High-energy, kHz, 2.1-$\mu$m OPCPA pumped by a cryogenic Yb:YAG laser and its application to high harmonic generation

We report on a mJ-level, kHz-repetition-rate, carrier-envelope phase (CEP)-stable ultrabroadband optical parametric chirped-pulse amplifier (OPCPA) at 2.1-μm wavelength, pumped by a high-energy, 14 ps, cryogenic Yb:YAG pump laser, and its application to high harmonic generation (HHG). The pulses were amplified to 0.85 mJ and compressed to 4.5 optical cycles with a spectral bandwidth of 474 nm. Initial HHG experiments with Xe showed a significant cutoff extension to >85 eV with an efficiency of ~10-10 per harmonic. Further systematic HHG studies will be presented