Laser-controlled ultrafast nonlinear optical responses of interacting e-h pairs in electromagnetically coupled GaAs quantum dots

Xuejun Lu, University of Massachusetts Lowell
Danhong Huang, Air Force Research Laboratory
Jeremy R. Gulley, Kennesaw State University


In this paper, by applying generalized density-matrix equations, we explore the ultrafast dynamics of photo-generated electron-hole pairs in the system composed of electromagnetically coupled GaAs/AlGaAs quantum dots and reveal the physics mechanism behind laser-controlled nonlinear-optical response of electron-hole pairs. For the single-dot system, we present numerical results to show the transient dependence of carrier occupations and induced quantum coherence of electron-hole pairs in the presence of either a single or double laser pulses, as well as for a step turning-on of the laser field. For a dipole-radiation coupled double-dot system, we study numerically the time dependence of both intradot and interdot self-consistent depolarization fields within and between two dots, respectively. Meanwhile, we further demonstrate the significance of phase matching between induced depolarization fields and incident-laser pulse in order to maximize the stimulated transitions of electron-hole pairs and ensure non-quenched Rabi oscillations in each quantum dot. The employed theoretical model and the associated numerical analysis method are expected to facilitate designing and developing artificial quantum molecules composed of arbitrarily dielectric-embedded quantum dots with non-local quantum interactions and entanglement, as well as optically manipulating electron states of artificial quantum molecules.