Berlin 2008 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 7: Semiconductor Nanophotonics: Materials, Models, Devices - Surface Emitters
DS 7.3: Vortrag
Montag, 25. Februar 2008, 12:15–12:30, H 2032
First VECSELs based on quantum dots — •Johannes Pohl1, Tim David Germann1, André Strittmatter1, Udo W. Pohl1, Dieter Bimberg1, Jussi Rautiainen2, Mircea Guina2, and Oleg G. Okhotnikov2 — 1Institute of Solid State Physics, TU Berlin, Germany — 2ORC, Tampere University of Technology, Finland
Optically Pumped Vertical External Cavity Surface Emitting Lasers (OP-VECSELs) provide excellent beam quality as well as high power continuous-wave (cw) operation and the possibilty of intra-cavity second harmonic generation. Quantum Dots (QDs) are an attractive alternative to quantum wells due to their broad and flat gain spectrum and high temperature stability. However, no QD-based VECSEL devices are reported so far possibly due to the low modal gain of QD ensembles. The first QD-VECSELs are grown by metalorganic vapor-phase epitaxy with alternative precursors. Two completely different QD growth techniques are used for the VECSELs aiming at high modal gain. Sub-Monolayer (SML) deposition of InAs/GaAs layers provides ensembles with very high QD areal densities yielding high modal gain at ground state transition energy. These QDs were used to demonstrate the first SML-QD VECSEL with an output power of 1.4 W cw at 1034 nm. Growth in the Stranski-Krastanow (SK) regime provides a QD ensemble with a broad gain spectrum expanding the operational temperature range of the VECSEL. High modal gain values are obtained by matching the cavity resonance to excited state transitions of the QDs. The VECSEL based on InGaAs SK-QDs operates at 1040 nm with an output power of 280 mW cw.