Precise determination and analysis of optical properties of large-sized La₂O₃–TiO₂-based glasses prepared by aerodynamic levitation technique

Abstract

La₂O₃–TiO₂ (LT)-based glasses are promising materials for a wide range of optical applications because of their exceptionally high refractive indices and relatively low optical absorption in the visible wavelength range. In this study, LT-based multicomponent glasses were developed using the aerodynamic levitation technique, and their thermal stability, refractive index dispersion, and optical transmittance spectra were comprehensively analyzed. The addition of ZrO₂ and SiO₂ significantly improved the thermal stability of the glasses against crystallization. This enabled the fabrication of samples having diameters up to 25 mm, which is substantially larger than the typical glass size (approximately 2–3 mm) that is achievable through containerless processing. The LT-based glasses exhibited refractive indices at 2.161–2.315 at 587.562 nm, along with excellent transmittance characteristics relative to those of general optical glasses. An analysis of the refractive index dispersion based on the Lorentz model revealed that the densely packed structures and high electronic polarizabilities of oxygen atoms are critical factors in achieving ultra-high refractive indices and superior transmittance characteristics. Prototype lenses and wafer-shaped optical elements were fabricated using a glass molding press to demonstrate the potential of LT-based glasses for use in practical applications.