Spectroscopic investigations of 1.06 µm emission and time resolved Z-scan studies in Nd3+-doped zinc tellurite based glasses

Abstract Zinc tellurite based glasses (TZNbTiNd: TeO 2 + ZnO + Nb 2 O 5 + TiO 2 ) doped with various Nd 3+ concentrations (0.01, 0.05, 0.1, 0.5, 1.0, 1.5 and 2.0 mol% Nd 2 O 3 ) were prepared and characterized through absorption, emission and decay rate measurements. Judd-Ofelt intensity parameters were derived from the absorption spectrum and used to calculate the radiative properties for the 4 F 3/2 → 4 I J/2 (where J = 9, 11 and 13) transitions of Nd 3+ ions. Strong near infrared emission at 1.062 µm ( 4 F 3/2 → 4 I 11/2 ) has been obtained for all the glasses upon 808 nm diode laser excitation. The decay times from 4 F 3/2 level is found to be quite single exponential for different concentrations of Nd 3+ ions with a shortening of lifetime with increasing concentration. In these measurements, the electronic refractive index variation is associated with the difference in the polarizabilities (Δα p ) of the Nd 3+ ion in its ground and excited states. The results indicate that in tellurite glasses, Δα p is relatively very high (4 × 10 −25  cm 3 ) compared to other Nd 3+ -doped glasses. We also measured the imaginary part of the non-linear refractive index (n 2 ′′) due to absorption saturation. Hence, the spectroscopic results indicate that the investigated glasses are potentially applicable as a 1062 nm laser host as well as optical devices.