【作者】 闫淑贤；

【导师】 富鸣；

【作者基本信息】 北京交通大学 ， 光学工程（专业学位）， 2021， 硕士

【摘要】 双曲超材料是介电张量矩阵具有非正定特性的亚波长微纳结构,具有开放的等频面,而且允许大波矢量模式的光传输,超材料内部相应的体等离子基于光谱特性具有对周围折射率环境敏感相应的优异特性,有望使相关结构应用于生物分子和环境传感检测领域。在本论文中,我们主要以金共型包裹的氧化硅纳米棒状阵列为基础,构建三维周期型双曲超材料,探究双曲超材料的折射率敏感型传感灵敏度与超材料微结构的依赖性关系,并通过超材料的实际构建简要研究了其在环境检测和生物分子检测中的特性。本文的主要研究内容如下:（1）金基三维棒阵列结构双曲超材料以及多种双曲超材料的光谱特性及折射率敏感性能的研究。通过时域有限差分方法在可见和近红外波段模拟了多种结构双曲超材料的反射光谱,等离激元模式对环境折射率敏感性体现在反射光谱的凹谷上。三维周期型双曲超材料在小于700 nm的低反射率区域内存在由局域等离子激元和表面等离子激元引起的特征丰富峰与谷;在880 nm-1350 nm波段内存在介电常数分量异号,形成非正定区间,因此在800 nm后的高反区域存在更加尖锐的由于允许大波矢量模式的光传输引起的反射谷,即体等离激元极化谷。在低反区域内由于表面等离子激元模式对折射率传感灵敏度约为一百nm/RIU量级,局域等离子激元模式对折射率传感灵敏度在几十nm/RIU量级,而在高反区域内体等离激元模式引起的折射率传感灵敏度高达几百nm/RIU,超过了其它两种激发模式。层状Au/Al₂O₃交替结构的反射光谱特性与三维周期型超材料类似,对折射率敏感的传感灵敏度达到了上千,而且随着层数增加激发波长会产生蓝移;表面单层纳米柱阵列结构双曲超材料由于纳米柱之间激发的等离激元模式,仅在400 nm-1200 nm产生了反射凹谷且反射率低于0.5,折射率传感灵敏度也达到上千。（2）探究金基三维棒阵列结构双曲超材料的折射率敏感型传感灵敏度对微观结构的依赖性关系。通过对金基棒阵列双曲超材料的结构几何参数等的优化,明确了不同金膜厚度、不同入射角度和不同长度下超材料的光谱特性,进而分析了折射率敏感型传感灵敏度与结构几何参数的关系。不同等离激元模式的折射率敏感型传感灵敏度的变化趋势略有差别,改变入射角度在20°到50°范围内,几个特征等离子谷分别在1045 nm、1300 nm和1390 nm,其中在30°时达到了最大传感灵敏度,分别为600 nm/RIU、966.67 nm/RIU和870 nm/RIU,对比发现所有特征峰的最大灵敏度为966.67 nm/RIU;包裹金膜厚度在5 nm-15 nm变化,金膜厚度为10 nm时双曲超材料传感灵敏度最大;双曲超材料棒长度从1500 nm到2000 nm变化时,所有体等离激元谷引起的折射率传感灵敏度的最大值依次为870 nm/RIU、966.67 nm/RIU和1120 nm/RIU,相对应的垂直介电分量为-7.26、-8.77和-14.72,随着金基棒阵列长度的增加,垂直介电分量减小,反射谷的灵敏度相对更高。通过对三维周期型双曲超材料的结构依赖关系分析,折射率敏感型传感灵敏度最大值达到了1120 nm/RIU,可以对周围介质环境变化实现高灵敏度传感。（3）完成了三维周期型金基双曲超材料的制备及其对蛋白分子及溶液环境变化的光谱响应研究。通过水解正硅酸乙酯制备出单分散的二氧化硅棒状结构,在样品上持续施加定向电场获得垂直模板,利用柠檬酸钠还原氯金酸制备出纳米金颗粒包裹在氧化硅的表面,构建出三维周期型金基双曲超材料。超材料反射光谱的测量结果与之前的模拟结果一致,在850 nm后的高反区域内由于等离激元激发表现出反射凹谷,对比超材料在空气和去离子水环境中的反射光谱响应,在945 nm附近处的反射凹谷对折射率环境最敏感,体等离激元谷发生红移,反射光谱对溶液环境的变化表现出响应特性。也对金基双曲超材料负载蛋白分子及光谱响应研究,通过自组装法将半胱氨酸分子链接在双曲超材料的表面,缩合反应将浓度为6μM的牛血清蛋白分子链接到半胱氨酸分子上,对比链接蛋白分子前后的反射光谱,反射凹谷从965.7 nm移动至978.1 nm时,该波长下对蛋白分子的检测灵敏度最高,灵敏度为12.39 nm/μM,说明三维周期型金基纳米柱双曲超材料可以实现对环境折射率响应及生物分子检测。更多还原

