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Proceedings Paper

GaSb-based VECSELs emitting at around 2.35 µm employing different optical pumping concepts
Author(s): Nicola Schulz; Marcel Rattunde; Christian Manz; Klaus Köhler; Christoph Wild; Joachim Wagner; Svent-Simon Beyertt; Uwe Brauch; Thomas Kübler; Adolf Giesen
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Paper Abstract

We report on the characteristics of (AlGaIn)(AsSb)-based optically pumped vertical-external-cavity surface-emitting lasers (VECSELs) emitting at wavelengths around 2.35 μm. For barrier-pumped VECSELs mounted substrate-side down without substrate thinning, typical room temperature cw output powers of 2 mW were achieved, limited by premature thermal rollover due to strong device overheating. The thermal impedance of the VECSEL semiconductor chip could be considerably reduced by bonding an intra-cavity polycrystalline CVD diamond heat spreader to the top surface of the chip. This way, at -18°C a maximum cw output power of 0.6 W and a slope efficiency of 10% were obtained for a multiple transverse mode output beam limited by the available pump power rather than by thermal rollover. Optimising the resonator for TEM00 mode operation (M2≈1.1), an output power exceeding 0.4 W was achieved. To reduce the large quantum deficit of more than 50% inherent to barrier-pumped (1.06 μm pump wavelength) GaSb-based VECSELs which emit at wavelengths above 2 μm, we realized a first in-well pumped (AlGaIn)(AsSb) VECSEL where the pump light is absorbed directly in the quantum wells, with the amount of absorbed light enhanced by a higher order microcavity resonance. Using a pump wavelength of 1.94 μm, the quantum deficit is reduced to only 18% and an output power of 5mW, limited by the available pump power, and a slope efficiency of 10% were achieved. Further optimisation of the pump optics is expected to result in a significant increase in device performance.

Paper Details

Date Published: 14 April 2006
PDF: 10 pages
Proc. SPIE 6184, Semiconductor Lasers and Laser Dynamics II, 61840S (14 April 2006); doi: 10.1117/12.661871
Show Author Affiliations
Nicola Schulz, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Marcel Rattunde, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Christian Manz, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Klaus Köhler, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Christoph Wild, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Joachim Wagner, Fraunhofer-Institut für Angewandte Festkörperphysik (Germany)
Svent-Simon Beyertt, Univ. Stuttgart (Germany)
Uwe Brauch, Univ. Stuttgart (Germany)
Thomas Kübler, Univ. Stuttgart (Germany)
Adolf Giesen, Univ. Stuttgart (Germany)

Published in SPIE Proceedings Vol. 6184:
Semiconductor Lasers and Laser Dynamics II
Daan Lenstra; Markus Pessa; Ian H. White, Editor(s)

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