Thermal and nonlinear optical properties of Tm³⁺-doped tellurite glasses

In the present work, thermal and nonlinear properties of tellurite glasses doped with Tm₂O₃ were investigated by means of thermal lens, thermal relaxation and z-scan measurements. The composition of the samples was (78 − x) TeO₂ + 4.5 Bi₂O₃ + 5.5 ZnO + 10.5 Li₂O + 1.5 Nb₂O₅ + xTm₂O₃ (x = 0.05, 0.1, 0.5, 1.0 and 1.5 mol%). Thermal diffusivity (D), specific heat (ρc), thermal conductivity (K) and optical path change with temperature (ds/dT) were determined as a function of Tm³⁺ concentration. Concerning thermal–optical properties, our results show that the 0.5 mol% Tm doped is the most suitable sample for laser applications as it presented the lowest ds/dT and highest thermal diffusivity (conductivity). Third-order nonlinearities were observed and discussed in 1.0 and 1.5 mol% samples. The nonlinear indices (n₂) found were 1.16 × 10⁻¹³ and 3.89 × 10⁻¹³ cm² W⁻¹, respectively. The data obtained show that the Tm³⁺-doped TBZLN glasses have potential for future opto-electronic devices.