Understanding and exploiting metrological fiber networks for Sagnac sensing, frequency dissemination and geosensing

Atomic clocks are the modern tools of timekeeping. Ever since the redefinition of the second in 1967 based on an atomic transition of Cesium 133, the atomic clocks have improved drastically. This has lead to many technological advancements the last 55 years, many of which require precise transfer of time and frequency signals, a prominent example being the Global Positioning System (GPS). With the recent advancements of the last generation of state-of-the-art atomic clocks, so called optical clocks, traditional means of disseminating their signals without degrading their performance are no longer adequate. The implementation of a new technology for such purposes has in recent years been implemented in several countries around the world, which utilizes optical fibers as a medium to transfer and compare the signals of the atomic frequency references.

This thesis contains the exploitation of such an optical fiber network in France, the discussion about the general noise processes of such fiber links, and their technical and fundamental limits. Then in-depth studies of several applications of a fiber network are presented. These studies include the evaluation of the uncertainty contribution of the French fiber network to the comparison of optical clocks. Also, the thesis contains also studies of the use of fiber networks for the sensing of effects arising from the Earth. This includes the sensing of the Sagnac effect in a fiber link deployed in a ring topology around Paris, a study of the detection of Earthquakes with the French fiber network, and a discussion of the prospects of the use of such a technology.

metrology, optical frequency, optical frequency transfer, fiber network, geosensing, REFIMEVE

Full document (EN) : TEL-04218313