| 摘要 |
PURPOSE:To produce an optical fiber having high strength and low loss by previously heat-treating a core rod in a specified atmosphere to suppress the generation of bubbles at the interface between the core rod and a clad when the core rod obtained by vitrifying a soot base material is used to produce the title base material by an external deposition method. CONSTITUTION:For example, the soot base material for a graded-type GI fiber is previously formed, and the base material is sintered and vitrified while being rotated and pulled down to obtain the core rod 6. The core rod 6 is then transiently pulled up, He and an F compd. such as SiF4 are supplied into a quartz muffle 1 from an inlet 3, and the core rod 6 is pulled down at the same temp. as before and heat-treated. The soot for a clad is deposited on the outer periphery of the core rod 6, and the soot is sintered and vitrified in the atmosphere of He and Cl2 to obtain an optical fiber base material. Bubbles are not recognized at the interface between the core rod and clad of the base material, and the base material is drawn to obtain the desired optical fiber. |
