Antireflective Multi‐Dielectric Metasurfaces Operating in the Visible

Abstract

As increasingly more demanding photonics applications are brought on‐chip, more complex design solutions are employed to deliver enhanced performance: e.g., meta‐molecules, inverse‐designed freeform structures, and multilayer metasurfaces. Instead, this study introduces anti‐reflective metasurfaces fabricated in a single nanolithography step that follows deposition of multiple dielectrics onto a substrate. Anti‐reflective metasurfaces offer fundamentally better transmission efficiencies compared to conventional equivalents. Conventional and anti‐reflective metalenses, both fabricated in the Ta2O5/SiO2 material platform for 461 nm operation, show an improvement in focusing efficiencies from ≈ 55% to ≈ 90% at low numerical apertures and from ≈ 35% to ≈ 65% at high numerical apertures. Simulations of ideal and imperfect metalenses indicate that anti‐reflective metasurfaces not only improve transmission at the design library level, but also reduce spurious diffraction and protect against higher‐order scattering.

Design of mid-wave infrared achromatic double-layer metalens with enhanced efficiency

“…Three approaches have shown promise for efficient midwave infrared metalenses: high-contrast dielectric metalens [10,11], Huygens metalens [12][13][14], and multi-layer metalens [15][16][17][18][19]. Zuo et al achieved up to 78% focusing efficiency at 4 µm wavelength with high-contrast dielectric metalens, utilizing hydrogenated amorphous silicon nanopillars and low-refractive MgF 2 substrate [11].…”