Metal–dielectric hybrid nanoantennas for efficient frequency conversion at the anapole mode

Valerio F Gili, Lavinia Ghirardini, Davide Rocco, Giuseppe Marino, Ivan Favero, Iännis Roland, Giovanni Pellegrini, Lamberto Duò, Marco Finazzi, Luca Carletti, Andrea Locatelli, Aristide Lemaître, Dragomir Neshev, Costantino De Angelis, Giuseppe Leo, Michele Celebrano

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Dielectric nanoantennas have recently emerged as an alternative solution to plasmonics for nonlinear light manipulation at the nanoscale, thanks to the magnetic and electric resonances, the strong nonlinearities, and the low ohmic losses characterizing high refractive-index materials in the visible/near-infrared (NIR) region of the spectrum. In this frame, AlGaAs nanoantennas demonstrated to be extremely efficient sources of second harmonic radiation. In particular, the nonlinear polarization of an optical system pumped at the anapole mode can be potentially boosted, due to both the strong dip in the scattering spectrum and the near-field enhancement, which are characteristic of this mode. Plasmonic nanostructures, on the other hand, remain the most promising solution to achieve strong local field confinement, especially in the NIR, where metals such as gold display relatively low losses.

Results: We present a nonlinear hybrid antenna based on an AlGaAs nanopillar surrounded by a gold ring, which merges in a single platform the strong field confinement typically produced by plasmonic antennas with the high nonlinearity and low loss characteristics of dielectric nanoantennas. This platform allows enhancing the coupling of light to the nanopillar at coincidence with the anapole mode, hence boosting both second- and third-harmonic generation conversion efficiencies. More than one order of magnitude enhancement factors are measured for both processes with respect to the isolated structure.

Conclusion: The present results reveal the possibility to achieve tuneable metamixers and higher resolution in nonlinear sensing and spectroscopy, by means of improved both pump coupling and emission efficiency due to the excitation of the anapole mode enhanced by the plasmonic nanoantenna.
Original languageEnglish
Pages (from-to)2306-2314
JournalBeilstein Journal of Nanotechnology
Volume9
DOIs
Publication statusPublished - 27 Aug 2018

Bibliographical note

© 2018 Gili et al.; licensee Beilstein-Institut.
This is an Open Access article under the terms of the
Creative Commons Attribution License
(http://creativecommons.org/licenses/by/4.0). Please note
that the reuse, redistribution and reproduction in particular
requires that the authors and source are credited.
The license is subject to the Beilstein Journal of
Nanotechnology terms and conditions:
(https://www.beilstein-journals.org/bjnano)
The definitive version of this article is the electronic one
which can be found at:
doi:10.3762/bjnano.9.215

Funding: MSCA-COFUND-MULTIPLY - Grant number 713694 - H2020.

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