Beam shaping for complex laser systems via a multi-stage dynamic convergence strategy

In complex laser systems, such as those used in inertial confinement fusion, achieving high-quality beam shaping is crucial yet challenging. This paper presents a multi-stage dynamic convergence strategy to mitigate near-field non-uniformity caused by multi-stage amplification and frequency conversion. Dynamic convergence functions dependent on fluence/power are derived through spatially modulated injection fields. An iterative control model from a spatial light modulator (SLM) to a third-harmonic (3ω) output is established for closed-loop regulation. Experimental results demonstrate that after 3 iterations, the modulation depth of the 3ω beam decreases from 1.8:1 to <1.5:1, with localized hotspot intensity significantly suppressed. This method, now routinely deployed in multiple large-scale laser facilities, enables high-precision near-field control while significantly reducing optical damage risks and ensuring high-fluence stability.