Abstract
The nonlinear spectra of absorption and dispersion near the band edge are calculated for quantum well wires with one subband. The calculations take into account phase space filling, plasma screening and band gap renormalization due to an optically excited electron-hole plasma. Large optical nonlinearities are obtained around the exciton ground state mainly due to state-filling by the optically excited thermal electron-hole plasma, while the plasma screening effects are found to have relatively little influence. For all plasma densities n (including n = 0), the free-carrier transition spectra differ strongly from those calculated with Coulomb interaction.