Abstract
In this study, by using an equivalent circuit method, a polarization-insensitive terahertz (THz) absorber based on multilayer graphene-based metasurfaces (MGBMs) is systematically designed, providing an extremely broad absorption bandwidth (BW). The proposed absorber is a compact, three-layer structure, comprising square-, cross-, and circular-shaped graphene metasurfaces embedded between three separator dielectrics. The equivalent-conductivity method serves as a parameter retrieval technique to characterize the graphene metasurfaces as the components of the proposed circuit model. Good agreement is observed between the full-wave simulations and the equivalent-circuit predictions. The optimum MGBM absorber exhibits absorbance in an extremely broad frequency band of 0.55–3.12 THz (). The results indicate a significant BW enhancement compared with both the previous metal- and graphene-based THz absorbers, highlighting the capability of the designed MGBM absorber. To clarify the physical mechanism of absorption, the surface current and the electric-field distributions, as well as the power loss density of each graphene metasurface, are monitored and discussed. The MGBM functionality is evaluated under a wide range of incident wave angles to prove that the proposed absorber is omnidirectional and polarization-insensitive. These superior performances guarantee the applicability of the MGBM structure as an ultra-broadband absorber for various THz applications.
© 2018 Optical Society of America
Full Article | PDF ArticleMore Like This
Arman Bordbar, Raheleh Basiry, and Alireza Yahaghi
Appl. Opt. 59(7) 2165-2172 (2020)
Vinit Singh Yadav, Sambit Kumar Ghosh, Somak Bhattacharyya, and Santanu Das
Appl. Opt. 57(29) 8720-8726 (2018)
M. H. Heidari and S. H. Sedighy
J. Opt. Soc. Am. A 35(4) 522-525 (2018)