title: Optical phase locking among femtosecond subharmonic pulses.
abstract: We stabilized the relative carrier-envelope phase slip among the pump pulse and its subharmonic signal and idler pulses in a femtosecond optical parametric oscillator, resulting in long-term phasecoherence among the pulses. The stabilized beat signal corresponding to the relative carrier-envelope phase slip among subharmonic pulses had an accumulated phase error of 0.24 rad in the 1-mHz-1-MHz region. The fluctuation of the beat frequency measured by a 1-s-averaged counter was less than 1 mHz in a 1480-s measurement.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba 305-8568, Japan. y.kobayashi@aist.go.jp
authors.forename: Yohei
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takada
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kakehata
authors.forename: Kenji
authors.initials: K
authors.lastname: Torizuka