New method of incoherent beam combining for fiber lasers based on concave grating

Aiming at the problems existing in the scheme of adaptive incoherent beam combining offiber lasers put forward by NRL, a novel scheme based on concave gratings was presented. The combined beam can be focused upon the target without any additional optical components and target tracking can be easily achieved just by adjusting the position of each fiber′s output end. The principle of beam combining was described in detail. The concave grating is designed and the combining effect is analyzed. The numerical simulation results show that 44Yb-doped fiber lasers can be combined with a combining efficiency of 82%. If 30 fiber lasers with 1 kW output power are combined, the total output power of the beam combining system can exceed 24.6 kW.

► A novel incoherent beam combining scheme for fiber lasers based on concave grating is presented.
► A concave grating with blazed structure for beam combining is designed.
► 44 Er/Yb-doped fiber lasers can be combined with a combining efficiency of 82%.