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.

Abstract:

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 P_3w/P_w > 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.

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.

Download videos presenting two Equipex (“Equipements d’Excellence” of the French Programme Investissements d’Avenir) in relation with FIRST-TF activities

REFIMEVE+: a metrological fiber network

MIGA: a giant atom interferometer

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/

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.

A Discussion Day on the Foundations of Quantum Physics will take place on 28 August 2017 at the Université de Technologie de Troyes in Troyes (France).

We will hear talks and exchange on issues concerning Quantum Foundations, including experimental work (note that a meeting of the COST Network Nanoscale Quantum Optics will take place immediately after the Discussion Day, for details see http://www.cost-nqo.eu/event/spss2017/).

Basic information as well as a preliminary list of speakers of the Discussion Day is available here: http://matzkin.u-cergy.fr/jf2017

Registration is free but mandatory. Register by sending your name and affiliation.

Possibility of accommodating a very limited number of contributed talks. Abstracts (1/2 page) should be sent before the 16th of July.

Nicolas VON BANDEL will defend his thesis on 30 June 2017 at 14:00, 0C-140 (Auditorium) – III-V Lab Campus Polytechnique 1 avenue Augustin Fresnel 91767 Palaiseau on the subject “Development and study of low noise laser diodes emitting at 894 nm for compact cesium atomic clocks”. This work was a collaboration between Institut d’Electronique et des Systèmes (Montpellier) and III-V Lab (Palaiseau).

Abstract : This PhD work deals with the design, the fabrication and the study of high-coherence semiconductor laser sources emitting at 894 nm, for application to compact, optically-pumped cesium atomic clocks in an industrial context. We are particularly interested in the electrically pumped ”Distributed-Feedback” in-plane laser diodes (DFB). The aim is to obtain a low-threshold, single-mode laser with high optical efficiency and a linewidth of less than 1 MHz. We first deal with the design and first-order characterization of the DFB diodes until they are put into modules for the clock. We then carry out an in-depth study of the physical properties of the laser emission in terms of coherence time. For that purpose, a new universal method for characterizing the optical frequency noise is introduced. Finally, we look further into the spectral properties of the emission in a servo configuration on a fluorescence line of the cesium (”Dither-Locking”). We show that the intrinsic properties of the component satisfy the requirements of the industrial system as defined in the study.

Keywords : Laser diodes, low noise, 894nm, cesium atomic clocks, frequency noise metrology, linewidth in servo

Within the framework of the CNES CCT “Optics and Optoelectronics Technical Center” and the “Material Technical Center”, a Workshop on Optical Materials by SCHOTT, HERAEUS and HELLMA, will be organized on 22nd & 23rd June 2017 at CNES (Room Leonard de Vinci), Toulouse.

The first day (Thursday 22^nd june) will be about all optical materials: Optical Glass, Filter Glass, Coated Filters, Fused Silica and Calcium Fluoride

The second day (Friday 23^rd june) will be dedicated to Zerodur® and Infrared optical materials.

The attached agenda details the different items that will be presented. Questions and open discussions will conclude each point.

Register deadline: june 14th.

Detailed program and Registration link : http://cct.cnes.fr/content/cct-ooe-20170622-optical-materials

If you are not member of the European Union and you wish to attend this workshop, please contact: Cedric VIRMONTOIS, Optical CCT manager (cedric.virmontois@cnes.fr)

First “call for papers” of the 31st European Frequency and Time Forum and the 71st consecutive meeting of the IEEE International Frequency Control Symposium which will be held as our 7th joint conference in Besançon, France, July 9th-13th 2017

Abstract submission deadline: March 3, 2017

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