Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 53: Optical properties

HL 53.1: Talk

Friday, February 29, 2008, 10:30–10:45, EW 201

Long coherence times of yellow 1S-paraexciton polaritons in Cu₂O — •Jan Brandt¹, Dietmar Fröhlich¹, Christian Sandfort¹, Manfred Bayer¹, and Heinrich Stolz² — ¹Institut für Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany — ²Fachbereich Physik, Universität Rostock, D-18051 Rostock, Germany

In a magnetic field the otherwise forbidden lowest exciton in Cu₂O (paraexciton of symmetry Γ₂⁺) gives rise to a narrow absorption line of 80 neV at a temperature of 1.2 K. By time resolved spectroscopy of polariton propagation beats we can distinguish between homogenous and inhomgenous broadening. A small damping and therefore a long coherence time up to 40 ns at 1.2 K is observed. The temperature dependence of the homogenous linewidth is compared with the linewidth from transmission experiments and discussed in terms of longitudinal acoustic phonon scattering.