【作者】 李冰；

【导师】 沈涛；

【作者基本信息】 哈尔滨理工大学 ， 光学工程， 2021， 硕士

【摘要】 微结构光纤广泛应用在环境监测、食品安全、化学、生物医学等领域;湿敏材料氧化石墨烯(Graphene Oxide,GO)可以通过吸附水分子改变自身折射率来达到对光波导器件的增敏作用,在基于表面等离子体共振(Surface Plasmon Resonance,SPR)中还可以保护金属层不被氧化。与现有的光纤湿度传感器相对比,本论文以湿敏材料GO、马赫曾德(Mach-Zehnder,M-Z)传感单元的研制、基于有限元仿真的理论与结构设计等方面展开研究,提出并实现了基于有限元的GO复合微结构光纤湿度传感系统。首先论文对湿敏材料GO和M-Z结构光纤在湿度影响下所引起的折射率变化原理进行分析。通过COMSOL Multiphysics全矢量有限元仿真软件对光纤复合敏感材料传感单元的电场进行仿真研究,并通过理论推导和仿真研究了不同传感单元材料性质变化,为微结构光纤湿度传感研究奠定了理论基础。其次,通过改善后的Hummers法制备GO,使用光纤熔融拉锥机和光纤熔接机制得M-Z传感结构光纤(多模光纤-单模微纳光纤-多模光纤),再利用浸涂法将GO涂覆在单模微纳光纤上。搭建直通式光路的光纤湿度传感系统,在49%RH～70%RH的湿度范围内对四种不同光纤M-Z传感结构进行湿度传感实验,得到了光纤M-Z传感结构灵敏度高达44.1pm/%RH的湿度传感器。最后,利用COMSOL设计了一种基于SPR效应的Ag-GO包覆PCF湿度传感器。通过在光子晶体光纤(Pohotonic Crystal Fiber,PCF)包层外侧包覆金属银薄膜和氧化石墨烯薄膜,设计了一种基于表面等离子共振高灵敏度的光子晶体光纤湿度传感器。在PCF中围绕大小不等的两排规则排列的小空气孔,在外两层分别包覆Ag-GO以构成SPR传感通道。同时,在其外层包覆琼脂糖凝胶材料以构成湿度传感介质层,最外层用完美匹配层(Perfect Matching Layer,PML)来限制光的损耗。数值分析结果表明该传感结构湿度灵敏度最高达0.3183d B/%RH。此外,在10～60%RH范围能实现平均灵敏度0.2131d B/%RH,可广泛应用于智能检测和安全监测领域。更多还原

【Abstract】 Microstructured optical fibers are widely used in environmental monitoring,food safety,chemistry,biomedicine and other fields;moisture-sensitive material graphene oxide(Graphene Oxide,GO)can increase the sensitivity of optical waveguide devices by adsorbing water molecules and changing its own refractive index.Based on surface plasmon resonance(Surface Plasmon Resonance,SPR),the metal layer can also be protected from oxidation.Compared with the existing optical fiber humidity sensor,this thesis conducts research on the preparation of humidity sensitive material GO,Mach-Zehnder(Mach-Zehnder,M-Z)sensing unit,theory and structural design based on finite element simulation,and proposes and A finite element-based GO composite microstructure fiber optic humidity sensor system is designed.First,the paper analyzes the principle of refractive index change caused by humidity-sensitive material GO and M-Z structure fiber under the influence of humidity.Through the COMSOL Multiphysics full vector finite element simulation software,the electric field of the optical fiber composite sensitive material sensing unit is simulated,and the material property changes of different sensing units are studied through theoretical derivation and simulation,which lays the foundation for the research of microstructure optical fiber humidity sensing basis.Secondly,GO is prepared by the improved Hummers method,the M-Z sensing structure fiber(multimode fiber-single-mode micro-nano fiber-multimode fiber)is obtained using the fiber fusion taper machine and fiber fusion splicing mechanism,and then the GO Coated on single-mode micro-nano fiber.Construct a fiber optic humidity sensing system with a direct high frequency optical path,and conduct humidity sensing experiments on different fiber optic MZ sensing structures within a humidity range of 49%RH～70%RH,and the sensitivity of the fiber optic MZ sensing structure is as high as 44.1pm/%RH Humidity sensor.Finally,using COMSOL,an Ag-GO coated PCF humidity sensor based on SPR effect was designed.By covering the outer side of the photonic crystal fiber(Pohotonic Crystal Fiber,PCF)cladding with a metallic argentum film and a graphene oxide film,a high-sensitivity photonic crystal fiber humidity sensor based on surface plasmon resonance was designed.The PCF surrounds two rows of regularly arranged small air holes of different sizes,and the outer two layers are respectively coated with argentum and graphene oxide(Ag-GO)to form the SPR sensing channel.At the same time,the outer layer is doped with agarose gel material to form the humidity sensing medium layer,and the outermost layer uses a perfect matching layer(PML)to limit light loss.Numerical analysis results show that the humidity sensitivity of the sensing structure is as high as 0.3183 d B/%RH.In addition,it can achieve an average sensitivity of 0.2131 d B/%RH in the range of 10～60%RH,which can be widely used in the field of intelligent detection and safety monitoring.更多还原