High average power picosecond Yb:YAG thin-disk lasers are being developed at Hilase. A compact 1 mJ/100 kHz and 4 mJ/100 kHz zero-phonon-line-pumped regenerative amplifiers PERLA C with a CVBG compressor provide <2 ps long pulses in a nearly diffraction-limited beam. The output was successfully converted to 2nd and 4th harmonic frequency with high conversion efficiency. High energy, QCW-pumped beamline PERLA B is operated at 45mJ/1kHz in fundamental spatial mode and pulse length < 2ps. Its second stage amplifier is being assembled and 1.8 J was extracted. The latest development status of all thin-disk beamlines at the Hilase center is reported.
We present recent progress in development of low-jitter all-normal dispersion (ANDi) Yb-doped fiber laser. We developed a timing jitter measurement scheme employing a broadband lock-in amplifier working up to 600 MHz operational frequency which allowed us to measure single side band (SSB) phase noise and long-term drift in laser repetition rate. Following the measurement, we were able to determine timing jitter of our oscillator in the most critical frequency range (10 Hz – 10 kHz) to 1.6 ps. Long-term drift has been successfully suppressed by applying a piezo motor-based active feedback in the cavity.
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 mrad. 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.