Active control of dual electromagnetically induced transparency in terahertz graphene-metal hybrid metasurfaces

Abstract

Active control of electromagnetically induced transparency (EIT) using metasurfaces has attracted growing interests in recent years, especially the ones that have multiple EIT windows. Here, we give out a metallic metasurface design that can achieve dual EIT (D-EIT) in the terahertz (THz) regime, and propose a strategy to individually and simultaneously control the two windows by integrating graphene structures into the design. The near-field simulations indicate that the physical mechanism lies in the composite effect of conductive graphene. The theoretical analysis reveals that the active modulation is attributed to the changes in the damping rates of the dark modes and the coupling coefficients between bright mode and dark modes. The proposed graphene-metal hybrid metasurfaces provide a way for designing compact dual-band slow-light and modulation devices, which may find potential applications in dual-frequency-channel THz wireless communications.

Dynamically Tunable Electric Split-Ring Resonators Based on 300 nm Gold Films on Silica for Reconfigurable Slow-Light Application

“…Electromagnetic-induced transparency (EIT) is a quantum mechanical effect observed in the atomic three-energy level system due to the quantum destructive interference between two different excitation pathways, giving rise to a narrow transparency window within a broad transmission dip. − This concept was then extended to plasmonic metamaterial systems. − The generation of an EIT analogue in metamaterial is realized by bright-dark mode coupling and bright–bright mode coupling. − The first approach requires a bright mode resonator with a low quality ( Q ) factor and a dark mode resonator with a high Q -factor. The bright mode can be directly excited by incident light, while the dark mode is activated through near-field coupling to the bright mode indirectly.…”