Multi-kW high-brightness fiber coupled diode laser

摘要

Fiber coupled diode laser devices are attractive light sources for applications in the area of solid-state laser pumping and materials processing. The ongoing improvement in the brightness of diode lasers, which means power per beam quality, makes more and more industrial applications accessible to diode lasers. For many applications in materials processing multi-kW output power with a beam quality of better than 30 mm x mrad is needed. Previously we have reported on a modular diode laser platform based on a tailored bar design (T-Bar) and have demonstrated an output power of up to 785 W out of a 200 μm NA 0.22 fiber at a single wavelength of 976 nm. We have now extended that tailored bar platform to different wavelengths in the range from 900 nm to 1100 nm. At each single wavelength efficient fiber coupling into a 200 μm NA 0.22 fiber will be demonstrated. One important concept for power scaling is coarse wavelength multiplexing with a spectral separation of typically about 40 nm. Combining of different wavelengths enables scalable multi-kW high-brightness diode laser units. Further power scaling can be achieved by dense wavelength multiplexing with a spectral separation of only about 5 nm. In this paper we report on a diode laser unit with 3.5 kW output power and a beam quality of 25 mm x mrad.