Postdoc position
ICMMO (Paris sud) and LSI (Ecole Polytechnique)
Over the last twenty years, rare-earth doped optical fibers have become key elements of high
volume markets like telecommunication or high power laser. Whereas these optical components are
now widely used, the interest in developing new applications for active optical fibers is now put to
the front, with a real need for components involving breakthrough technologies and offering high
perspectives in terms of intellectual property and profitability. Manufacturing fiber amplifiers and
lasers in a versatile and cost effective way while controlling optical performances thus becomes a
real technology differentiator. To this end, this project aims at studying the contribution of the
nanostructuring of the glass matrix to the performances of optical fibers doped with rare-earth
ions.
The benefit of nanostructuring will be specifically studied in the case of Erbium-doped or ErbiumYtterbium co-doped fibers Amplifiers, in terms of amplifying properties (linear gain, gain bandwidth)
and reliability, including resistance to ionizing radiations (UV and gamma irradiation). The
applications fields targeted are high-power amplifiers, compact amplifiers and radiation-resistant
amplifiers. To reach these goals, it is proposed to study process/nanostructure/optical property
relationships for different nanostructured materials: nanoporous glass doped with rare-earth ions
glass doped with rare-earth –doped nanoparticles.
Besides this original nano-material approach, specific design will be developed for the optical fiber
itself. More precisely, depressed clad conventional fibers and air/silica Photonic Crystal Fibers will be
combined to Erbium-doped or Erbium-Ytterbium co-doped materials in order to develop optimized
design of optical fibers amplifiers. In parallel to nano-based Erbium or Erbium-Ytterbium doped glass
and fiber manufacturing, an important part of the studies will be devoted to the understanding of
the nano-approach on glass structure in terms of intrinsic and radiation-induced defects. The
consortium of the project (ANR NanoFiber) is composed of Draka, an industrial leader in optical fiber
manufacturing, and four academic partners, PhLAM, IES, IRAMIS (CEA) and ICMMO specialized
respectively in glass/fiber manufacturing, characterization of optical components and investigation of
structural properties of materials.
The main objectives of the postdoc will be :
- To determine the evolution of the local glass structure in Sol-gel and nanoparticules-doped silica
performs during fiber manufacturing in studying defects centers and rare-earth environment.
- To determine the evolution of the local glass structure in Sol-gel and nanoparticules-doped silica
silica fibers under radiative environment in studying defects centers and rare-earth environment.
- To predict the fiber optical degradation and rare earth optical response according to the irradiation
dose (and dose rate) for optimized optical fibers.
To reach those 3 scientific objectives, this task is divided into 3 sub-tasks described below.
- Defects and rare-earth environment characterization on bulk materials
- Degradation of bulk materials and optical fibers under radiation
- Reliable prediction of the long term degradation
Experimental techniques:
We will proceed to spectroscopic measurements, followed by their analysis and interpretation (in
terms of glass structure defects deduced from spectrum fit and literature information) on starting
materials and mostly innovative by working directly with optical fibers using the following
techniques.
- Cathodoluminescence for NBOHC and ODC defect tracking that will allow optical fiber cartography
with a high spatial resolution (typ. 1 mm). VUV-NIR absorption spectroscopy for additional defects
(like E’ centers) and to provide quantitative information (concentrations and related attenuation that
extends up to the NIR range). TEM will be undertaken to probe the Er/Yb NP size distribution after
the fiber drawing.
- Raman spectroscopy for comparing the preform and fiber structure
- After studying the Photo-Luminescence properties (absorption, emission and lifetime) by PhLAM
the Er3+ and Yb3+ (paramagnetic ions) local environment will be investigated by EPR. Our approach
will consist in combining CW (LSI) and pulsed EPR (Collaboration H. Vezin LASIR, Lille1). Thanks to
different pulsed EPR sequences based on electron spin echo techniques (3P-ESEEM, HYSCORE), we
will determine the hyperfine interaction between Er3+ and Yb3+ with 27Al and 31P nuclei (e.g. local
environment changes) and to detect any cluster evidence. Moreover Yb/Er distances may be
determined.
Knowledge on EPR, luminescence and absorption techniques or defects in glasses will be
appreciated
Duration: 24 months
Salary: 2200euros/month
Contacts:
A/Prof. Matthieu LANCRY
Université Paris Sud
Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO)
Laboratoire de Physico-Chimie de L'Etat Solide (LPCES)
UMR CNRS-UPS 8182
Bat 410, 91405 Orsay Cedex
FRANCE
Matthieu.lancry@u-psud.fr
Dr. Nadège Ollier
Laboratoire des solides irradiés (LSI)
CEA IRAMIS/CNRS/Ecole polytechnique
Ecole Polytechnique
91122 Palaiseau cedex
France
nadege.ollier@polytechnique.edu
01 69 33 45 18