Recent advances in high-contrast metastructures, metasurfaces, and photonic crystals

In the past decade, the research field that uses arrays of high-index-contrast near-wavelength dielectric structures on flat surfaces, known as high-contrast metastructures (HCMs) or metasurfaces, has emerged and expanded rapidly. Although 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. We summarize the similarities and differences among HCMs, metasurfaces, and PhCs. New findings are presented regarding the physical connection between PhC band structures and 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 in HCMs, metasurfaces, and PhCs are reviewed and compared for applications such as broadband mirrors, waveguides, couplers, resonators, and reconfigurable optics. (c) 2018 Optical Society of America