Optically Induced Long-Range Coupling Studies in a Single GaAs Laterally Coupled Quantum Dot

Excitation intensity dependent time-integrated/-resolved photoluminescence measurements have been performed on a single GaAs laterally coupled quantum dot to understand the long-range (over 30-nm distance) optical couplings. When linearly polarized laser excitation is increased parallel to the lateral coupling direction [110], a coupled bi-exciton, which comes from both quantum dots 1 and 2 of a coupled dot, emerges with a spectral redshift. Drastically different power factors are observed separately in two different localized excitons, and an extremely larger diamagnetic coefficient is measured from a coupled bi-exciton. In addition, a decay time in coupled bi-exciton is obtained that is nearly two times longer than those in localized bi-excitons when the excitation intensities are increased. The correlations from power-dependent photoluminescence intensities and decay rates are attributed to exciton transfer between the two quantum dots based on dipole dipole interactions.