Dresden 2017 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 18: Semiconductor Lasers II

HL 18.1: Vortrag

Montag, 20. März 2017, 14:45–15:00, POT 06

Pump-power-driven mode switching in quantum-dot microlasers — •Heinrich A.M. Leymann^1,2, Daniel Vorberg², Thomas Lettau¹, Caspar Hopfmann³, Christian Schneider⁴, Martin Kamp⁴, Sven Höfling⁴, Roland Ketzmerick^2,5, Jan Wiersig¹, Stephan Reitzenstein³, and André Eckardt² — ¹OvG Universität Magdeburg — ²MPI PKS Dresden — ³Technische Universität Berlin — ⁴Universität Würzburg — ⁵Technische Universität Dresden

We investigate the switching of the steady-state lasing mode of a high-β quantum-dot microlaser, occurring in bimodal lasers when varying the pump power. Comparing experiment to theory, we identify the underlying mechanism to be based on the competition between the effective gain on the one hand and the inter-mode kinetics on the other. We show that, while the largest effective gain determines the laser mode for weak pumping (just above the lasing threshold), it is the inter-mode kinetics that selects the laser mode in the limit of strong pumping. We point out that the latter mechanism is akin to (non-equilibrium) condensation of massive bosons. This similarity allows us to describe the mode switching by generalizing the theory of Bose selection and to obtain an analytical criterion for the mode selection. Within this framework, we find that the excitation-power-dependent switching from one laser mode to the other occurs via an intermediate phase, where both modes are lasing. Finally, we employ exact numerical simulations to investigate the origin of the experimentally observed super-thermal intensity fluctuations of the non-lasing mode.