Sub-30-fs high-power laser based on a solid multi-pass cell and application for high flux high harmonic generation

A multi-pass cell (MPC) serves as a highly effective post-compression solution; however, conventional solid MPC can only accept incident laser pulses with relatively low energy and moderate power. In this Letter, an improved water-cooled solid MPC is introduced for pulse compression of a 186 W high-power femtosecond Yb fiber laser at a 1 MHz repetition rate. Pulse duration of 225 fs is compressed down to 28.3 fs with 161 W output power, which corresponds to a peak power of 5.35 GW. Due to the high peak power, the system was applied to drive high-order harmonics generation (HHG), the XUV light spanned from 20.47 eV to 46.95 eV, with a maximum photon flux up to 1.07 × 10 11 photons/s, which is conducive to the application of time-resolved photoemission spectroscopy.