微纳尺度光纤布拉格光栅折射率传感的理论研究

亚波长直径微纳光纤强倏逝场传输的光学特性,使其对周围介质折射率的变化具有极高的灵敏度.本文提出一种基于微纳尺度光纤布拉格光栅(MNFBG)的折射率传感器,结合微纳光纤倏逝场传输和光纤布拉格光栅(FBG)强波长选择的特性来实现高精度折射率传感,对其制备可行性进行了讨论.论文中对MNFBG折射率传感机理进行了深入的理论分析,并使用OptiGrating软件进行了数值模拟,模拟数据显示MNFBG折射率测量的灵敏度随着光纤半径的减小而增加,其中光纤半径为400 nm的MNFBG灵敏度可达到993 nm/RIU,相比于包层蚀刻的FBG灵敏度增加了170倍,说明MNFBG对发展微型化、高灵敏度折射率传感器具有良好的应用前景. 关键词： 微纳光纤 光纤布拉格光栅 折射率传感

Theoretical investigation on refractive index sensor basedon Bragg grating in micro/nanofiber

Subwavelength and nanometer diameter optical fibers have the optical property of enhanced evanescent fields, which makes them very sensitive to the index change of the ambient medium. In this paper, a novel refractometric sensor based on fiber Bragg grating in micro/nano-fiber (MNFBG) is proposed, integrating the enhanced evanescent fields of micro/nano-fiber (MNF) with wavelength choice feature of FBG, and the fabrication about MNFBG is discussed. Refractive index sensing characteristics is comprehensively investigated in theories, and the simulation of sensing the variation of ambient refractive index is performed by using the software of OptiGrating. Results show the sensitivity of the MNFBG is increasing with the decrease of the radium of the MNF. MNFBG with the radius of 400nm can achieve the sensitivity as high as 993nm/RIU. This value is enhanced by 170 times over that of the FBG with etched cladding, which demonstrates that MNFBG has great potential of application in miniaturized, high-sensitivity refractometric sensors.