We compared the performance of two post-compression techniques, a gas-filled hollow-core fiber (HCF) and a multi-pass cell (MPC), using a high-power ytterbium-doped fiber laser. The HCF produced 27 fs pulses from 230 fs inputs at >50% efficiency, whereas the MPC achieved 34 fs pulses with significantly higher efficiency (>88%). Both results aligned well with numerical simulations. Crucially, spatial wavefront analysis revealed that the HCF acts as a modal filter, improving beam quality, whereas the MPC introduces aberrations through cumulative mirror errors. Furthermore, we characterize the photon flux of high harmonic generation driven by the post-compressed pulses from the HCF and MPC. These finding highlights that post-compression technique based on self-phase modulation is efficient for the intensity boosting of femtosecond laser system, providing opportunities for generating high quality extreme ultraviolet (XUV) sources. In addition, further improvement of spatial wavefront quality is suggested using the HCF as a single compressor or output component of the cascade compressor.

We compared the performance of two post-compression techniques, a gas-filled hollow-core fiber (HCF) and a multi-pass cell (MPC), using a high-power ytterbium-doped fiber laser. The HCF produced 27 fs pulses from 230 fs inputs at >50% efficiency, whereas the MPC achieved 34 fs pulses with significantly higher efficiency (>88%). Both results aligned well with numerical simulations. Crucially, spatial wavefront analysis revealed that the HCF acts as a modal filter, improving beam quality, whereas the MPC introduces aberrations through cumulative mirror errors. Furthermore, we characterize the photon flux of high harmonic generation driven by the post-compressed pulses from the HCF and MPC. These finding highlights that post-compression technique based on self-phase modulation is efficient for the intensity boosting of femtosecond laser system, providing opportunities for generating high quality extreme ultraviolet (XUV) sources. In addition, further improvement of spatial wavefront quality is suggested using the HCF as a single compressor or output component of the cascade compressor.

Post-compression based on self-phase modulation (SPM) is widely used for femtosecond pulse shortening. However, the influence of the driving beam wavefront on different compression schemes remains unexplored. Using a Yb-doped fiber laser (230 fs, 200 kHz), we experimentally compare pulse compression in a hollow-core fiber (HCF) and a multi-pass cell (MPC). The HCF compresses pulses to 27 fs with an efficiency of approximately 55% and improves beam quality via modal filtering. The MPC achieves 34 fs pulses with an efficiency of approximately 90% and exhibits a quasi-waveguide mode-filtering effect, substantially enhancing output wavefront quality even when the input wavefront is poor. High-harmonic generation (HHG) experiments show that the HCF-driven source yields a higher photon flux (1.25 × 10¹¹ photons/s) compared to the MPC-driven source (4.95 × 10¹⁰ photons/s). Using a second Yb-doped fiber laser (223 fs, 100 kHz), a cascaded MPC–HCF scheme generates 7.5 fs pulses with an overall efficiency of approximately 70%, enabled by employing a larger-core HCF in the second compression stage. HHG experiments performed with the compressed pulses demonstrate that spatial phase evolution is a critical parameter in post-compression design for such applications.