Research On High Performance Terahertz Refractive Index Sensor Based On Hyperbolic Metamaterials

With the rapid development of information processing technology,people are committed to the pursuit of integration,miniaturization and precision of new generation devices.Terahertz waves have unique characteristics such as good spectral fingerprint,penetration and low energy consumption,so that the use of these properties to design high-performance terahertz devices is widely used in various fields.However,the limited development of the optical field has hindered the rapid development of terahertz devices.In recent years,the combination of micro-nano structure array and hyperbolic metamaterials specific function has greatly improved the interaction between light and matter,and can suppress radiation loss and wide-range light field enhancement.The change of the refractive index of the external environment is very sensitive to the influence of the light field,so the use of these characteristics to design a high-performance refractive index sensor provides an ideal new idea.In this paper,we mainly study high-performance refractive index sensors based on micro-nano structures.First,we theoretically design metal-dielectric-metal nanopillar arrays,cross-tie graphene arrays,and hyperbolic metamaterial structures.Then the time domain finite difference method?FDTD?and strictly coupled wave?RCWA?are used to simulate the influence of structural geometric parameters on the spectrum,and the sensor refractive index sensing characteristics,including sensitivity,figure of merit?FOM?and quality factor?Q value?,the main research contents of this article are as follows:1.A novel surface lattice resonance?SLRs?based on metal-dielectric-metal nanopillar array structure is proposed,which theoretically illustrates that the formation of the SLRs is due to the in-plane dipole and the out-of-plane dipole Resonance coupling.The study found that in the more asymmetric dielectric environment,the Q value of the SLRs is higher:in the asymmetric dielectric environment of air/glass,the SLRs excited by direct incidence and oblique incidence have Q values of up to 62 and 147,respectively.This feature is completely opposite to traditional SLRs,which opens up a situation for SLRs'sensing applications.The sensor sensitivity based on the SLRs is 316nm/RIU,and the FOM is as high as 25RIU^-1.2.A plasma refractive index sensor with a cross-tie graphene array structure is proposed.Using the surface plasmon effect generated at the interface between graphene and dielectric,a double resonance transmission valley is obtained.The chemical potential,number of layers and the graphene in the structure are studied.The influence of geometric parameters on the transmission spectrum is to use the electrically adjustable characteristics of graphene to realize the dynamic modulation of the transmission spectrum.The results show that the refractive index sensitivities of the two plasmon resonance modes are 1280±24nm/RIU and 2800±49nm/RIU,and the FOM is 17.1RIU^-1 and 12.3RIU^-1,respectively.3.A terahertz refractive index sensor based on hyperbolic metamaterials is proposed,which reveals the physical essence of hyperbolic metamaterial multilayer films through far-field and near-field distribution.The simulation results show that the reflection spectrum of the structure has an ultra-narrow resonance valley under direct incidence of TM polarization,with a Q value of up to 516,a refractive index sensitivity of up to1.56THz/RIU,and a FOM of up to 355RIU^-1.In addition,according to the law of scaling dimensions,by changing the array period and width of the grating,the frequency of the resonance valley can also be tuned.