Dynamic mode control and beam quality improvement of Laguerre-Gaussian beams in a laser amplifier

High-power lasers with specially modified intensity distributions are constrained by thermally induced aberrations in solid-state amplifiers. This paper introduces a novel, to the best of our knowledge, precompensation architecture for thermal aberrations based on a spatial light modulator (SLM). For the first time, the SLM is employed both as a dynamic mode generator and as a phase compensation element. By employing a dual 4f imaging system and controlling the propagation, a precise mapping is established between the modulation and measurement planes, enabling aberration correction without relying on complex feedback algorithms. The proposed architecture effectively suppresses thermal aberration-induced degradation of the M² factor while safeguarding the SLM from high-power damage in a master oscillator power amplifier system for Laguerre-Gaussian beams. Experimental results demonstrate a 15 times single-pass gain while maintaining the M² factor consistent with its pre-amplification value.