OPTICAL FIBER AND ITS PRODUCTION

摘要

PURPOSE:To improve the fatigue of a quartz optical fiber and to provide the optical fiber having high strength and excellent long-period reliability by providing a quartz glass layer added with nitrogen to the outermost layer of the quartz optical fiber. CONSTITUTION:The production of the multimode optical fiber having the nitrogen-added quartz glass layer 1' as the outermost layer and having a quartz glass clad layer 2 and SiO2-GeO2 glass core 3 is executed in the following manner: The porous quartz glass layer is uniformly stuck by using an oxyhydrogen burner 4 on the outside of a base material 5 for the multimode optical fiber constituted of the core 3 and the clad 2. Such base material 5 is placed in the central part of a heating element 7 in an electric furnace 5 and is heated and held in a mixed atmosphere composed of He and NH3 to clarify the layer 6 and to incorporate the nitrogen into the layer 6, by which the nitrogen-added glass layer 6' is formed and a base material 9 is obtd. Such material 9s is heated by a drawing furnace 1 and is made into the fiber. The fiber is subjected to plastic coating by a die 11, by which the optical fiber 12 is completed.