Femtosecond-pulse propagation in resonantly excited semiconductors is investigated by numerically solving the semiconductor Maxwell-Bloch equations for plane waves. For excitation at the exciton resonance, it is shown that the pulse absorption exhibits a strongly nonlinear dependence on the input pulse area. Very long propagation distances for strong pulses are observed, but even when all dephasing processes have been neglected, no lossless propagation (self-induced transparency) was found. The influence of the electron-hole many-body effects, nonequilibrium carrier relaxation, and optical dephasing on the pulse-propagation dynamics is studied. The exchange interaction in the electron-hole plasma is shown to support large propagation distances. For excitation of the continuum states, the dependence of the absorption on the intensity of the input pulse is reduced due to the rapid carrier relaxation into quasiequilibrium distributions.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics