Observation of back-surface reflected luminescence in GaAs excited by ultrashort pulses

Multiple peaks observed in the temporal evolution of the luminescence of GaAs excited by an ultrashort pulse are attributed to the effect of back-surface reflection. The luminescence components originating from the direct emission and the back-surface reflection are well distinguished using up-conversion luminescence. At an appropriately high excitation energy a sharp peak in the luminescence evolution is observed in a self-assembled InGaAs/GaAs quantum dot sample, which is attributed to stimulated emission excited by the back-surface reflection.