Metasurfaces (MTSs) [1] , [2] , [3] , [4] , [5] are the surface equivalent of metamaterials (MTMs): artificial materials composed of subwavelength inclusions embedded in a host medium tailored to exhibit unconventional electromagnetic (EM) properties. In contrast to MTMs, which are characterized in terms of homogenized material parameters, the EM responses of MTSs are often characterized by homogenized boundary conditions (BCs). MTSs can be designed to exhibit abrupt amplitude and phase discontinuities to perform extreme wavefront transformations. Classical “surface EMs” [3] took on fresh and exciting research directions with MTSs, revealing fascinating phenomena and new applications.

中文翻译：

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EM超表面[客座社论]

超表面（MTS）[1] ,[2] ,[3] ,[4] ,[5]是超材料 (MTM) 的表面等效物：由嵌入在主体介质中的亚波长夹杂物组成的人造材料，以表现出非常规的电磁 (EM) 特性。与以均质材料参数为特征的 MTM 相比，MTS 的 EM 响应通常以均质边界条件 (BC) 为特征。MTS 可以设计为表现出突然的幅度和相位不连续性，以执行极端的波前变换。经典的“表面 EM”[3]与 MTS 一起承担了新的和令人兴奋的研究方向，揭示了令人着迷的现象和新的应用。