Computational analysis of octagonal torus-shaped nano meta-atom through fractional absorption bandwidth for applications in the terahertz regime

Abstract

In this paper, we present a computational analysis method for the study of silicon dioxide (SiO2) graphene-based and amorphous silicon (a-Si)-graphene based nano meta-atoms in the terahertz (THz) regime. The proposed meta-atoms were modeled using a SiO2 substrate, optimized using a-Si substrate, and “sandwiched” between graphene layers. The octagonal-shaped torus was geometrically designed as a 3D structure to achieve optimal electromagnetic wave absorption from separate atoms. The upper and lower tori had identical diagonal arms to capture the maximum number of photons with minimal absorption losses. Graphene was chosen as the upper and ground layer material to optimize the electrical and optical properties of our proposed nano metamaterial. Finally, the following four fractional bandwidths with absorption percentages were optimized from the simulation: 4 bands (225.7–254.74 THz, 99.8%; 356.64–401.1 THz, 97.28%; 525.4 THz, 99.19%; 656.34 THz, 94.94%). The multi-band fractional absorption characteristic in the THz regime highlighted our proposed nano meta-atom as a potential candidate for absorption in the infrared and visible spectrum.