High-power 0.4-mJ picosecond CPA system based on an extra-large-mode-area triple-clad fiber

A high-average-power, high-pulse-energy picosecond chirped pulse amplification (CPA) laser system based on an extra-large-mode-area (XLMA) triple-clad fiber (TCF) was demonstrated. The ultrashort pulses, generated from all-fiber mode-locked oscillator, stretched and then were pre-amplified to 10 W through a series of fiber power amplifiers. Subsequently, the average output power was amplified to 620 W corresponding to a pulse energy of 0.62 mJ via XLMA TCF. Additionally, the amplified pulses were compressed to a pulse duration of 7.6 ps with an average power of 423 W and a compression efficiency of 68.2%. The ultrashort laser is a promising light source for application of water-guided laser processing, albeit with a beam quality factor of 20 and 21 along two orthogonal axes.