Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 59: Quantum Dots and Wires, Optical Properties V

HL 59.1: Vortrag

Donnerstag, 25. März 2010, 16:00–16:15, H14

How to watch a pulse become coherent — •Marc Aßmann¹, Franziska Veit¹, Manfred Bayer¹, Christopher Gies², Frank Jahnke², Stephan Reitzenstein³, Sven Höfling³, Lukas Worschech³, and Alfred Forchel³ — ¹Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany — ²Institute for Theoretical Physics, University of Bremen, 28334 Bremen, Germany — ³Technische Physik, Physikalisches Institut, Universität Würzburg, 97074 Würzburg, Germany

Ultrafast changes of the statistical properties of light emission are studied for quantum-dot micropillar lasers. Using pulsed excitation with varying power we follow the time-evolution of the output intensity as well as the second-order correlation function g⁽²⁾(t,τ=0) reflecting two-photon coincidences. Due to the previously impossible time resolution of 2 picoseconds we can study the dynamical transition between thermal and coherent light emission. The build-up and breakdown of coherence during a pulsed emission occurs with the same time dependence as the variation of the output intensity in the emission pulse and broadens with increasing excitation. This shows that the same physical mechanisms, the interplay of stimulated emission and cavity losses, determines both, the mean photon number and two-photon coincidences. Results of a microscopic theory confirm the experimental findings.