Research On Terahertz Fano Resonance And Sensing Based On Dirac Semimetal Metamaterials

Terahertz(THz)wave is the electromagnetic radiation between infrared and microwave,its frequency range is 0.1?10THz.Because THz wave has unique spectrum analysis ability,high penetrability and low energy radiation,it has a wide range of application value in security detection,sensor,imaging,biomedical and communication technology.However,the traditional THz materials are mostly made of metal materials,there are many problems,such as:metal materials have large ohmic loss,the dielectric constant is difficult to control and so on,which lead to the development of THz technology in many application fields is limited.Three dimensional(3D)Dirac semi metal has ultra-high carrier mobility and can dynamically tune its conductivity by changing its Fermi level.It will play a unique role in the functional devices of THz metamaterials.In this paper,we propose a metamaterial structure based on Dirac semimetal.Through the modeling simulation and theoretical analysis of the structure,we study the Fano resonance phenomenon in THz band.The main research contents and conclusions are as follows:The Fano resonance based on the asymmetric Dirac semimetallic ring structure is studied.The results show that when the upper and lower split rings are symmetrical,the incident light directly excites the dipole mode,and the upper and lower split rings produce LC resonance.If the upper and lower split rings become asymmetric,Fano resonance will occur,and the Q factor can reach 20.19.The influence of the important geometric parameters(the asymmetry of the upper and lower split rings)on Fano is discussed.Based on the Lorentz coupling theory,the Fano resonance is simulated numerically.the sensitivity of the designed structure in the refractive index sensing performance is studied by adding analyte.Fano resonance and quadrupole resonance are as high as 0.6 THz/refractive index unit(RIU)and 0.933 THz/RIU,respectively.Finally,by changing the Fermi level of the Dirac semimetal,the sensing characteristics of Fano resonance tunable are studied.A Fano resonance phenomenon based on the structure of a Dirac semi metallic bow tie metamaterial is studied.In this structure,the Fano resonance is caused by structural asymmetry.When the asymmetry degree of the structure is increased,the energy begins to concentrate in the upper half,and the Fano resonance intensity is increasing.The Q factor can reach 34.11.Then,on this basis,we change the structure to complementary bowtie structure.The research shows that when the asymmetry of complementary bowtie structure is small,Q factor can be as high as 51.66,which is obviously better than non complementary bowtie structure.In addition,the frequency range of the structure can be adjusted by adjusting the Fermi level of the Dirac semimetal.Finally,the performance of the two structures in biochemical material sensing was studied.The sensitivity of non complementary bowtie structure can reach 800 GHz/RIU,and that of complementary bowtie structure is 200 GHz/RIU.