Frequency standard transfer over a 43-km optical fiber

The paper presents an ultra-stable fiber optic frequency link used to transfer reference frequency signal through a standard telecommunication optical fiber between SYRTE (Observatoire de Paris) and LPL (Villetaneuse). The characterization of new ultra-stable frequency standards under progress at LPL , such as the CO₂/SF₆ two-photon frequency standard in the 30-THz spectral region or Ar/I₂ requires such ultra stable frequency distribution system that surpasses the phase stability of all systems previously developed.