Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 25: Focussed Session: Strong Light Matter Coupling II

HL 25.5: Talk

Tuesday, March 23, 2010, 15:15–15:30, H13

Strong light-matter coupling in ZnO Nano-Pillar Resonators — Annekatrin Meissner, •Rüdiger Schmidt-Grund, Helena Hilmer, Chris Sturm, Jesus Zúñiga-Pérez, Martin Lange, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig, Germany

Strong light-matter coupling (formation of exciton-polaritons) in microcavity resonators is of great interest in current research towards polariton lasers. ZnO is a suitable material to be used as active medium due to its large exciton oscillator strength and binding energy. In 1D confined ZnO-based resonators, strong coupling was observed up to 410K with a coupling strength of V=55meV [1]. Further 2D or 3D confinement by means of Bragg-reflector (BR) coated nano-pillars is expected to enhance the coupling strength due to the reduced mode volume and to provide efficient relaxation channels for a strong population of the exciton-polariton ground state.

We present strong coupling in cylindrical resonators containing ZnO nano-pillar cavities (diameters 80…200nm, length ≈5µm). The pillars are coated with a concentric cylindrical shell and, for the 3D case, as well with a top dielectric BR. PL and reflectivity measurements are carried out on the lateral surface of the pillars in dependence on temperature, exit angle and polarization. We were able to investigate the exact same pillar before and after coating. The experimentally observed optical modes can be well described using the exciton-polariton concept involving 2D (V=80meV) and 3D Fabry-Pérot modes.

[1] C. Sturm et al., New J. Phys. 11, 073044 (2009).