Strong emission at 1000 nm from Pr³⁺/Yb³⁺-codoped multicomponent tellurite glass

Abstract

We have investigated the spectroscopic properties of Pr3+-doped and Pr3+/Yb3+-codoped tellurite glass with the molar composition 78TeO2–10Nb2O5–5PbO–1PbF2–5Li2O–1La2O3. Analysis of the absorption data has allowed us to calculate the radiative lifetimes of 3P0 excited state of Pr3+ ions and 2F5/2 excited state of Yb3+ ions as being equal to 9.43 and 440 µs, respectively. These values appear to be much higher than those obtained from the lifetime measurements indicating the presence of various energy transfer mechanisms. This conclusion is supported by analysis of the emission spectra obtained for doped glasses under the 445 nm excitation; the visible spectra consist of only Pr3+ transitions, while the near infrared spectrum of Pr3+/Yb3+-codoped glass demonstrates a strong emission from the 2F5/2 excited state of Yb3+ ion around 1000 nm. This emission is a result of the Pr3+–Yb3+ down-conversion energy transfer and its efficiency for our Pr3+/Yb3+-codoped glass is estimated as 29%. For potential applications, it is important to increase this efficiency and further studies are desirable, in particular, an optimal choice of Pr3+ and Yb3+ concentrations to minimize non-radiative energy transfers among the ions through cross-relaxation and energy migration processes.

Enhanced Emission of Tellurite Glass Doped with Pr3+/Ho3+ and Their Applications

“…The obtained values of the Ω i (I = 2,4,6) parameters follow the same pattern as those observed for different Ho 3+ -doped tellurite glasses and follow the same sequence, namely Ω 2 > Ω 4 > Ω 6 [29]. On the other hand, the sequence is different with Tellurite glasses doped with Pr +3 [24,28].…”

“…The refractive index dispersion of samples T0 and TPr, obtained from ellipsometric data, is presented in our previous work [28], as being very well described by the Sellmeier model of the form n(λ) = [A + Bλ 2 /(λ 2 − C 2 ) − Dλ 2 ] 1/2 , where A, B, C, and D are the fitting parameters. Adopting the same procedure for sample TPrHo, the values of the fitting parameters have been found as A = 2.729, B = 1.764, C = 244.16 nm, and D = 2.52 × 10 −9 nm −2 .…”

“…As was mentioned before while describing the sample's emission spectra, sample TPr has a high concentration of Pr 3+ ions, which results in an effective cross-relaxation (CR). When compared to the J-O radiative lifetime (9.43 µs [28]), the Pr 3+ : 3 P 0 effective lifetime is significantly reduced by the CR mechanism, going down to τ eff = 2.47 µs. The concentration of Pr 3+ ions in sample TPrHo is two times lower than in sample TPr, so one would expect that τ eff would be significantly higher and equal to 3.92 µs [28].…”

“…Figure 1 shows the net absorption bands of Pr 3+ and Ho 3+ ions, obtained by subtraction of the monotonic background absorption of the glass matrix (shown for sample T0 in [28]) from the total absorption determined for samples TPr and TPrHo.…”

“…Table 3 includes the lifetimes of the 3 P 0 excited state of the Pr 3+ ions as well as the predicted lifetime values and experimental data in order to compute the ET efficiency from these ions to Ho 3+ ions. The 3 P 0 Lifetimes of TPr are taken from our previous work [28]. The ( 3 F 4 + 5 S 2 ) lifetime of TPrHo was measured and calculated as shown in Table 3.…”