Impact of replacing Na+ with Ag+ on the optical and spectroscopic properties of Er3+-doped tellurite glasses

• Substituting Na 2 O with Ag 2 O in tellurite glass increases thermal stability, refractive index, and promotes network depolymerization. • Diffusion of Ag + , glass etching, and surface crystallization are expected to occur when immersing the tellurite glass in AgNO 3 -KNO 3 -NaNO 3 molten salt bath. • The 80TeO 2 - 10 ZnO - 10 Na 2 O (mol%) glass is the most stable in the molten salt baths, making it suitable for ion exchange and waveguide fabrication. Er 3+ doped tellurite glasses have attracted significant interest due to their broad emission band at 1.5 µm, the telecommunication window. Among them, the glasses in the TeO 2 -ZnO-Na 2 O system are particularly suitable for waveguide fabrication using ion exchange. This study investigates the impact of substituting Na 2 O with Ag 2 O in the tellurite glass doped with Er 3+ ions on its optical and spectroscopic properties, as well as its chemical durability when immersed in AgNO 3 -KNO 3 -NaNO 3 molten salt baths, usually used for Ag + -Na + exchange. The replacement of Na 2 O with Ag 2 O leads to an increase in thermal stability and refractive index due to the depolymerization of the glass network. When immersed in Ag-containing salt baths, the glass surface reacts with the molten salt bath, the reaction of which depends on the glass and molten salt bath composition. Diffusion of Ag + and preferential etching of TeO 2 can be obtained, as well as surface crystallization. The glass with the composition 80 TeO 2 – 10 ZnO – 10 Na 2 O (in mol%) was found to be the most stable in the molten salt bath probably due to its polymerized network and so the most suitable glass for ion exchange processes and waveguide fabrication.