Bao Youpeng, Ren Xue, Liao Shaowei, Xue Quan
Guangdong Provincial Key Laboratory of Millimeter-Wave and Terahertz School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510006, China.
College of Electronics and Information Engineering, Shenzhen University, Shenzhen 518060, China.
ACS Appl Mater Interfaces. 2023 Aug 23;15(33):40022-40031. doi: 10.1021/acsami.3c07410. Epub 2023 Aug 9.
The efficient manipulation of the electromagnetic wavefront using metasurfaces (MSs) has attracted a continuous amount of attention in recent years. MSs with arbitrarily controllable amplitude and phase are highly desirable in many emerging fields. However, in previous research, the resonance effect has mainly been used to accomplish the task. This article presents a nonresonant metamaterial element with stronger capacitive coupling. The broadband sandwich-structured meta-atom achieves an enhanced refractive index ranging from 2.44 to 8.90. By using the enhanced refractive index elements, the proposed transmissive MS has an ultrathin thickness (0.23 free-space wavelength). It consists of a specially designed gradient index MS placed on top of the transmitting antenna. The MS is designed to convert the spherical surface wave into a plane wave with high efficiency. One core layer (CL) gradient index MS and two impedance matching layers (IMLs) have been designed to transform the magnitude and phase of the radiation beam from the transmitting antenna. An efficient transmissive MS has been designed and experimentally evaluated with a maximum measured efficiency of over 85%. The proposed control strategy increases the design flexibility of the MS and shows great potential for broadband applications in the realization of efficient functional devices.
近年来，利用超表面（MSs）对电磁波前进行有效操控一直备受关注。具有任意可控幅度和相位的超表面在许多新兴领域都非常受欢迎。然而，在以往的研究中，主要是利用共振效应来完成这项任务。本文提出了一种具有更强电容耦合的非共振超材料元件。这种宽带三明治结构的超原子实现了从2.44到8.90的增强折射率。通过使用增强折射率元件，所提出的透射型超表面具有超薄的厚度（0.23个自由空间波长）。它由一个特别设计的渐变折射率超表面放置在发射天线顶部组成。该超表面旨在将球面波高效地转换为平面波。设计了一个核心层（CL）渐变折射率超表面和两个阻抗匹配层（IMLs）来改变发射天线辐射波束的幅度和相位。设计并通过实验评估了一种高效透射型超表面，实测最大效率超过85%。所提出的控制策略增加了超表面的设计灵活性，并在实现高效功能器件的宽带应用中显示出巨大潜力。
