As artificial 2D materials made of subwavelength inclusions, metasurfaces bear exotic optical and electromagnetic properties not obtainable in naturally occurring materials. Based on unique wave behaviors such as short effective wavelength and local field enhancement that stem from the strongly local light–matter interaction, metasurfaces have the ability to overcome many tough problems faced by traditional optical engineers. Here, the history, basic principles, practical applications, and recent advancements of metasurfaces are reviewed in three main aspects: the breaking of the diffraction limit, the generalized laws of refraction and reflection, as well as the localized enhancement of light absorption. These landmark achievements could open a door for the optical engineering at the subwavelength scale, i.e., for Engineering Optics 2.0, and provide alternatives to traditional approaches based on bulky optical components. Moreover, multifunctional metasurfaces have also been introduced which could simultaneously achieve several different functionalities with a single device. As a concluding remark, the major challenges faced by this developing field are discussed.

中文翻译：

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超表面波的亚波长光学工程

作为由亚波长夹杂物制成的人造2D材料，超表面具有自然存在的材料无法获得的奇异光学和电磁特性。基于独特的波行为，例如短的有效波长和源于强烈的局部光-物质相互作用的局部场增强，超颖表面具有克服传统光学工程师面临的许多棘手问题的能力。在此，从三个主要方面对超颖表面的历史，基本原理，实际应用和最新进展进行了概述：衍射极限的突破，折射和反射的一般规律以及光吸收的局部增强。这些里程碑式的成就可以为亚波长规模的光学工程打开一扇门，例如，为Engineering Optics 2.0，并提供基于笨重的光学组件的传统方法的替代方案。此外，还已经引入了多功能超表面，其可以在单个设备中同时实现几种不同的功能。最后，讨论了这一发展中领域面临的主要挑战。