Development of a closed-loop cryogenically cooled sub-picosecond regenerative amplifier

Abstract

We are developing joule level picosecond pulse duration laser system operating at repetition rate of 120 Hz. The laser system consists of a seed mode-locked fiber laser and two cryogenically cooled amplifier stages: a single slab regenerative amplifier and a single slab multi-pass amplifier. We have found the displacement of the probe beam caused by mechanical vibrations of the cryostat is less than 0.7 µrad. We have also improved our in-situ gain measurement system by decreasing the spectral line of the narrow band source down to 50 pm. We have found that the emission bandwidth of Yb:YGAG at 160 K is around 7 nm.