Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 25: Quantum dots and wires: Optical properties II

HL 25.10: Vortrag

Dienstag, 27. März 2007, 16:30–16:45, H17

Gain reduction in Semiconductor Quantum Dots — •Michael Lorke, Jan Seebeck, Paul Gartner, and Frank Jahnke — Institut für Theoretische Physik, Universität Bremen

In recent years, semiconductor quantum dots (QDs) have been studied extensively due to possible applications in optoelectronic devices like LEDs, lasers, or amplifiers. In the rapid emerging field of quantum information technology, QDs have been successfully used to demonstrate the generation of single photons or correlated photon pairs. Furthermore, the strong coupling regime for QD emitters in optical microcavities has been demonstrated. A common aspect in these fundamental studies and for practical applications of QDs is the critical role of dephasing processes. They determine the homogeneous linewidth of the QD resonances, limit the coherence properties of QD lasers and theirultrafast emission dynamics, and have a strong influence on coherentoptical nonlinearities.

A microscopic theory is used to study the optical properties of semiconductor quantum dots. The dephasing of a coherent excitation and line-shifts of the interband transitions due to carrier-carrier Coulomb interaction and carrier-phonon interaction are determined from a quantum kinetic treatment of correlation processes which includes non-Markovian effects.

We find a strong saturation and even reduction of the optical gain with increasing carrier density. For this dependencies of the peak gain on carrier density we present new fitting functions for these dependencies.