Strong coupling regime in semiconductor microcavities

In a Quantum Well embedded in a planar optical microcavity, excitons can be strongly coupled to the electromagnetic standing wave and form 2D polaritons. If N Quantum Wells are placed in the microcavity, they cooperate to a collective polariton state. The luminescence dynamics under resonant excitation is modified by the cavity and varies continuously with the detuning between the exciton and the cavity mode. However, since only 10% of the exciton radiant states are in the strong coupling regime, as soon as scattering by acoustic phonons has occurred, mainly states in the weak coupling regime are populated and govern the luminescence dynamics. As a consequence, cavity effects are significant only under resonant excitation and for short time delays. To improve the modifications of spontaneous emission, it seems promising to study pillar microcavities where the light is confined in all directions and could be strongly coupled to a larger fraction of exciton states.