Designing Si sphere metagratings: From perfect reflection to large-angle diffraction

TL;DR

This paper presents a comprehensive theoretical analysis of silicon nanosphere arrays, demonstrating their ability to control light reflection and diffraction through electric and magnetic resonances, with potential applications in visible light manipulation.

Contribution

It introduces a systematic design approach for Si nanosphere metasurfaces that achieve efficient, large-angle light diffraction and unidirectional transmission in the visible spectrum.

Findings

Optimized Si nanosphere arrays channel transmitted light into a single diffraction order.

Huygens' metasurfaces with Si nanosphere dimers enable large-angle unidirectional light deflection.

The design rules are based on physical insights and validated by simulations.

Abstract

A thorough theoretical study of the optical properties of periodic Si nanosphere arrays is undertaken, placing particular emphasis on the synergy between electric and magnetic Mie resonances, which occur in high-refractive-index nanoparticles and can lead to a rich variety of phenomena ranging from perfect reflection to controlled diffraction. By means of systematic calculations using the layer-multiple-scattering method that we properly extended so as to describe periodic arrays with many scatterers per unit cell, in conjunction with finite-element simulations, we optimized surfaces of Si nanospheres that efficiently channel the transmitted light into a single, first-order diffraction beam, following simple design rules based on physical insight. Our results provide compelling evidence that Huygens' metasurfaces consisting of simple Si nanosphere dimer lattices constitute a promising platform for large-angle unidirectional deflection of transmitted light in the visible, at wavelengths shorter than the diffraction edge of the lattice.