Up-conversion by using /spl Gamma/-X-/spl Gamma/ carrier transport in asymmetric double quantum well systems

We demonstrate up-converted light emission from an asymmetric double quantum well (QW). Carriers in the wide QW, which are photogenerated by a long wavelength light, are transferred and collected into the adjacent narrow quantum well by using /spl Gamma/-X-/spl Gamma/ electron transfer and simultaneous hole tunneling, thus generating short wavelength light emission.