Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 12: Quantum dots and wires: Optical properties I
HL 12.8: Vortrag
Montag, 26. März 2007, 16:45–17:00, H17
Single quantum dot lasing effects in high quality AlAs/GaAs micropillar cavities — •Carolin Hofmann1, Stephan Reitzenstein1, Steffen Münch1, Andreas Löffler1, Martin Kamp1, Anatoli Bazhenov1,2, Alexander Gorbunov1,2, Vladimir Kulakovski1,2, and Alfred Forchel1 — 1Technische Physik, Universität Würzburg, Würzburg, Germany — 2Institute for Solid State Physics, Russian Academy of Science, Chernogolovka, Russia
We report on lasing effects based on individual quantum dots (QDs) in optically pumped high-Q micropillar laser-structures. The laser-structures are based on planar GaAs/AlAs microcavities with a low density layer of InGaAs QDs embedded as active material in the center of a λ-cavity. Lasing associated with ultra-high spontaneous coupling factors is identified by the change of a linear to a superlinear input-output characteristic at the transition from spontaneous emission to laser operation. We will show that laser characteristics such as threshold pump power are strongly influenced by the gain-contribution of single QDs. In particular, the threshold pump power can be controlled by the spectral detuning between a single QD and the lasing mode with a lowering of the threshold power when the QD is brought on resonance. The single dot influence is confirmed by photon correlation experiments which show a transition from antibunching with g(2)(0) = 0.36 at low excitation powers to g(2)(0) = 1 at about 4 times the threshold power in the on-resonance case.