均分直槽微结构光纤光栅磁场传感器

Magnetic field FBG sensor with even straight-trenches microstructure

对微结构光纤磁场传感器的增敏性能进行研究,设计了一种基于飞秒激光微加工的均分直槽型微结构光纤磁场传感器。利用飞秒激光在刻有光纤布拉格光栅(FBG)的单模光纤(SMF)包层上刻蚀均分直槽微结构,并采用HF溶液清除直槽内的残留碎屑和应力集中点,随后用磁控溅射技术在加工部位溅射一层磁致伸缩薄膜TbDyFe。当外界磁场强度变化时,通过观测传感器中心波长的变化可实现对磁场强度的测量。直槽微结构能减小光纤横截面积,改善光纤轴向伸缩性能,增大薄膜附着表面积,从而提高传感器探头灵敏度。理论分析了直槽微结构提高传感器性能的工作原理,介绍了传感器探头的制备工艺和性能影响因素,给出了不同参数传感探头的磁场测试结果。实验结果表明,利用飞秒激光加工直槽微结构能明显改善传感器探头灵敏度,其中直槽个数对性能影响最为明显;相对于无微结构传感器探头,有微结构光纤探头灵敏度最高可提升3.8倍。

A kind of magnetic field sensor with even straight-trenches microstrueture is designed based on femtosecond laser micromachining. The femtosecond laser is used to ablate straight-trenches into clad- cling of fiber Bragg grating （FBG） ,and the HF is employed to remove the residual debris and stress con- centration in the straight-trenches. Then the magnetostrictive film （TbDyFe） is deposited on tb/e pro- eessing region by magnetron sputtering process. When the intensity of external magnetic field changes,it can be measured by the change of the central wavelength of the sensor. The microstructure can reduce the fiber cross-sectional area,improve the axial retractility of fiber and increase the deposited surface are- a, so as to improve the sensitivity of sensor probe. The principle of improving the sensor performance by straight-trenches microstructure is analyzed and the fabrication process the and factors affecting sensor performance are described. The magnetic response results of several probes with different parameters are demonstrated. The experimental results show that processing straight grooves microstructure by femto- second laser can significantly improve the sensitivity of the sensor probe and the number of straight- trenches is the most significant influence factor. The sensitivity of the probe with microstructure can be improved by nearly 4. 5 times compared with that without microstructure.