The underlying significance of exotic electromagnetic phenomena in the operation of metasurfaces is primarily due to certain resonant conditions. The ratio of wavelength in use and the dimensional feature of metasurface remains the determining factor for the observed spectral characteristics with certain features [1–3]. As such, the designing and fabricating artificially engineered structures that are capable of manipulating electromagnetic waves remain greatly attractive. In view of this, the engineering of mediums has been one of the greatly focused topics in the research frontline during the span of a decade or so [4–6]. In the operation ofmetasurfaces, which are specially designed periodic arrays ofmicronor nano-sized objects (or meta-atoms) forming the lattice geometry (of engineered mediums), the electromagnetic phenomenaof surface lattice resonance reveals thepropagation of surface waves [7–9]. These periodic structures can be considered as effective mediums [10,11], wherein the existing surface waves result in certain latticemodes that themetasurfaces support and exhibit extraordinary electromagnetic response – the feature that can be exploited to a broad spectrum of applications in the current technological scenario. Some of the exemplified applications would be the energy harvesting devices, perfect absorbers, nonlinear mediums for communications, sensors for environmental monitoring and/or medical diagnostics, antenna structures, superlenses, etc. [12–17]. Considering the importance of this field of research, the joint editors-in-chief of the Journal of Electromagnetic Waves and Applications (JEMWA) had the thought of bringing out a Special Issue – Waves in Resonant Metasurfaces – on this topic so that some of the recently reported results relevant to this fascinating area of research can be brought together to focus on. This Special Issue encapsulates 2 review articles and 11 research papers. Through these, the authors report research results highlighting the different aspects ofmetasurfaces – the prime constituent of varieties of metamaterial-based devices for different kinds of applications. This Special Issue starts with 2 review articles. One of these discusses the resonance in metamaterials observed in the terahertz (THz) regime of the electromagnetic spectrum. In the article, Banerjee et al. touch upon the fundamentals of resonance conditions exhibited by the inductor-capacitor (LC) circuits and relate the situations with those that happen in the case of split-ring resonators-based metamaterials. Apart from these, the authors also discuss the importance of relevant phenomena, such as Fano resonance, electromagnetically induced transparency, plasmon-induced transparency, in the context of metamaterials. Overall, this review article throws a glimpse of the different resonance phenomena observed in THz metamaterials and may serve as ready reference for investigators dedicated to this area of research. Theother reviewarticle by Rhee et al. emphasizesmoreon the recent developments in metamaterial-based perfect absorbers. The authors talk about the investigationof varieties of suchperfect absorbers operating indifferent frequency regimes

中文翻译：

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共振超表面中的波

奇异电磁现象在超表面运行中的潜在意义主要是由于某些共振条件。使用的波长与超表面的尺寸特征的比率仍然是观察到的具有某些特征的光谱特征的决定因素[1-3]。因此，设计和制造能够操纵电磁波的人工工程结构仍然非常有吸引力。有鉴于此，介质工程已成为近十年左右研究前沿的重点课题之一[4-6]。在超表面的操作中，超表面是专门设计的微米或纳米尺寸物体（或超原子）的周期性阵列，形成晶格几何（工程介质），表面晶格共振的电磁现象揭示了表面波的传播[7-9]。这些周期性结构可以被认为是有效的介质 [10,11]，其中现有的表面波导致超表面支持的某些晶格模式并表现出非凡的电磁响应——这一特征可以在当前技术场景中广泛应用. 一些示例性应用将是能量收集设备、完美吸收器、通信非线性介质、环境监测和/或医疗诊断传感器、天线结构、超级透镜等 [12-17]。考虑到这一研究领域的重要性，Journal of Electromagnetic Waves and Applications (JEMWA) 的联合主编曾考虑推出一个特刊——共振超表面中的波——关于这个主题，以便最近报道的一些结果与这个迷人的领域相关研究可以集中起来进行。本期特刊收录了 2 篇评论文章和 11 篇研究论文。通过这些，作者报告了研究结果，重点介绍了超表面的不同方面——用于不同类型应用的各种基于超材料的设备的主要组成部分。本期特刊以 2 篇评论文章开头。其中之一讨论了在电磁频谱的太赫兹 (THz) 范围内观察到的超材料中的共振。在文章中，班纳吉等人。触及电感电容 (LC) 电路所表现出的谐振条件的基本原理，并将这些情况与基于裂环谐振器的超材料中发生的情况联系起来。除此之外，作者还讨论了相关现象的重要性，例如法诺共振、电磁感应透明、等离子感应透明，在超材料的背景下。总体而言，这篇评论文章概述了在太赫兹超材料中观察到的不同共振现象，可以作为致力于这一研究领域的研究人员的现成参考。Rhee 等人的另一篇评论文章。更多地强调了基于超材料的完美吸收器的最新发展。作者讨论了对在不同频率范围内运行的各种此类完美吸收器的研究