Abstract
Abstract
Transverse mode instability (TMI) critically limits the power scaling of high-brightness fiber lasers. While recent experiments have empirically demonstrated that the TMI threshold can be significantly enhanced by temporal modulation, the fundamental physical mechanism governing this stabilization remains unknown, preventing the rational design of high-power systems. Here, we present a comprehensive numerical framework that incorporates nonlinear optical effects into the analysis of TMI dynamics under temporal modulation. We identify self-phase modulation as the dominant stabilizing mechanism, which generates a chaotic thermal grating to suppress resonant energy transfer between the fundamental and higher-order modes, thereby disrupting the TMI process. Building upon this insight, we derive a quantitative, predictive model that directly links modulation parameters and fiber properties to the TMI threshold. This work provides the missing physical foundation for understanding nonlinear TMI suppression and offers a powerful, predictive design tool for overcoming the power-scaling bottleneck in next-generation fiber laser systems.