PRODUCTION OF BASE MATERIAL FOR OPTICAL FIBER

摘要

PURPOSE:To decrease relatively the change of the refractive index in a diametral direction and to produce economically an optical fiber having a high refractive index in a process for producing a base material for the optical fiber by a vapor phase axial deposition method by supplying a gaseous raw material to a multi-layered burner by a specific method. CONSTITUTION:The multi-layered burner consisting of >=3 concentrical layers is used as the burner. More specifically, (i) silicon compd. (gaseous raw material), germanium compd. (gaseous dopant) and gaseous hydrogen are introduced to the 1st layer positioned at the center, (ii) the silicon compd., a large quantity of the germanium compd. and inert gas are introduced to the 2nd layer adjacent to the outside of the 1st layer and (iii) gaseous oxygen is introduced to the 3rd layer adjacent to the outside of the 2nd layer to bring these gases into reaction.