Hannover 2020 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 22: Posters: Quantum Optics and Photonics II

Q 22.14: Poster

Dienstag, 10. März 2020, 16:30–18:30, Empore Lichthof

Gap-size dependence of optical near-fields in a variable nanoscale two-tip junction — •Jonas Heimerl, Takuya Higuchi, Maximilian Ammon, M. Alexander Schneider, and Peter Hommelhoff — Department Physik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91058 Erlangen

Optical field enhancement of metallic nanostructures under illumination with near-infrared fs-laser pulses enables nonlinear electron emission with comparably low pulse energies. When two nanostructures are brought into nanometer vicinity, the optical near-fields of both structures couple and the field is even more enhanced. Here we demonstrate an ambient-conditioned STM-setup allowing us to align two metal needle tips on the sub-nanometer scale facing each other. By measuring the photocurrent as a function of the gap size, we can retrieve the peak electric field at the tip apices. We observe field enhancement up to 15.9 at one tip apex, being four-times larger than for a single tip. Moreover, by scanning the laser focus near this gap junction, we show that field enhancement is well localized to the gap junction, which we can separate from mainly thermal expansion effects visible when we illuminate the tip shank.