Theory of ultrafast nonlinear optics of Coulomb-coupled semiconductor quantum dots:: Rabi oscillations and pump-probe spectra

We investigate the optical properties of a Coulomb-coupled double-quantum dot system excited by coherent light pulses. Basic effects of Coulomb coupling regarding linear and nonlinear optical processes are discussed. By numerically solving the Heisenberg equation of motion we are able to present the temporal evolution of the system's density matrix for a wide range of coupling parameters. The two main coupling effects in dipole approximation, biexcitonic shift and Forster energy transfer, are investigated and their qualitative and quantitative influence on absorption spectra, Rabi oscillations, and single- and two-pulse excitation is discussed. We present simulated differential transmission spectra to allow for comparison with recent experimental studies.