Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 97: Semiconductor laser II: Microcavities and quantum-dot laser

HL 97.5: Vortrag

Donnerstag, 3. April 2014, 16:30–16:45, POT 051

Excited state lasing and ground state quenching in quantum dot lasers: An analytical approach — •Andre Röhm, Benjamin Lingnau, Eckehard Schöll, and Kathy Lüdge — Institut f. Theo. Physik, Sekr. EW 7-1, Technische Universität Berlin, Hardenbergstr. 36, 10623Berlin, Germany

We theoretically investigate semiconductor quantum dot (QD) lasers and their transition from ground state (GS) lasing to two-state lasing as well as the physical mechanisms behind GS quenching. The QD laser device is described by a rate-equation approach based on the semiconductor-Bloch equations, and the electric field dynamics by Maxwell’s equations. We compare our numerical simulations with an analytical approach. Based on that we are able to predict regions of GS as well as excited state (ES) lasing as a function of the different energy gaps between GS and ES for electrons and holes. Different ground state quenching mechanisms are studied in the framework of this analytical approach. Key parameters and their impact on the two-state lasing properties of the QD laser are discussed, which allows to predict the different lasing regimes for a wide range of possible QD sets. Furthermore, the influence of doping is investigated.

The GS quenching can be mainly attributed to a charge carrier asymmetry in the quantum dots which increases with pump current. This critical electron to hole ratio can be influenced by temperature, gain and GS-ES energy separation.