| 摘要 |
PURPOSE:To enable the formation of the optical waveguide by exactly controlling the boundary of a core and clad. CONSTITUTION:While fuel and gaseous raw materials are supplied to a burner 4, an Si substrate 1 is scanned thereon by the flame thereof in a step (a). The synthesized glass particulates are deposited on the substrate and form a first porous glass layer 5 to be a lower clad layer. The first porous glass layer 5 is heated by the flame alone in a step (b). The bulk density in the upper layer part of the first porous glass layer 5 increases to 0.3g/cm<2>. The upper layer part increased in the bulk density constitutes a shielding layer for GeO2. A second porous glass layer 6 to be a core layer is uniformly deposited on the first porous glass layer 5 in a step (c). The first and second porous glass layers are sintered in the ensuing step. The evaporation of the GeO2 component in the second porous glass layer and the diffusion thereof into the first porous glass layer are prevented by the presence of the high-density shielding layer in such a case. |
