Advent of a gigawatt-class, tabletop, isolated-attosecond-pulse light source

We have produced a soft x-ray supercontinuum with a pulse energy of 0.24-$\mu$J using high-order harmonics from a multiterawatt, 10-Hz, stable, three-channel waveform synthesizer [Sci. Adv. eaay2802 (2020)]. We report here an attosecond streaking scheme, which is designed for measuring low-repetition-rate, high-energy, isolated attosecond pulses. The retrieved pulse duration is 226 as, which conclusively demonstrates the realization of 1.1-gigawatt isolated attosecond pulses at the generation point. The gigawatt-level peak power of this tabletop, isolated-attosecond-pulse light source is equivalent to that of an x-ray free-electron laser in a large facility.