Effect of titania dopant on optical performance of silica glass

Abstract

The distortion caused by temperature change in optical materials seriously impacts the accuracy and stability of optical systems, and it is vital to develop a transmission and reflection optical material with ultra-high optical stability. Doping TiO2 in silica glass can greatly reduce the thermal expansion coefficient of silica glass, improve the thermal stability of silica glass, and improve its optical stability. We used SiCl4 and TiCl4 as precursors to prepare glass materials with different titanium contents by CVD process in this work. After the precursors are thoroughly mixed, they enter the high-temperature furnace with a hydrogen-oxygen flame for chemical reactions. The granular SiO2 and TiO2 mixture generated by the reaction is deposited on the bottom of the furnace under gravity and sintered layer by layer to form a transparent glass body. The spectral transmittance and structural characteristics of glasses with different titanium contents were characterized by Raman spectroscopy and ultraviolet-visible-near infrared spectrophotometer to analyze the spectral transmittance and microstructure characteristics of the materials. The test results show that silica glass doped with 7.5- 10wt% TiO2 has good optical stability, and the transmittance of visible light and near-infrared light is greater than 90%. The doping of TiO2 makes the silica glass network show a specific ‘deaggregation’ phenomenon, but the tetrahedral framework of the silica glass is maintained. In addition to the tetrahedral form of Ti ions in the silica glass network, there is also the six-coordinated octahedral form.