High-brilliance diode lasers with monolithically-integrated surface gratings as sources for spectral beam combining

A high output power and a good beam quality are required for the application of diode lasers for direct material processing. One possible way to increase the output power while keeping the beam quality almost constant is spectral beam combining. The required stabilization of the emission wavelengths of the single emitters can be achieved by the monolithic integration of Bragg gratings into the chips, which is a promising way to reduce fabrication costs in comparison to the utilization of volume Bragg gratings. A DFB laser with a stripe width of 30 μm is presented, which reached a side mode suppression ratio of 50 dB and an output power of 5.5 W. Aspects of the simulation and the fabrication of the Bragg gratings will be discussed.