【作者】 刘光宇；

【导师】 田凤军； 陈强；

【作者基本信息】 哈尔滨工程大学 ， 光学工程（专业学位）， 2022， 硕士

【摘要】 太赫兹波的频谱位于高频微波和远红外光之间,具有脉冲短、光子能量低、穿透力强等特性,且许多物质在太赫兹波段内具有特殊的光谱响应。表面等离子体共振（Surface Plasmon Resonance,SPR）光纤传感器由于其灵敏度高、可远程监测、免标记、非破坏性等优异特性,在生物医学和化学领域具有重要应用价值。但在实际测试环境中,环境温度的变化以及非目标分子之间的反应都会影响检测的准确性。利用多通道传感技术引入参考待测物能够有效解决上述问题,并且还能满足对分析物进行多参数、多通道、自参考测量的需求。因此,开发太赫兹波段的SPR多通道传感器有着重要应用价值。本论文设计了基于SPR机理的太赫兹双通道光纤传感器,可以在太赫兹波段内实现多通道测量和自参考测量功能,为太赫兹波段内的SPR光纤传感器的设计提供了一种新的方案。本论文研究了新型太赫兹光纤的设计方法及光学特性。设计了太赫兹六角密排光子晶体光纤、太赫兹蜂窝状结构光子晶体光纤和太赫兹八边形光子晶体光纤。采用有限元法对上述光纤进行建模。讨论了纤芯结构、纤芯空气孔的直径、基底材料对其传感特性的影响。分析了太赫兹光纤SPR传感器的最佳结构。结果表明,具有较高占空比的六角密排光子晶体光纤更有利于达到相位匹配条件,Zeonex的材料特性和传输特性最适宜用于光纤的基底材料。上述工作为后文设计双通道太赫兹光纤SPR传感器奠定了基础。所设计的基于Zeonex的双通道太赫兹光纤SPR传感器,其纤芯为六角密排空气孔结构,纤芯外侧环绕两个半圆形空气通道包层。聚偏氟乙烯（Ferroelectric Polyvinylidene Fluoride,PVDF）薄膜涂覆在两个半圆形空气通道的内表面,以激发SPR效应。讨论了纤芯占空比以及PVDF层厚度对传感特性的影响。分析了太赫兹SPR光纤的测量范围和双通道测量的可能性。分析表明,太赫兹光纤传感器具有1.000-1.030的折射率范围,并且可以实现双通道测量。通过在传感通道引入介质层,克服多通道串扰,提高双通道传感的独立性。研究了在不同结构参数下,多通道测量的效果优化情况,可以通过调节结构参数将共振波长容易地调谐到期望值。研究了该光纤的双通道传感特性,该光纤传感器的灵敏度可达1100μm/RIU,分辨率为2.4×10^-4 RIU。本论文设计的双通道太赫兹光纤传感器灵敏度高,可以在太赫兹波段内实现多通道测量和自参考测量功能,很好地展示了将可见和近红外波段的多通道SPR光纤传感器扩展至太赫兹波段的方法,在生物医学、食品安全和环境监测等领域具有广阔的应用前景。更多还原

【Abstract】 Terahertz（THz）wave has unique and excellent characteristics,such as low photon energy and strong penetrability,due to its special position between infrared and microwave.It is expected that many substances have special spectral responses in THz range.Surface Plasmon Resonance（SPR）fiber optic sensors have important applications in the fields of biomedicine and chemistry due to their excellent properties such as high sensitivity,remote monitoring,label-free,and non-destructive properties.However,in the actual test environment,changes in ambient temperature and reactions between non-target molecules can affect the accuracy of detection.The above problems can be solved by introducing a reference test object using multi-channel sensing technology.And it can also meet the needs of multi-parameter,multi-channel,self-reference measurement of analytes.Therefore,it is of great value to develop SPR multi-channel sensors in the terahertz band.In this way,a terahertz dual-channel fiber optic sensor based on the SPR effect is designed,which can realize multi-channel measurement and self-reference measurement functions in the terahertz band,and provides a new solution for the design of SPR fiber optic sensors in the terahertz band.The design method and optical properties of new terahertz optical fibers are studied.Terahertz photonic crystal fibers with hexagonal lattice air holes,honeycomb air holes and octagonal air holes structures are designed.The finite element method was used to model the above-mentioned photonic crystal fibers.We discussed the design method of the core structure,the diameter of the core air hole,the influence of the substrate material on the transmission characteristics of the fiber,and analyzed the optimal structure of the terahertz SPR fiber sensor.The results show that the hexagonal dense photonic crystal fiber with higher porosity is more favorable to achieve the phase matching condition,and Zeonex’s material properties and transmission properties are more suitable for the substrate material of the fiber.The above work lays the foundation for the design of a dual-channel terahertz fiber SPR sensor in the following.For the dual-channel optical fiber SPR sensor based Zeonex,two semicircular large air hole channels are used to achieve multi-channel measurement in terahertz region.The SPR effect can be excited by coating the ferroelectric polyvinylidene fluoride（PVDF）layer on the inner surfaces of the channels.The influence of the porosity and the thickness of the PVDF layer on the sensing characteristics is discussed,and the measurement range of the THz SPR fiber and the possibility of dual-channel measurement are analyzed.Analysis shows that the THz fiber optic sensor has a refractive index range of 1.000 to 1.030,and can achieve dual-channel measurement.By introducing a dielectric layer into the sensing channel,multi-channel crosstalk is overcome and the independence of dual-channel sensing is improved.The optimization of the effect of multi-channel measurement under different structural parameters is studied,and the resonance wavelength can be easily tuned to the desired value by adjusting the structural parameters.The dual-channel sensing characteristics of the fiber were studied.The proposed optical fiber sensor has a sensitivity of 1100μm/RIU and a resolution of 2.4×10^-4 RIU.The designed dual-channel terahertz fiber SPR sensor has high sensitivity and can realize multi-channel measurement and self-reference measurement in the terahertz band,which is a good demonstration of extending the multi-channel SPR fiber optic sensor in the visible and near-infrared bands to terahertz.The band method has broad application prospects in the fields of biomedicine,food safety and environmental monitoring.更多还原