Coherent Optical-Fiber Link Across Italy and France

C. Clivati; M. Pizzocaro; E.K. Bertacco; S. Condio; G.A. Costanzo; S. Donadello; I. Goti; M. Gozzelino; F. Levi; A. Mura; M. Risaro; D. Calonico; M. Tønnes; B. Pointard; M. Mazouth-Laurol; R. Le Targat; M. Abgrall; M. Lours; H. Le Goff; L. Lorini; P.-E. Pottie; E. Cantin; O. Lopez; C. Chardonnet; A. Amy-Klein

doi:10.1103/physrevapplied.18.054009

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Coherent Optical-Fiber Link Across Italy and France

C. Clivati et al.

2022Physical Review Applied 18, 054009CC BY 4.0LCP000027

Phys. Rev. Appl. 18, 054009 (2022) · DOI: 10.1103/physrevapplied.18.054009

License: CC BY 4.0.

Abstract

The dissemination of atomic clocks with fiber-based techniques finds application in the fields of metrology, fundamental physics, navigation, and spectroscopy but is a challenge in terms of reliability, maintenance, and performance. Here, we describe the realization of a 1023-km-long fiber link between the metrological institutes of Italy and France that shares the infrastructure with the Internet traffic and exploits segmentation in shorter, cascaded spans to fight optical losses exceeding 280 dB. With four months of quasicontinuous operation of this link, we compared the Cs, Rb, and Yb atomic clocks at our laboratories, highlighting the potential of this tool to assess the clock uncertainty budgets, characterize advanced satellite techniques, and develop optical timescales.

Figures

12 panels with data across 4 figures. Each panel page shows the plot, its columns and its files; each data.csv begins with a header naming the paper, the panel, the source, the license and the provenance route.

Fig. 1

Illustrative figure, no extractable data. Shown in the paper PDF.

Fig. 2

panel (1): Link instability, as overlapping Allan deviation, against averaging time (s) on log-log axes: the end-to-end SYRTE-Modane-SYRTE link (orange) and the measured INRIM-Modane segment (blue), each with its shaded uncertainty region, and the expected INRIM-Modane instability from delay-unsuppressed noise (blue dashed). data.csv

Fig. 3

panel (1): Daily fractional uptime of the SYRTE(comb) stage against MJD $-$ 59514, one bar per day, from 27 October 2021 to 24 February 2022; a day with no bar had no uptime. Panel 1, counted from the top, of the six stacked panels of the printed figure. data.csv
panel (2): Daily fractional uptime of the SYRTE to TH2 segment against MJD $-$ 59514, one bar per day, from 27 October 2021 to 24 February 2022; a day with no bar had no uptime. Panel 2, counted from the top, of the six stacked panels of the printed figure. data.csv
panel (3): Daily fractional uptime of the TH2 to Modane segment against MJD $-$ 59514, one bar per day, from 27 October 2021 to 24 February 2022; a day with no bar had no uptime. Panel 3, counted from the top, of the six stacked panels of the printed figure. data.csv
panel (4): Daily fractional uptime of the Modane to INRIM segment against MJD $-$ 59514, one bar per day, from 27 October 2021 to 24 February 2022; a day with no bar had no uptime. Panel 4, counted from the top, of the six stacked panels of the printed figure. data.csv
panel (5): Daily fractional uptime of the INRIM(comb) stage against MJD $-$ 59514, one bar per day, from 27 October 2021 to 24 February 2022; a day with no bar had no uptime. Panel 5, counted from the top, of the six stacked panels of the printed figure. data.csv
panel (6): Daily fractional uptime of the whole link combined (Total) against MJD $-$ 59514, one bar per day, from 27 October 2021 to 24 February 2022; a day with no bar had no uptime. Panel 6, counted from the top, of the six stacked panels of the printed figure. data.csv

Fig. 4

panel (a-1): Fractional frequency ratio FO2-Cs/IT-CsF2, $y$ ($10^{-15}$), against MJD, each point an average over 864 s. The top of the three stacked axes of printed panel (a), which share one MJD axis; hosted as its own panel. data.csv
panel (a-2): Fractional frequency ratio FO2-Rb/IT-CsF2, $y$ ($10^{-15}$), against MJD, each point an average over 864 s. The middle of the three stacked axes of printed panel (a), which share one MJD axis; hosted as its own panel. data.csv
panel (a-3): Fractional frequency ratio FO2-Rb/FO2-Cs, the local comparison at SYRTE,, $y$ ($10^{-15}$), against MJD, each point an average over 864 s. The bottom of the three stacked axes of printed panel (a), which share one MJD axis; hosted as its own panel. data.csv
panel (c): Instabilities of the three ratios of panel (a) as overlapping Allan deviations against averaging time (s) on log-log axes: FO2-Cs/IT-CsF2 (squares), FO2-Rb/IT-CsF2 (triangles) and FO2-Rb/FO2-Cs (circles), with error bars. Gray lines: white noise of IT-CsF2 (solid), of FO2-Rb/FO2-Cs (dashed) and the zero-density extrapolation (dotted), named in the legend; the print explains them in its caption. data.csv

Fig. 5

panel (1): Instabilities of IT-Yb1/FO2-Cs (squares), IT-Yb1/FO2-Rb (triangles) and the local IT-Yb1/IT-CsF2 (circles) as overlapping Allan deviations against averaging time (s) on log-log axes, with error bars. The gray lines are the white noise of IT-CsF2 (solid) and the short-term instability of FO2-Rb and FO2-Cs (dashed), named in the legend; the print explains them in its caption. data.csv

Cite

C. Clivati et al. (25 authors). Coherent Optical-Fiber Link Across Italy and France. Phys. Rev. Appl. 18, 054009 (2022). https://doi.org/10.1103/physrevapplied.18.054009

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