Observation of energy transfer between InAs quantum dots by pump-and-probe micro-photoluminescence measurement

Using pump-and-probe micro-photoluminescence measurement, we observed the nonlinear photoluminescence (PL) of multilayer InAs quantum dots (QDs), which originated from energy transfer between dots. In double- and five-layered InAs QDs, the differential PL intensity, ΔI/Iprobe, became negative at certain pump intensity. With changes in the pump intensity, ΔI/Iprobe decreases or increases. This is explained by the generation of a non-radiative path and the saturation of non-radiative sites by the pump pulses. Our experimental results suggest that InAs QDs can act as AND- and NOT-gates by using suitable thresholds and control lights.