Abstract-Experimental demonstration of ultra-large-scale terahertz all-dielectric metamaterials

Ke Bi, Daquan Yang, Jia Chen, Qingmin Wang, Hongya Wu, Chuwen Lan, and Yuping Yang

Microscope images of the fabricated (a) ZrO2${\mathrm{ZrO}}_2$ and (b) Al2O3${\mathrm{Al}}_2{\mathrm{O}}_3$ all-dielectric metamaterials. Photographs of (c) the fabrication process and (d) the fabricated ultra-large-scale flexible all-dielectric metamaterial using the MTAS method. (e) Simulated and measured transmissions for ZrO2${\mathrm{ZrO}}_2$ and Al2O3${\mathrm{Al}}_2{\mathrm{O}}_3$ all-dielectric metamaterials. The insets are simulated magnetic field intensity distributions at the corresponding resonance dips in the H–k plane.

https://www.osapublishing.org/prj/abstract.cfm?uri=prj-7-4-457

All-dielectric metamaterials have emerged as a promising platform for low-loss and highly efficient terahertz devices. However, existing fabrication methods have difficulty in achieving a good balance between precision and cost. Here, inspired by the nano-template-assisted self-assembly method, we develop a micro-template-assisted self-assembly (MTAS) method to prepare large-scale, high-precision, and flexible ceramic microsphere all-dielectric metamaterials with an area exceeding 900  cm×900  cm$900\mathrm{cm}\times 900\mathrm{cm}$. Free from organic solvents, vacuum, and complex equipment, the MTAS method ensures low-cost and environmentally friendly fabrication. The ceramic microsphere resonators can be readily assembled into nearly arbitrary arrangements and complex aggregates, such as dimers, trimers, quadrumers, and chains. Finally, using the heat-shrinkable substrate and dipole coupling effect, a broadband reflector with a bandwidth of 0.15 THz and a reflection of up to 95% is demonstrated. This work provides a versatile and powerful platform for terahertz all-dielectric metamaterials, with potential to be applied in a wide variety of high-efficiency terahertz devices.

© 2019 Chinese Laser Press

Abstract-Molecular Rotation-Vibration Dynamics of Low-Symmetric Hydrate Crystal in the Terahertz Region

Xiaojian Fu , Hongya Wu , Xiaoqing Xi , and Ji  Zhou

J. Phys. Chem. A, Just Accepted Manuscript

DOI: 10.1021/jp411609t

Publication Date (Web): December 22, 2013

Copyright © 2013 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/jp411609t?journalCode=jpcafh

The rotational and vibrational dynamics of molecules in copper sulfate pentahydrate crystal are investigated with terahertz dielectric spectra. It is shown that the relaxation-like dielectric dispersion in the low frequency region is related to the reorientation of water molecules under the driving of terahertz electric field, whereas the resonant dispersion can be ascribed to lattice vibration. It is also found that, due to the hydrogen-bond effect, the vibrational mode at about 1.83 THz along [-111] direction softens with decreasing temperature, that is, the crystal expands in this direction when cooled. On the contrary, the mode hardens in the direction perpendicular to [-111] during the cooling process. This contributes to the further understanding of the molecular structure and bonding features of hydrate crystals.