Post-Compression with Enhanced Temporal Pulse Quality via Chirped Ellipse Rotation

Multi-pass cell (MPC)-based post-compression has emerged as a key technique for generating high-power, few-femtosecond laser pulses [1]. However, due to spectral modulations intrinsic to self-phase modulation (SPM), the compressed output pulse is accompanied with pre- and post-pulses deteriorating the temporal contrast with increasing compression factor [2]. This phenomenon does not only reduce the energy of the main pulse but may be detrimental to applications where pre-pulses can initiate undesirable interactions. A prominent approach to enhance the temporal contrast is nonlinear polarization ellipse rotation (NER), which can effectively suppresses weak signals outside the temporal window of the main pulse through intensity-dependent polarization rotation [3]. Another efficient method involves operating the MPC in a positive dispersion regime, known as enhanced frequency chirping (EFC) which reduces the spectral modulations caused by SPM [4].