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O: Fachverband Oberflächenphysik
O 91: Plasmonics and Nanooptics V: Waveguides and Antennas
O 91.6: Talk
Friday, March 31, 2023, 11:45–12:00, CHE 89
From Static to Dynamic Modulation of Second Harmonic Generation from Plasmonic Hotspots — •Jessica Meier1, Luka Zurak1, Andrea Locatelli2, Thorsten Feichtner1, René Kullock1, and Bert Hecht1 — 1Nano-Optics and Biophotonics Group, Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany — 2Department of Information Engineering, University of Brescia, Italy
Plasmonic dimer antennas feature strong intensity enhancement squeezed into nanoscale gaps, which makes them highly attractive for boosting nonlinear processes, such as multiphoton excitation and harmonic generation [1]. Such phenomena, alongside large field enhancement, often require control over the field symmetry in the gap, which is challenging considering the nanometer length scales. Here, by means of strongly enhanced second harmonic (SH) generation, we demonstrate unprecedented control over the field distribution by systematically introducing geometrical asymmetry. We use focused helium ion beam milling of mono-crystalline gold to realize asymmetric-gap dimer antennas in which an ultra sharp tip with 3 nm apex faces a flat counterpart [2]. By tuning the tip opening angle, we systematically vary the field asymmetry, which in turn modulates the release of SH radiation to the far-field. We further extend the concept of inducing local field asymmetry to reversible tuning of the SH signal from a single antenna by applying an external voltage.
[1] P. Dombi et al., Reviews of Modern Physics 92, 025003 (2020).
[2] J. Meier et al., arXiv:2210.14105 (2022).