| 摘要 |
PURPOSE:To provide a forming method of a glass film for a light waveguide having a glass thin film layer of high refractive index on its surface by using a core waveguide which is a light transmission part of a glass waveguide. CONSTITUTION:A substrate 6 the surface of which is coated with a glass film having low refractive index is disposed, preferably maintained at <=400 deg.C, in a low temp. plasma atmosphere 5 in vacuum. A gas containing org. oxysilane vapor, and oxygen, and a dopant to glass thin film on the surface of the glass film of the substrate 6. The obtd. glass thin film has higher refractive index than the first glass film, contains the dopant to control the refractive index, and has no crack. Then the substrate is heat treated at least once. Thus, a light waveguide glass film having glass thin film of specified thickness is produced. |
