Compact High Brightness Diode Laser Emitting 500 W from a 100 μ m Fiber

High power, high brightness diode lasers are beginning to compete with solid state lasers, i.e. disk and fiber lasers. The core technologies for brightness scaling of diode lasers are optical stacking and dense spectral combining (DSC), as well as improvements of the diode material. Diode lasers have the lowest cost of ownership, highest efficiency and most compact design among all lasers. Multiple Single Emitter (MSE) modules allow highest power and highest brightness diode lasers based on standard broad area diodes. Multiple single emitters, each rated at 12 W, are stacked in the fast axis with a monolithic slow axis collimator (SAC) array. Volume Bragg Gratings (VBG) stabilizes the wavelength and narrow the linewidth to less than 1 nm. Dichroic mirrors are used for dense wavelength multiplexing of 4 channels within 12 nm. Subsequently polarization multiplexing generates 450 W with a beam quality of 4.5 mm*mrad. Fast control electronics and miniaturized switched power supplies enable pulse rise times of less than 10 μs, with pulse widths continuously adjustable from 20 μs to cw. Further power scaling up to multi-kilowatts can be achieved by multiplexing up to 16 channels. The power and brightness of these systems enables the use of direct diode lasers for cutting and welding. The technologies can be transferred to other wavelengths to include 793 nm and 1530 nm. Optimized spectral combining enables further improvements in spectral brightness and power.