Time-resolved optical spectra of highly excited semiconductors- theory

Time-resolved measurements of optical spectra of highly excited semiconductors yield a variety of information about fundamental microscopic interaction processes. But up to now experimental results were only interpreted in terms of phenomenological models. A microscopic theory has to treat the evolution of one- and two-particle properties on the time-scale induced by the exciting pulse. Thus a nonequilibrium Bethe-Salpeter equation and a coupled set of Boltzmann equations has to be solved simultaneously. We present numerical results for one-particle distribution functions and absorption spectra for the case of high excitation well below the LO-phonon emission threshold. This leads to the phenomenon of spectral hole burning.