Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 50: Plasmonics and Nanooptics V
O 50.1: Vortrag
Mittwoch, 16. März 2011, 15:00–15:15, WIL A317
Optical Nanoantennas for Ultrafast Spectroscopy of Single Nanoparticles — •Thorsten Schumacher1,2, Daniela Ullrich1,2, Kai Kratzer1,2, Mario Hentschel1,2, Harald Giessen2, and Markus Lippitz1,2 — 1Max Planck Institute for Solid State Research, Stuttgart — 24th Physics Institute, University of Stuttgart
Nonlinear spectroscopy investigates the deviations from linear light-matter interaction. The already weak signals are reduced further when single nanoobjects such as quantum dots, molecules, or nanoparticles are investigated. Here, we demonstrate how such an extremely weak nonlinear signal can be enhanced by an optical nanoantenna. For this purpose we use the transient optical response of a mechanically oscillating single gold nanodisc. Our antenna is another gold nanostructure which is placed closely next to the small disc. In this configuration we find a strong plasmonic coupling what can be described by a plasmon hybridization model and numerical simulations. Our calculations show how this plasmonic interaction cause a transfer of the weak nonlinear response of the nanoparticle to the much stronger antenna signal. With ultrafast pump-probe spectroscopy we verify the theoretical predictions and show a measured signal enhancement by a factor of 10, what is in good agreement with our simulations. Finally we can give an outlook for more advanced antenna structures to further increase the enhancement factor.