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Q: Fachverband Quantenoptik und Photonik

Q 30: Poster II

Q 30.65: Poster

Tuesday, March 3, 2009, 16:30–19:00, VMP 9 Poster

Characterisation of single nano-structures with highly focused beams — •Sabine Dobmann, Peter Banzer, Ulf Peschel, and Gerd Leuchs — MPI für die Physik des Lichts, IOIP FAU Erlangen

The optical investigation of sub-wavelength nano-structures becomes more and more important since those will form the building blocks of new optical materials. Those so-called metamaterials gain their rather counter-intuitive properties mainly from the excitation of electric and magnetic resonances in the individual nano-structures which form this 'artifical matter'. For the investigation of these resonances we use highly focused polarisation tailored light which provides a non-homogeneous polarisation distribution at a sub-wavelength scale. Pure longitudinal electric or magnetic field components are formed on-axis, depending on the chosen incoming polarisation structure (radial or azimuthal), while transverse electric and magnetic field components persist off-axis. By placing sub-wavelength nano-structures in the beam different coupling scenarios can be achieved. By choosing beams with the respective polarization pattern structures can be selectively exposed either to pure electric or magnetic fields. To characterize the excited resonances of the nano-structures, we measure the forward- and back-scattered intensities and check for the polarisation distribution of the transmitted or reflected far-fields.