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Q: Quantenoptik und Photonik

Q 35: Poster Photonische Kristalle

Q 35.13: Poster

Dienstag, 14. März 2006, 16:30–18:30, Labsaal

QED in an absorbing crystal: the fate of the band structure — •Andreas Kurcz and Carsten Henkel — Institut für Physik, Universität Potsdam, Germany

The Bloch theorem is of fundamental importance for the field quantization in a periodic medium because the quasi-periodic Bloch functions can be used as modes. This approach becomes problematic in the presence of absorption because the Bloch frequencies are complex [1]. We generalize the mode expansion of the field operator using a quantization scheme for the macroscopic Maxwell equations [2,3]. The usual Bloch modes are recovered for vanishing absorption. We also show that the band structure in the (k, ω )-plane gets broadened by the absorption. The calculation is based on the spontaneous decay of a collective state of N two-level systems, similar to the emission by a phased antenna array.

[1] Tip, Moroz, Combes: J. Phys. A 33 (2000) 6223

[2] Huttner, Baumberg, Barnett: Europhys. Lett. 16 (1991) 177

[3] Knöll, Scheel, Welsch: in Coherence and Statistics of Photons and Atoms, edited by J. Peřina (John Wiley & Sons, Inc., New York, 2001)