Reflection compensation mediated by electric and magnetic resonances of all-dielectric metasurfaces [Invited]

Abstract

All-dielectric nanostructures have recently emerged as a promising alternative to plasmonic devices, as they also possess pronounced electric and magnetic resonances and allow effective light manipulation. In this work, we study optical properties of a composite structure that consists of a silicon nanoparticle array (metasurface) and high-index substrate aiming at clarifying the role of substrate on reflective properties of the nanoparticles. We develop a simple semi-analytical model that describes interference of separate contributions from nanoparticle array and the bare substrate to the total reflection. Applying this model, we show that matching the magnitudes and setting the π-phase difference of the electric and magnetic dipole moments induced in nanoparticles, one can obtain a suppression of reflection from the substrate coated with metasurface. We perform numerical simulations of sphere and disk nanoparticle arrays for different permittivities of the substrate. We find full agreement with the semi-analytical results, which means that the uncoupled-element model adequately describes nanostructure reflective properties, despite the effects of induced bi-anisotropy. The model explains the features of the reflectance spectrum, such as a number of dips and their spectral positions, and show why it may not coincide with the spectral positions of Mie resonances of the single nanoparticles forming the system. We also address practical aspects of the antireflective device engineering: we show that the uncoupled-element model is applicable to the structures on top of silicon substrates, including lithographically defined nanopillars. The reflectance suppression from nanoparticle array on top of the silicon substrate can be achieved in a broad spectral range with disordered nanoparticle array and for a wide range of incidence angles.

Resonant Lattice Kerker Effect in Metasurfaces With Electric and Magnetic Optical Responses

“…For single silicon nanosphere, ED and MD resonances do not overlap, and only non-resonant Kerker effect is possible: the suppression of backward scattering is observed at the wavelength either larger than the wavelength of the magnetic dipole (MD) resonance [13] or smaller than the wavelength of the electric dipole (ED) resonance. [26,27,[30][31][32] There is a number of studies, starting with the pioneering work, [33] that suggest designing nanoparticle geometry and obtaining spectral overlap of electric and magnetic multipole resonances using nanoparticles with more complex shape, such as disks, [30,[34][35][36][37] , cubes, [38,39] cones, or pyramids. [39] The elements with resonant ED and MD overlap construct so-called Huygens' metasurfaces and enable ultra-thin, high-efficiency optics.…”

“…As has been shown in the earlier work, if electric and magnetic polarizabilities of a nanoparticle are equal each other in magnitude and phase (the first Kerker condition), light scattering from this nanoparticle is suppressed in the backward direction, and recently, it is referred as a Kerker effect. For single silicon nanosphere, ED and MD resonances do not overlap, and only non‐resonant Kerker effect is possible: the suppression of backward scattering is observed at the wavelength either larger than the wavelength of the magnetic dipole (MD) resonance or smaller than the wavelength of the electric dipole (ED) resonance . There is a number of studies, starting with the pioneering work, that suggest designing nanoparticle geometry and obtaining spectral overlap of electric and magnetic multipole resonances using nanoparticles with more complex shape, such as disks,, cubes, cones, or pyramids .…”

Self-assembled antireflection coatings for light trapping based on SiGe random metasurfaces

“…Efficient anti-reflection coatings (AR) have been intensively studied with many different approaches having been explored for this purpose [1][2][3] , such as multi-layered thinfilms 4,5 , graded index matching via surface texturing with micro-and nano-structures [6][7][8][9][10][11] , plasmonic metasurfaces [12][13][14] and more recently, metasurfaces [15][16][17][18][19][20][21] based on ordered arrays of sub-micrometric dielectric antennas (dielectric Mie resonators [22][23][24][25][26][27][28] ). Depending on the application of the AR different aspects (lowest value of the total reflectance, broad spectral range, broad acceptance angle, transparency or light trapping) determine the optimal features and fabrication method.…”

“…The superior AR properties of disordered systems account for the importance of this approach with respect to its ordered counterparts and it has been recently proposed 20 and implemented 19 using dielectric Mie resonators. Such results, obtained via top-down methods, 19 demonstrate that combining disorder and Mie resonators provides efficient AR coatings at visible frequencies.…”

Lattice Zenneck Modes on Subwavelength Antennas

“…So far, the main research interest has been focused on plasmonic nanostructures: the interface between media with positive and negative permittivities that can support interface‐confined modes, which either propagate along the interface ( Figure a) or are localized within the particle (Figure b). Alternative mechanisms for mode localization have been proposed very recently, and the studied cases are mainly concerned with Mie resonances (Figure f) in high‐refractive‐index materials and phonon–polariton excitations, including materials with hyperbolic dispersion . Being restricted in the material platform to low‐loss metals, such as silver or gold, and high‐refractive‐index dielectrics, the possibilities to design optical elements and photonic devices are severely limited.…”