Hybrid laser system for chirped-pulse amplification using Yb fiber and Yb:YAG thin-rod amplifiers

Subject of study. The study focuses on schematic solutions for a laser system designed for generating and amplifying femtosecond laser pulses. Aim of study. The aim was to develop and investigate a femtosecond laser system with high peak and average powers. In addition, two variants of pulse stretchers used to lengthen laser pulses before amplification were compared . Method. In the proposed method, first, a fiber master oscillator with self-mode locking based on a semiconductor saturable-absorber mirror was used. Next, a fiber pulse stretcher was used to stretch the pulse, which was subsequently amplified using Yb-doped fiber and Yb:YAG thin-rod amplifiers. Finally, pulse compression was performed by a diffraction grating compressor. Main results. A compact hybrid laser system was developed and experimentally demonstrated. The operational characteristics of two stretcher configurations incorporated into the laser system—one based on a 500 m passive fiber and the other based on a chirped fiber Bragg grating—were compared. The duration of the compressed pulses at maximum output power reached 721 fs with an average power of 27.9 W when the fiber stretcher was used. In contrast, a pulse duration of 889 fs, with an average power of 31.2 W, was obtained using the fiber Bragg grating stretcher. The differences in the autocorrelation functions of the compressed pulses obtained with these two stretcher types were analyzed. Practical significance. The developed laser source can be applied in various fields, including the precision micromachining of materials, biomedicine and cosmetology, nonlinear optics (such as efficient frequency conversion of laser radiation), rangefinding, and remote sensing.