Structural and optical study of silicate glasses for nonlinear optical devices

Nonlinear optical glasses with fast response times and very low absorption coefficients are promising materials for use in ultra-fast (picosecond) all-optical switches. We have recently reported a relatively high third-order optical nonlinearity in equimolar TiO 2· B 2 O 3· Na 2 O· SiO 2 glass. The nonlinear index coefficient n 2 for this glass composition was found to be 4 × 10 −19 m 2/W. In order to determine the relationship of the various physical properties to the structure and/or composition in these glasses, we have synthesized series of glasses in the four-component TiO 2· Nb 2 O 5· Na 2 O· SiO 2 system. Their structures have been studied by Raman spectroscopy, and their linear refractive indices and nonlinear index coefficients were measured. The data show that the linear refractive index is mainly determined by the total concentration of Ti + Nb, whereas the nonlinear index coefficient is much larger for Ti than for Nb doping. The combined presence of Ti and Nb extends the glass forming region in this system.