Graphene-Based Metasurface for Tunable Absorption and Transmission Characteristics in the Near Mid-Infrared Region

Abstract

This article reports a graphene-based metasurface to work at terahertz domain as a wideband tunable absorber along with a property of electromagnetic transmittivity. This indeed for the first time claims the widest possible absorption band produced by a graphene metasurface-based rasorber operating in terahertz frequencies (2.24–4.67 THz). Each unit cell comprises stacked graphene, silicon dioxide, and slotted gold layer featuring 99.9% absorptivity as well as 34.01% transmittivity across the respective bands. The other novel feature lies in its ultrathin characteristics ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{\mathrm {g}}$ </tex-math></inline-formula> /10.70), which is improved by more than a factor of 4 relative to its closest competitor, and also in the compactness in periodicity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{\mathrm {g}}$ </tex-math></inline-formula> /12.49), which is identically improved by a factor of 6. The design is executed using an extensive analysis of simulated results. The lack of experimental facility at those frequencies accessible to the authors in their country has been compensated by verifying the simulated prediction using a circuit model developed inhouse. A new biasing scheme for achieving tunable absorption has been illustrated. This work also promises some features, i.e., polarization-insensitive transmission and absorption together with angularly stable characteristics of the incident wave up to 40°. The proposed structure should find potential applications in terahertz, including communication security, satellite communication systems, and stealth applications.