Abstract-Dirac semimetals based tunable narrowband absorber at terahertz frequencies

Gui-Dong Liu, Xiang Zhai, Hai-Yu Meng, Qi Lin, Yu Huang, Chu-Jun Zhao, and Ling-Ling Wang

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-9-11471

In this paper, a bulk Dirac semimetals (BDSs) based tunable narrowband absorber at terahertz frequencies is proposed and it has the attractive property of being polarization-independent at normal incidence because of its 90° rotational symmetry. Numerical results show that the absorption bandwidth is about 1.469e-2 THz and the total quality factor Q, defined as Q = f0/Δf, reaches about 94.6, which can be attributed to the low power loss of the guided mode resonance in the dielectric layer. The simulation results are analyzed with coupled mode theory. Interestingly, on the premise of maintaining the absorbance at a level greater than 0.95, the absorption frequency can be tuned from 1.381 to 1.395 THz by varying the Fermi energy of BDSs from 50 to 80 meV. Our results may also provide potential applications in optical filter and bio-chemical sensing.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-A Simple Design of a Multi-Band Terahertz Metamaterial Absorber Based on Periodic Square Metallic Layer with T-Shaped Gap

Hai-Yu Meng,  Ling-Ling Wang, Xiang Zhai, Gui-Dong Liu, Sheng-Xuan Xia

http://link.springer.com/article/10.1007%2Fs11468-017-0509-1

We present a multi-band terahertz absorber formed by periodic square metallic ribbon with T-shaped gap and a metallic ground plane separated by a dielectric layer. It is demonstrated that absorption spectra of the proposed structure consist of four absorption peaks located at 1.12, 2.49, 3.45, and 3.91 THz with high absorption coefficients of 98.0, 98.9, 98.7, and 99.6%, respectively. It is demonstrated that the proposed absorber has the tunability from single-band to broadband by changing the length of square metallic ribbon and we can also select or tune the frequencies which we want to use by changing polarization angles. Importantly, the quality factor Q at 3.91 THz is 30.1, which is 5.6 times higher than that of 1.12 THz. These results indicate that the proposed absorber has a promising potential for devices, such as detection, sensing, and imaging.