| 摘要 |
PURPOSE:To obtain the titled preform having prescribed refractive index distribution and form, by integrating a silicon oxide soot cylinder to form a glass clad layer with an oxide powder having different refractive index from that of the above soot and inserted into said cylinder, and dehydrating and vitrifying the composite. CONSTITUTION:A glass clad cylinder 10 made of silicon oxide soot optionally doped with fluorine oxide, etc., is prepared beforehand. An oxide or silicon oxide powder 14 having a refractive index different from that of the soot is filled in the cylinder 10, and the composite is dehydrated, sintered and vitrified to obtain the preform 16 having stepped refractive index distribution. The clad layer and the core layer can be formed concentrically, and a preform can be manufactured at a high speed irrespective of the refractive index distribution and the form of the preform. |
