Chapter 2 - The refractive index of silica glass and its dependence on pressure, temperature, and the wavelength of the incident light

Abstract

This chapter discusses the refractive index of silica glass and its dependence on pressure, temperature, and the wavelength of the incident light. Study of refractive index in a wide range of wavelengths of the incident light and at different pressures and temperatures is important for understanding: the electro-optic effects, faraday effect, nonlinear effect, piezoelectricity, photoelasticity, and microstructures of materials. Two concepts were used in studying the effect of temperature, pressure, and frequency of the incident light on refractive index: (1) the effective field, and (2) mean polarizability. Densification experiments were performed on silica glasses at high pressures and high temperatures. The structures of the densified silica glasses were discussed in terms of the X-ray diffraction. The ultraviolet (UV) and infrared (IR) spectra were recorded for densified silica glasses, and the density and refractive index of densified silica glasses were discussed by the proposed relation. The interferometric method was used for determination of the temperature dependence of the refractive index and dispersion of silica glass in the IR wavelength region by IR spectroscopy. The refractive index at a given wavelength was found to increase with increasing temperature.