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DEMETRA, the “DEMonstrator of Egnss services based on Time Reference Architecture”, is an European Project funded by the European Union in the Horizon 2020 program. The main aim of the project was to develop and test a prototype of Time Service Provider based the European Global Navigation Satellite System (GNSS) providing innovative or improved time services based on different technologies and embedded...
Molecular precision spectroscopy opens new perspectives on tests of fundamental laws of physics and of fundamental constants variation [1]. The mid infrared (IR) is a key region for molecular spectroscopy, and the efforts towards the development of versatile, spectrally pure, and tunable coherent sources in this region have been constantly growing in the last decade. A convenient way to generate a...
The H2020 research project, DEMETRA (DEMonstrator of EGNSS services based on Time Reference Architecture) is funded by the European Union and aims to develop and test several time services based on the European Global Navigation Satellite System (GNSS) and introducing important new features such as certified time stamping, improved accuracy, or integrity, not yet provided by GNSS systems. The demonstrator...
In 2015 and 2016 a European Consortium of 15 scientific and industrial partners from 8 different countries collaborates on the DEMETRA (DEMonstrator of EGNSS services based on Time Reference Architecture) project, funded by the European Union in the frame of the Horizon 2020 program, aimed at developing and experimenting time dissemination services based on the European GNSS. The project aims at being...
DEMETRA aims to be a prototype of an European time dissemination service, based on the timing signal of the European Galileo system, adding particular features like - among the others - certification, calibration, or integrity, that could be of interest to a wide range of users belonging to different sectors as traffic control, energy distribution, finance, telecommunication, and scientific institutions...
Optical fiber links offer the best performance to transfer time and frequency. They are beneficial to primary metrology, and there is a strong effort to develop a European network of T&F fiber links. In Italy, we realized a coherent optical fiber link from the National Metrological Institute INRIM to the INAF radio-antennas in Medicina, Bologna and the physics laboratories in Sesto Fiorentino,...
Optical fiber links are beneficial not only for frequency metrology, but also for other fields of physical research, such as radioastronomy and geodesy. We realized the first optical fiber link from a National Institute of Metrology to a Radiotelescope used for Very Long Baseline Interferometry and for geodetic measurements, over a distance of 544 km. We performed a remote calibration of the hydrogen-maser...
In this work we report the results of a study on phase-coherent transfer of narrow linewidth optical frequencies in single-mode fiber links employing bi-directional distributed Raman amplification (DRA). Both co- and counter-propagating amplification pump schemes have been investigated and with optimized input parameters, a coherent optical frequency at 1542 nm was transferred on a 305 km fiber. We...
This paper reports a study on distributed Raman amplification (DRA) in the phase-coherent transfer of narrow linewidth optical frequencies in single-mode fiber links. Both co-and counter-propagating amplification pump schemes have been investigated and with optimized input parameters, a coherent optical frequency at 1542 nm was transferred on a 305 km fiber. Moreover, we report on the successful use...
We performed a two-way remote optical phase comparison on optical fiber. Two optical frequency signals were launched in opposite directions in an optical fiber and their phases were simultaneously measured at the other end. In this technique, the fiber noise is passively cancelled, and we compared two optical frequencies at the ultimate 10−21 stability level. The experiment was performed on a 47km...
We realized a coherent optical fiber link in Italy, with a fiber haul of 642 km. To characterize the link, we doubled the link to 1284 km, demonstrating a characterization technique based on the double round trip on a single fiber. The link is intended to significantly improve the frequency references used in radio-astronomy and precision measurements in atomic physics. The data analysis is based...
It is well known that temperature variations and acoustic noise affect ultrastable frequency dissemination along optical fiber. Active stabilization techniques are in general adopted to compensate for the fiber-induced phase noise. However, despite this compensation, the ultimate link performances remain limited by the so called delay-unsuppressed fiber noise that is related to the propagation delay...
In this paper we analyze Distributed Raman Amplification (DRA) for phase-coherent optical links, showing the promising features as well as the existing limits for such a new technique. After the demonstration of an optical frequency transfer on 200 km in single fiber span in our experiment, with a frequency instability of 3×10−19 at 100–1000 s, we present an analysis aimed in particular at extending...
We describe the realization of a coherent optical fiber link for the metrological frequency dissemination on the national scale. This infrastructure will improve the frequency references used in radio-astronomy and in atomic physics and will benefit several laboratories in Italy involved in high resolution spectroscopy, matter physics and radioastronomy. The present infrastructure will be part of...
To significantly improve the frequency references used in radio-astronomy and the precision measurements in atomic physics, we provide frequency dissemination through a 642-km coherent optical fiber link. On the frequency transfer, we obtained a frequency instability of $$3\times 10^{-19}$$ 3 × 10 - 19 at 1,000 s in terms of Allan deviation on a 5-mHz measurement bandwidth, and an accuracy...
We report on the realization of the coherent optical link for time and frequency dissemination developed in Italy. The fiber backbone connects scientific laboratories that need accurate time and frequency measurements located in Torino, Milano, Bologna and Firenze. We briefly describe the technique, and report the status of installation and preliminary characterization.
This work describes the use of Distributed optical Raman Amplification for the realization of coherent optical fiber links for frequency dissemination. The main advantages of this technique are high gain and feasibility of long fiber spans with a simple apparatus, without degrading the link stability.
This work describes the realization of a fiber optic gyroscope with a sensitivity of 10−8 (rad/s)/√Hz. Such a high sensitivity is obtained using a 47 km long single mode fiber of the urban optical telecommunication network, that is shared with other users and encloses an area of 20 km2. This setup has been used to investigate ground motion in occurrence of earthquakes.
We report on the design and the realization of a digital architecture based on a tracking direct digital synthesizer (DDS) driven by a Field Programmable Gate Array (FPGA) for the implementation of a coherent optical link for time and frequency dissemination. The realized digital system has been implemented and characterized on a real fiber link on a 47 km metropolitan optical telecommunication network...
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