Design and analysis of spectral beam combining system for fiber lasers based on a concave grating

A novel fiber laser spectral beam combining scheme based on a concave grating is presented. The principle of the presented system is analyzed, and a concave grating with blazed structure for spectral beam combining is designed. The combining potential of the system is analyzed, and the results show that 39 Yb-doped fiber laser can be spectrally beam combined via the designed system. By using scalar diffraction theory, the combining effect of the system is analyzed. The results show that the diffraction efficiency of the designed concave grating is higher than 72% over the whole gain bandwidth, and the combining efficiency is 73.4%. With output power of 1 kW for individual fiber laser, combined power of 28.6 kW can be achieved.