基于飞秒激光微加工的光纤磁场传感器

Fiber Optic Magnetic Field Sensor Based on Femtosecond Laser Micromachining

提出了一种基于光纤三维微结构加工的磁场传感技术方案。利用波长为780nm的飞秒激光脉冲在刻写有光纤布拉格光栅(FBG)的单模光纤包层上加工螺旋微结构,并采用磁控溅射方法在其上溅射磁致伸缩膜(TbDyFe),制备了一种新型光纤磁场传感器探头。微结构能改善光纤轴向伸缩性,增加薄膜沉积的表面积,从而提高探头的磁场敏感性。建立了螺旋微结构改善传感灵敏度的理论基础,介绍了光纤磁场传感探头的制备工艺方法与技巧,给出了不同参数传感探头的磁场测试结果。实验结果表明,螺距为50μm时,对应的传感探头对磁场最为敏感;相比于无微结构的标准光纤探头,有微结构的光纤探头理想情况下灵敏度可提高近5倍。

A kind of magnetic field sensing solution is proposed based on 3-D microstructure machining of fiber. The femtosecond laser with wavelength of 780 nm is employed to ablate a spiral microstructure into cladding of fiber Bragg grating （FBG）, and the magnetostrictive film （TbDyFe） is deposited in the microstructure by magnetron sputtering process to form a new fiber optic magnetic field sensor. The microstructure can improve the axial retractility of fiber and enhance the surface area of the thin film deposition in order to enhance the sensitivity of probe. The theory of enhancing sensitivity from spiral microstructure is established and the preporation methods and techniques of the fiber optic magnetic field sensor probe are described. The magnetic response results of several probes with different parameters are demonstrated. It is shown that from the experimental results, the sensing probe with pitch of 50 μm is most sensitive to magnetic field. In ideal case, the sensitivity of the probe with microstructure can be enhanced nearly five times as high as that with non-microstructured standard FBG.