Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 88: Lasers

HL 88.10: Talk

Friday, March 18, 2011, 12:45–13:00, POT 151

2.0 µm GaSb-based semiconductor disk lasers optically pumped at different wavelengths — •Tino Töpper, Benno Rösener, Marcel Rattunde, Sebastian Kasper, Christian Manz, Klaus Köhler, and Joachim Wagner — Fraunhofer IAF, Tullastrasse 72, D-79108 Freiburg, Germany

Semiconductor disk lasers, also known as vertical-external-cavity surface-emitting laser (VECSEL), combine the wavelength versatility and efficiency of diode lasers with the capability of a high output power emitted in a nearly diffraction-limited circular beam inherent to solid-state lasers. VECSEL in the wavelength range of 2-3µm are of interest for a broad range of applications including material processing, medical therapy and trace gas sensing.

We will report on the direct comparison of two GaSb-based VECSEL structures, both with an emission wavelength of 2.0µm but with different active region designs, optimized for barrier-pumping at 1.0µm (AlGaAsSb-barriers) and 1.5µm (GaSb-barriers). Both structures were characterized in pulsed mode in order to reduce thermal heating effects. At room temperature, the power efficiency of the 1.5µm-pumped structure is 1.43-times higher than the 1.0µm-pumped structure, reflecting directly the reduced quantum deficit due to the longer pump-wavelength. Temperature dependant measurements revealed that the decrease in power efficiency and increase in threshold pump power with increasing temperature is more pronounced for the 1.5µm-pumped structure. We attribute this effect to the reduced barrier height of the latter structure and thus increased heterobarrier leakage.