Hybrid spatial manipulation method on the high-power stimulatedBrillouin amplification beam combining system

Laser beam combining based on stimulated Brillouin amplification (SBA) promises numerous applications, since it can not only boost the power of the pulsed laser from multi-pump energy transfer but also permit the active spatial intensity manipulation process for the diverse-targeted beam profile, such as a square or round flat-top beam. In this paper, in order to further enhance the output laser beam intensity, a hybrid spatial manipulation method, which combines the structure and beam intensity optimization, has been proposed for the first time, to our knowledge. Based on the simulation results of the SBA beam combining models, a round flat-top combined output with a spatial intensity modulation index of <i>M</i>=1.42 is realized from an initially Gaussian beam profile experimentally. Simultaneously, the peak intensity, from initially 200<i>M</i><i>W</i>/<i>c</i><i>m</i>² to exceeding 1<i>G</i><i>W</i>/<i>c</i><i>m</i>², was obtained in the five-beam-combining system, with the combining efficiency reaching 78.5%. This hybrid manipulation method paved the way for practical application of SBA beam combining systems towards tens-of-joule-level repetitive nanosecond laser pulse output in the field of material processing and petawatt laser pumping, etc.