High-contrast OPCPA front end in high-power petawatt laser facility based on the ps-OPCPA seed system

A high-energy, high-beam-quality, high-contrast picosecond optical parametric chirped-pulse amplification (ps-OPCPA) laser system was demonstrated. The pulse from a femtosecond oscillator was stretched to 4 ps, after which it was amplified from 140 pJ to 600 µJ by an 8 ps/6 mJ pump laser in two non-collinear OPCPA stages. The total gain was >10⁶, and the root mean square of the energy stability of the laser system was 1.6% in 10 h. The contrasts of the solid and fiber mode-locked femtosecond oscillator-seeded ps-OPCPA systems were compared, and a signal-to-noise ratio of >10¹¹ was achieved. Using this system, the contrast of the front end in high-power picosecond petawatt laser facility was improved by ∼40 dB to >10¹¹, beyond ∼200 ps ahead of the main pulse with an output level of 60 mJ.