The role of optical excitation power on the emission spectra of a strongly coupled quantum dot-micropillar system.

A strongly coupled quantum dot-micropillar cavity system is studied under variation of the excitation power. The characteristic double peak spectral shape of the emission with a vacuum Rabi splitting of 85 microeV at low excitation transforms gradually into a single broad emission peak when the excitation power is increased. Modelling the experimental data by a recently published formalism [Laussy et al., Phys. Rev. Lett. 101, 083601 (2008)] yields a transition from strong coupling towards weak coupling which is mainly attributed to an excitation power driven decrease of the exciton-photon coupling constant.