In the recent decade, the research field using arrays of high-index-contrast near-wavelength dieletric structures on flat surfaces, known as high-contrast metastructures (HCMs) or metasurfaces, has emerged and expanded rapidly. Although the HCMs and metasurfaces share great similarities in physical structures with photonic crystals (PhCs), i.e. periodic nanostructures, many differences exist in their design, analysis, operation conditions, and applications. In this paper, we provide a generalized theoretical understanding of the two subjects and show their intrinsic connections. We further discuss the simulation and design approaches, categorized by their functionalities and applications. The similarity and differences between HCMs, metasurfaces and PhCs are also discussed. New findings are presented regarding the physical connection between the PhC band structures and the 1D and 2D HCM scattering spectra under transverse and longitudinal tilt incidence. Novel designs using HCMs as holograms, spatial light modulators, and surface plasmonic couplers are discussed. Recent advances on HCMs, metasurfaces and PhCs are reviewed and compared for applications such as broadband mirrors, waveguides, couplers, resonators, and reconfigurable optics.

中文翻译：

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高对比度超结构、超表面和光子晶体的最新进展

在最近十年中，在平坦表面上使用高指数对比度近波长介电结构阵列（称为高对比度超结构（HCM）或超表面）的研究领域已经出现并迅速扩展。尽管 HCM 和超表面在物理结构上与光子晶体 (PhC) 具有很大的相似性，即周期性纳米结构，但在它们的设计、分析、操作条件和应用方面存在许多差异。在本文中，我们提供了对这两个主题的概括性理论理解，并展示了它们的内在联系。我们进一步讨论了按功能和应用分类的模拟和设计方法。还讨论了 HCM、超表面和 PhC 之间的相似性和差异。提出了关于 PhC 带结构与横向和纵向倾斜入射下的一维和二维 HCM 散射光谱之间的物理联系的新发现。讨论了使用 HCM 作为全息图、空间光调制器和表面等离子体耦合器的新设计。回顾并比较了 HCM、超表面和 PhC 的最新进展，用于宽带反射镜、波导、耦合器、谐振器和可重构光学器件等应用。