REFIMEVE+: Towards a Wide Optical Fiber Network for Optical Frequency Standard Dissemination

We report on the progress of a metrological fiber network on the French territory, with extensiONS to Europe, which aims to provide an ultra-stable frequency signal to around 20 laboratories. We present a low sensitivity multi-branch Michelson interferometer serving as a node for the dissemination to several network branches. We show in addition reliable and robust operation over several months of operation of a 1400 km, which instability is in the - 10
^-20
range at long-term. This work is an important step towards the realization of an effective fiber network disseminating optical frequency standards to a wide variety of research laboratories.