GaSb-based VECSEL exhibiting multiple-watt output power and high beam quality at a lasing wavelength of 2.25µm

We report the realization of GaSb-based optically pumped vertical-external-cavity surface-emitting lasers (VECSELs) emitting at 2.25 µm which are capable of multiple-Watt output power. VECSEL structures were grown on GaSb-substrates by molecular beam epitaxy. SiC heat spreaders were capillary bonded onto the surface of the VECSEL chip in order to facilitate efficient heat removal. A continuous-wave output power of more than 3.4 W was recorded at a heat sink temperature of -10 °C. At room temperature (20 °C) we still obtained more than 1.6 W output power. A beam propagation factor in the range of M(exp 2)<=5 was measured at maximum output power. In adjusting the fundamental mode diameter on the VECSEL chip to the pump spot diameter the beam quality could be further improved resulting in a beam propagation factor of M(exp2) about 1.5. Furthermore, initial results on a GaSb-based dual-chip VECSEL are reported, capable of delivering a maximum output power of 3.3 W for a heat sink temperature of 20 °C and an emission wavelength of 2.25 µm.