26th of October 2017 (Paris) – PhD defense of Hélène FLEURBAEY

Hélène Fleurbay will defend her thesis on 26th october 2017 in the Durand amphitheater at UPMC (Paris) at 2 pm on the subject “Frequency metrology of the 1S-3S transition of hydrogen: contribution to the proton charge radius puzzle”. This work has been done in Laboratoire Kastler Brossel (LKB) under the supervision of François Nez.

The defense will be in english.

11th of October 2017 (Paris) – PhD defense of Maxime Favier

Maxime Favier will defend his thesis on 11th october 2017 at IAP (Paris) at 14:00 on the subject “Mercury optical lattice clock: from high-resolution spectroscopy to frequency ratio measurements”, realized at the SYRTE under the direction of Sébastien Bize and supervised by Sébastien Bize and Luigi De Sarlo.

The defense will take place in room “Salle des séminaires” of the “Institut d’Astrophysique de Paris” (IAP) located 98 bis boulevard Arago, 75014 Paris, in front of a jury composed of Martina Knoop, Leonardo Fallani, Thomas Udem, Philippe Grangier and Jean-Michel Raimond.

The defense will be in english.

⇒ More information

ITSNT 2017, symposium on Navigation and Timing

ITSNT 2017, symposium on Navigation and Timing : 14-17 Nov 2017 at ENAC (Toulouse, France).

The International Technical Symposium on Navigation and Timing also known as the ITSNT, is an annual event organized by CNES and ENAC for professionals and researchers working with or interested in navigation and timing technologies and their use. This event focuses specifically on technical topics that are addressed by experts from all around the world that share their ideas, expertise and views. The audience can easily engage in discussion with these experts during the question sessions and  round tables. The ITSNT also provides a great environment for networking and visiting our sponsors’ exhibition stands.

Key elements:

  • International event
  • A high quality and recognized scientific committee
  • Technical presentations on hot topics related to navigation and timing
  • Internationally recognized guest speakers
  • Selective call for abstract
  • Round tables
  • Exhibition area
  • Networking
  • Tutorials


21st of September 2017 (Paris) – PhD defense of Charles PHILIPPE

Charles PHILIPPE will defense his PhD on the 21st of September, 2017 at IAP (Paris) on the topic “Source laser à 1.5 µm stabilisée en fréquence sur l’iode moléculaire”. This work took place at SYRTE laboratory under the supervision of Ouali ACEF and Peter WOLF.



This thesis reports on the development of a frequency stabilization of a 1.54 µm laser diode on iodine hyperfine line at 514 nm, after a frequency tripling process.

An important part of this work is dedicated to the development of the frequency tripling process of a 1.54 µm laser diode, using two periodically polled wave guided Lithium Niobate nonlinear crystals.  A nonlinear conversion efficiency P3w/Pw > 36 % is obtained. This result is the best efficiency ever demonstrated for a CW frequency tripling process. 300 mW of harmonic power is generated at 514 nm from a fundamental optical power of 800 mW at 1.54 µm. The optical setup is fully fibered. The total power consumption needed to fulfill this frequency tripling process is 20 W only. According a specific operation mode, this laser setup emits simultaneously three frequency-stabilized and intense radiations at 1.54 µm, 771 nm and 514 nm.

Following this development, a very compact laser spectroscopy setup is buildup, based on a short sealed quartz cell, which contains the molecular iodine vapor. An optical power lower than 10 mW in the green is sufficient to fulfill the iodine vapor interrogation, and to detect the hyperfine saturation transitions, whose have a high factor around 514 nm (Q > 2×109).

A frequency stability at the level of 4.5 x 10-14 t-1/2 with a minimum value of 6 x 10-15 from 50 s to 100 s is demonstrated in this study. This frequency stability is the best result ever conferred to a laser diode at 1.54 µm, using in simple way a Doppler-free iodine spectroscopy technique.

This work has allowed to identify the major key components, in order to develop in near future, a fully fibered and compact stabilized laser prototype occupying a total optical volume < 10 liters.

