Thermo-optical properties and nonradiative quantum efficiency of Er3+-doped and Er3+/Tm3+-co-doped tellurite glasses

Thermal lens (TL) measurements were performed in tellurite glasses, 70TeO2–19WO3–7Na2O–4Nb2O5 (mol%), undoped, doped with Er3+ (1.19 × 1020 ions/cm3) and co-doped with Er3+ (1.19 × 1020 ions/cm3)/Tm3+ (1.56 × 1020 ions/cm3). The absolute nonradiative quantum efficiency (ϕ) was determined by the TL method. The ϕ values for Er3+/Tm3+-co-doped and Er3+-doped tellurite glasses were 0.98 and 0.74, respectively. Fluorescence spectra were performed at λe = 488 nm and used to estimate the fluorescence quantum efficiency (η) using the TL results. These values were compared with results obtained by Judd–Ofelt calculations.