Investigation of spectral output of Er³⁺and Yb³⁺/Er³⁺doped TeO₂-ZnO-BaO glasses for photonic applications

Er³⁺and Yb³⁺/Er³⁺doped TeO₂-ZnO-BaO glasses were synthesized using the melt quenching technique with two different Er³⁺concentrations. The refractive index was calculated to be around 2.14 from the optical band gap energies of the glasses. Under 975 nm laser excitation, weak blue, strong green and red emissions were observed in the visible region, while broadband emission around 1530 nm was recorded in the near infrared region. The increase in red emission intensity as a result of energy transfer from Yb³⁺ions to Er³⁺ions in Yb³⁺/Er³⁺co-doped glasses is clearly reflected in the change in color coordinates. The temperature sensing abilities of the glasses were determined from the intensity ratios of light emitted from thermally coupled energy levels (²H_11/2and⁴S_3/2) of Er³⁺ions. The highest absolute sensitivity was determined as 0.0046 K⁻¹at 453 K for Er³⁺doped glass and 0.0067 K⁻¹at 353 K for Yb³⁺/Er³⁺co-doped glass. These results show that Er³⁺and Yb³⁺/Er³⁺doped TeO₂-ZnO-BaO glasses are promising candidates for both lighting and optical temperature sensors.