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-Highly Efficient Active All-Dielectric Metasurfaces Based on Hybrid Structures Integrated with Phase-Change Materials: From Terahertz to Optical Ranges

Chuwen Lan, He Ma, Manting Wang, Zehua Gao, Kai Liu, Ke Bi, Ji Zhou and Xiangjun Xin

https://pubs.acs.org/doi/abs/10.1021/acsami.8b22466?mi=aayia761&af=R&AllField=nano&target=default&targetTab=std

Recently, all-dielectric metasurfaces (AMs) have emerged as a promising platform for high-efficiency devices ranging from the terahertz to optical ranges. However, active and fast tuning of their properties, such as amplitude, phase and operating frequency, remains challenging. Here, a generic method is proposed for obtaining high-efficiency active AMs from the terahertz to optical ranges by using “hybrid structures” integrated with phase-change materials. Various phase-change mechanisms including metal–insulator phase change, nonvolatile phase change, and ferroelectric phase change are investigated. We first experimentally demonstrate several high-efficiency active AMs operating in the terahertz range based on hybrid structures composed of free standing silicon microstructures covered with ultrathin phase-change nanofilms (thickness d << λ). We show that both the frequencies and the strength of the Mie resonances can be efficiently tuned, resulting in unprecedented modulation depth. Furthermore, detailed analyses of available phase-change materials and their properties are provided to offer more options for active AMs. Finally, several feasible hybrid structures for active AMs in the optical range are proposed and confirmed numerically. The broad platform built in this work for active manipulation of waves from the terahertz to optical ranges may have numerous potential applications in optical devices including switches, modulators and sensors.

Abstract-Experimental realization of Mie-resonance terahertz absorber by self-assembly method

Jiannan Gao, Chuwen Lan, Qian Zhao, Bo Li, and Ji Zhou

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-10-13001

Mie-resonance terahertz absorbers by self-assembly method are designed and demonstrated in experiments and simulations. A monolayer of zirconium dioxide (ZrO2) microspheres fixed on a copper film with designed grids that were manufactured by direct writing with a composite ink system composed of polydimethylsiloxane (PDMS). More importantly, different spacing and array configurations were created economically and efficiently, showing visual performance. Magnetic resonance leads to near-unity absorption at about 0.4 THz in the samples. This work demonstrates efficient terahertz absorbers and highlights a novel direct writing fabrication method that can be extended to produce other optical devices for applications.

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

Abstract-Flexible all-dielectric metamaterials in terahertz range based on ceramic microsphere/ PDMS composite

Chuwen Lan, Ke Bi, Baiwei Li, Yanjiao Zhao, and Zhaowei Qu

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-23-29155

A flexible all-dielectric metamaterials composed of single-layer ceramic microspheres embedded in elastomeric medium is proposed and experimentally demonstrated in terahertz (THz) range. The THz waves are strongly confined in the high-permittivity and low-loss ceramic (ZrO2) microspheres resulting in remarkable Mie magnetic resonances, which can be effectively tuned with strained elastomeric medium. The first resonance mode would experience red shifts with the increased strain along magnetic field direction, while it would experience blue shifts with the increased strain along electric field direction. These properties are well explained by dipole-dipole coupling theory. This work provides an easy and cheap method to obtain tunable all-dielectric metamaterials in THz range.

© 2017 Optical Society of America under the terms of the OSA Open Access Publishing 

Abstract-Hyperbolic metamaterial based on anisotropic Mie-type resonance

   

 
                                                
Chuwen Lan, Ke Bi, Bo Li, Xiaohan Cui, Ji Zhou, and Qian Zhao  »View Author Affiliations

 http://www.opticsinfobase.org/DirectPDFAccess/39485C48-C2C1-9228-2B4472D09D9DE1EE_274791/oe-21-24-29592.pdf?da=1&id=274791&seq=0&mobile=yes
A hyperbolic metamaterial (MM) based on anisotropic Mie-type resonance is theoretically and experimentally demonstrated in microwave range. Based on the shape-dependent Mie-type resonance, metamaterials with indefinite permeability or permittivity parameters are designed by tailoring the isotropic particle into an anisotropic one. The flat lens consisting of anisotropic dielectric resonators has been designed, fabricated and tested. The experimental observation of refocusing and a plane wave with ominidirectional radiation directly verify the predicted properties, which confirm the potential application in negative index material and superlens. This work will also help to develop all-dielectric anisotropic MM devices such as 3D spatial power combination, cloak, and electromagnetic wave converter, etc.