Removal of hydroxyl groups from Er3+/Yb3+ codoped flurotellurite glasses

In this work, we present a safe and relatively simple procedure to eliminate hydroxyl groups from Er3+ and Yb3+ codoped new flurotellurite glasses. It was shown that adding a convenient amount of BaF2 as drying agent reduced the absorption coefficient and the concentration of hydroxyl groups inside the glass samples. However, to remove efficiently water from the glasses, it was necessary to subject the samples to supplementary heat treatment in two steps. A drastic decrease of the density of hydroxyl groups accompanied with a significant enhancement of the erbium emission was observed after the heat treatment procedure. The obtained results showed that this method might be a veritable alternative to obtain nearly water free tellurite glasses suitable for many optical devices with small sizes or thickness. However, for a good use of this procedure, we tried to elucidate what has happened at the microscopic scale for the glass taking as a guide the available explanations dealing with the removal of water from silica-based glasses. (C) 2017 Elsevier Ltd. All rights reserved.