Optical and spectroscopic properties of Eu-doped tellurite glasses and glass ceramics

Abstract

Tellurite glasses doped with trivalent europium were prepared by the conventional melt quenching technique, in the chemical composition of (85−x) TeO2+5La2O3+10TiO2+xEu2O3 by varying the concentration of the rare-earth ion in the order 0.5, 1 and 1.5mol%. Using Judd–Ofelt analysis, we calculated intensity parameters (Ω2 and Ω4), spontaneous emission probabilities, the radiative lifetime, luminescence branching factors, the quantum yield of luminescence, and the stimulated emission cross-sections for 5D0→7F2 transition. The change in optical properties with the variation of Eu3+ ion concentration have been discussed and compared with other glasses. The luminescence intensity ratio, quantum efficiency and emission cross-section values support that the TeEu1.5 tellurite glass is a suitable candidate for red laser source applications. Optical properties for Eu3+ doped tellurite glass, heated for different temperature, were investigated. Crystalline phases for α-TeO2, γ-TeO2 and TiTe3O8 system were determined by the XRD method. The effect of heat treatment on luminescence properties in the tellurite glass was discussed. By using Eu3+ as a probe, the local structure of rare-earth ion in tellurite glass, vitro-ceramic and ceramic glass has been investigated. The evaluated J–O intensity parameters have been used to calculate different radiative and laser characteristic parameters of the 5D0 excited level. The large magnitudes of stimulated emission cross-section (σe), branching ratio (β) and Gain bandwidth (σe×Δλeff) obtained for 5D0→7F2 (613nm) transition for ceramic glass indicate that the present glass ceramic is promising host material for Eu3+doped fiber amplifiers. The measured lifetime of 5D0 excited state increases with increase of the heat treatment which further indicate that some Eu3+ ions were successfully embedded in the crystal phase and prove the low phonon energy environment of Eu3+ ions in the nanocrystals precipitated in the glass ceramics.