Photoluminescence and in-plane diffusion of indirect excitons

In-plane spatial diffusion of indirect excitons in GaAs/AlGaAs coupled quantum wells (QWs) is studied theoretically. In spatial photoluminescence (PL) diagrams obtained from experiments, two rings of PL appear around the excitation spot, and their size and intensity depend upon the lattice temperature T _b and the optical pump intensity. We explain and model numerically the first PL ring, by using coupled nonlinear equations for the diffusion, thermalization and optical decay of the excitons. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)