Investigation of strong coupling between single quantum dot excitons and single photons in pillar microcavities

We are reporting on investigations in the regime of strong coupling between an atom-like emitter (i.e. a quantum dot exciton) and the electromagnetic field of a single photon in a high finesse cavity. In order to observe strong coupling between a quantum dot exciton and a cavity mode, we grew high quality Bragg reflector AlAs/GaAs planar cavities with a low density In0.3Ga0.6As quantum dot layer by molecular beam epitaxy. Using electron beam lithography and deep plasma etching, micropillars with high Q-factors (about 8000 for 1.5 pm diameter) were realized. In microphotoluminescence experiments, the high oscillator strength of the In0.3Ga0.6As quantum dots together with a small mode volume in high finesse micropillar cavities allowed us to observe strong coupling characterized by a vacuum Rabi splitting of 140 mu eV. All the conditions necessary to realize such a strongly coupled system and investigate its fundamental properties are discussed in detail. (c) 2006 Elsevier B.V. All rights reserved.