Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 29: Quantum dots: Optical properties II

HL 29.8: Vortrag

Mittwoch, 25. März 2009, 11:30–11:45, BEY 154

Low threshold lasing in electrically pumped high-Q quantum dot-micropillar cavities — •Tobias Heindel, Caroline Kistner, Arash Rahimi-Iman, Christian Schneider, Sven Höfling, Stephan Reitzenstein, and Alfred Forchel — Technische Physik, Physikalisches Institut, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany

High-Q semiconductor microcavities are very attractive structures for the study of low threshold lasing with quantum dot (QD) gain media. Exploiting cavity quantum electrodynamics (cQED) effects these structures are good candidates for a thresholdless laser as they feature a large fraction β of spontaneous emission coupled into the lasing mode. So far, most of the studies on microcavity lasers have focussed on lasing in optically pumped QD-microcavity systems. However, in light of an ultimate thresholdless microcavity laser, it is crucial to combine pronounced cQED effects with the possibility of electrically pumping the active medium.

We report on low threshold lasing in high-Q electrically pumped QD-micropillar cavities. Lasing action associated with threshold currents as low as 8 µA at 10 K is observed for micropillar lasers with quality factors exceeding 10.000. An optimized contact scheme allows us to observe lasing for pillar structures with diameters as small as 1.5 µm, containing on average less than 100 quantum dots as gain medium. Photon autocorrelation studies reveal pronounced photon bunching near threshold as a clear signature for the transition from spontaneous to stimulated emission.