| 摘要 |
PURPOSE:To obtain an oxide glass thin film low in loss and having a desired refractive index structure by suppressing the volatilization of the additive in the deposited porous film when the film is vitrified in the production of the oxide glass thin film. CONSTITUTION:A fine glass particle contg. an additive and consisting essentially of SiO2 is deposited on a substrate to form a porous thin film, and then the thin film is heated and vitrified. In this case, the vapor of the oxide of an additive is mixed into the heating and vitrifying atmosphere, hence the additive in the deposited porous film is not volatilized, the additive added to a core layer is not diffused, and the volatilization of the component having a vitrification temp. lower than that of the additive (P2O5, B2O3, GeO2, etc.) is effectively prevented. As a result, a desired refractive index structure is obtained, and an oxide glass thin film low in light scattering loss, etc., due to bubbles is produced since the film is not sintered. |
