Cascade optical excitation of an artificial exciton molecule in a coupled quantum dot

We investigated the formation dynamics of the artificial exciton molecule state, which consists of two different excitons confined in each quantum dot of a pair of quantum dots, namely a coupled quantum dot (CQD). By the selective optical excitation of the inherent energy states of two different excitons using two color continuous wave (CW) and pulsed lasers, we successively created Xb excitons and an artificial exciton molecule state, and monitored the photoluminescence, namely the population, of the artificial exciton molecule states. By employing the power dependence of the two colors and the excitation energy dependence, we succeeded in controlling the cascade optical excitation of an artificial exciton molecule.