Rare-earth-doped (RE) silica-based optical fiber lasers and amplifiers are developed for numerous applications. However, silica glass has certain characteristics (high phonon energy, low RE solubility, ...) which may be detrimental for the luminescence properties of RE. To overcome this issue, the incorporation of RE in nanoparticles is investigated to tailor the spectroscopic properties through the control of their composition [1]. Such optical fibers are elaborated by a high temperature fiber drawing (2000°C) of nanoparticles-doped optical preforms.

This communication focuses on the thermodynamical and morphological changes undergone by nanoparticles throughout the fiber drawing. Dissolution and growth of particles induced by high temperatures will be discussed. Also, tomography-based (FIB/SEM) and X-ray nanotomography Multiscale imagery show that nanoparticles elongate and can even break-up during the fiber drawing [2]. Such modifications are explained by Rayleigh-Plateau instabilities and the competition between viscous forces and surface tension. These observations allow us to envision a new top-down strategy, the use of these phenomena to tailor optical properties through the control of the size and shape of nanoparticles during the drawing step.

[1] W. Blanc et al., Journal of Optics 45, 247-254 (2016)

[2] M. Vermillac et al., Journal of the American Ceramic Society 100, 1814-1819 (2017)