Tunable Broadband THz Waveband Absorbers Based On Graphene for Digital Coding

Abstract

A method of coding patterns is proposed to achieve flexible control of absorption response at terahertz frequencies. The designed absorber consists of an Au-graphene pattern layer, a SiO2 layer and a metal reflective layer. Among them, we use concentrical circle structure to achieve broadband absorption, and adjust graphene’s Fermi level to achieve tunable absorption. In addition, we propose an encoding method that can achieve flexible control of the absorption response at the terahertz frequency based on the external voltage applied on the graphene membrane, thereby having a programmable function. We also use COMSOL to simulate the electric field distribution diagram to explain the underlying physical mechanism. The programmable broadband adjustable absorber proposed in this paper has potential application prospects in the fields of optical equipment, information transmission, digital coding and artificial intelligence (AI).

Review of Broadband Metamaterial Absorbers: From Principles, Design Strategies, and Tunable Properties to Functional Applications

“…[ 306–317 ] Broadband absorption responses obtained by top‐down lithography can be further divided into the following categories, such as i) planar design method, [ 271–273 ] ii) vertical design method, [ 159,274–276 ] iii) adding active materials design method, [ 173,277–279 ] and iv) coding design method. [ 71,280–281 ] In describing self‐assembly technology for designing and manufacturing BMAs, we summarize previous works and divide them into two main aspects: the direct sputtering design approach, [ 285–293 ] and template assisted design method. [ 294–305 ] Finally, we also briefly summarize the current emerging construction methods for low‐cost broadband absorption, such as the all‐dielectric design method, [ 318–330 ] and unpatterned method.…”

“…Reproduced under the terms of CC‐BY license. [ 280 ] Copyright 2020, the Author(s), published by MDPI. g) Structural diagram of bilateral encoded BMA.…”

Tunable Perfect Absorber of Graphene Metamaterial in the Terahertz Band and Its Sensing Properties

“… is the scattering rate; τ is the relaxation time; is the chemical potential (Fermi level); and j is the imaginary part. [ 25 ] Within the terahertz band at a temperature T = 300 K, when the photon energy (), the intraband conductivity of graphene can be neglected based on the Pauli exclusion principle, i.e., the effective surface conductivity of graphene only depends on the interband conductivity. [ 26,27 ] Therefore, the Equation (), which is used to calculate the effective surface conductivity of graphene, can be simplified to the Drude model.…”

Ultra‐Wideband Integrated Graphene‐Based Absorbers for Terahertz Waveguide Systems

“…Periodic structures or metamaterials may be employed as an alternative means of realizing absorbers and can even allow for tuning of the absorption properties. [ 20–24 ] The operational bandwidth of such devices is limited by their inherent periodicity, while their implementation requires precision fabrication. [ 21 ]…”

“…Periodic structures or metamaterials may be employed as an alternative means of realizing absorbers and can even allow for tuning of the absorption properties. [20][21][22][23][24] The operational bandwidth of such devices is limited by their inherent periodicity, while their implementation requires precision fabrication. [21] The aforementioned requirements and the limitations of existing solutions drive the search for new absorber materials, where a variety of approaches have been reported to date.…”