Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 76: Plasmonics & Nanooptics V: Nanostructures and Nanoantennae

O 76.1: Vortrag

Donnerstag, 4. April 2019, 10:30–10:45, H8

Near-field characterization of V-shaped plasmonic antennas — •Lukas Naumann, Mike Prämassing, and Stefan Linden — Physikalisches Institut der Universität Bonn, D-53115 Bonn

Optical metasurfaces offer fascinating possibilities for controlling light e.g. beam-shaping, steering or polarizing conversion [1,2]. The functionality of a metasurface is governed by the geometry of its subwavelength building blocks, so called metaatoms. One possible type of a metaatom is a V-shaped plasmonic antenna, providing two plasmonic resonances which are tunable by the geometric parameters and can introduce arbitrary phase shifts to the scattered light [2].

Here we investigate the near-field distribution of single V-shaped antennas by the means of scattering-type scanning near-field optical microscopy (s-SNOM) in transmission mode configuration with an interferometric detection scheme, enabling amplitude- and phase-resolved measurements. Depending on wavelength and polarisation of the incoming laser beam as well as on the size of the antennas either the fundamental (asymmetric) mode, the first higher (symmetric) mode or a mixture of both can be excited. The relative phase offsets between different antennas can be deduced from our measurements and can be explained by simple theoretical considerations.

[1] Flat optics with designer metasurface; Nanfang Yu, Federico Capasso; Nature Naterials 13, 139-150 (2014)

[2] Light Propagation with Phase Discontinuities: Generalized Laws of Reflection and Refraction; Federico Capasso et al.; Science 334 (6054), 333-337 (2011)