Absorption and upconversion of (Nd3+/Er3+) doped tellurite glass

Abstract

A serie of tellurite glass of the system 78TeO₂-10PbO-10Li₂O-(2-x)Nd₂O₃-xEr₂O₃, where x = 0, 0.5, 1.0, 1.5 and 2.0 was successfully been fabricated. A study of absorption and upconversion luminescence of the (Nd³⁺/Er³⁺) co-doped tellurite glass has been carried out. From the absorption spectra, the excitation spectrum is found dominant at 585 nm. Two absorption peaks of Nd³⁺ are found to overlap to Er³⁺ centered at 525 nm and 805 nm which correspond to the (Nd³⁺: ⁴I_9/2→⁴G_7/2, Er³⁺: ⁴I_15/2→²H_11/2) and (Nd³⁺: ⁴I_9/2→²H_9/2, Er³⁺: ⁴I_15/2→⁴I_9/2) respectively. Meanwhile, there are eight significant upconverted luminescence spectra correspond to Nd³⁺ ions centered at 485nm, 560nm, 605nm, 880nm, 1062nm and 1340nm with two more spectra that contributed from Er³⁺ ions centered at 493 nm (⁴F_7/2→⁴I_15/2) and 524 nm (⁴S_3/2→⁴I_15/2) respectively have been observed The upconversion mechanism of the co-doped tellurite glass has been shown in the schematic energy diagrams In this works, it is found that the excited state-absorption (ESA) is still dominant in the upconversion excitation process as the upconversion excitation mechanism of the Nd³⁺ excited-state levels is accomplished through a stepwise multiphonon process An efficient excitation energy transfer (ET) has been observed between Nd³⁺ as a donor and Er³⁺ as the acceptor. As a result, respective emission spectra had been observed. From Judd-Ofelt analysis the results of experimental lifetimes τ_exp and the emission cross section, σ Tare found to vary with respect to compositions.