Milli-joule class femtosecond regenerative amplifier enabled by a narrowband fiber oscillator

作者：Guo, Zhengru; Liu, Zhaocun; Liu, Tingting; Shao, Yumin; Li, Min; Hao, Qiang^*

来源：Infrared Physics and Technology, 2024, 136: 105067.

DOI：10.1016/j.infrared.2023.105067

• Ultrashort pulse laser
• Yb-doped laser
• Regenerative amplification
• Nonlinear amplification

We report on a room-temperature operated, Yb:CaF2 based, chirped-pulse regenerative amplifier system with a pulse duration of 300 fs and an output pulse energy of 2.0 mJ. A novel front end comprising a narrowband fiber oscillator and a nonlinear fiber amplifier is adopted to seed the regenerative amplifier. To achieve broadband spectral coverage for femtosecond pulse generation, nonlinear fiber amplification is implemented and spurs a 7folded spectral extension. After the successive pulse stretching, spectral reshaping, regenerative amplifying, and compressing, optimum pulses with 300-fs duration and 6.7-GW peak power are obtained. Such intense pulses are capable of inducing laser filament at 0.4-mJ energy with a loosely focusing geometry. Our method demonstrates the potential of narrowband fiber lasers to enable femtosecond regenerative amplifiers and paves the way toward compact, robust, and cost-effective millijoule-class lasers.