Abstract: High-power fiber lasers have become indispensable tools across science, advanced manufacturing, and defense. For decades, power scaling has relied on single- or few-mode fibers to preserve beam quality. However, the very tight optical confinement that enables diffraction-limited performance also enhances nonlinear effects, imposing fundamental limits on further power scaling. In this talk, I will present a different approach: embracing highly multimode fiber amplifiers as a pathway toward mitigating nonlinearities while enabling substantially higher output power. While multimode fibers are traditionally associated with complex and unstable spatial dynamics, we demonstrate that this complexity can be harnessed rather than avoided. By applying spatial wavefront shaping to the input field, we achieve deterministic control over both the spatial profile and the polarization state of the amplified beam. This strategy enables high-power, high-efficiency, narrow-linewidth operation in a highly multimode platform, challenging the conventional paradigm that beam quality and multimode propagation are incompatible. The results open new opportunities for scalable coherent beam combining, large-scale interferometry, and remote sensing, and suggest a new direction for the future of high-power fiber laser technology
Bio: Hui Cao is the John C. Malone Professor of Applied Physics, a Professor of Physics, and a Professor of Electrical Engineering at Yale University. She received her Ph.D. degree in Applied Physics from Stanford University in 1997. Prior to joining the Yale faculty in 2008, she served on the faculty of Northwestern University for a decade. Her research spans mesoscopic physics, complex photonic materials and devices, nanophotonics, and biophotonics, with an emphasis on light–matter interactions in complex and disordered systems. Cao is a Fellow of AAAS, IEEE, SPIE, APS and OSA. She is a member of the US National Academy of Sciences and the American Academy of Arts and Sciences, and a Fellow of the National Academy of Inventors.
