Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 95: Quantum Dots and Wires: Optical Properties III (mainly Cavities and Ultrafast Response)

HL 95.1: Vortrag

Freitag, 30. März 2012, 09:30–09:45, EW 201

Directional whispering gallery mode lasing in limaçon shaped electrically driven quantum dot micropillars — •Caspar Hopfmann^1,2, Ferdinand Albert¹, Christian Schneider¹, Alfred Forchel¹, Martin Kamp¹, and Stephan Reitzenstein¹ — ¹Technische Physik, Universität Würzburg, D-97074 Würzburg, Germany — ²Present address: Institute of Solid State Physics, Technische Universität Berlin, D-10623 Berlin, Germany

High quality factor and low mode volume microresonators featuring pronounced cavity quantum electrodynamics (cQED) effects are attracting considerable scientific attention with respect to efficient light sources. In this respect, electrically driven quantum dot based micropillar lasers are of particular interest because of straightforward current injection by a top contact. While standard micropillar lasers show highly directional emission normal to the sample surface, we report on directional lasing of whispering gallery modes (WGMs) confined in the central cavity layer of the micropillar. The in-plane directionality of emission is achieved by a controlled deformation of the pillar’s cross-section using the limaçon-geometry. We present distinct directional WGM high β lasing with Q-factors up to 15.000 and laser threshold currents below 40 µ A at 20 K, where the directionality of emission depends sensitively on the limaçon-parameter ε, i.e. the strength of deformation. Our devices provide a significantly better heat sinking compared to standard WGM lasers based on microdisks and have high potential to act as integrated light sources in planar photonic networks.