2-μm all-fiber high-energy soliton laser enabled by narrowband FBG filtering

We demonstrate a 2-μm all-fiber passively mode-locked laser based on an energy-managed soliton architecture, which adopts a 0.31-nm narrowband fiber Bragg grating (FBG) combined with nonlinear polarization evolution (NPE) to achieve mode locking. Benefiting from the synergy between narrowband filtering and energy management, the laser realizes stable single-pulse mode locking, with a maximum single-pulse energy of 77.4 nJ, a pulse duration of 48.3 ps, and a fundamental repetition rate of 6.97 MHz. The strong intracavity filtering completely eliminates the Kelly sidebands ubiquitous in conventional soliton fiber lasers. Numerical simulations reveal the intracavity soliton evolution and the core mechanism of pulse energy enhancement, providing a compact all-fiber implementation scheme for high-energy picosecond pulse laser sources in the 2-μm band.