Abstract-Terahertz dual phase gradient metasurfaces: high-efficiency binary-channel spoof surface plasmon excitation

Li-Zheng Yin, Tie-Jun Huang, Di Wang, Jiang-Yu Liu, Yan Sun, and Pu-Kun Liu

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-45-2-411

Spoof surface plasmon meta-couplers are compact antennas that link propagating waves and surface waves. However, most of them are designed with a fixed phase gradient and channel for the incident waves with specific polarization, which limits their further applications in multichannel scenarios. In this Letter, a new, to the best of our knowledge, method that combines the Brillouin zone folding theory with the generalized Snell’s law is proposed. We demonstrate that when the phase gradient of the metasurface is large enough, Brillouin zone folding effect will occur, which will create dual phase gradient space in a single metasurface. With this method, we design two novel terahertz meta-couplers with functionalities of symmetrical and asymmetrical binary-channel spoof surface plasmon (SSP) excitation. Furthermore, finite element method simulations are performed to demonstrate their functionalities. Considering the orthogonality of the incident waves, there can be a total of four independent space channels to excite SSPs on one metasurface. This work may open up new routes in multichannel SSP meta-couplers and multibeam surface wave antennas.

© 2020 Optical Society of America

Abstract-Mechanical Terahertz Modulation Based on Single-Layered Graphene

Long Cheng, Zuanming Jin, Zongwei Ma, Fuhai Su, Yang Zhao, Yongzhuan Zhang, Tongyu Su, Yan Sun, Xueli Xu, Zhi Meng, Yuecheng Bian, Zhigao Sheng


http://onlinelibrary.wiley.com/doi/10.1002/adom.201700877/full

The 2D terahertz (THz) modulator, enabling efficient manipulation of such versatile band in nanoscale, is crucial for THz microdevices and systems, but its implementation is difficult and remains challenging in practice. Here, a novel 2D THz modulator based on single-layered graphene under mechanical strain is demonstrated. Bidirectional, i.e., both positive and negative, THz modulation effect is realized by utilizing unconventionally distributed strains on graphene. Such mechanical modulation is found to be stable and reversible, and its modulation depth can exceed 26% at 1 THz under 10–2 GPa strain. Observations of both the strain and frequency dependent modulation behavior evidence the mechanical strain-induced change of the Dirac-like energy dispersion in graphene, which is distinctive from that of the electrical and optical approaches. Due to the reliability and wide applicability of mechanical forces, these results provide an alternative route for chip-scale THz modulation devices based on 2D materials.