| 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. |
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