## 1 Introduction  
Germanate and tellurite glasses possess several fundamental properties that make them highly suitable for applications in optical techniques. They have a high refractive index [1], which is essential for the development of optical fibers, waveguides and lenses. Secondly, both types of glasses exhibit broad infrared transparency, making them ideal candidates for infrared optics and telecommunications [2; 3]. Germanate glasses possess excellent thermal stability, allowing them to withstand high temperatures without significant structural changes, which makes them suitable for applications in high-power lasers and other optical devices operating under extreme conditions [4]. Tellurite glasses exhibit low phonon energy, which promotes the incorporation of rare-earth ions and facilitates the realization of highly efficient luminescent materials for lasers and amplifiers. In addition to favorable optical properties, tellurite glasses reveal other beneficial qualities, such as excellent chemical durability, mechanical strength and low processing temperature [5]. Compared with germanate glass, tellurite glass is characterized by lower phonon energy (-750 cm\({}^{-1}\)) but less advantageous thermal stability [6]. The integration of tellurite and germanate components imparts unique properties to these glasses, making them highly suitable for versatile optical applications. The motivation behind choosing the germanate tellurite glass system was to take advantage of the superior qualities of both types of glass. Regarding germanate-tellurite glass, it combines the advantages of both germanate and tellurite glasses, corresponding to relatively low phonon energy, suitable thermal stability and high luminescent ion solubility [7]. The combination of numerous structural units such as TeO\({}_{4}\) bi-pyramid, TeO\({}_{3}\) trigonal pyramid and GeO\({}_{4}\) tetrahedron or GeO\({}_{3}\) octahedron gives rise to considerable structural diversity. Accordingly, the location of rare earth ions in these variable surroundings may result in intense and broad band optical spectra [8]. Therefore, this amorphous system is a promising optical and luminescent material that is useful for various photonic applications. Optical materials doped with Tb\({}^{3+}\) and Eu\({}^{3+}\) ions have gained significant attention for their applications as luminescent materials [9; 10; 11]. Tb\({}^{3+}\) ions exhibit strong green emission, while Eu\({}^{3+}\) ions display characteristic red emission when excited by suitable wavelengths of light. By incorporating these ions into host materials such as glasses, crystals or nanoparticles, luminescent materials with tunable emission properties can be achieved [12]. Furthermore, substantial and effective coupling between terbium and europium can be observed and studied in some optical materials. For instance, [PERSON] et al. recently documented the phenomena of excitation, emission and energy transfer between Tb\({}^{3+}\) and Eu\({}^{3+}\) at low and room temperatures. An effective 60% yield of Tb-Eu energy transfer in GAB (20 at.%Tb, 20 at.%Eu) was achieved, and the efficient impact of terbium on the relaxation dynamic of europium luminescent level was also recognized [13]. These different materials find applications in various fields, including lighting, displays and sensors, especially in luminescence thermometry--a technique for measuring temperature based on the temperature-dependent emission characteristics of dopant ions [14]. Tb\({}^{3+}\) and Eu\({}^{3+}\) ions exhibit characteristic emissions that can be sensitive to temperature change, making them suitable for this purpose [15]. The current hosts for Eu\({}^{3+}\) and Tb\({}^{3+}\) used in the mentioned fields include polycrystalline oxides [16; 17; 18]. Glass materials offer the advantage of tailoring the glass composition to achieve specific temperature sensitivity and response ranges [19; 20].