Berlin 2012 – wissenschaftliches Programm
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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 34.27: Poster
Dienstag, 27. März 2012, 18:15–21:45, Poster E
Mapping of gold nanostructure-induced near-field enhancement — •Oksana Kostiuchenko1,2, Jacek Fiutowski2, Christian Maibohm2, Jakob Kjelstrup-Hansen2, Horst-Günter Rubahn2, and Heinz Sturm1 — 1BAM - Div. Nanotribol. & Nanostruct., Berlin — 2Univ. of Southern Denmark, Mads Clausen Inst., NanoSYD, 6400 Sønderborg, DK
Sub-diffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancements on gold nanosquares and nanotriangles via laser scanning femtosecond (fs) ablation of polymer thin films and via second harmonic generation (SHG) is reported. Using electron beam lithography, periodical patterns of gold squares and triangles on gold thin films are fabricated. Subsequently, poly(methyl methacrylate) (PMMA) is spin coated on top of such nanostructures. Illumination by a scanning fs laser beam induces an electromagnetic surface field, which is locally enhanced at the edges of the nanostructures and - under appropriate excitation wavelength conditions - also between the structures due to surface plasmon excitation. This enhancement lowers the threshold for nonlinear optical effects such as surface second harmonic generation or deformation and ablation of the polymer coating. The scanning laser beam thus results in a two-dimensional map of near field enhancement, imprinted into the polymer and directly seen via SHG. A variation of the polymer film thickness enables one to discriminate between edge and surface plasmon enhancement effects.