Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 58: Photonic Crystals: Experiment

HL 58.3: Talk

Thursday, March 25, 2010, 16:30–16:45, H13

Angle-resolved fluorescence detection by defocused wide-field imaging — •Rebecca Wagner, Georg Kropat, and Frank Cichos — Molecular Nanophotonics Group, University of Leipzig, Linnéstraße 5, 04103 Leipzig

Photonic Crystals (PCs) are materials where the dielectric constant varies periodically. Multiple scattering of light on this spatially modulated refractive index leads to the formation of a photonic band structure including photonic band gaps where light can not propagate through the material. This band structure can for example be probed by angle resolved reflection spectroscopy. However, for every angle of incidence the detection angle has to be varied since reflections can occur on different lattice plane families, which makes this method very time consuming. A faster method is angle resolved fluorescence spectroscopy of internal emitters where only the angle of detection has to be varied. Still the problem remains to make sure that one measures always at the same position, otherwise one averages over different crystal domains and defects. We are developing a way to collect light emitted in all directions in one measurement, based on defocused imaging of single emitters in 3D PCs. Since these images result from the diffraction of electromagnetic waves from the aperture of the microscope objective, the diffraction patterns change when light emission in certain directions is inhibited by the PC. We observe this modification for example in a threefold symmetry of the image, which we attribute to reflections on different lattice plane families of the PC.