Spectral analysis of Er³⁺-, Er³⁺/Yb³⁺- and Er³⁺/Tm³⁺/Yb³⁺-doped TeO₂-ZnO- WO₃-TiO₂-Na₂O glasses

In this paper, we present the spectroscopic properties of Er³⁺-, Er³⁺/Yb³⁺- and Er³⁺/Tm³⁺/Yb ³⁺-doped novel tellurite glasses. From the measured absorption spectra, Judd-Ofelt (JO) intensity parameters (Ω₂, Ω₄ and Ω₆) have been evaluated for the Er ³⁺-doped glass. With 980 nm excitation three strong upconversion emission bands centered at 505, 520 and 630 nm were observed for both Er ³⁺- and Er³⁺/Yb³⁺-codoped glasses and the characteristic near-infrared emission bands were spectrally centered at 1.535 νm. The near-infrared spectra of Er³⁺- and Er³⁺/Yb ³⁺-doped glasses have shown full width at half-maxima (FWHM) around 100 nm and 120 nm for the erbium transition, respectively. The measured maximum decay times of the transition (at wavelength 1.535 νm) are about 7.24 ms and 7.68 ms for 1.0Er³⁺ and 1.0Er³⁺/ 2Yb³⁺ (mol%)-codoped glasses, respectively. The maximum stimulated emission cross sections for the transition of Er³⁺ and Er³⁺/Yb ³⁺ are 8.64 × 10^-21 and 6.78 × 10 ^-21 cm². From 1Er³⁺/ 1Tm³⁺/ 2Yb ³⁺ (mol%)-codoped glass, broad near-infrared emission bands centered at 1510 nm () and 1637 nm () with full width at half-maxima (FWHM) around 52 nm and 60 nm, respectively, were observed. These glasses with broad near-infrared emissions should have potential applications in tunable lasers and broadband optical amplification at low-loss telecommunication windows