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Q: Fachverband Quantenoptik und Photonik

Q 65: Poster Photonik

Q 65.5: Poster

Donnerstag, 22. März 2007, 16:30–18:30, Poster C

Selective excitation of electric and magnetic resonances in nanoscopic structures with radially and azimuthally polarized light — •Peter Banzer, Susanne Quabis, Ulf Peschel, and Gerd Leuchs — Max Planck Researchgroup, Institute of Optics, Information and Photonics, Guenther-Scharowsky-Straße 1, 91058 Erlangen, Germany

A couple of years ago the research in the domain of so-called metamaterials started. Metamaterials are a form of effective media of which the properties do not depend on the intrinsic material parameters but their macroscopic periodic structure. They can show a rather contra intuitive behaviour. In this context the electric and magnetic resonances of the nanoscopic unit cells of the material play an important role.

We investigate the selective excitation of magnetic and electric resonances in single nano-structures. For this purpose we use radially and azimuthally polarized light which provides a non-homogeneous polarisation distribution at a sub-wavelength scale. The polarized light is focussed by a high numerical aperture microscope objective (NA 0.9). The existence of longitudinal and transversal electric and magnetic fields which are formed in the focal plane of the beam allow us to choose the direction of the induced electric and/or magnetic dipole and therefore its plane of radiation. In order to check for resonances we measure angular spectrum of the scattered light sensitive to polarisation with a tuneable light source.

The measurements are performed using single sub-wavelength gold spheres as well as so-called split-ring-resonators.