Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

O 71: Poster: Plasmonics and Nanooptics

O 71.2: Poster

Wednesday, March 20, 2024, 18:00–20:00, Poster D

Plasmonic lightning-rod effect — •Vlastimil Křápek, Rostislav Řepa, Michael Foltýn, Tomáš Šikola, and Michal Horák — Brno University of Technology, Czechia

Field enhancement is one of the key targets in plasmonics [1,2,3]. Intuitively, it is expected that plasmonic antennas (PAs) produce a strong electric field near their sharp features. However, there are other factors besides local curvature contributing to the field enhancement, including the evanescent nature of surface plasmon polaritons or the magnitude of the induced charge for a specific excitation.

In our communication, we isolate the contribution of the local curvature of a PA to the magnitude of the electric field of its dipole plasmon resonance. We design a set of rod-like PAs of identical length with two cylindrical terminations, one with a fixed radius and one with a variable radius. The PAs are investigated by electron energy loss spectroscopy (EELS) and electromagnetic simulations. At the fixed-radius end, we observe the identical loss intensity and field enhancement for all the PAs. This ensures that the variations in the response at the variable-radius end can be attributed purely to the local curvature. Finally, we present an intuitive phenomenological model for the induced electric field based on an effective induced point charge.

[1] M. Hrtoň et al., Phys. Rev. Applied 13, 054045 (2020).

[2] V. Křápek et al., Nanophotonics 9, 623 (2020).

[3] O. Bitton et al., Nat. Commun. 11, 487 (2020).

Keywords: plasmonics; field enhancement; localized surface plasmon; lightning-rod effect