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Effect of the cavity resonance-gain offset on the output power characteristics of GaSb-based VECSELs

Einfluss des Kavitäts-Gewinn-Offsets auf die Leistungscharakteristik von GaSb-basierenden Halbleiter-Scheibenlasern
: Schulz, N.; Rattunde, M.; Ritzenthaler, C.; Rösener, B.; Manz, C.; Köhler, K.; Wagner, J.


IEEE Photonics Technology Letters 19 (2007), Nr.21, S.1741-1743
ISSN: 1041-1135
Fraunhofer IAF ()
GaSb; GaInAsSb; modeling; Modellierung; infrared; Infrarot; vertical-external-cavity surface-emitting laser; VECSEL; semiconductor disc laser; Halbleiter-Scheibenlaser

In spite of elaborate heat-sinking employing intra-cavity heat-spreaders, the maximum output power of current (AlGaIn)/AsSb)-based vertical-external-cavity surface-emitting lasers (VECSELs) is still limited by thermal rollover (e.g., 0.8 W at 20 deg C at a peak emission wavelength of 2.35 µm). To identify the mechanisms underlying this thermal limitation, VECSEL structures with different cavity resonance-gain offsets have been fabricated and characterized. The resulting data have been analyzed using a thermooptical model. The temperature-dependent spectral alignment of quantum-well gain and microcavity resonance (so-called “gain offset”) is found to be one of the key parameters in optimizing high-power performance. A 45% increase in maximum room-temperature output power is obtained if the gain offset is chosen such that the gain spectrum matches the cavity resonance at operating pump power, i.e., at elevated active region temperatures.