| 摘要 |
PURPOSE:To prevent the strength of an optical fiber from deteriorating, by removing an organic auxiliary from a porous base material formed from SiO2 as a main raw material, dehydrating the remained porous base material, forming into a preform comprising transparent glass, and subsequently drawing the preform. CONSTITUTION:SiO2 fine particles as a core raw material, SiO2 fine particles as a clad raw material, an organic auxiliary such as 2 binder (e.g. methyl cellulose), a lubricant or a dispersant, and pure water are mixed to prepare a molding raw material. The prepared core raw material 14 and the prepared clad raw material 18 are fed into the inner passageway 12 and the outer passageway 16, respectively, and subsequently doubly extruded into a core 24 and a clad 26 through dies 20 and 22. The produced porous extruded product is dried, subjected to an organic auxiliary-removing treatment at approximately 200 to 800 deg.C under an O2 atmosphere, and subsequently dehydrated with heating in e.g. He/Cl2 mixed gas atmosphere. The product is burned into a pore-free transparent glass base material in a He gas atmosphere, etc., and drawn into an optical fiber by a thermal drawing method. |
