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HL: Fachverband Halbleiterphysik
HL 18: Quantum dots and wires I
HL 18.10: Vortrag
Montag, 16. März 2020, 18:00–18:15, POT 151
GaAs based quantum dot structures for VECSEL and MIXSEL applications — •Tanja Finke1, Vitalii Sichkovskyi1, Jacob Nürnberg2, Matthias Golling2, Ursula Keller2, and Johann Peter Reithmaier1 — 1Institute of Nanostructure Technologies and Analytics (INA), Technische Physik, CINSaT, University of Kassel, Germany — 2Institute for Quantum Electronics, Ultrafast Laser Physics Laboratory, ETH Zürich, Switzerland
By integration of a semiconductor saturable absorber mirror (SESAM) into a vertical external cavity surface emitting laser (VECSEL), one can form a mode-locked integrated external-cavity surface emitting laser (MIXSEL). InGaAs quantum dots (QDs) were used for the gain and absorber regions and optimized by MBE towards high dot density and narrow photoluminescence (PL) emission. The influence of the growth parameters as well as a post-growth rapid thermal annealing (RTA) on the optical and morphological properties of QDs was studied. Furthermore, distributed Bragg mirrors (DBR) were grown and maximum reflectivity values of 99.8 % could be achieved. All the sections were integrated into a single VECSEL structure. To improve the absorption and fast recovery dynamics of high-quality QD-SESAMs, p-type doping recombination centers close to the QD layers were introduced. The effect of the beryllium δ-doping level and post-growth RTA on the optical properties of the QDs was studied and QD-SESAMs with different designs were characterized by nonlinear reflectivity and pump-probe experiments. A fast recovery time of 2 ps and saturation parameters comparable to QW based SESAMs were achieved.