High brightness external cavity broad area diode laser bar using off-axis spectral beam combining

High power broad area diode laser bars are interesting devices for material processing or cladding pumping of fibre amplifiers. The main advantages of these devices are that they are of comparatively smaller size than solid state or gas lasers, i.e., the order of a few cubic millimetres; they can deliver relatively high output power levels above 100W. They have a long life time of 10,000s of hours. They also have very high wall-plug efficiency even up to 75%. But the main draw back of these devices includes poor beam quality and low spatial brightness that is a result of the high divergence along the slow axis caused by a broad emitter area. We have demonstrated an efficient method to improve the beam quality of a laser bar to an extend that exceeds the freely running single emitter beam quality.