Dual‐band terahertz metamaterial absorber using hexagon graphene structure

Abstract

A dual‐band terahertz metamaterial absorber using one‐layer periodically patterned hexagon graphene structure is proposed. By periodically loading six graphene stubs to the honeycomb hexagon graphene structure without increase of the overall size, a new high‐frequency absorption peak will be obtained to realize a dual‐band frequency response. By tuning the structural parameters or Fermi energy levels of the presented terahertz metamaterial absorber, both of the two absorption bands will be changed to the required working frequencies for design specifications. Moreover, the proposed terahertz metamaterial absorber has the properties of polarization independence and incident angle insensitivity, which are of great significance in the applications of some detecting and sensing systems. This work will be a good candidate for the design guidance of various metamaterial absorbers using graphene with single or dual absorption bands.

A polarization‐insensitive dual‐band terahertz absorber using triangle graphene metamaterial structure

“…Based on the Kubo formulas, 29 the surface conductivity of graphene σ ( f ) can be expressed as, $$$\sigma (f)=j\frac{{e}^{2}{k}_{B}T}{\pi {\hslash }^{2}(2\pi f+j{\tau }^{-1})}[\frac{{E}_{F}}{{k}_{B}T}+2\,\mathrm{ln}({e}^{-\frac{{E}_{F}}{{k}_{B}T}}+1)]\,+j\frac{{e}^{2}}{4\pi \hslash }\mathrm{ln}[\frac{2|{E}_{F}|-\hslash (2\pi f+j{\tau }^{-1})}{2|{E}_{F}|+\hslash (2\pi f+j{\tau }^{-1})}],$$$where e denotes the electron charge, k B represents the Boltzmann constant, T is the Kelvin temperature, ħ means the reduced Planck constant, τ denotes the electron–phonon relaxation time, and E F is the Fermi energy level (or chemical potential). Under the room temperature T , which is about 300 K, () will be simplified as a Drude‐like model, 25 $$$\sigma =\frac{j{e}^{2}{E}_{F}}{\pi {\hslash }^{2}(2\pi f+j{\tau }^{-1})}.$$$…”

“…Moreover, the devices based on graphene material can be actively tuned by changing the doping or chemical potential of graphene. Benefiting from these advantages of graphene, many absorbers using graphene metamaterial structures have been proposed, including wideband absorbers 16–20 and multiband absorbers 20–26 …”

“…Benefiting from these advantages of graphene, many absorbers using graphene metamaterial structures have been proposed, including wideband absorbers [16][17][18][19][20] and multiband absorbers. [20][21][22][23][24][25][26] In this study, a single-layer periodically triangle graphene metamaterial structure loaded with T-shaped strips is constructed to achieve a polarization-insensitive dual-band terahertz absorber. Compared with the previous dual-band absorbers, [23][24][25][26] the unit cell of the proposed triangle metamaterial design has a relatively stable structure with a smaller size.…”

Tunable dual‐band filter based on monolayer black phosphorus

“…Since 2004, when researchers managed to isolate and characterize a sheet of graphene, 1 which is a two-dimensional (2D) material 2 with a thickness of one carbon atom, many works on graphene nanophotonic devices were published, among them filters, 3,4 optical switches, 5 photodetectors, 6 sensors, 7 absorbers, 8 just to name a few. One of the effects of this great investment in research and applications was the search for obtaining other 2D materials.…”

Polarization‐independent dual narrow‐band perfect metamaterial absorber for optical communication

“…1,2 Nowadays, 3 plasmonic devices, especially perfect absorbers, have aroused widespread interest due to the wide range of applications such as wavelength selective thermal emitters, 4 solar energy, 5 sensing, [6][7][8][9] light detection, [10][11][12] and so on. Various absorbers, typically consisting of metal-insulator-metal sandwiched structures, have been demonstrated theoretically and experimentally in the microwave, 13,14 terahertz, 15,16 infrared, [17][18][19] and optical frequencies 20 regime since Landy et al gave the first experimental demonstration in 2008. 21 In these studies, most of them mainly focus on the absorption characteristics of multiband or broadband.…”