Heidelberg 2015 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 65: Nano-Optics IV
Q 65.4: Talk
Friday, March 27, 2015, 11:45–12:00, C/HSO
Optical field enhancement at nanotips: dependence on geometry and material — •Sebastian Thomas1, Georg Wachter2, Michael Förster1, Christoph Lemell2, Joachim Burgdörfer2, and Peter Hommelhoff1 — 1Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstraße 1, D-91058 Erlangen — 2Technische Universität Wien, Wiedner Hauptstraße 8-10, A-1040 Wien
The enhancement of optical electric fields at nanostructures enables a large variety of applications due to the localization of electromagnetic energy on a sub-wavelength scale. Previously, we studied optical field enhancement at tungsten and gold nanotips and found relatively low enhancement factors both in experiments and in simulations, in good agreement with each other [1]. Here we present additional numerical simulations of optical near-fields at nanotips with a wide range of parameters. We find that both the radius of curvature and the opening angle play a large role in the resulting field enhancement factor. The strongest field enhancement is observed at tips with small radii of curvature and large opening angles (> 20∘ full cone angle). This is true for all materials. Additionally, tips made of plasmonic materials like gold or silver achieve a higher field enhancement factor than other materials under some conditions due to resonance effects.
[1] S. Thomas, M. Krüger, M. Förster, M. Schenk, P. Hommelhoff, Nano Letters 13, 4790 (2013)