Among the glassy materials, tellurite glasses exhibit low phonon energy (∼780 cm−1), good mechanical stability, chemical durability, and high linear and nonlinear refractive indices, with a wide transmission window (typically 0.4–6.0 μm), which make them promising materials for photonic applications. In this work, tungsten–zirconium–tellurite glasses doped with several Tb3+ concentrations (0.1–4.0 mol. % Tb2O3) were prepared and characterized through absorption, emission, excitation spectra and fluorescence decay rate measurements. Only the green/yellow emission due to the 5D4 level was observed since the 5D3 was not observed in either the absorption or emission spectra due to cutoff absorption of the host matrix at ∼470 nm. A concentration quenching effect was observed in the 545 nm green emission (5D4 → 7F5) with a critical Tb3+ concentration of 6.2×1020 cm3 (1.7 mol. %). Thermal lens (TL) was performed in order to determine the thermo-optical properties of the glass such as thermal diffusivity (D ∼ 3.3×10−3 cm2/s) and optical path temperature coefficient (ds/dT ∼ 2.5 × 10−5 K−1). The energy transfer efficiency from the host matrix to the Tb3+ was estimated from excitation spectra as ∼3%, in agreement with TL measurements which indicate that nearly all absorbed energy is converted into heat for 488 nm excitation (7F6 → 5D4). Z-scan measurements in the cw regime indicate a dominant thermal nonlinearity in agreement with TL data. However, the fluorescence measurements in the Z-scan indicate a strong saturation of the green fluorescence attributed to the effect of excited state absorption.

中文翻译：

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Tb3+ 掺杂钨-锆-碲酸盐玻璃的光热和光谱表征

在玻璃材料中，碲酸盐玻璃表现出低声子能量（~780 cm-1）、良好的机械稳定性、化学耐久性、高线性和非线性折射率，以及宽的透射窗口（通常为 0.4-6.0 μm），这使得它们用于光子应用的有前途的材料。在这项工作中，制备了掺杂多种 Tb3+ 浓度（0.1-4.0 mol.% Tb2O3）的钨-锆-碲酸盐玻璃，并通过吸收、发射、激发光谱和荧光衰减率测量进行表征。仅观察到由于 5D4 水平引起的绿色/黄色发射，因为由于主体基质在~470 nm 处的截止吸收，在吸收光谱或发射光谱中均未观察到 5D3。在 545 nm 绿色发射 (5D4 → 7F5) 中观察到浓度猝灭效应，临界 Tb3+ 浓度为 6.2×1020 cm3 (1.7 mol. %)。进行热透镜 (TL) 以确定玻璃的热光学特性，例如热扩散率 (D ∼ 3.3×10−3 cm2/s) 和光路温度系数 (ds/dT ∼ 2.5 × 10−5 K-1)。根据激发光谱估计从主体基质到 Tb3+ 的能量转移效率为 ~3%，与 TL 测量一致，这表明几乎所有吸收的能量都转化为 488 nm 激发的热量（7F6 → 5D4）。连续波状态下的 Z 扫描测量表明与 TL 数据一致的主要热非线性。然而，