Manufacturing method of optical fiber preform, optical fiber preform, and optical fiber

Abstract

Provided is a manufacturing method of an optical fiber preform, comprising: depositing SiO2 fine particles by adhesion onto a starting preform formed of quartz glass to obtain a soot preform, the starting preform including a core having a high refractive index and a cladding having a lower refractive index than the core; sintering the soot preform to dehydrate and vitrify it sequentially from one end in a dehydration gas atmosphere; and prior to the sintering, preheating at least a vicinity of a sintering-process-start end of the soot preform. Provided is an optical fiber preform formed of quartz glass and including a core having a high refractive index and a cladding having a lower refractive index than the core, wherein an average of OH concentrations in a radial direction of the optical fiber preform is 25 ppm or less throughout a section of 90% or more in a longitudinal direction.

Dependencies are inferred from the claim text.