Impact of coulomb scattering on the ultrafast gain recovery in InGaAs quantum dots

The application of quantum dot (QD) semiconductor optical amplifiers (SOAs) in above 100-Gbit Ethernet networks demands an ultrafast gain recovery on time scales similar to that of the input pulse ∼100GHz repetition frequency. Microscopic scattering processes have to act at shortest possible time scales and mechanisms speeding up the Coulomb scattering have to be explored, controlled, and exploited. We present a microscopic description of the gain recovery by coupled polarization- and population dynamics in a thermal nonequilibrium situation going beyond rate-equation models and discuss the limitations of Coulomb scattering between 0D and 2D-confined quantum states. An experiment is designed which demonstrates the control of gain recovery for THz pulse trains in InGaAs QD-based SOAs under powerful electrical injection.