Structural investigation of new tellurite glasses belonging to the TeO2-NbO2.5-WO3 system, and a study of their linear and nonlinear optical properties

Abstract

The glass-forming domain, density, thermal, structural and optical properties of new glasses within the TeO2-NbO2.5-WO3 system have been investigated. By means of Raman spectroscopy, a thorough structural analysis of these glasses has been undertaken on the basis of a full-scale spectral decomposition process. The optical transmission window, refractive index dispersion and third-order nonlinear susceptibilities χ(3) were measured by UV–Vis-NIR spectroscopy, spectroscopic ellipsometry and Z-scan method respectively. Consistent correlations are successfully established between the measured structural, linear and nonlinear optical properties. In general, the structural features of the glass network are found to evolve mildly upon adding NbO2.5 or WO3. Nonetheless, a weak structural depolymerization of the TeOTe bond network as a result of adding NbO2.5 is evidenced and discussed in detail. Upon continuous addition of NbO2.5 and/or WO3, the glass network becomes progressively richer in NbO2.5-rich and/or WO3-rich regions before the crystallization of Nb6TeO17 (NbO2.5:TeO2 ratio of 6:1) and WO2.83 compounds respectively. The studied glasses exhibit high linear refractive indices with an average of ~2.13 and very high third-order nonlinear susceptibilities χ(3) with an average of 5.48 *10−13 esu (~37 times higher than that of SiO2 glass).