Millijoule pulse energy high repetition rate femtosecond fiber chirped-pulse amplification system

Abstract

We report on an ytterbium-doped fiber chirped-pulse amplification (CPA) system delivering millijoule level pulse energy at repetition rates above $100\mathrm{kHz}$ corresponding to an average power of more than $100\mathrm{W}$. The compressed pulses are as short as $800\mathrm{fs}$. As the main amplifier, an $80\mu \mathrm{m}$ core diameter short length photonic crystal fiber is employed, which allows the generation of pulse energies up to $1.45\mathrm{mJ}$ with a B-integral as low as 7 at a stretched pulse duration of $2\mathrm{ns}$. A stretcher–compressor unit consisting of dielectric diffraction gratings is capable of handling the average power without beam and pulse quality distortions. To our knowledge, we present the highest pulse energy ever extracted from fiber based femtosecond laser systems, and a nearly 2 orders of magnitude higher repetition rate than in previously published millijoule-level fiber CPA systems.