High-energy half-cycle cutoffs in high harmonic and rescattered electron spectra using waveform-controlled few-cycle infrared pulses

We developed a few-cycle waveform-controlled light source for infrared pulses at 1.6 mu m that is based on optical chirped-pulse amplification in BiB3O6 (BIBO) crystals pumped by Ti:sapphire lasers. Using this source, we observe soft x-ray high harmonics that extend up to a photon energy of approximate to 320 eV, as well as high-energy photoelectrons up to approximate to 1 keV. The spectra of the high harmonics and photoelectrons have clear signatures of half-cycle cutoffs that can be used to extract electronic and molecular dynamics on an attosecond time scale.