Wavelength selective charge storage in self-assembled InGaAs/GaAs quantum dots

We present a wavelength selective optical memory device based on optically-induced charge storage in an inhomogeneously broadened ensemble of InGaAs quantum dots. We show that electrons and holes can be efficiently and resonantly stored without thermal redistribution of charge between dots over timescales much longer than 25 μs at 10 K. Direct information on the absorption mechanisms are obtained for self-assembled dots. The maximum efficiency of the charge storage process is estimated to be close to unity.