OPTICAL FIBER PREFORM PRODUCING METHOD, OPTICAL FIBER PRODUCING METHOD, AND OPTICAL FIBER

摘要

To provide a manufacturing method for an optical fiber preform and a manufacturing method for an optical fiber in which the optical fiber with a complex profile is produced at high precision, and an optical fiber. The invention provides the method for manufacturing the optical fiber preform comprising a central core portion having a maximal value Nc of refractive index in the center, and outside the central coreportion, comprising at least a depressedportion having a minimal value Nd of refractive index, a ring portion having a maximal value Nr of refractive index and an outside cladding layer having a maximal value No of refractive index, the optical fiber preform satisfying a relation of Nc≥Nr>No>Nd among the values of refractive index. This method is characterized by comprising a glass rod fabrication step of fabricating a glass rod by inserting a rod containing at least the central core portion into a pipe containing at least the depressed portion and integrating them by collapse, a glass pipe fabrication step of fabricating a glass pipe having the ring portion, and an integration step of fabricating a vitreous body by integrating the glass rod and the glass pipe by collapse after inserting the glass rod into the glass pipe.