【Abstract】 Hyperbolic metamaterials are sub-wavelength micro-nano structures with non-positive definite properties of the dielectric tensor matrix.They have open equal-frequency surfaces and allow light transmission in large-wave vector modes.The corresponding bulk plasma inside the metamaterial has an impact on the surroundings based on the spectral characteristics.The excellent properties of refractive index and environmental sensitivity are expected to make relevant structures applicable to the fields of biomolecules and environmental sensing and detection.In this thesis,we mainly build a three-dimensional periodic hyperbolic metamaterial based on a gold-coated silicon oxide nanorod array,and explore the dependence of the refractive index-sensitive sensing sensitivity of the hyperbolic metamaterial and the microstructure of the metamaterial.Sexual relationship,and briefly studied its characteristics in environmental detection and biomolecular detection through the actual construction of metamaterials.The main research contents of this paper are as follows:(1)Research on the spectral characteristics and refractive index sensitivity of hyperbolic metamaterials with gold-based three-dimensional rod array structure and a variety of hyperbolic metamaterials.The reflection spectra of hyperbolic metamaterials with various structures are simulated in the visible and near-infrared bands by the finite difference time domain method.The sensitivity of the plasmon mode to the environmental refractive index is reflected in the valleys of the reflection spectrum.The three-dimensional periodic hyperbolic metamaterials have characteristic-rich peaks and valleys caused by local plasmons and surface plasmons in the low reflectivity region less than 700nm;there are different dielectric constant components in the 880 nm-1350 nm band.No.,forming a non-positive definite interval,so there is a sharper reflection valley in the high reflection area after 800 nm,which is caused by the light transmission of the large-wave vector mode,that is,the volume plasmon polarization valley.In the low transmissive region,the sensitivity of surface plasmon mode to refractive index sensing is about 100 nm/RIU,and the sensitivity of local plasmon mode to refractive index sensing is on the order of tens of nm/RIU.The sensitivity of the refractive index sensing caused by the bulk plasmon mode in the high-reflection region is as high as several hundred nm/RIU,which exceeds the other two excitation modes.The reflection spectrum characteristics of the layered Au/Al2O3 alternating structure are similar to the three-dimensional periodic metamaterials,and the sensitivity of the refractive index-sensitive sensor reaches thousands,and the excitation wavelength will blue shift as the number of layers increases;the surface single-layer nano-pillars Due to the plasmon mode excited between the nanopillars of the array structure hyperbolic metamaterials,only reflection valleys are generated at 400nm-1200 nm,and the reflectivity is lower than0.5,and the refractive index sensing sensitivity has reached thousands.(2)Explore the dependence of the refractive index-sensitive sensing sensitivity of the gold-based three-dimensional rod array hyperbolic metamaterial on the microstructure.By optimizing the structural geometric parameters of the gold-based rod array hyperbolic metamaterial,the spectral characteristics of the metamaterial under different gold film thicknesses,different incident angles and different lengths are clarified,and then the sensitivity and structure of the refractive index-sensitive sensor are analyzed.The relationship of geometric parameters.The change trend of the refractive index-sensitive sensing sensitivity of different plasmon modes is slightly different.The incident angle is changed within the range of 20° to 50°,and several characteristic plasma valleys are respectively at 1045 nm,1300nm and1390 nm,of which at 30° When the maximum sensitivity is reached at 600nm/RIU,966.67nm/RIU and 870nm/RIU,the maximum sensitivity of all characteristic peaks is found to be 966.67nm/RIU by comparison;the thickness of the coated gold film varies from 5nm to 15 nm,and the gold film thickness Sensing sensitivity of hyperbolic metamaterials is the highest when it is 10nm;when the length of hyperbolic metamaterials rod changes from 1500 nm to 2000 nm,the maximum sensitivity of refractive index caused by all bulk plasmon valleys is 870nm/RIU,966.67nm/ The corresponding vertical dielectric components of RIU and 1120nm/RIU are-7.26,-8.77 and-14.72.As the length of the gold-based rod array increases,the vertical dielectric component decreases,and the sensitivity of the reflection valley is relatively higher.Through the analysis of the structural dependence of the three-dimensional periodic hyperbolic metamaterials,the maximum sensitivity of the refractive index-sensitive sensing has reached 1120nm/RIU,which can achieve high-sensitivity sensing to changes in the surrounding medium environment.(3)The preparation of the three-dimensional periodic gold-based hyperbolic metamaterial and the study of its spectral response to changes in protein molecules and solution environment have been completed.The monodispersed silica rod-like structure was prepared by hydrolyzing ethyl orthosilicate,and the vertical template was obtained by continuously applying a directional electric field on the sample.The gold nanoparticles were prepared by reducing chloroauric acid with sodium citrate and wrapped on the surface of silica.A three-dimensional periodic gold-based hyperbolic metamaterial was developed.The measurement results of the metamaterial reflectance spectra are consistent with the previous simulation results.In the high reflectance region after 850 nm,the reflection valleys are exhibited due to plasmon excitation.Compare the reflectance spectral response of metamaterials in air and deionized water environments.The reflection valley near 945 nm is most sensitive to the refractive index environment,and the volume plasmon valley has a red shift,and the reflection spectrum shows a response characteristic to the change of the solution environment.Also studied the protein loading and spectral response of gold-based hyperbolic metamaterials.The self-assembly method was used to link cysteine molecules on the surface of the hyperbolic metamaterial,and the condensation reaction linked 6u M bovine serum protein molecules to cysteine.On the amino acid molecule,comparing the reflection spectra before and after the linked protein molecule,when the reflection valley moves from 965.7 nm to 978.1nm,the detection sensitivity for protein molecules at this wavelength is the highest,with a sensitivity of 12.39nm/μM,indicating that the three-dimensional periodic gold base Nano-pillar hyperbolic metamaterials can achieve environmental refractive index response and biomolecule detection.更多还原