Strong and weak coupling of single quantum dot excitons in pillar microcavities

We report on strong as well as weak coupling of self assembled In0.30Ga0.70As quantum dots (QDs) in high-Q semiconductor micropillar cavities grown by molecular beam epitaxy. Using electron beam lithography and deep plasma etching, micropillars with high Q-factors (about 10000 for 1.6 mu m diameter) were realized. The low QD density in the present structures allows us to investigate the interaction of single QD excitons and the vacuum field of the microcavity by temperature tuning of exciton lines into resonance with the cavity mode. We will present an example where QD excitons with different emission energies show strong or weak coupling with the optical mode of the same micropillar at different resonance temperatures. Here, the individual coupling behaviour is described in terms of a different spatial position of the QDs relative to the field maximum of the cavity mode. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.