March 10, 2020 TiFOON partners PTB, LPL (Université Paris 13) and LNE-SYRTE have demonstrated more than 5 days of phase-coherent operation of the optical fibre link between Braunschweig and Strasbourg. The architecture, a combination of a Repeater Laser Station and Fibre Brillouin Amplifiers, was analysed over several long segments of continuous operation, covering 65 days of data in total. The frequency dissemination uncertainty was shown to be better than 1/10th of the estimated uncertainty of today’s best optical atomic clocks. The study, published in New Journal of Physics, also looked at the correlation of phase noise between the two individual fibres in the pair used for the link. A correlation of > 98% has been found, indicating that the practise of out-of-loop verification using doubled-up links indeed provides reliable results. The publication is freely available on the Zenodo TiFOON community hub.
