A Wide Spectrum Yb-Doped All-Fiber-Integrated Chirped Pulse Amplification System Based on Parabolic Shaping

Abstract

Nonlinear effect in an ultrafast fiber laser has always been a major obstacle in realization of laser with narrow pulse width and high energy. To achieve higher peak power, we herein introduce pre-chirping management and pre-amplification before the chirped pulse amplification (CPA) system. The self-phase modulation effect is used to effectively stretch the spectrum when the pulse reaches a high peak power, and then the parabolic pulse and spectrum are obtained in a fiber amplifier. This parabolic pulse effectively reduces the impact of nonlinear effect in subsequent fiber amplifier and realizes the amplification of chirped pulse with a higher peak power compared with conventional CPA system. We finally achieved a mode-locked pulse with 143 fs pulse duration, 8.57 W average power, 85.7 μJ single pulse energy, M2 < 1.10 beam quality, and without obvious pulse degeneration. The reported pulse energy is the highest among all-fiber CPA systems based on nonlinear amplification technology.