Nonlinear Spatiotemporal Evolution and Pulse Compression of Femtosecond Pulses in a Bulk Multi-Pass Cell

Nonlinear pulse compression is a key technique for generating ultrashort and ultraintense laser pulses. However, spectral modulation often introduces phase distortions that limit compression performance. In this work, we develop a numerical model for femtosecond pulse propagation in a bulk multi-pass cell (MPC) based on the generalized nonlinear Schrödinger equation (GNLSE), combined with the ABCD transfer matrix for beam evolution. By systematically varying the soliton number and medium thickness, we investigate the influence of dispersion and nonlinearity on pulse shaping. The results demonstrate that proper tuning of these parameters effectively suppresses post-compression pulse pedestal and sidelobe formation. Under optimal dispersion compensation, the sidelobe intensity is reduced to 3.9%, and the energy ratio increases to 94.0%. This research reveals the dynamics of spectral broadening and pulse compression in a bulk MPC post-compression system and provides theoretical guidance and parameter optimization strategies for the generation of high-quality ultrashort pulses.