Comparison study of optical properties on erbium-doped and silver-doped zinc tellurite glass system for non-linear application

Abstract

The melt-quenching method was employed in order to fabricate a series of erbium-doped and silver-doped zinc tellurite glass systems with the chemical composition of [(TeO2)0.7 (ZnO)0.3]1−x (Er2O3)x and [[(TeO2)0.7 (ZnO) 0.3]0.96 (Er2O3)0.04]]1−y (Ag2O)y at different molar fraction of x and y = 0.01, 0.02, 0.03, 0.04 and 0.05. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, density and optical measurements were utilized to characterize the provided glass samples. At room temperature, all the results of XRD, FTIR, density and optical properties are tabulated respectively. An amorphous nature of glass samples is proven by the XRD spectra for both glass series. The analysis of FTIR spectra displays the existence of functional vibration of tellurite network. It is observed that the density of both glass system increases with the addition of dopants into the glass system. In erbium-doped glass series, the value of molar volume is found to be directly proportional to the density. This in turn results in the creation of excess free volume due to the difference of bond length between erbium and tellurite. As in the case of silver-doped glass series, it is observed that the value of molar volume is inversely proportional to the density. The optical properties of the prepared glasses were identified by UV–VIS analysis. The optical absorption spectra reveal the fundamental absorption edge for both glass series which shifts to higher wavelength as the content of dopants increases. The values of direct and indirect band gap decrease while the Urbach energy and refractive index of erbium-doped zinc tellurite glass are viewed to increase as the concentration of dopants is included in the glass sample. This may be due to the presence of non-bridging oxygen within the vitreous network of the glass sample. Meanwhile in silver-doped glass series, the band gaps are found to be non-linearly decreased while the Urbach energy and refractive index are viewed to be non-linearly increased when the concentration of dopants are added into the zinc tellurite glass system. As a whole, the trends for respective parameters can be correlated to the presence of non-bridging oxygen within the vitreous network of the glass sample.