Design and analysis of terahertz EIT structure based on cross split ring

Electromagnetic induced transparency (EIT) was first discovered in the three energy levels atomic system, and its excellent electromagnetic and optical properties are fascinating, which has aroused the research interest of many scholars. In this paper, a cross-double-ring resonant unit with four openings(CDRFO) is designed. Through numerical calculation, the metamaterial formed by this unit can produce electromagnetically induced transparent window at 3.29THz frequency, and the reflection peaks on both sides can be adjusted independently by changing the parameters. At the same time, the structure is insensitive to polarization, and has strong angular stability. That can produce strong dispersion and group delay in the corresponding 3.12-3.4THz frequency band, which will slow down the propagation speed of optical pulses. The mechanism of EIT phenomenon is further discussed by studying the structural parameters of the resonant unit. The two resonant peaks near the window are directly excited by the incident wave, which belongs to the bright bright mode excitation of electromagnetic induced transparency. Finally, by studying the cross arm part of the structure, a new excitation mode based on the bright-bright mode is proposed according to the phase coupling principle. Terahertz electromagnetically induced transparency is of great help to the research of slow light and even optical buffer devices, and can promote the development of next generation communication technology-6G.