Highly stable conductively cooled 1 kW - QCW diode laser stacks with high duty cycle

A new mini-bar design with densely packed 13 emitters in 1,6 mm aperture has been developed These mini-bars deliver > 200 W output. With a very low divergence of 95% power enclosed in 25deg they are suitable for fast axis collimation (FAC) lenses with large working distance. The mini-bars are mounted on compact CuW carriers, which are further integrated into a custom stack assembly where they are conductively cooled from both sides. This completely AuSn soldered stack consists of only CTE matched materials and was 100 times temperature cycled from -40degC...85degC without any change. The beam parameter product (95% power) of a 12 layer Stack is in the vertical direction (after FAC) les45 mmmiddotmrad and in the lateral direction les75 mmmiddotmrad. Thus the stack can be coupled to an 1.2 mm multi mode fibre with a coupling efficiency of 90% using only low-cost lenses.