| Metamaterial refers to a kind of material with artificial structure array.Compared with natural materials,it has fantastic unique physical properties.The effective control of the properties can further control the propagation characteristics of electromagnetic wave in this material.In recent years,the use of metamaterials to enhance the performance of terahertz devices has become the focus of researchers.Novel terahertz devices based on metamaterials such as filter,absorber,sensor,polarizer,modulator and so on have been developed.One of the representative aspects is the simulation of electromagnetic induced transparency based on metamaterial.Owing to its excellent slow light performance,it is helpful to the development of terahertz switching and terahertz modulator.In this paper,electromagnetic induced transparency structure based on metamaterial structure is designed,and the performance parameters are simulated and analyzed.The main research contents are as follows:1.This paper presents an active metamaterial structure which is based on graphene patch and split ring resonators to achieve terahertz broadband electromagnetic induced transparency.LC resonance produced by the split ring resonator is used as dark mode and the dipole plasmonic resonance produced by graphene materials is used as bright mode at the same time.And increasing the number of the dark mode resonators on the planar structure can enhance the coupling between the resonators to get the frequency band broadened.The transmission spectrum,electric field distribution and surface current distribution of the structure are simulated and analyzed.So the characteristics of broadening the frequency band by enhancing the electromagnetic coupling are revealed.And it can be demonstrated that the active control of electromagnetic induced transparency window is feasible by adjusting the resonant frequency of the bright atom.2.Taking advantage of the theory of three-atom system and broadband,a terahertz dual-mode broadband electromagnetic induced transparency structure based on metamaterial is designed.The transparency window bandwidths are 0.30 THz and 0.24 THz,respectively.We Use the transmission spectra and electric field distribution obtained by simulation to analyze the mechanism of electromagnetic induced transparency made by the single resonator or the combination of bright mode resonator,dark mode resonator and quasi-dark mode.The results show that the dual-mode electromagnetic induced transparency can be demonstrated by using the structure who can make the alternately coupling between the bright mode resonator with the dark mode resonator and the bright mode resonator with the quasi-dark mode resonator.Then the factors affecting the multilayer structure such as the broadband characteristics,geometric parameters and dielectric layer are analyzed. |
