Abstract

Semiconductor quantum dots (QDs) are popular light sources in contemporary solid-state quantum optics and used extensively for, e.g., all-solid-state single-photon sources [1,2], In order to design and understand such devices, a detailed understanding of the optical properties of QDs is needed. QDs are not ideal two-level emitters, and effects of non-radiative processes, dephasing, and exciton fine structure must be carefully considered. Here we investigate the influence of dark excitons on the radiative dynamics of QDs. Dark excitons have total angular momentum of 2 and contribute to the fine structure of the exciton ground state. As opposed to bright excitons that have total angular momentum 1, dark excitons cannot recombine directly via electric dipole transitions. However, slow recombination does take place since the dark exciton can undergo a spin-flip process thereby transferring it into a bright exciton, see Fig. 1(a).

© 2009 IEEE