scholarly journals Tunable Broadband Terahertz Waveband Absorbers Based on Fractal Technology of Graphene Metamaterial

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 269
Author(s):  
Tong Xie ◽  
Dingbo Chen ◽  
Huiping Yang ◽  
Yanhong Xu ◽  
Zhenrong Zhang ◽  
...  

In this paper, a metasurface Terahertz absorber based on the fractal technology of a graphene geometry resonator to realize ultra-wideband, ultrathin, adjustable double-layer cross-fractal formation is introduced. This paper proposes a dynamically tuned graphene absorbing material. The structure is composed of one- to four-level-fractal graphene pattern layers, MgF2 layers and metal reflective layers to form a two-sided mirror of an asymmetric Fabry–Perot cavity. To confine the terahertz electromagnetic wave, four different fractals are integrated into a supercell, and the coupling and superposition of adjacent resonant cavities form a broadband high-absorption absorber. Using finite element-based full-wave electromagnetic simulation software to simulate the response frequency of 0.4–2.0 THz, we found that the absorber achieves a broadband 1.26 THz range (absorption > 80%) and a relative bandwidth of 106.8%. By adjusting the Fermi energy, it can realize free switching and expand to wider broadband terahertz absorption, by adjusting the polarization angle (Φ) from 0 to 90° to prove that the structure is not sensitive to polarization, the absorber provides a 60° large angle of incidence, polarization for TE and TM the absorption pattern remains basically the same. Compared with the previous work, our proposed structure uses fractal technology to expand the bandwidth and provide dynamic adjustable characteristics with great degrees of freedom. The appearance of the fractal structure reduces the difficulty of actual processing.

Author(s):  
Alireza Fardoost ◽  
Fatemeh Ghaedi Vanani ◽  
Seied Asaad Amirhosseini ◽  
Reza Safian

2012 ◽  
Vol 571 ◽  
pp. 721-724
Author(s):  
Cai Peng

A miniature ultra-wideband (UWB) bandpass filter using three-quarters wavelength resonators is presented in this paper. Direct-connected feed method is employed between the input/output ports and the resonators in order to overcome the shortcomings due to the gap-coupled feed method and produce two transmission zeros in the lower and upper stopbands. On the other hand, two quarter-wavelength matching transmission lines are introduced to the input/output ports to improve the reflection loss characteristic in the passband of the filter. In addition, the resonators are folded to be open ring structures, which are more miniaturized than the conventional linear structure. As a consequence, the filter is compact in size and exhibits good performance. The filter is successfully realized in theory and verified by full wave EM simulation, and simulated frequency response results show that the fabricated filter has an insertion loss of better than 1dB in the passband and two rejections of greater than 25dB in most of the stopbands.


2012 ◽  
Vol 20 (12) ◽  
pp. 13566 ◽  
Author(s):  
Dae-Seon Kim ◽  
Dong-Hyun Kim ◽  
Sehyun Hwang ◽  
Jae-Hyung Jang

2011 ◽  
Vol 9 (s1) ◽  
pp. s10402-310404 ◽  
Author(s):  
Dainan Zhang Dainan Zhang ◽  
Qiye Wen Qiye Wen ◽  
Yunsong Xie Yunsong Xie

2016 ◽  
Vol 45 (11) ◽  
pp. 1105001
Author(s):  
郭剑琴 GUO Jian-qin ◽  
徐德刚 XU De-gang ◽  
刘鹏翔 LIU Peng-xiang ◽  
王与烨 WANG Yu-ye ◽  
钟凯 ZHONG Kai ◽  
...  

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1096
Author(s):  
Jiali Wu ◽  
Xueguang Yuan ◽  
Yangan Zhang ◽  
Xin Yan ◽  
Xia Zhang

A dual-controlled tunable broadband terahertz absorber based on a hybrid graphene-Dirac semimetal structure is designed and studied. Owing to the flexible tunability of the surface conductivity of graphene and relative permittivity of Dirac semimetal, the absorption bandwidth can be tuned independently or jointly by shifting the Fermi energy through chemical doping or applying gate voltage. Under normal incidence, the device exhibits a high absorption larger than 90% over a broad range of 4.06–10.7 THz for both TE and TM polarizations. Moreover, the absorber is insensitive to incident angles, yielding a high absorption over 90% at a large incident angle of 60° and 70° for TE and TM modes, respectively. The structure shows great potential in miniaturized ultra-broadband terahertz absorbers and related applications.


2020 ◽  
Vol 128 (9) ◽  
pp. 093104 ◽  
Author(s):  
Ling Liu ◽  
Wenwen Liu ◽  
Zhengyong Song

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