Nanofocusing of Hyperbolic Phonon-Polaritons in a Tapered Boron Nitride Slab

Abstract

Nanofocusing of light offers new technological opportunities for the delivery and manipulation of electromagnetic fields at sub-diffraction limited length scales. Here, we show that hyperbolic phonon polarity,HPP, modes in the mid infrared as supported by a hexagonal boron nitride, h-BN, slab can be nanofocused (i.e. both field enhanced and wavelength compressed) by propagation along a vertical taper. Via numerical simulations, we demonstrate that field enhancement factors of 90, for steep tapers, and wavelength compression of more than an order of magnitude for adiabatic tapers, can be expected. Employing scatteringtype scanning near field optical microscopy ,s SNOM, we provide for the first time proof of principle experimental evidence of a significant HPP wavelength compression. We expect these functionalities to provide diverse applications, from biosensing and non-linear optics to optical circuitry.

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Photonics, copyright \c{opyright} American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see: https://pubs.acs.org/doi/abs/10.1021/acsphotonics.6b00186

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• Optical Nanoimaging of Hyperbolic Surface Polaritons at the Edges of van der Waals Materials
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• Plasmonic antenna coupling to hyperbolic phonon-polaritons for sensitive and fast mid-infrared photodetection with graphene
• Probing Mid-Infrared Phonon Polaritons in the Aqueous Phase
• Lattice Kerker effect in the hexagonal boron nitride antenna array
• Near-unity light-matter interaction in mid-infrared van der Waals nanocavities
• An adaptive boundary element method for the transmission problem with hyperbolic metamaterials
• Multifrequency Excitation and Detection Scheme in Apertureless Scattering Near Field Scanning Optical Microscopy