Efficient optical enhancement of Er3+ doped lead–tellurite glass embedded with gold nanoparticles: role of heat-treatment

Enhancing the optical response of rare earth doped glasses for miscellaneous optical applications is challenging in materials science and technology. Influences of heat treatments in modifying the spectral features of melt-quench synthesized gold nanoparticles embedded Er3 +-doped lead–tellurite glasses are investigated. Time of heat treatment is varied from 1 to 24 h. Modifications in physical, optical and structural parameters are ascribed to the alteration of non-bridging oxygen due to heat treatments. X-ray Diffraction patterns of all glass samples confirm their amorphous nature in the presence of crystalline peak at 28.66°. Transmission Electron Microscopic images reveal the nucleation of gold nanoparticles having average diameter in the range 1.24–8.40 nm for the heat-treated samples. The ultraviolet–visible-near-infrared spectra exhibit seven absorption bands centered at 490, 526, 551, 652, 800, 979 and 1520 nm corresponding to 4f–4f transitions of Er3 + ions. The up-conversion emissions peaks centered at 520, 550 and 660 nm are assigned to 2H11/2–4I15/2,4S3/2–4I15/2 and 4F9/2–4I15/2 transitions, respectively. Intensity enhancement displayed by heat treated glass samples is attributed to the local field effect of gold NPs. The intensity parameters related to the radiative transitions within 4fn configuration of Er3 + ion are determined and analyzed using Judd–Ofelt theory.