WANG Yan1, LIU Jia-ping1, LIU Ji-hong1, HU Xing-liu2, FANG Ting1
（1. School of Electrical and Information Engineering, Anhui University of Technology, Maanshan 243000, China； 2. College of Intelligent Science and Control Engineering, Jinling Institute of Technology, Nanjing 211169, China）
Abstract： To obtain the influence rules of the coating parameters of a long-period fiber grating (LPFG) with respect to temperature, strain and refractive index sensing properties, based on the mode coupling theory, a strict four-layer theorietical model of a metal film coated LPFG is established, and these parameters that affect the spectral characteristics of the metal film coated LPFG are studied. The simulation results show that there is an optimal metal film thickness on the surface of the LPFG that will induce the surface-plasmon resonance (SPR) effect, which results in higher sensitivity to the environmental temperature and refractive index but has little influence on the strain. There is theoretical evidence that when the silver thickness is between 0.8 and 1.2 nm, the refractive index sensitivity will reach the peak point of 42.402 6, at which the refractive index sensor sensitivity is increased by 4.5%. The theoretical results of coating a long-period fiber grating provide a good theoretical basis and guidance for LPFG design and parameters optimization.
Key words： metal film coated long-period fiber grating (LPFG); surface plasmon resonance (SPR); transmission spectrum; sensing characteristics
CLD number： TN201 Document code： A
Article ID： 1674-8042（2017）01-0089-08doi： 10.3969/j.issn.1674-8042-2017-01-014
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镀金属膜长周期光纤光栅的传感特性
王彦1， 刘加萍1， 刘吉虹1， 胡兴柳2， 方挺1
（1. 安徽工业大学 电子与信息工程学院， 安徽 马鞍山 243000； 2. 金陵科技学院 智能科学与控制工程学院， 江苏 南京 211169）
摘要： 本文基于耦合模理论， 建立了严格的四层金属膜理论模型， 探讨了镀金属膜长周期光纤光栅（Long-period fiber grating， LPFG）的温度、 应变及折射率特性， 以及镀膜参数对镀金属膜长周期光纤光栅光谱特性的影响。仿真结果表明， 长周期光纤光栅表面最优的金属膜厚度将引起表现等离子共振(Surface-plasmon resonance, SPR)特性， 这一特性将使得LPFG 对稳定及折射率都有较高的敏感性， 而对应变影响较小。 理论分析表明， 银膜厚度在0.8-1.2 nm 范围内时， 折射率敏感度达到最大值为42.402 6， 敏感度增加4.5%。 仿真结果为镀膜长周期光纤光栅的设计及参数优化提供了理论指导。
关键词： 镀金属膜长周期光纤光栅； 表面等离子共振； 传输光谱； 传感特性
引用格式：WANG Yan, LIU Jia-ping, LIU Ji-hong, et al. Sensing characteristics of a metal film coated long-period fiber grating. Journal of Measurement Science and Instrumentation, 2017, 8(1)： 89-96. ［doi： 10.3969／j.issn.1674-8042.2017-01-014］
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