This development could answer to numerous needs of space mission’s projects requiring ultra-stable frequency optical link, inter-satellite or ground to space, for the space geodesy (GRICE), the earth gravitational field measurement (GRACE-FO, NGGM), the gravitational waves detection (LISA) , etc …


Keywords: Metrology, frequency stabilization, ultra-stable lasers, Iodine optical clock, nonlinear optic, tripling frequency process, Telecom Laser, 1.5 µm, 514 nm, space.

Appointment of Dr P. Tavella as the Director of the BIPM Time Department

Dr Tavella is currently a Research Director at the Istituto Nazionale di Ricerca Metrologica (INRIM), responsible for the UTC(IT) Laboratory and the Galileo Timing Research Infrastructure. She is deeply involved in the design and testing of the European GNSS Galileo timing system through more than 30 European projects. Dr Tavella is the previous Chair of the CCTF Working Groups on International Atomic Time (WGTAI) and Algorithms (WG-ALGO).

In addition, Dr Tavella is a Distinguished Lecturer for the Institute of Electrical and Electronics Engineers (IEEE) Ultrasonics, Ferroelectrics and Frequency Control Society (UFFC), a member of the IEEE UFFC Administrative Committee, Vice-Chair of the International Union of Radio Science Commission A (URSI Comm A), and Vice-Chair of the European Frequency and Time Forum (EFTF) Executive Committee.

Dr Tavella has considerable experience of time scales and clock modelling, having conceived, designed, and developed, in collaboration with different colleagues, several methods and techniques for the time scale definition and measurement data treatment. These include possible uses and drawbacks of the Kalman filter in the ensemble time scale; contribution to the ensemble algorithm for a pulsar time scale; and the application of stochastic processes to model the atomic clock deviation and survival time within error thresholds, applied also to the determination of calibration interval.

Official announcement: http://www.bipm.org/en/news/full-stories/2017-06/2017-07-new-directors.html.

Symposium: “The fundamental constants of physics: what are they and what is their role in redefining the SI”

Symposium: “The fundamental constants of physics: what are they and what is their role in redefining the SI”. On 7 September 2017 at BIPM (Sèvres, France).

This symposium is organized by the Consultative Committee for Units (CCU) to celebrate the work accomplished towards a redefinition of the SI in terms of invariant physical constants.

The main topics of the discussion will be: the profound nature of the different fundamental physical constants; the different types of fundamental constants as well as their role in the evolution of physical theory, in particular in gravitation, cosmology and in string theory. The role of the fundamental constants in the forthcoming definition of the SI will be examined.

The Symposium aims at promoting scientific exchange amongst the National Metrology Institutes and leading scientists in the field of fundamental constants.

Deadline for registration: 24 July 2017 on http://www.bipm.org/en/conference-centre/bipm-workshops/fundamental-constants/

How best to communicate the revised SI?

The 2017 Communications Workshop on ‘How best to communicate the revised SI?’ is organised by CMI and EURAMET. The event will take place on Tuesday, 17 and Wednesday, 18 October 2017 at CMI, Prague (Czech Republic).

Provided the experimental data are satisfactory, the 26th CGPM in 2018 is expected to accept a resolution to revise the International System of Units (SI).
The possible revision of the SI is an extraordinary opportunity to communicate the importance of metrology and the future SI.
This task is similar for many NMIs and DIs in Europe.

Therefore, EURAMET will organise a two-day workshop on ‘How best to communicate the revised SI?’, hosted by CMI, the Czech National Metrology Institute.

The two-day workshop will contain:
– An introduction to the planned revision of the SI
– Information about the BIPM Brand Book ‘Future Revision of the SI’
– A workshop on how to convey the SI at school
Best practice examples of communicating the SI
Practical sessions on how and when to communicate the future revision of the SI

The workshop is tailored for employees of NMIs and DIs who are working in communications and public relations.
There is no fee for the workshop, but places are limited and registration is essential.
Please forward this announcement to colleagues in your institutes who may find it of interest.

Deadline for registration: Friday, 15 September 2017.
Detailed information and registration: https://www.euramet.org/event-commsworkshop2017.
This training workshop is funded by the Human and Institutional Capacity Building strand of EMPIR in the area of communications.