A 940 km optical fiber link between MPQ and PTB for frequency transfer

CPQM seminar

“A 940 km optical fiber link between MPQ and PTB for frequency transfer” by Gulnara A. Vishnyakova

 When: March 28, 16:00

Where: Skoltech, E-R2-B5-2026 (New Campus)


Long optical fiber links allow to disseminate ultrastable frequency and time signals between distant laboratories [1,2]. I will report on the new established underground dark fiber connecting the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig and the Max-Planck-Institut für Quantenoptik (MPQ) in Garching near Munich via the Karlsruhe Institute of Technology (KIT) with the length of 940 km (“west” link) (fig. 1). The link is equipped with 4 fiber Brillouin amplifiers and 1 erbium-doped fiber amplifier for the compensation of attenuation in the fiber which is 0.23 dB/km at 1.5 µm wavelength.

Active noise compensation allows to reach relative instability and uncertainty lower than 10-18 after 40 000 seconds of averaging which gives negligible impact on chronometric levelling with a transportable optical clock [3].

Another interesting application may be the measuring of the Sagnac effect if combine this “west” link with another “east” link to form ring interferometer and measure the deviations of the signal due to variety of geo- and seismic- effect [4].

  • Grosche et al. Optical frequency transfer via 146 km fiber link with 10-19 relative accuracy // Optics Letters -2009 -Т.34 -№15 -С.2270
  • Droste et al. Optical-Frequency Transfer over a Single-Span 1840 km Fiber Link // Physical Review Letters -2013  -Т.111 -С.110801
  • Grotti et al. Geodesy and metrology with a transportable optical clock // Nature Physics -2018 -Т.14 -С.437
  • Salvermoser et al. An Event Database for Rotational Seismology // Seismological Research Letters -2017 -Т.88 -С.935


Gulnara A. Vishnyakova graduated from Moscow Institute of Physics and Technology on the Subject “Investigation of Coherent Population Trapping Resonances in Rb-87 in the Presence of Magnetic Field”. On the basis of the same institute she got the master’s and Ph.D. degrees on “Investigation of the probe field delay under condition of coherent population trapping in Rb-87 vapor” and “Second Stage Laser Cooling of Thulium Atoms”. Now she works as an Engineer, Junior Researcher, Researcher on Optical Division of P.N. Lebedev Physical Institute of the Russian Academy of Sciences.