Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 25: Focussed Session: Strong Light Matter Coupling II
HL 25.6: Talk
Tuesday, March 23, 2010, 15:30–15:45, H13
Strong light matter coupling with free and localized donor bound excitons — •Chris Sturm, Helena Hilmer, Rüdiger Schmidt-Grund, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Linnéstraße 5, 04103 Leipzig
The strong light-matter coupling in two, one and zero dimensional confined electronic systems is still of interest due to its fascinating properties such as non-linear optical effects and a formation of a Bose-Einstein-condensate. Of special interest are ZnO based resonators since here exciton-polaritons are stable well above room temperature [1]. In this work we present the simultaneously coupling of the cavity-photon with the donor bound excitons (D0,X), which are strongly localized, and the free exciton in a ZnO-based Bragg reflector resonator. This allows to investigate the coupling behaviour of these two excitonic systems with the same photonic mode. The exciton polaritons were observed by PL measurements. Beside the lower polariton branch (LPB) a second mode is observable with an energy close to the (D0,X) for low temperatures ((10−70) K). The energy of this mode increases with increasing emission angle and the LPB converges at high emission angles to an energy close to the (D0,X). This indicates that the (D0,X) couple with the cavity-photon and the second mode can be attributed as a middle polariton branch. From the dispersion behaviour of the two polariton branches we obtain a coupling strength of about 4 meV, which is half of the (D0,X) broadening. The coupling strength with the free exciton was determined to be about (D0,X).
[1] C. Sturm et al., New. J. Phys. 11, 073044 (2009).