Advancing Waveguide Laser Performance: An In-Depth Analysis of the Physical, Thermal, and Spectroscopic Properties of...

A series of Sm³⁺-doped potassium borotellurite (TBK) glass samples are fabricated using melt quenching technique. Differential thermal analysis is conducted to understand thermal stability of glasses, with increasing glass transition temperature and onset crystallization indicating enhanced network connectivity within the glass matrix as Sm³⁺ content rises. Optical absorption measurements show that both direct and indirect band gaps increase with the higher concentration of Sm³⁺ ions, whereas refractive index decreases. Raman spectral analysis has been done to investigate the presence of TeO₄, TeO₃, and TeO_3 + 1 structural units. By analyzing Judd-Ofelt intensity parameters (Ω_2,4,6 × 10^-20 cm²), derived from experimental oscillator strengths of absorption spectra, the radiative properties of fluorescent transitions ⁶H_5/2 → ⁶F_3/2, ⁶F_5/2, ⁶F_7/2, and ⁶F_9/2 of Sm³⁺ ions in TBK glasses are estimated, offering valuable insight into the potential of these materials for visible laser applications. Photoluminescence emission spectra depict maximum intensity for ⁴G_5/2 → ⁶H_7/2 transition at 602 nm, characteristic of Sm³⁺ ions emitting in the reddish-orange region. The radiative transition probability and branching ratio for ⁴G_5/2 → ⁶H_7/2 transition also dominate among all other transitions. The CIE chromaticity coordinates of the Sm³⁺-doped TBK also confirms the emission in orange-red color.