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

Multi-pass cell (MPC) is a highly effective post-compression solution; conventional solid MPC can only accept incident laser pulses with relatively low energy and moderate power. In the letter, an improved water-cooled solid MPC is introduced for pulse compression of 186W high-power femtosecond Yb fiber laser at 1 MHz repetition rate. Pulses duration of 225 fs was compressed down to 28.3 fs with 161W output power, corresponding to a peak power of 5.35 GW. Due to the high peak power, it was applied to drive high-order harmonics generation (HHG), the XUV light covered from 20.47 eV to 46.95 eV was achieved with maximum photon flux up to 1.07×1011 phs/s, which is conducive to the application of time-resolved photoemission spectroscopy.