Diode laser arrays for 1.8 to 2.3 μm wavelength range

Abstract

High-power diode lasers in the mid-infrared wavelength range between 1.8μm and 2.3μm have emerged new possibilities for application fields like materials processing, medical surgery and for military applications like infrared countermeasures. GaSb based diode lasers are naturally predestined for this wavelength range and offer clear advantages in comparison to InP based diode lasers in terms of output power and wall-plug efficiency. We will present results on different MBE grown (AlGaIn)(AsSb) quantum-well diode laser single emitters and linear laser arrays, the latter consisting of 19 emitters on a 1 cm long bar, emitting at different wavelengths between 1.8 and 2.3 μm. Each emitter has a resonator length of 1.0 mm or 1.5 mm and stripe widths of 90 μm or 150 μm. The distance from emitter to emitter is 500μm for both types, resulting in 20% and 30% fill factors. For single emitters the electrooptical and beam behaviour and the wavelength tunability by current and temperature have been carefully investigated in detail. For diode laser arrays mounted on actively cooled heat sinks, nearly 20W at 1.94μm in continuous-wave mode have been achieved at a heat sink temperature of 20 °C. Even at 2.2μm more than 15W with a wall plug efficiency of 23% have been measured, impressively demonstrating the potential of GaSb based diode lasers well beyond wavelengths of 2μm.