Optical phase locking among femtosecond subharmonic pulses.
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.
Kobayashi
Yohei
Y
National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba 305-8568, Japan. y.kobayashi@aist.go.jp
Takada
Hideyuki
H
Kakehata
Masayuki
M
Torizuka
Kenji
K