Highly stable Yb-fiber laser amplifier of delivering 32-μJ, 153-fs pulses at 1-MHz repetition rate

We demonstrated a sub-200-fs polarization-maintaining Yb-fiber laser amplifier based on chirped-pulse amplification (CPA) technology with high energy and stability. The seeding laser pulses were picked to 1 MHz from a nonlinear polarization evolution (NPE) self-similar mode-locked Yb-fiber laser oscillator at 40.3 MHz. A specially designed chirped fiber Bragg grating (CFBG) was employed as the pulse stretcher, which provide compensation for higher order dispersion introduced by grating compressor. Laser pulse as short as 153 fs with energy of 32 μJ was obtained after the compressor, which corresponds to a peak power of 209 MW. The measured output power fluctuation of root mean square was 0.64% in 24 h and the M2 factor was 1.3. It shows a great potential in many applications such as scientific researches, medical therapy, and industrial micromachining.