the variation of characteristic wavelength as the effective refractive index of MF changes with the variation of magnetic field intensity. The transmission peak of FBG is insensitive to magnetic field intensity, the experimental results show that, when the magnetic field intensity varies from 0mT to 20 mT, the magnetic field sensitivity is 0.11 nm/mT. Experimental results show that, the temperature sensitivities of the interference peak of MZI and the transmission peak of FBG are 0.401 5 nm/℃ and 0.011 4 nm/℃, respectively. Therefore, the simultaneous measurement of the magnetic field intensity and temperature is demonstrated based on the sensitive matrix.