REFIMEVE frequency and time network and applications

We present the development and current status of the REFIMEVE national research infrastructure, which disseminates time and frequency reference signals generated at LNE-SYRTE to research labs all over France. Using mainly the optical fiber backbone of RENATER, the French National Research and Education Network, REFIMEVE currently provides an optical frequency reference to around 15 labs, and to connection points to Germany, the UK, Italy and Switzerland. The robustness of the various types of equipment specifically developed for the transfer of ultrastable frequencies and the efficient supervision system have enabled us to demonstrate uptimes of over 90%. We show the latest development we have carried out to extend the network to CERN in Switzerland, with a branching link showing residual frequency fluctuations of 3×10 −15 for 1 s measurement time, and a few 10 −19 at long term. We discuss the issue of data processing for long periods of time and how to mitigate the effects of missing data to achieve reliable link uncertainty estimates. Thanks to these performances, the REFIMEVE network has been used for the precise comparison of primary and optical clocks in Europe, and the REFIMEVE optical signal is currently being exploited in France by user laboratories for photonics, laser stabilisation or control and atomic and molecular high-resolution spectroscopy.