Simulation study on spectrum beam combining based on reflection volume Bragg grating

Single fiber laser can reach kilowatt level output. Higher power output is limited by nonlinear effect inside the fiber, heat deposition and pump power. Spectral beam combining of multiple laser beams with offset wavelengths into a single near-diffraction-limited beam is an effective solution to increasing energy brightness and scaling output power of high-power lasers. The loss factors of effect on the diffraction efficiency of the gratings are discussed. Design principles and technical approach for spectral beam combining (SBC) of two channels and three channels by reflecting volume Bragg grating are investigated. Two and three channels SBC are numerically analyzed when the input beam divergence is 0.06mrad. The results show the SBC efficiencies are 98.65% and 97.57% when the spectral width is 0.1nm, and the efficiencies are 92.16% and 88.98% when the spectral width is 0.3nm, respectively.