Karl Franzens University Graz

Graz University of Technology 

Nearfield optics of resonant nano-plasmonic structures
Ralf Vogelgesang
Max Planck Institut für Festkörperforschung, Stuttgart
17:00 - 18:00 Tuesday 12 May 2009 KFU HS 05.01

Localized surface plasmons, being a resonant excitation in metallic nanoparticles, provide intriguing opportunities for novel, ultra-efficient devices. Understanding the intriguing interplay between the geometry of the nanoparticles and the field distribution of their eigenmodes is essential to optimize their resonant character. Their reliable experimental characterization can be viewed as a starting point of all further considerations. In this presentation, the focus is on the examples of metallic disk structures and nano-wire antennas. To measure their eigenmodes, we use apertureless Scanning Near-Field Optical Microscopy (aSNOM) with cross-polarized excitation and scattered radiation [1]. This approach allows mapping nearly unperturbed eigenmodes of plasmonic nanostructures [2]. We demonstrate how, from the combinatorial imaging of many different structures under virtually identical excitation conditions, important properties of the fabricated can be extracted, such as resonant geometry, effective propagation wavelength, or reflection phase.