Studies On The Sensing And Absorbing Mechanism Of Dirac Semimetal Terahertz Metamaterials

Terahertz(THz)wave has attracted tremendous attention because of its dramatic properties including low photo energy,high penetrability and transient property,which shows potential applications in many areas including wireless communication,imaging technology,sensing,and security detection.Three-dimensional(3D)Dirac semimetal(known as 3D graphene)is a new quantum material,However,compared with graphene,Dirac semimetal are more robust against environmental defects or excess conductive bulk states,and it also processes higher carier mobility.It has unique advantages in the study of terahertz optical devices.This paper focuses on the research of the mechanism of Dirac semimetal based sensor and absorber.The main contents and conclusions of this paper are summarized as follows:1.Based on bright-dark model coupling method,we construct classical ?-shaped metamaterial structure to induce the EIT optical effect and discuss the refractive index sensing property.The study shows that two parallel Dirac semimetal strips lying along the polarized direction of the electric field can be excited by the incident light,which can be regarded as bright models;and the vertical Dirac semimetal cannot be excited by the incident light,which can be regarded as dark model.In this section,we also study the dependence of the refractive index on frequency to demonstrate the practical application of the EIT letamaterial in sensing,and the simulation results show that a higher figure of merit(FoM)value of about 10.99 is obtained.2.We design and investigate three complementary Dirac semimetal structures,and optimal structural parameters optimize the size of the structure.The simulation results shows that perfect absorptions are obtained at 6.19THz(complementary cross-shaped structure),8.08THz(complementary cut-wire-shaped structure),6.11 THz(complementary circle-shaped structure)respectively.We also discuss the polarization independent properties of proposed structures.The multiple reflection theory is used to study the physical mechanism and the feasibility of the simulation method is proved.At last,by tuning the Fermi energy of Dirac semimetal,the absorb band can be dynamically tuned.