High-average-power, few-cycle, 2.1 µm OPCPA laser driver for soft-X-ray high-harmonic generation

Repetition-rate upscaling of intense, femtosecond-duration pulses in the short-wave infrared is necessary to further develop and apply tabletop, ultrafast soft-X-ray sources. Here, we present a 20 fs-pulse-duration, 2.1 µm-central-wavelength, optical parametric chirped-pulse amplification laser, which outputs 52 W of amplified signal power at a repetition rate of 52.6 kHz. Despite the potential for deleterious thermal processes, the laser output exhibits excellent spatial and temporal profiles in a 45 W beam at a soft-X-ray-generation target after ∼5 m of propagation. In argon gas, this enables high-harmonic generation up to ∼190 eV photon energies, demonstrating the system's potential for ultrashort soft-X-ray-pulse production.