Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 3: Quantum dots: Microcavities and photonic crystals
HL 3.4: Vortrag
Montag, 25. Februar 2008, 12:00–12:15, ER 270
Influence of the Spontaneous Emission Factor β on the Coherence Time of Semiconductor Microcavity Lasers — •Serkan Ateş1, Christopher Gies2, Sven M. Ulrich1, Jan Wiersig2, Stephan Reitzenstein3, Andreas Loeffler3, Alfred Forchel3, Frank Jahnke2, and Peter Michler1 — 1Institut für Halbleiteroptik und Funktionelle Grenzflächen, Universität Stuttgart, Germany — 2Institut für Theoretische Physik, Universität Bremen, Germany — 3Technische Physik, Universität Würzburg, Germany
We present experimental and theoretical investigations on the coherence properties of (In,Ga)As/GaAs quantum dot (QD) based high-β (β = 0.01 to 0.05) semiconductor micropillar lasers. Power-dependent g(1)(τ) first-order correlation function measurements have been performed by Michelson interferometry to investigate the coherence properties of the fundamental mode emission. A nonlinear increase of the coherence time (i.e., from τc ≈ 30 ps to ≈ 990 ps for a β = 0.01 micropillar) is found in the transition regime from spontaneous to dominantly stimulated emission. This increase is accompanied by a qualitative change in g(1)(τ) measurements from a Gaussian-like profile to an exponential-type behavior. In addition, the emission coherence time of different diameter micropillars at comparable excitation conditions is found to be strongly influenced by the β factor. Devices with larger β exhibit shorter coherence times due to a stronger contribution of spontaneous processes coupled into the laser mode. The measurements are compared to results of a microscopic theory for coupled light-matter dynamics that describes the lasing properties of QD micropillars.