GaSb-BASED HETEROSTRUCTURES FOR HIGH POWER AND PULSED LASER OPERATION

We have studied monolithically grown GaSb-based vertical-cavity heterostructures. First we demonstrate GaSb-based optically pumped vertical-external-cavity surface-emitting laser (OP-VECSEL) emitting multi-watt output power. A VECSEL gain structure comprising 15 In0.2Ga0.8Sb quantum wells grown on (100) n-doped GaSb substrate emitted continuous wave output power of over 4 W at 1970 nm wavelength operating near room temperature. Lasing was detected even at 50 ◦C mount temperature. We also present a GaSb-based semiconductor saturable absorber mirror (SESAM) operating at 2 µm wavelength region. For the purpose of generating short laser pulses, the SESAM was carefully designed to attain a large modulation depth. The device was utilised successfully to passively Q-switch a 2 µm Tm3+-/Ho3+-doped fibre laser, demonstrating record-short Q-switch pulses of about 20 ns