Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 23: Electronic and Optical Properties

CPP 23.1: Vortrag

Mittwoch, 25. März 2009, 14:00–14:15, ZEU 114

Analyzing Anisotropic Light Propagation by Defocused Imaging of Single Emitters — •Rebecca Wagner and Frank Cichos — Molecular Nanophotonics Group, University of Leipzig, Linnéstraße 5, 04103 Leipzig

Many materials introduce an optical anisotropy to internal emitters due to their internal structure. Layers of oriented polymer molecules have different dielectric constants parallel and perpendicular to the layer, i.e. they are birefringent. Photonic crystals, materials with periodic variation of the dielectric constant, have stop bands for certain directions in which propagation of light is prohibited. These effects have been measured for example by angle resolved fluorescence spectroscopy for ensembles of emitters, thereby averaging over extended areas. However, if the anisotropy is caused by the local environment of the emitters, a spatially-resolved measurement is necessary. We show that optical anisotropy can be measured locally by defocused imaging microscopy of internal emitters. This leads to asymmetric diffraction patterns that contain information about the spatial dependence of the emission. We show how these patterns are influenced by the angle dependence of the refractive index ellipsoid. The technique is demonstrated exemplarily on photonic crystals to measure the fractional local density of states, i.e. the angle dependence of the photonic stop band.