Observation of Fano Resonances in All‐Dielectric Nanoparticle Oligomers

Abstract

It is well-known that oligomers made of metallic nanoparticles are able to support sharp Fano resonances originating from the interference of two plasmonic resonant modes with different spectral width. While such plasmonic oligomers suffer from high dissipative losses, a new route for achieving Fano resonances in nanoparticle oligomers has opened up after the recent experimental observations of electric and magnetic resonances in low-loss dielectric nanoparticles. Here, light scattering by all-dielectric oligomers composed of silicon nanoparticles is studied experimentally for the first time. Pronounced Fano resonances are observed for a variety of lithographically-fabricated heptamer nanostructures consisting of a central particle of varying size, encircled by six nanoparticles of constant size. Based on a full collective mode analysis, the origin of the observed Fano resonances is revealed as a result of interference of the optically-induced magnetic dipole mode of the central particle with the collective mode of the nanoparticle structure. This allows for effective tuning of the Fano resonance to a desired spectral position by a controlled size variation of the central particle. Such optically-induced magnetic Fano resonances in all-dielectric oligomers offer new opportunities for sensing and nonlinear applications.

Nano-optomechanical nonlinear dielectric metamaterials

“…supported on a lower-index substrate. [5][6][7][8][9][10][11][12][13] The metamaterial employed in the present study shows, however, that strong localized resonances can also be excited in "negative" dielectric nanostructures, i.e., a pattern formed by slots cut into a continuous layer of highindex material. The free-standing configuration has the additional advantage of maximizing refractive index contrast with the near-field environment and thereby resonance quality factor.…”

“…Non-metallic metamaterial nanostructures currently attract intense attention as they promise to reduce the losses and costs associated with the use of noble metals in traditional plasmonic architectures. 1 It has already been shown that oxides and nitrides, 2 graphene, 3 topological insulators, 4 and high-index dielectrics [5][6][7][8][9][10][11][12][13] can be used as platforms for the realization of high-Q resonant metamaterials. A variety of non-metallic media, such as graphene, 14 carbon nanotubes, 15 liquid crystals, 16 and semiconductors, 17,18 have also been engaged through hybridization with plasmonic metamaterials to create media with strongly enhanced optical nonlinearities, while a nano-optomechanical nonlinearity has recently been observed in a plasmonic metamaterial.…”

All-dielectric phase-change reconfigurable metasurface

“…A wide range of passive alldielectric metasurface planar optical elements for steering, splitting, filtering, focusing and variously manipulating beams have been demonstrated, very typically using silicon for visible to near-IR wavelengths. [13][14][15][16][17] Active functionalities have been demonstrated on the basis of hybridization of a silicon metasurface with a liquid crystal, 18 two photon absorption on silicon metasurfaces 19,20 and nonlinear optomechanical reconfiguration in a free-standing silicon membrane metasurface. 21 By virtue of their compositionally-controlled high-index, low-loss characteristics, which extend over a broad spectral range from the visible to long-wave infrared, and can moreover be reversibly switched (electrically or optically) in a non-volatile fashion, the chalcogenides (binary and ternary sulphides, selenides, and tellurides) provide an exceptionally adaptable material base for the realization of optically reconfigurable meta-devices.…”

Boosting Fano resonances in single layered concentric core–shell particles

“…clusters 66,67 . Figure 4.a shows the scattering efficiency of a dielectric core (r c = 100 nm) surrounded by a SiO 2 shell (r s = 500 nm).…”