Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 34: Semiconductor Laser

HL 34.10: Talk

Wednesday, February 27, 2008, 16:45–17:00, EW 202

Dynamic Response of Quantum-Dot Lasers – Influence of Nonlinear Electron-Electron Scattering — •Kathy Lüdge, Ermin Malić, Andreas Knorr, and Eckehard Schöll — Institut für Theoretische Physik, Sekr. EW7-1, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

We show that the dynamic response of electrically pumped quantum dot lasers can be quantitatively understood by including the strongly nonlinear character of electron-electron scattering processes. The numeric simulations presented here combine a microscopic approach used for calculating the non-radiative scattering rates with a rate equation model used for modeling the complex dynamic turn-on behavior. The quantum-dot laser is described by a 5-dimensional system, where the electrons and holes are first injected into a wetting layer before being captured into the quantum dot. The latter is considered as a two-level system for electrons and holes.

The calculated electron-electron scattering rates show a strongly nonlinear dependence on the electron and hole densities in the wetting layer which is found to be responsible for the strong damping of the relaxation oscillations of the laser. Furthermore we demonstrate the importance of the mixed (e-h) Auger capture processes that depend on both the electron and the hole density in the wetting layer. Finally we are able to explain experimental data over a wide range of different pump currents.