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Resonant high-index dielectric nanostructures have recently emerged as a new direction in nanophotonics, which might compliment and/or substitute conventional plasmonics in multiple application areas [1]. Major advantages of dielectric nanoantenna approach are low losses at optical frequencies and wide range of appropriate materials such silicon, germanium, gallium arsenide, titanium dioxide, and other semiconductors, which are well known and widely accepted by existing semiconductor industries. Apart from that, high-index dielectric nanostructures naturally possess strong optical magnetic and electric resonances, which open opportunities to observe novel effects related to optical magnetism as well as to interference of coherent electric and magnetic responses. Some of such new effects related to directional light scattering (also known as Kerker conditions), Huygens’ dielectric metasurfaces and generalized Brewster effect have already been demonstrated over the last few years [1]. In this talk, I will focus on application of resonant effects in dielectric nanoantennas and metasurfaces to design devices with unique functionalities. In particular I will show how resonance interference in dielectric metasurfaces can be applied to efficiently bend visible light at extremely high angles (>80 degrees). Based on this effect I will demonstrate flat lenses with free-space numerical aperture of ~0.99, which significantly exceed all flat and bulk optics analogues. I will also show how metasurfaces can be designed to operate simultaneously at all RGB wavelengths in the visible spectrum.
References:
1) A. I. Kuznetsov et al., “Optically resonant dielectric nanostructures”, Science 354, aag2472 (2016).
2) R. Paniagua-Domínguez et al., “A metalens with near-unity numerical aperture”, arXiv:1705.00895 (2017).
3) E. Khaidarov et al., “Asymmetric nanoantennas for ultra-high angle broadband visible light bending”. Nano Letters (2017), DOI: 10.1021/acs.nanolett.7b02952.
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