High-power diode laser arrays at 2 µm for materials processing

GaSb based diode laser arrays emitting at 2 mu m have a. huge potential especially for materials processing. Determined by the absorption characteristics of thermoplastic materials at wavelengths around 2 mu m the energy of the diode laser arrays will be absorbed by the material itself without any alteration by adding pigments for example. We will present results on (AlGaIn)(AsSb) quantum-well diode laser single emitters and linear arrays with 20 emitters on a 1 cm long bar emitting at 1.97 mu m. For the single emitters output powers well above 1.5 W with an excellent longterm stability have been observed. More than 13 W in continuous-wave mode at a heatsink temperature of 20 deg C have been achieved with the arrays resulting in wall-plug efficiencies of more than 17%. Even more than 22% of wall-plug efficiency has been measured in quasi continuous wave mode, which is comparable to results obtained for single emitters. These efficiencies are among the highest values, published for GaSb based lasers, and allow passively cooled and therefore less expensive packaging technologies.