Theoretical study of density-dependent intraexcitonic transitions in optically excited quantum wells

We present a theoretical study of the terahertz-pulse-induced intraexcitonic dynamics of optically created excitons in quantum wells, providing an explanation of the density dependence of the 1s-2p intraexcitonic transitions observed experimentally. We find that two types of many-body interactions, the phase space filling and the exchange interaction, are responsible for the observed red-shift of the resonance frequency. In addition to calculating the density renormalized exciton energy levels, which offer indirect information regarding the density-dependent 1s-2p transitions, we developed a mean-field approach to examine the intraexcitonic transition process directly. The resulting dynamic equation provides a useful tool to gain insight into the intraexcitonic transitions in semiconductor nanostructures.