Tip coupling and array effects of gold nanoatennas in near-field microscopy
File(s)SNOM_antennas_SI_revised.pdf (1.45 MB) SNOM_antennas_revised.pdf (1.37 MB)
Supporting information
Accepted version
Author(s)
Büchner, Rebecca
Weber, Thomas
Kühner, Lucca
Maier, Stefan A
Tittl, Andreas
Type
Journal Article
Abstract
Scattering-type scanning near-field optical microscopy (s-SNOM) is one of the predominant techniques for the nanoscale characterization of optical properties. The optical response of nanoantennas in s-SNOM is highly sensitive to their environment, including influences of the probing tip or neighboring resonators. Dielectric tips are commonly employed to minimize tip-related perturbations, although they provide a comparatively weak scattering signal. Here we show that when using metallic tips, it is possible to select between distinct weak and strong tip–antenna coupling regimes by careful tailoring of the illumination conditions and resonator orientation. This enables the use of highly scattering metallic instead of dielectric tips for mapping plasmonic modes with comparatively higher signal strengths. This is a particular advantage for the retrieval of near-field spectra, which simultaneously require high near-field signals and unperturbed field patterns. We leverage our approach to analyze the collective effects of nanoantenna arrays, phenomena that are well understood in the optical far-field but have not been extensively studied in the near-field. Probing the dependence of the optical response on the array field size, we identify three regimes: the single rod regime, the intermediate regime, and the array-like regime. We show that these array effects give rise to characteristic spectral features originating from a complex interplay of radiative coupling and plasmon hybridization. These results provide evidence that long-range interactions of antennas also influence the local optical response that is probed in s-SNOM and demonstrate how collective resonances emerge from single building blocks, providing guidelines for optimized array designs for near- and far-field applications.
Date Issued
2021-12-15
Date Acceptance
2021-10-01
Citation
ACS Photonics, 2021, 8 (12), pp.3486-3494
ISSN
2330-4022
Publisher
American Chemical Society (ACS)
Start Page
3486
End Page
3494
Journal / Book Title
ACS Photonics
Volume
8
Issue
12
Copyright Statement
© 2021 American Chemical Society
Identifier
https://pubs.acs.org/doi/10.1021/acsphotonics.1c00744
Subjects
0205 Optical Physics
0206 Quantum Physics
0906 Electrical and Electronic Engineering
Publication Status
Published
Date Publish Online
2021-10-14