强度调制的光纤布拉格光栅磁场传感器

Intensity-modulated magnetic field sensor based on optical fiber Bragg grating

设计了一种基于光纤布拉格光栅啁啾效应的磁场传感器,导出了光纤布拉格光栅的反射谱带宽与磁感应强度的关系.传感器工作时,磁场中的圆盘形软铁受到通电螺旋管线圈磁场力的作用,引起矩形悬臂梁变形,从而导致粘贴在悬臂梁侧边的光纤布拉格光栅的反射光谱带宽发生变化;利用光谱分析仪,通过检测光纤布拉格光栅反射谱带宽的变化量,即可得到被测磁场磁感应强度的大小.当光谱分析仪的分辨率为0.001 nm时,可测量磁感应强度为6～70mT.实验结果表明：该光纤布拉格光栅反射光谱带宽的变化量对温度变化不敏感,当温度从0℃变化到45℃时,3 dB带宽的变化小于8 pm.实验结果和理论分析一致,表明该方案切实可行.

A novel magnetic field sensor based on a chirped effect of Fiber Bragg Grating（FBG） was proposed. The relationship between the magnetic induction intensity and the variable bandwidth of re- flection spectrum of the FBG was derived. The working principle of the sensor was introduced. First- ly, the magnetic force from an energized spiral coil was applied to a disc-shaped soft iron in a magnetic field to make the rectangular cantilever beam deformed, which resulted in the bandwidth change of the reflection spectrum of FBG that was mounted at a side of the cantilever. As mentioned above, the magnetic induction intensity could be obtained by measuring the variable bandwidth of the reflection spectrum of the FBG with a spectral analyzer. The experiments show when the optical spectral analy- zer is with a resolution of 0. 001 nm, the measuring range of the sensor is up to 6--70 mT. Experi- mental results demonstrate that the variable bandwidth of the reflection spectrum of FBG is not sensi- tive to temperature change. The 3 dB bandwidth change is less than 8 nm when the temperature changes from 0 to 45 ~C, which is consistent with theoretical value well. The sensor scheme is feasible and practical.