Abstract-A tailored broadband terahertz metamaterial absorber based on the thermal expansion feature of liquid metal

Author links open overlay panelHai-Feng Zhang, Zi-Long Wang, Cai-Xin Hu, Hou-Bing,



https://www.sciencedirect.com/science/article/pii/S2211379719337660

In this paper, a novel temperature field tailored broadband terahertz absorber is proposed, which consists of the metallic mercury resonance units. When the ambient temperature (T) alters, the mercury can be expanded through the vertebral body channel, middle cross glass cavities, cylindrical hole and fill the upper cross glass cavities of such an absorber, which leads to the absorption bands changed. The simulated results indicate that when T = −30 ℃, the wideband absorption (WBA) regions over 90% can be achieved, which are located at 4.53–5.79 THz and 8.15–9.49 THz, and their relative bandwidths (RBs) are 24% and 15.5%, respectively. If T is increased to 300 ℃, such two WBA areas will move to 2.83–3.39 THz and 5.90–7.74 THz, whose RBs are changed to 18% and 13.3%. To investigate the performance of such an absorber, the effects of incident angle, polarization angle and structural parameters on the absorption are discussed. Similarly, the electric and magnetic field intensity distributions, the surface current distributions, power flow and power loss density of the presented absorber are also given to expound the physical mechanism of absorption. The scheme put forward in this paper will provide a new idea for the study of tunable absorbers.

Abstract-Broadband terahertz metamaterial absorber based on simple multi-ring structures

AIP Advances

Guoqing Shen, Ming Zhang, Yanping Ji, Wanxia Huang, Honglin Yu,  Jianping Shi,

Three-dimensional diagram of the unit cell (a) and top view (b) of the terahertz metamaterial absorber. P is the period of the unit cell, L is the length of the metal square ring and a, b, c, d represent four sub-cells, respectively.

https://aip.scitation.org/doi/10.1063/1.5024606

Single-layer metallic rings are the effective structure cell which are widely used to design single-band and multiband perfect metamaterial absorbers owning to their electromagnetic resonance. However, the absorbers based on the single-layer metallic rings have a common shortcoming, that is the narrow absorption bandwidth. To overcome the limitations, here we proposed a single-layer, flexible and broadband terahertz metamaterial absorber, which consists of four sub-cells with multiple metal rings and a metal ground plane separated by a dielectric layer. By enhancing the coupling response between adjacent metallic rings and merging the adjacent resonant peaks of multi-resonators, we experimentally observed broadband characteristics at the terahertz band. The average absorption of 88% from 0.63 to 1.34 THz and the relative absorption bandwidth of 95% at the incident angle of 15o for TE polarization. Correspondingly, for TM polarization the absorption of more than 80% from 0.61 to 1.1 THz with the relative absorption bandwidth of 80% were also observed. The results went far beyond the previous single-layer absorbers based on metal rings and were much better than the fractal-cross structure reported recently [Kenney et al., ACS Photonics 4, 2604 (2017)]. We had reason to believe that the presented terahertz metamaterial absorber with broad absorption bandwidth and simple structure can find important applications in communication, stealth, energy harvesting systems and so on.