Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 21: Photonic Crystals I

HL 21.4: Vortrag

Montag, 26. März 2012, 17:45–18:00, EW 203

Influence of cracks on photonic stop bands — •Lars Heerklotz, Rebecca Wagner, and Frank Cichos — Molecular Nanophotonics, University of Leipzig, Germany

Periodical spatial variations of a materials properties lead, via the Bloch condition, to the formation of bands, causing partial and total band gaps. That holds for electrons in a semiconductor, where the core potential is periodic, as well as for photons in a photonic crystal (PC), where the dielectric constant is periodic. In the photonic case this means, that light cannot propagate in the stop band directions and thus the fractional density of states (fDOS) vanishes. To observe these features we produced face-centered cubic (fcc) PCs by vertical deposition. We used our home-built confocal setup to investigate the behavior of light emitted from the polystyrene inside the PC. Imaging the light of the objectives back focal plane onto a slit and afterwards onto a spectrometer leads to angle dependent spectra. The novel advantage is the acquisition of 100 spectra for up to 73.5° of emission in one measurement. This method, angle resolved fluorescence spectroscopy, is applied to measure the fDOS locally (lateral resolution of 300 nm) in order to observe the three folded structure of the first Brillouin-zone of the fcc-lattice. Due to non-confocal detection there is no resolution along the optical axis. We use this method to analyze the influences a crack has on the fDOS.