Visible-frequency hyperbolic plasmon polaritons in a natural van der Waals crystal

Fuente: arXiv
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Auteurs principaux: Venturi, Giacomo, Mancini, Andrea, Melchioni, Nicola, Chiodini, Stefano, Ambrosio, Antonio
Format: Preprint
Publié: 2024
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author Venturi, Giacomo
Mancini, Andrea
Melchioni, Nicola
Chiodini, Stefano
Ambrosio, Antonio
author_facet Venturi, Giacomo
Mancini, Andrea
Melchioni, Nicola
Chiodini, Stefano
Ambrosio, Antonio
contents Controlling light at subwavelength scales is one of the main challenges of nanophotonics. Leveraging hyperbolic polaritons supporting arbitrarily large wavevectors can lead to extreme light confinement, effectively overcoming the diffraction limit. Hyperbolicity was initially realized in artificial metamaterials, but their performances are limited by high losses in the metallic components. While recently discovered natural low-loss hyperbolic phonon polaritons initiated a revival in the interest for hyperbolic materials, they are confined to the mid-infrared frequency range, limiting their use for several applications. Some hyperbolic materials at visible frequencies have been studied, but they are either very lossy or only feature out-of-plane hyperbolicity. Here, we demonstrate the presence of low-loss, in-plane hyperbolic plasmon polaritons in the visible and near-infrared in thin films of $\mathrm{MoOCl}_2$, a natural van der Waals crystal. The polariton dispersion is predicted based on the framework of light propagation in biaxial media, and experimentally confirmed by real space nano imaging on exfoliated flakes. $\mathrm{MoOCl}_2$ constitutes a novel material platform for visible-range applications leveraging the unboundedness of hyperbolic modes, such as hyperlensing, Purcell factor enhancement and super-resolution imaging, without the drawbacks of metamaterials.
format Preprint
id arxiv_https___arxiv_org_abs_2405_15420
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Visible-frequency hyperbolic plasmon polaritons in a natural van der Waals crystal
Venturi, Giacomo
Mancini, Andrea
Melchioni, Nicola
Chiodini, Stefano
Ambrosio, Antonio
Optics
Mesoscale and Nanoscale Physics
Controlling light at subwavelength scales is one of the main challenges of nanophotonics. Leveraging hyperbolic polaritons supporting arbitrarily large wavevectors can lead to extreme light confinement, effectively overcoming the diffraction limit. Hyperbolicity was initially realized in artificial metamaterials, but their performances are limited by high losses in the metallic components. While recently discovered natural low-loss hyperbolic phonon polaritons initiated a revival in the interest for hyperbolic materials, they are confined to the mid-infrared frequency range, limiting their use for several applications. Some hyperbolic materials at visible frequencies have been studied, but they are either very lossy or only feature out-of-plane hyperbolicity. Here, we demonstrate the presence of low-loss, in-plane hyperbolic plasmon polaritons in the visible and near-infrared in thin films of $\mathrm{MoOCl}_2$, a natural van der Waals crystal. The polariton dispersion is predicted based on the framework of light propagation in biaxial media, and experimentally confirmed by real space nano imaging on exfoliated flakes. $\mathrm{MoOCl}_2$ constitutes a novel material platform for visible-range applications leveraging the unboundedness of hyperbolic modes, such as hyperlensing, Purcell factor enhancement and super-resolution imaging, without the drawbacks of metamaterials.
title Visible-frequency hyperbolic plasmon polaritons in a natural van der Waals crystal
topic Optics
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2405.15420