Abstract
A recent progress in a study on phase-matched high-order harmonic generation by intense femtosecond laser pulses is reviewed. We present a phase-matching model, which is established for enhancing brightness of high-order harmonics. Recent experimental results are also described, showing that, by employing 800-nm, 30-fs, 4-mJ laser pulses as fundamental wave, it is possible to produce a single-mode, >10 nJ light at 27 nm from 10-mm, 20-Torr argon, and single-mode, 1 nJ light at 9 nm to 26 nm from 70-Torr, 3-mm neon. Improvement of the coherence and the tunability of high-order harmonic light is also shown.
