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O: Fachverband Oberflächenphysik

O 34: Poster Session I (Graphene; Plasmonics and nanooptics; Coherence and coherent control in nanophotonics and plasmonics)

O 34.49: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster E

Fabrication and characterization of complex nano antennas generated by evolutionary algorithms — •Oleg Selig, Thorsten Feichtner, Markus Kiunke, and Bert Hecht — Nano- Optics & Biophotonics Group, Experimentelle Physik 5, Physikalisches Institut, Wilhelm-Conrad-Röntgen-Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074, Würzburg, Germany

Plasmonic nano antennas are used to enhance visible light-matter interaction on the nanometer scale and thus can improve e.g. single molecule detection and the coupling of light into plasmonic waveguides. Most of the established nano antenna designs are inspired by wellknown concepts from the radio-frequency regime. In order to find new designs, which account for the plasmonic behavior of metals in the optical regime we used an evolutionary algorithm which finds optimized structures for defined properties. The working principal is basically to etch holes in an array of gold in the right position and size to get an good value for the desired property and then recombine and mutate good structure to further improve them. By using rounded corners, gaussian excitation and realistic material thickness a very good approximation to feasible experimental conditions was achieved. For the realization we dropcasted mono crystalline gold flakes on ITO-covered glass. The structures calculated by the evolutionary algorithms were then written by means of focused ion beam milling. The optical properties were measured by confocal two-photon-photo-luminescence and compared to the simulation results, showing a substantial agreement.