Metasurfaces, kinds of planar ultrathin metamaterials, are able to modify the polarization, phase, and amplitude of physical fields of optical light by designed periodic subwavelength structures, attracting great interest in recent years. Based on the different type of the material, optical metasurfaces can be separated in two categories by the materials: one is metal and the other is dielectric. Metal metasurfaces rely on the surface plasma oscillations of subwavelength metal particles. Nevertheless, the loss caused by the metal structures has been a trouble, especially for devices working in transmit modes. The dielectric metasurfaces are based on the Faraday-Tyndall scattering of high-index dielectric light scattering particles. By reasonably designing the relevant parameters of the unit structure such as the size, direction, and shape, different functions of metasurfaces can realize and bring a wide range of applications. This article focuses on the metasurface concepts such as anomalous reflections and refractions and the working principle of different types of metasurfaces. Here, we briefly review the progress in developing optical over past few years and look into the near future.

中文翻译：

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二维光学超表面：从等离子体到电介质

超表面是一种平面超薄超材料，能够通过设计的周期性亚波长结构来改变光物理场的偏振、相位和幅度，近年来引起了极大的兴趣。根据材料的不同类型，光学超表面可以根据材料分为两类：一类是金属，另一类是电介质。金属超表面依赖于亚波长金属粒子的表面等离子体振荡。然而，金属结构造成的损耗一直是一个问题，特别是对于工作在传输模式下的设备。介电超表面基于高指数介电光散射粒子的法拉第-廷德尔散射。通过合理设计单元结构的尺寸、方向、形状等相关参数，超表面的不同功能可以实现并带来广泛的应用。本文重点介绍异常反射和折射等超表面概念以及不同类型超表面的工作原理。在这里，我们简要回顾了过去几年光学发展的进展并展望了不久的将来。