Abstract
We report on the development of an ultrafast optical parametric chirped-pulse amplifi er, which produces
9.0-fs, 0.55-mJ, 1600-nm optical pulses at 1-kHz repetition rate with carrier-envelope phase（ CEP）
stabilization, and its application to CEP-dependent high harmonic generation in the soft x-ray region.
The high harmonics are extended to 325 eV well beyond the carbon K edge at 284 eV. Dependence of
soft x-ray harmonic spectra on the CEP of the IR pulses verifi es the generation of an isolated attosecond
pulse. A laser-based soft x-ray light source, which possesses unprecedented femtosecond to attosecond
time resolution, is now becoming complementary to synchrotron-based light sources and free electron
lasers.
