Spectrally shaped chirped pulse amplification of an all-normal dispersion Yb-doped fibre laser

We show experimentally and theoretically that the spectral profile of the seed pulse of an Yb-doped fibre-based chirped pulse amplifier (CPA) plays a dominant role for achieving an ultrashort compressed pulse. The picosecond seed pulse from an all-normal dispersion Yb-doped fibre laser can be compressed to 350 fs with a peak power of 25 MW. Better compressed pulse quality and a shorter pulse was achieved by the spectrally shaped CPA system as opposed to the system without spectral shaping.