Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 22: Photonic crystals II

HL 22.6: Talk

Tuesday, March 27, 2007, 15:30–15:45, H13

Defocused Imaging of Single Quantum Dots in Photonic Crystals — •Rebecca Wagner and Frank Cichos — Molecular Nanophotonics, Universität Leipzig, Linnéstraße 5, 04103 Leipzig

Photonic crystals are materials with a periodically varying dielectric constant, which introduces a photonic band structure and photonic band gaps by multiple scattering of light on this spatially modulated refractive index. The spatial variation of the refractive index immediately implies that the optical density of states inside a photonic crystal has to be a local property too. Thus a detailed examination and especially the efficient use of even weak photonic systems requires a local probe for the study of local optical properties. So far this has only been achieved for 2D photonic structures by means of near field scanning microscopy. We show with extensive numerical calculations and experimental studies, that single quantum dots can be used as local probes for the study of the optical properties of photonic crystals. As an example, anisotropic light propagation in photonic crystals is measured by imaging a single quantum dot with defocused fluorescence microscopy. A numerical fitting procedure is applied to invert the obtained experimental results to the angular dependence of the photonic stop band. Models are presented how a fractional local optical density of states can be defined and how it influences the emission of single chromophores inside photonic crystals.