All-fiber high-peak power chirped pulse amplifier based on a triplecladding fiber for pulse stretching and a highly-Yb-doped pedestal fiber for pulse amplification

We demonstrate an all-fiber chirped-pulse amplification system, where pulses are stretched in a triple-cladding fiber designed to match a grating-pair compressor in second- and third-order dispersion and then amplified in a highly-Yb-doped large-mode area fiber with a Ge-pedestal with only 23-cm in length. The chirped pulses centered at 1026 nm were stretched up to similar to 500 ps, amplified and compressed in a transmission grating compressor down to 400 fs with almost absence of pedestal at autocorrelation trace. The pulses had average power of 4.2 W and 20.4 uJ pulse energy, corresponding to record-high peak power of 50.9 MW. In experiments on amplification 24 ps pulses we were able to achieve 320 kW of peak power and 10.2W of average power being limited by the stimulated Raman scattering effect. The output stage of the system demonstrated diffraction-limited beam quality with M-2 of 1.15/1.12 and pump-to-signal conversion efficiency of similar to 60%.