Spectrally selective chiral silicon metasurfaces based on infrared Fano resonances

Abstract

Metamaterials and metasurfaces represent a remarkably versatile platform for light manipulation, biological and chemical sensing, and nonlinear optics. Many of these applications rely on the resonant nature of metamaterials, which is the basis for extreme spectrally selective concentration of optical energy in the near field. In addition, metamaterial-based optical devices lend themselves to considerable miniaturization because of their subwavelength features. This additional advantage sets metamaterials apart from their predecessors, photonic crystals, which achieve spectral selectivity through their longrange periodicity. Unfortunately, spectral selectivity of the overwhelming majority of metamaterials that are made of metals is severely limited by high plasmonic losses. Here we propose and demonstrate Fano-resonant all-dielectric metasurfaces supporting optical resonances with quality factors Q4100 that are based on CMOS-compatible materials: silicon and its oxide. We also demonstrate that these infrared metasurfaces exhibit extreme planar chirality, opening exciting possibilities for efficient ultrathin circular polarizers and narrow-band thermal emitters of circularly polarized radiation.

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.…”

“…In "all-dielectric" metamaterials nonradiative losses are a priori limited, so with appropriate design they can present even stronger optical resonances, and thereby generate stronger optical forces, than plasmonic counterparts. 22 Previous works have demonstrated that highindex media such as silicon can support optical frequency resonances [5][6][7][8][9][10][11][12][13] and we harness that characteristic here to engineer an ultrathin medium with optical properties that are highly sensitive to structural reconfiguration.…”

“…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.…”

Evidence of Optical Circular Dichroism in GaAs‐Based Nanowires Partially Covered with Gold

“…[6] It has been shown that plasmonic nanostructures forming 1D [7] elements, 2D metasurfaces, [8][9][10] and 3D metamaterials [11] can exhibit linear chiral response due to their own, intrinsic chirality. Also semiconductor nanostructures can exhibit chiral features.…”

Active tuning of high-Q dielectric metasurfaces

“…Importantly, the interference of electric and magnetic Mie-type resonant modes of the same strength allows for fundamentally new effects to be realized, such as unidirectional scattering 10 and unity transmission in the Huygens regime [11][12][13] . Furthermore, the Fano interference of bright and dark modes in the dielectric resonators [14][15][16] provides a pathway to obtaining narrowband resonances with quality-factors of up to several hundred 17 . Such quality factors open up new applications for dielectric metasurfaces, such as high-sensitivity sensors 14,15 and narrow-band filters 18 .…”