Investigating on the electromagnetically induced absorption metamaterial in the terahertz region realized by the multilayer structure

Abstract

In recent years, electromagnetically induced absorption (EIA) has had potential application value in nonlinear optics and other fields, which attracts more and more attention. Based on the bright-dark-quasi-dark theory, an electromagnetically induced transparency (EIT) metamaterial is proposed which realizes the transition from EIT to EIA by adjusting the coupling distance. At the same time, a substantial enhancement in absorption has been achieved by adding four nested split-ring resonators (SRRs) as the quasi dark modes which are obtained by rotating the first nested split resonator 90° in turn, and the absorption peak can reach 0.8969 at 0.412 THz. The study proves that the inter-layer coupling causes magnetic resonances which could lead to enhanced absorption. The structure also has polarization-insensitive characteristics. The influences of different structural parameters on absorption performance are further discussed in this paper. This absorption enhancement method has universal applicability and has huge potential application value in many fields such as optical signal processing, optical storage, quantum switching, and optical sensing, which also can be extended to microwave and infrared bands.