Research On Electromagnetically Induced Reflection Of Terahertz Metamaterials Based On Dirac Semimetal

Terahertz(THz)waves refer to electromagnetic waves in the frequency range of 0.1?10THz.THz waves have extremely important applications in engineering fields such as material detection and identification,safety detection,medical imaging,and military radar because its unique spectrum analysis capabilities,excellent penetration,and high security.However,most of the traditional terahertz metamaterials are made of metal materials.The application and development of THz technology are seriously limited by the ohmic loss of metal itself and the dielectric constant that is difficult to change."Three-dimensional graphene"-the study of Dirac semimetals has provided a new direction for the development of electromagnetic metamaterials.Compared to metal materials with large ohmic losses and graphene susceptible to dielectric interference,Dirac semi-metals have ultra-high carrier mobility and super photoelectric performance,promoting the development of terahertz functional devices.This paper proposes metamaterial structures based on complementary Dirac semimetals.Through theoretical analysis and modeling simulation of the structure,the phenomenon of electromagnetically induced reflection(EIR)of the complementary metamaterial structure is studied.The specific research content is as follows:1.The tunable electromagnetic induced reflection phenomenon based on the complementary Dirac semimetal metamaterial structure is studied.This structure consists of two U-shaped grooves structures placed symmetrically on both sides of a strip-shaped groove structure.The research shows that the reflection window can be perfectly modulated by changing the vertical distance of the U-groove structure,and the modulation of the reflection window is theoretically analyzed using the dual-resonator coupling model.Based on the study of electromagnetic field distribution in two special vertical distances of U-groove structure,the mechanism of magnetic excitation and electric excitation is analyzed.Using the tunable properties of Dirac semimetal,the EIR phenomena at different Fermi levels were studied,and due to the tunability of the EIR window,we calculated the group delay under different EIR spectra.2.The phenomenon of double electromagnetic induced reflection based on the double complementary Dirac semimetal metamaterial structure is studied.The structure is divided into upper and lower parts,each part is consists of two U-shaped grooves structures placed symmetrically on both sides of a strip-shaped groove structure.Through the adjustment of the structural parameters,the amplitudes of the two reflection windows can be independently modulated without affecting each other.By studying the electric field density distribution at the peak,it is found that the modulation of each window changes from the bright mode structure to the dark mode structure due to the electric field transfer of the independent structure;Also using the tunability of Dirac's semi-metal conductivity,changing the Fermi level of the upper and lower structures separately can achieve the red-shift and blue-shift phenomenon of a single window.This feature has broad application prospects in THz filter devices.3.The double-modulated electromagnetic induced reflection phenomenon based on the complementary Dirac semimetal and photosensitive silicon combined metamaterial structure was studied.The amplitude modulation of the reflection window is realized by adjusting the conductivity of the photosensitive silicon blocks on the top of the two arms of the structure.The frequency shift characteristics of the structure at different Fermi energy levels were studied,and the reflection spectrum was linearly fitted,with a sensitivity of up to 50.2(GHz/meV).The effect of different substrate refractive index on the reflection spectrum was studied,and the results were linearly fitted with a frequency shift of 1.09THz/RIU.