2025 General Assembly
The 2025 General Assembly of the REFIMEVE Researche Infreastructure will be hosted by the Université Grenoble Alpes, at the MaCI on the Saint Martin d’Hères Campus (339 avenue Centrale, Saint Martin d’Hères, just in front of the Gabriel Fauré – MUSE tramway station – lines B or C).
Registration is free but mandatory.
For participants whose travel expenses will be covered by REFIMEVE (one person per partner laboratory and invited guests), you must not book train/plane tickets or hotel reservations on your own. Such expenses cannot be reimbursed, as all bookings must go through the CNRS or USPN systems and contracts. Please check with the REFIMEVE representatives of your respective units. The organizers will contact you directly regarding the arrangements for expense coverage.
For logistical reasons, registration will close on November 7, 2025, at 12:00 p.m.
Performance and uses of the Refimeve metrological signal, 1000 km from the source
Abstract : We present a detailed analysis of the end-user performance of the metrological signal at 1542 nm disseminated by the French national fiber network Refimeve, about 1000 km from the source. By means of a local ultrastable laser at 729 nm and an optical frequency comb, we are able to carry out instability and phase noise measurements of the signal with respect to the local laser. With a focus on phase noise analysis, we identify different timescales of interest for the use of this signal in optical frequency metrology. First, we identify a flicker frequency noise plateau at 2×10-15 on the local laser between 1 and 12 s. We then deduce from our measurement that the linewidth of the receivedRefimeve laser is 6.2 kHz for an averaging time higher than 40 ms.
Vol. 42, No. 11 / November 2025 / Journal of the Optical Society of America B
M. Collombon, E. Cantin, G. Hagel, P.-E. Pottie, M. Houssin and C. Champenois
Read more in Journal of the Optical Society of America B
Discover the “Customer Story” published by Exail: Delivering industry-grade solutions for ultra-stable optical frequency transfer over the Internet
For over a decade, Exail has been the industrial partner of REFIMEVE, the French national Metrological Fiber Network with European Vocation. Selected to industrialize a laboratory prototype, Exail developed a turnkey, industry-grade solution for transferring optical frequency reference over long-distances. The REFIMEVE network now spans from Paris to more than 30 sites across France and neighboring countries. One of the latest links was deployed at CERN, enabling the transmission of an optical clock signal with greater accuracy than what can be achieved using GNSS.
Read more on Exail’s website
Read more on LinkedIn
Unprecedented optical clock network lays groundwork for redefining the second
In a new study, researchers carried out the most extensive coordinated comparison of optical clocks to date by operating clocks and the links connecting them simultaneously across six countries. Spanning thousands of kilometers, the experiment represents a significant step toward redefining the second and ultimately establishing a global optical time scale.
Physicsworld News Releases
OPTICA News Releases
Read the article published in the journal OPTICA
SENSEI: Unlocking infrastructure and environmental sensing capabilities of telecommunication fibre networks
SENSEI aims to develop new photonic devices and technologies to enhance the security, resilience, and efficiency of telecommunication fibre networks through improved supervision capabilities, while exploiting them as large-scale distributed environmental sensors. Funded by the European Commission under the Horizon Europe programme with €5 million over 3 years, the project brings together 15 partners from 6 EU countries with diversified and complementary expertise in photonics, optical metrology, geoscience, optical networking and network provisioning.
Deployment of the industrialised Multi-branch Laser System (MLS)
We are happy to share some early results on the ongoing improvements to the REFIMEVE network.
We are accelerating the deployment of the industrialised MLS (Multi-branch Laser System) across the network. The first installation of the industrialised MLS took place on the TH2 Paris datacenter during the week of May 6–7, 2025. Initial observations are promising, showing significant improvements in both stability, accuracy and reliability for the national links of REFIMEVE.
We are demonstrating an order of magnitude gain in long-term stability of the frequency transfer compared to before, by compensating internal optical paths in the new MLS. The figure above shows the stability limit of the TH2 Paris Multibranch Laser Station.
We expect further enhancements, especially in terms of uptime, across long-haul links throughout the network.
Multibranch frequency transfer laser station allowing the transfer on 6 links with state of the art performances (© Grégoire Coget Exail)
SENSEI Kick-Off Meeting
SENSEI partners gathered at INRIM in Turin on December 4th and 5th 2024 to get the project started. About 25 people met there in person, and others joined virtually. The Consortium will meet very 6 months, alternating virtual and in-person meetings at partners’ headquarters. The next in-person meeting will be in May at CNRS-Paris.
https://senseiproject.eu/
General assembly T-REFIMEVE 2024
The FIRST-TF research federation (Laboratory of Escellence) and the REFIMEVE French Research Infrastucure, are joining together this year for organizing 3 events important for the french Time and Frequency community: their respective General Assemblies, and a workshop on precision synchronization and networks.
These events will be the opportunity for a vast community to network, have scientific exchanges and get the latest informations about FIRST-TF and REFIMEVE.
All the events will take place at Institut Galilée, on the Université Sorbone Paris Nord campus in Villetaneuse.
The dates are the following:
– 30th of Septembre 2024, afternoon: lab visits at the Laboratoire de Physique des Lasers,
– 1st of Octobre 2024: General Assembly of FIRST-TF
– 2nd of Octobre 2024: Workshop on “Precision Synchronization and networks”
– le 3 octobre 2024: General Assembly of REFIMEVE
Lunches for the 1st, 2nd and 3rd of Octobres are included in the organization. Dinners for the 1st and 2nd of Octobre evening will be organized as joint social events.
Registration is free, but mandatory, for members of structures affiliated to FIRST-TF, REFIMEVE, as well as for invited guests. For logistical reasons, registration will close on September 12 at 12pm (CEST).
For some members of laboratories and structures affiliated to FIRST-TF and/or REFIMEVE, travel and living expenses can be provided by the organization. Please contact the corresponding person for FIRST-TF and/or REFIMEVE in your laboratry if you want to ask of it. We will contact you directly about the modalities. UNDER NO CIRCUMSTANCE should you directly book a hotel or a transport ticket, as we will not be able to refund you: it is mandatry to pass through the sytem of CNRS or USPN.
