Recent status of the SYLOS 2 laser system of ELI-ALPS

This manuscript presents the most recent upgrades made on SYLOS2 laser system in ELI-ALPS1. These modifications on the system were done based on the feedback from the experimental end-stations during the last 3 years. First, the long virtual propagation of the super-Gaussian output beam reduced by modifying the imaging telescope after the amplification stages, which significantly improved the beam profile hindered by the propagation-related diffraction pattern. The optical parametric chirped pulse amplification (OPCPA) stages were equipped with new nonlinear crystals which enabled to reach 42 mJ output energy with <8 fs pulse duration, which is 10 mJ more than the previous configuration. To increase the high-harmonic generation (HHG) efficiency a spatial filter was installed in the laser system which provides a nearly Gaussian beam profile at the output with 80% transmission. The spatial filter is based on a glass cone and is operated under vacuum. Currently, <20 mJ, <8 fs CEP-stable pulses are provided at the user stations after the beam transport system.