Effect of WO 3 in the third-order optical nonlinearities of tungsten lead pyrophosphate glasses

The binary glassy system Pb 2 P 2 O 7 -WO 3 demonstrates promising photonics applications owing to its high polarizability and chemical stability. The domain of glass's chemical state and linear and nonlinear optical properties have been investigated using X-ray photoelectron spectroscopy (XPS), UV-visible spectroscopy, and the Zscan technique, respectively. The optical absorption spectra revealed that the absorption edge was redshifted with increased WO 3 content, suggesting a decrease in bandgap energy. Nonlinear refractive index increased with the WO 3 content from an average value of 0.70 x 10 -19 m 2 W - 1 to 0.98 x 10 -19 m 2 W -1 . Such an increase is due to the rise of non-bridging oxygens and the polarizability of W 6+ and W 5+ species. XPS studies found that a high concentration of WO 3 leads to the transformation of the oxidation state of W 6+ and W 5+ related to the presence of oxygen vacancies. Therefore, our high nonlinear refractive index and polarizability results indicate that the glass system studied here is a potential candidate for photonic devices.