High-power spatiotemporal mode-locked Yb-doped fiber laser based on transverse modes division control.

Spatiotemporal mode-locking (STML) in multi-mode fibers provides a novel approach, to our knowledge. to overcoming the power limitations of conventional single-mode lasers. However, the existing spatial filtering-based STML schemes are limited by the number of locked transverse modes, which severely constrains the power enhancement. In this Letter, we propose a transverse modes division control technique that theoretically permits arbitrary multi-mode locking by independently engineering dispersion for each mode via mode multiplexers/demultiplexers. Implemented in a Figure-eight STML Yb-doped fiber laser, we achieve solitons with 15 nJ pulse energy (75 nJ intracavity) at 14.49 MHz repetition rate. By dynamically selecting locked modes, a quasi-flat-top beam with 150 mW average power is further demonstrated. This work establishes a universal framework for multi-mode STML manipulation, advancing high-power ultrafast fiber laser development.