All-fiber Integrated Gain-Managed Nonlinear Amplification System Delivers Ultrafast Lasers with 3.6 MW Peak Power and 45 Fs Pulse Duration

In this work, we demonstrate numerically and experimentally an all-fiber-integrated gain-managed nonlinear (GMN) amplification system. The seed is a nonlinear amplifying loop mirror (NALM) mode-locked Yb-doped fiber laser with a pulse duration of 8.7 ps. By employing a chirped fiber Bragg grating (CFBG) or a bandpass filter (BPF), the pulse duration of seed is reduced to similar to 1 ps. The pulses are then injected into the Yb-doped fiber amplifier for GMN evolution. Subsequently, hollow-core photonic bandgap (HC-PBG) fibers are employed for dispersion compensation on the amplified pulse. In the BPF-filtered configuration, the entire system accumulates lower higher-order dispersion and is capable of delivering femtosecond pulses with a pulse energy of 163 nJ, a pulse duration of 45 fs, and a peak power of 3.6 MW, all while maintaining a highly favorable beam quality factor (M-2) of 1.05. Compared to previously reported GMN amplification systems, our entire system, which eliminates any sections of free-space optics, is highly attractive due to its ability to enhance stability and compactness, reduce maintenance demands and lower costs. We believe this compact femtosecond fiber laser system, with its ultrashort pulse duration and high peak power, holds potential for applications in scientific research and precision manufacturing.