Steps towards integrating isolated parts and developing a joint time and frequency distribution fiber infrastructure in Europe

Ultra-stable frequency transfer and highly accurate time transfer methods, using optical fibers, have made a significant progress in recent years, demonstrating exceptional performance. Optical fiber links (cables) are increasingly relevant for other modern and demanding applications and novel scientific research activities, such as metrology, relativistic geodesy, distributed fiber sensing, quantum key distribution (QKD), fundamental research (including high energy physics), redefinition of SI units, optical clocks comparison and other advanced topics and various industrial and societal applications (GPS, distant early warnings). Optical fibers can offer a valuable alternative to radio- and satellite-based methods (because of serious concerns related to failures of such services especially known for the last few years). While many countries worldwide (not limited to Europe) have been building and developing national time and frequency dissemination fiber networks and establishing international fiber connections, a generic pan-European fiber network connecting these national fiber networks, and research time and frequency facilities (optical fountains, frequency cavities) does not yet exist. In response to recognized need, the GÉANT Association has launched an ambitious initiative to connect these nowadays isolated fiber components and create a fiber-based infrastructure for widespread distribution of time and frequency throughout Europe. This initiative, to be implemented in the next phase of GÉANT’s GN5-2 project, will enhance existing national fiber connections and support time and frequency transfers. The result will be a comprehensive, Europe-wide time and frequency fiber infrastructure for before mentioned fields.