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HL: Fachverband Halbleiterphysik

HL 18: Semiconductor Lasers II

HL 18.9: Vortrag

Montag, 20. März 2017, 17:15–17:30, POT 06

Measuring the Photon Number Distribution of a Bimodal Quantum Dot Microlaser — •Elisabeth Schlottmann¹, Martin von Helversen¹, Marco Schmidt^1,2, Felix Krüger¹, Heinrich A.M. Leymann³, Thomas Lettau⁴, Alexander Foerster⁴, Mikayel Khanbekyan⁴, Christian Schneider⁵, Sven Höfling⁵, Martin Kamp⁵, Jörn Beyer², Jan Wiersig⁴, and Stephan Reitzenstein¹ — ¹Technische Universität Berlin — ²Physikalisch Technische Bundesanstalt — ³MPIPKS Dresden — ⁴Universität Magdeburg — ⁵Universität Würzburg

Microlasers operating in the regime of cavity quantum electrodynamics (cQED) exhibit enhanced coupling of spontaneous emission into the cavity mode. This leads to a smooth transition from thermal to coherent emission at threshold which makes it difficult to prove lasing solely by the input-output behavior. Against this background, measuring the second order auto-correlation function g⁽²⁾(τ) has become a valuable tool to identify laser action. Beyond that, g⁽²⁾(τ) is also indicative for superradiance, mode-switching or thermal emission.
Here, we apply for the first time a photon number resolving transition edge sensor (TES) to directly access the photon number distribution of quantum dot microlasers. Our combined experimental and theoretical study demonstrates that TES detectors can be used to differentiate between mode-switching and thermal emission of bimodal microlasers. Both show a g⁽²⁾(0)≈ 2, but in the case of switching, a linear combination of a thermal and a coherent distribution appears in the photon number distribution.