OFTEN: Optical frequency transfer - a European network

The EMPIR project OFTEN follows on from the EMRP project NEAT-FT (SIB02)

The enormous potential of optical carrier frequency transfer has been already demonstrated within the Opens external link in new windowjoint research project (JRP) SIB02 NEAT-FT, which achieved instability and uncertainty at the level of about 5×10-19 over a distance of >1000 km with an averaging time of less than an hour when comparing the frequency at the remote end with that at the local end of a fibre link. Within SIB02 NEAT-FT techniques and tools for long-haul frequency dissemination over optical fibres were initially developed.

However, reliable operation of these links on an autonomous, day-to-day basis is needed. In addition, routine clock comparisons via optical fibres require further improvement of equipment and a deeper understanding of the noise processes limiting the stability of an optical fibre link as well as the development of real-time evaluation tools for multiple clock comparisons.


In the last three years, the project has answered this need by providing a unique opprtunity to perform fast and accurate frequency comparisons of Europe's optical and Cs-fountain clocks at the highest possible level of accuracy and to unlock the full potential of OCs for future applications.

The project is closed since June 1st 2019 but essential aspects of OFTEN will be continued in the EMPIR project TiFOON.

TiFOON started on June 1st, 2019.

For more details see Opens external link in new windowhttp://empir.npl.co.uk/tifoon/