GaSb-based semiconductor disk lasers: recent advances in power scaling and narrow linewidth operation

Abstract

The (AlGaIn)(AsSb) semiconductor materials system has been shown to be ideally suited to realize optically pumped Vertical External Cavity Surface Emitting Lasers (VECSELs) for the 2-3 μm wavelength range. For a 2 μm emitting single-chip VECSEL with a ternary GaInSb quantum well active region, employing a linear planar-concave resonator geometry, a maximum continuous wave (cw) output power of 4.2 W at 20°C heatsink temperature (6 W at 0°C) has been achieved. Standard fiber-coupled 980 nm diode lasers have been used for optical barrier pumping. Employing a W-shaped resonator with two optically pumped gain chips acting as planar folding mirrors, a maximum cw output power of 5.5 W has been achieved at a heatsink temperature of 20°C, increasing to 10.4 W when reducing the heatsink temperature to -10°C. The resonator versatility of a VECSEL also allows the insertion of additional optical elements into the optical cavity for wavelength selection and linewidth control. Employing a V-shaped folded cavity with the gain chip acting as the planar end mirror, single-mode operation with a linewidth <100 kHz at 1 W optical output power has been achieved at a lasing wavelength of 2.05 μm.