  The light emission of self-assembled (In,Ga)As/GaAs quantum dots embedded in
single GaAs-based micropillars has been studied by time-resolved
photoluminescence spectroscopy. The altered spontaneous emission is found to be
accompanied by a non-exponential decay of the photoluminescence where the decay
rate strongly depends on the excitation intensity. A microscopic theory of the
quantum dot photon emission is used to explain both, the non-exponential decay
and its intensity dependence. Also the transition from spontaneous to
stimulated emission is studied.
