Abstract-Non-periodic metallic gratings transparent for broadband terahertz waves

Xiao-Ping Ren, Ren-Hao Fan, Ru-Wen Peng, Xian-Rong Huang, Di-Hu Xu, Yu Zhou, and Mu Wang

http://journals.aps.org/prb/accepted/df07cO48H1b13926f6ed29b47501c94f9f1a79ec8

In this work, we demonstrate both theoretically and experimentally that non-periodic metallic gratings can become transparent for broadband terahertz waves. It is shown that broadband high transmission appears in aperiodic metallic gratings (including quasi-periodic and disordered ones), which originates from the non-resonant excitations in the grating system. Quasi-periodic and disordered metallic gratings effectively weaken and even eliminate Wood's anomalies, which are the diffraction-related characters of periodic gratings. Consequently, both the transparence bandwidth and transmission efficiency are significantly increased due to the structural aperiodicity. And an optimal condition is also achieved for broadband high transparency in aperiodic metallic gratings. Experimental measurements at terahertz regime reasonably agree with both analytical analysis and numerical simulations. Furthermore, we show that for a specific light source, for example, a line source, a corresponding non-periodic transparent grating can be also designed. We expect that our findings can be applied for transparent conducting panels, perfect white-beam polarizers, antireflective conducting solar cells, and beyond.

Abstract-Asymmetric transmission of terahertz waves through a graphene-loaded metal grating

Yu Zhou¹, Ye-Qing Dong¹, Ren-Hao Fan¹, Qing Hu^1,2, Ru-Wen Peng^1,a) andMu Wang¹

1 National Laboratory of Solid State Microstructures and Department of Physics, National Center of Microstructures and Quantum Manipulation, Nanjing University, Nanjing 210093, China
2 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
a) Author to whom correspondence should be addressed. Electronic mail: rwpeng@nju.edu.cn
Appl. Phys. Lett. 105, 041114 (2014); http://dx.doi.org/10.1063/1.4891818

http://scitation.aip.org/content/aip/journal/apl/105/4/10.1063/1.4891818

In this work, we theoretically investigate the propagation of terahertz (THz) waves through a graphene-loaded metal grating under external magnetic field. It is found that resonant modes in the system can be converted between transverse-electric and transverse-magneticpolarizations due to Hall conductivity of graphene. As a consequence, asymmetric transmission of THz waves through this graphene-loaded metal grating is achieved. Furthermore, by adjusting either the external magnetic field or the Fermi level of graphene, such asymmetricwave propagation can be significantly tuned. The investigations may provide a unique way to achieve the graphene-loaded optodevices for THz waves.

Abstract-Dual-mode electromagnetically induced transparency and slow light in a terahertz metamaterial

Kun Zhang, Cheng Wang, Ling Qin, Ru-Wen Peng, Di-Hu Xu, Xiang Xiong, and Mu Wang  »View Author Affiliations
http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-39-12-3539

Optics Letters, Vol. 39, Issue 12, pp. 3539-3542 (2014)
http://dx.doi.org/10.1364/OL.39.003539

In this Letter, we construct a metamaterial with dual-mode electromagnetically induced transparency (EIT)-like behavior by introducing “bright atoms,” “quasi-dark atoms,” and “dark atoms” simultaneously. The dual-mode EIT-like behavior has been demonstrated both experimentally and theoretically in terahertz (THz) regime. At two EIT-like modes, slow light is also observed as two time-delayed wave packets, and the effective group refractive index can reach 102. Furthermore, stable dual-mode EIT-like behavior is verified in this metamaterial for a wide range of oblique incident angles. Our work provides a design approach to mimic dual-mode EIT, and such an approach may achieve potential applications on miniaturized and versatile THz devices.

© 2014 Optical Society of America