High average power room temperature laser based on a 300-mJ 100-Hz Ti:Sa disk amplifier

We report on results obtained at the output of a titanium:sapphire (Ti:Sa) laser working at a repetition rate of 100 Hz and generating femtosecond pulses with an energy exceeding 200 mJ. Such a high average power is obtained thanks to a bow-tie multipass pre-amplifier followed by a water-cooled thick-disk amplifier delivering 300 mJ pulses. Both are pumped by a diode-pumped frequency-doubled Nd:YAG laser delivering 750 mJ at 100 Hz. The combination of an OPCPA front-end with this disk amplifier provides outstanding temporal performance. The spectrum at the disk amplifier output is 80 nm wide (FWHM), compatible with a Fourier transform limit (FTL) below 25 fs. We also demonstrate a high contrast, close to 10^-8 at 10 ps, 10^-10 at 30 ps, and 10^-11 at 100 ps. These results are coupled to good energy and beam pointing stabilities (respectively < 1% RMS and < 3 μrad RMS measured at the output of the disk amplifier).