| 摘要 |
PURPOSE:To prevent the generation or remaining of bubbles when a deposited soot layer to be a clad layer is vitrified in the producing method of an optical waveguide structure. CONSTITUTION:An optical waveguide core 7 to be used as a light transmission passage is formed on an optical substrate 1, a glass soot layer to be the clad layer covering the core is deposited, then the soot layer is heated, melted and vitrified to form the clad layer, and an optical waveguide substrate is produced. A control additive is added to make the m.p. of the lower layer of the soot layer 20 close to the core 7 lower than that of the upper layer, and the lower layer is vitrified before the upper layer is vitrified. |
