Abstract

Abstract The development of all-dielectric metasurfaces vigorously prompts the applications of optical metasurfaces for the visible and near-IR light range. Compared to IR or longer wavelength light, visible and near-IR light have shorter wavelengths. As a result, surface roughness and imperfections of all-dielectric metasurfaces have larger scattering or absorption of visible and near-IR light, thereby directly affecting the performance of an all-dielectric metasurface. In this article, a volume-current method is adopted to study the effect of metasurface roughness. Numerical calculations based on the finite difference time domain (FDTD) method are also used to study the relationship between the effects of metasurface roughness and the optical resonant modes. Numerical predictions based on our theoretical studies fit the experimental data well. Further, the effect of different roughness levels on the all-dielectric metasurface performance is predicted. More importantly, a method utilizing resonant-mode engineering to enhance the metasurface performance (e.g. incident angle insensitivity) is also proposed and demonstrated. This work deepens our understanding of the working mechanism of all-dielectric metasurfaces and paves the way for their use in a broad spectrum of applications.

Highlights

  • The nature of all-dielectric metasurfaces ensures their high transmission and diffraction efficiencies compared to plasmonic nanostructures [1,2,3,4,5,6,7]

  • Numerical calculations based on the finite difference time domain (FDTD) method are used to study the relationship between the effects of metasurface roughness and the optical resonant modes

  • The development of all-dielectric metasurfaces has vigorously promoted the applications of optical metasurfaces for the visible and near-IR light; examples include flat lenses [8], spectrum splitters [9,10,11], ultra-broadband reflectors [12], and full-color reflective displays [13,14,15]

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Summary

Introduction

The nature of all-dielectric metasurfaces ensures their high transmission and diffraction efficiencies compared to plasmonic nanostructures [1,2,3,4,5,6,7]. Previous works have dealt with the effects of fabrication errors (e.g. dimensional deviations and steepness angle of nanopillars) on the performance of metasurfaces [16, 17] It is still unclear how random metasurface roughness affects the metasurface’s performance. With the red light (625–740 nm) band reflector of a full-color display system based on all-­ dielectric metasurfaces as an example, the effects of metasurface roughness on its performance are analyzed. H. Yang et al.: Effects of roughness and resonant-mode engineering in all-dielectric metasurfaces proposed. Yang et al.: Effects of roughness and resonant-mode engineering in all-dielectric metasurfaces proposed The feasibility of this method is demonstrated by an example using a hybrid metasurface structure to improve the incident angle insensitivity of the red light band reflector

Roughness and imperfection of fabricated metasurfaces
Effects and study of the metasurface roughness
Engineering of resonant modes
Numerical calculations
Fabrication

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