High brightness spectral beam combining to 8.2 kW

We report on the spectral beam combining of four narrow-linewidth fiber amplifier chains running at different wavelengths. The main amplifier stage consists of a large mode area photonic crystal fiber delivering more than 2 kW of optical power. The four output beams are geometrically (incoherent) combined using a polarization-independent dielectric reflective diffraction grating to an output power of 8.2 kW preserving the beam quality of the individual fiber amplifiers.