Synthesis and Characterization of Oxyuoride Glasses Doped With Rare-Earth Ions

Abstract

This thesis investigates the synthesis and spectroscopic characterization of two lead germanate-based oxyfluoride glass systems: a ternary GPF matrix (GeO₂–PbO–PbF₂) co-doped with Tb³⁺/Yb³⁺ ions and a quaternary GPFC matrix (GeO₂–PbO–PbF₂–CdF₂) doped with Er³⁺ ions. The main objective is to evaluate their potential for photonic applications, particularly frequency conversion and optical amplification. The samples were synthesized using the melt-quenching method followed by annealing, and their amorphous nature was confirmed by X-ray diffraction (XRD). In the Tb³⁺/Yb³⁺ co-doped GPF system, luminescence studies reveal an up-conversion mechanism assisted by Yb³⁺ ions under near-infrared excitation. Power dependence measurements confirm a two-photon process involving cooperative energy transfer from Yb³⁺ to Tb³⁺ ions. In parallel, the Er³⁺-doped GPFC system was analyzed using the Judd–Ofelt formalism to determine the intensity parameters Ωt. The Ω₂ value (2.76 × 10⁻20 cm²) indicates significant local asymmetry and covalent character of the bonding environment. With a spectroscopic quality factor of 0.87 and a radiative lifetime of 4.31 ms for the ⁴I₁₃/₂ level, this glass exhibits strong potential for optical amplification in the C-band of optical communications (1530–1565 nm). These results highlight the strong potential of low-phonon-energy oxyfluoride glasses for advanced photonic devices and high-performance light sources.