Double-pass Multipass Cell Compressor for Peak Power Enhancement of µJ Pulse Energies

Multipass cells (MPCs) have demonstrated to be a robust and versatile solution for pulse compression of high average power Yb-based high-power ultrafast lasers with multi-100 fs pulse durations. However, generating very short pulses at low pulse energy (few-µJ) with compact setups remains challenging because of the relatively low available nonlinearity. In this paper, we present a simple approach using a bulk-based double-pass MPC scheme for nonlinear pulse compression at µJ pulse energy with large compression ratio. Operating at 112 W and 12.7 MHz, we compress 8.8 µJ pulses from 600 fs to 40 fs with a compression ratio of 15, achieving a final peak power of 122 MW and peak power enhancement of 9.3, while maintaining an impressive overall optical efficiency of 89% and excellent spatial beam quality. The high peak intensity of our system is confirmed by generating a microplasma in ambient air that will be used in THz generation in future experiments.