A 40kw Fiber-Coupled Diode Laser for Material Processing and Pumping Applications

In this paper we present the next step on the roadmap “system scalability towards an output power above 100 kW”, first time presented in 2014 [1]. To take a step forward the optical power of the fiber-coupled diode laser has been increased beyond the power level 40kW. The power conversion efficiency exceeds 40%. The laser contains modules with 4 different wavelengths (960nm, 1020nm, 1040nm, 1060nm) there are two modules for each wavelength polarization multiplexed. After the slow-axis collimation these wavelengths are combined using dense wavelength coupling before focusing onto the fiber endface. The delivery-fiber is an uncoated fiber with a diameter of 2 mm and NA 0.22 corresponding a BPP of 220 mm mrad. In a stability test the laser delivered a constant maximum output power with less than ±0.5 % variation over 100h. Further results of the optical properties of the laser will be presented in this paper. This new laser is based on a turn-key industrial platform, allowing straight-forward integration into almost any industrial application, like welding or large area heat treatment. As application examples laser welding of thick sheet metal and pumping of an active fiber will be presented. The footprint of the complete system is 2.8 m² with a height below 1.8 m.