Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 70: Quantum Dots and Wires: Theory

HL 70.11: Vortrag

Donnerstag, 17. März 2011, 13:00–13:15, POT 151

Nonclassical light and stimulated emission in the strong coupling regime for single-quantum dot lasers — •Christopher Gies, Kolja Schuh, Matthias Florian, and Frank Jahnke — Institute for Theoretical Physics, University of Bremen, Germany

With a single quantum dot (QD) emitter in a high-quality cavity, the ultimate limit of miniaturization for a semiconductor laser has been reached and new physical effects emerge. Recent experiments on single-QD lasers exhibit an s-shaped input/output curve known from ensemble-based lasers. Also surprising is the transition from photon antibunching to bunching in the laser threshold region before coherent emission is reached. We present a microscopic theory and explain both effects in terms of competing contributions from multi-exciton states that start to contribute at elevated pumping conditions. Excitation-induced dephasing and screening facilitate the off-resonant coupling of multi-exciton transitions. Furthermore, we study stimulated emission in the presence of strong coupling. With increasing pump we can identify signatures of higher rungs of the Jaynes-Cummings ladder in the emission spectrum before excitation-induced dephasing carries the system into the weak coupling regime.