Evolution of beam spatial characteristics in high-power Yb:YAG Innoslab amplifier

We investigated the spatial distribution of the output beam of our existed high-power Yb: YAG Innoslab laser amplifier and proposed that the generation of sidelobes was caused by spherical aberration distortion. A beam propagation model based on the reconstructed crystal temperature distribution was established to study the beam evolution in the Innoslab laser amplifier, and the degradation of the beam profile and phase distribution of the signal during amplification was presented. The simulation reproduced the beam characteristics of the signal during amplification. The generation of sidelobes in the output beam profile was observed in the simulation, which was in agreement with the experimental measurements. The beam profile distribution of the signal began to exhibit sidelobes in the third pass, which became increasingly apparent during the subsequent amplification process, resulting in beam splitting and the sidelobe effect.