| 摘要 |
PURPOSE:To easily produce the title decentralized-shift single-mode optical fiber by inserting a core base material consisting of an SiO2 central layer contg. GeO2 and an SiO2 outer layer part into an SiO2 cylindrical clad base material contg. F, and integrating the materials on heating. CONSTITUTION:A soot body consisting of the central layer consisting of SiO2 contg. GeO2 and the outer layer part surrounding the central layer and consisting essentially of pure SiO2 is prepared by a VAD process. The soot body is dehydrated, sintered, and clearly vitrified. The obtained transparent glass body is drawn in an atmosphere free of an H atom, and the double-structure core base material consisting of a GeO2-contg. part at the central part and essentially pure SiO2 on the outside is obtained. The essentially pure SiO2 soot body formed by a VAD process is heated at a high temp. in an F-contg. atmosphere to add F to the soot body. The soot body is then sintered and clearly vitrified, a hole is bored at the central part, and a cylindrical clad base material is obtained. The core base material is inserted into the clad base material, both materials are integrated on heating, and the base material for the fiber having a step- formed refractive index is obtained. |
