高功率光纤激光器是用于科学、工业和国防的强大工具。单频光纤激光放大器进一步放大功率的主要障碍是受激布里渊散射。学界已努力减轻这种非线性过程，但大多局限于具有良好光束质量的单模或少模光纤放大器。
研究组探索了一种高度多模光纤放大器，通过大光纤芯降低光强，多模激发拓宽布里渊散射谱，受激布里渊散射得到了极大的抑制。将空间波前整形技术应用于非线性放大器的输入光，可将输出光束聚焦到衍射极限光斑上。该多模光纤放大器可在高功率、高效率和窄线宽下工作，确保了高相干性。光波前整形可以实现多模激光放大的相干控制，在相干光束组合、大规模干涉测量和定向能量传输方面具有应用潜力。
附：英文原文
Title: Wavefront shaping enables high-power multimode fiber amplifier with output focus
Author: Stefan Rothe, Chun-Wei Chen, Peyman Ahmadi, KyeoReh Lee, Kabish Wisal, Mert Ercan, Nathan Vigne, A. Douglas Stone, Hui Cao
Issue&Volume: 2025-10-09
Abstract: High-power fiber lasers are powerful tools used in science, industry, and defense. A major roadblock for further power scaling of single-frequency fiber laser amplifiers is stimulated Brillouin scattering. Efforts have been made to mitigate this nonlinear process, but these were mostly limited to single-mode or few-mode fiber amplifiers, which have good beam quality. Here, we explored a highly multimode fiber amplifier in which stimulated Brillouin scattering was greatly suppressed due to a reduction of light intensity in a large fiber core and a broadening of the Brillouin scattering spectrum by multimode excitation. By applying a spatial wavefront shaping technique to the input light of a nonlinear amplifier, the output beam was focused to a diffraction-limited spot. Our multimode fiber amplifier can operate at high power with high efficiency and narrow linewidth, which ensures high coherence. Optical wavefront shaping enables coherent control of multimode laser amplification, with potential applications in coherent beam combining, large-scale interferometry and directed energy delivery.
DOI: ady2226
Source: https://www.science.org/doi/10.1126/science.ady2226