Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 26: Poster Session: Heterostructures - Preparation and Characterization - Impurities / Amorphous Semiconductors
HL 26.6: Poster
Monday, March 26, 2012, 16:00–19:00, Poster D
Investigation of the polarisation properties of the polariton emission — Steve Linke, •Steffen Richter, Chris Sturm, Helena Franke, Rüdiger Schmidt-Grund, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig, Germany
Strong light-matter coupling between excitons and photons leads to the formation of exciton-polaritons revealing a modified dispersion relation with respect to the pure excitonic or photonic ones. Stokes-vector analysis of the emission from non-resonantly excited exciton-polaritons in a ZnO-based microcavity was used to obtain information about their spin polarisation. The TE-TM splitting of the lower polariton branch (LPB) and the Stokes vector of its emission were investigated in angular-resolved photoluminescence spectra as a function of temperature and detuning.
Resulting from a large TE-TM splitting of the cavity mode, the LPB shows a separation of the two orthogonal linear polarisation states of up to 12meV. The splitting increases with more negative detuning, i.e. a more photonic-like character of the polaritons. The contribution of elliptical polarisation follows roughly the k-dependent behavior of the TE-TM splitting. It increases also with more negative detunings. This elliptically polarised contribution is most likely caused by coherent TE-TM state interactions and/or in a non-negligible coupling with the neighboring D0X donor bound exciton. For a given detuning, the degree of circular polarisation decreases with increasing temperature, probably connected with a higher scattering rate into the ground state.