Control of the strong light-matter interaction between an elongated In_{0.3}Ga_{0.7}As quantum dot and a micropillar cavity using external magnetic fields.

We have studied a strongly coupled quantum dot-micropillar cavity system subject to an external magnetic field. The large diamagnetic response of elongated In_{0.3}Ga_{0.7}As quantum dots is exploited to demonstrate magneto-optical resonance tuning in the strong coupling regime. Furthermore, the magnetic field provides an additional degree of freedom to in situ manipulate the coupling constant. A transition from strong coupling towards the critical coupling regime is attributed to a reduction of the quantum dot oscillator strength when the magnetic confinement becomes significant with regards to the exciton confinement above 3 T.

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.