High average power femtosecond fiber CPA system

We report on a diode-pumped ytterbium-doped low-NA large mode area fiber based chirped pulse amplification system delivering 125 W average power at a repetition rate of 75 MHz and diffraction limited beam quality. Femtosecond laser pulses at 1060 nm center wavelength are stretched in a single mode fiber and recompressed after amplification to 350 fs pulse duration.