NanoSlim

Fibre lasers and amplifiers have grown considerably through their uses in industry (materials processing), civil engineering (sensors) and medical (LASIK), to name few examples. Such fibres rely on the doping of the glass by luminescent ions, generally rare-earth ions. As the luminescent properties of the latter depend on their atomic environment, the choice of material is paramount. Silica is the preferred material for optical fibres because it has many mechanical and economic advantages. However, the use of this glass limits certain luminescent properties. The development of new applications therefore requires new glass compositions. In this context, the encapsulation of luminescent ions in nanoparticles is proposed since it makes it possible, in principle, to practice engineering of the luminescence properties through the environmental control of rare-earth ions. Such fibres would allow combining the advantages of silica and offering spectroscopic properties which would not exist in this glass. The development of these fibres is confronted with the problem of transparency management. Nanoparticles less than 50 nm are required to minimize light scattering induced losses. The current approach consists in preparing a preform (rod drawn in fibre) already containing small nanoparticles. However, it is difficult to carry out such a preform, as well as to maintain the integrity of the small nanoparticles during the drawing which takes place at 2000 ° C. This project aims to propose a radically different approach. Indeed, we propose to take advantage of the drawing step to obtain small nanoparticles in the fibre starting from "big" nanoparticles in the preform. This process is based on the elongation of the nanoparticles during the drawing and their rupture induced by Rayleigh-Plateau instabilities. Such fragmentation depends on various parameters such as the size of the nanoparticles, the viscosity of the matrix and of the nanoparticles and the surface tension between the two media. To develop in a controlled manner such a process, we propose to carry out a systematic study of these parameters. The work schedule is organized in 42 months following 3 tasks. The purpose of task 1 is to provide model samples: monoliths of silica with nanoparticles of controlled size and composition. The compositions of the nanoparticles will be MgO, xMgO-(1-x)SiO2 and xCaO-(1-x)SiO2 to study the role of the size, structure and viscosity of the nanoparticles as well as to study the influence of rheological and thermodynamic effects. Task 2 includes very specific characterization techniques for studying size, morphology, structure and composition at nanometric scales (atom probe tomography, high resolution electron microscopy, etc.). The luminescence properties will be analyzed through the study of the europium ion. We also propose an analysis of the process through numerical simulations (task 3). Two complementary approaches will be implemented: finite elements and molecular dynamics. At the end of this project, we will demonstrate the validity of the new process by producing an optical fibre with improved luminescence properties. To carry out this project, the consortium consists of 7 teams covering all aspects related to manufacturing, chemical / structural characterization of nanoparticles, optical characterizations as well as structural and spectroscopic numerical simulation techniques. This technology will have an impact in a very large number of Key Enabling Technologies such as photonics, nanotechnologies, advanced materials and processes.