Theoretical study of beam quality degradation caused by grating dispersion in a spectral beam combining system

In this paper, we investigated the association between beam quality and beam characteristic in theory in a spectral beam combining system and built a model to describe the dispersion. We analyzed that how the beam quality varies with different input beam parameters such as the waist radius 𝑤𝑤0 and the spectral width Δλ. There is a surprising result that the increased w0 and Δλ have a coefficient influence on the beam quality degradation, and the degradation is pretty sensitive to the increase of waist radius w0. The result gives us a guidance that besides using the narrow linewidth laser, we also need reduce the waist radius of the input beam in the SBC system appropriately to abate the beam quality degradation caused by dispersion.