Fujikura Limited

Takakazu Gotoh

Naritoshi Yamada

Koichi Harada

Kentaro Ichii

A method for manufacturing an optical fiber preform includes a process A of applying flame polishing to a center glass rod, a process B of determining a ratio r/r, which is a ratio of a radius rof the center glass rod expressed in millimeters with respect to a radius rof a target optical fiber preform expressed in millimeters, based on a refractive index profile of a target optical fiber preform, and a process C of determining an amount of fine glass particles to be deposited on the center glass rod so that a ratio r/r/c falls within a range from 0.002 to 0.01, where 'c' is a maximum value of hydroxyl group concentration expressed in ppm in the vicinity of a boundary between the center glass rod and an outer layer, which is formed by depositing fine glass particles on the center rod and by being vitrified.

Optical fiber preform and manufacturing method therefor

A method for fabricating a porous silica preform includes the steps of supplying fuel gas for generating an oxyhydrogen flame to a glass synthesizing burner; supplying Gas A containing silicon and Gas B containing fluorine to the burner; synthesizing glass particles; and depositing the glass particles around a starting rod, in which when glass particles are deposited directly on the starting rod, a supply of Gas A and a supply of Gas B supplied to the burner are adjusted so that a ratio of the number of fluorine atoms to the number of silicon atoms in the gas supplied to the burner satisfies the following Formula (1):{(number of F atoms)/(number of Si atoms)}&#x2266;0.1&#x2003;&#x2003;(1).

Method for fabricating porous silica preform

A method for fabricating a porous silica preform includes the steps of supplying fuel gas for generating an oxyhydrogen flame to a glass synthesizing burner; supplying Gas A containing silicon and Gas B containing fluorine to the burner; synthesizing glass particles; and depositing the glass particles around a starting rod, in which when glass particles are deposited directly on the starting rod, a supply of Gas A and a supply of Gas B supplied to the burner are adjusted so that a ratio of the number of fluorine atoms to the number of silicon atoms in the gas supplied to the burner satisfies the following Formula (1):{(number of F atoms)/(number of Si atoms)}&#x2266;0.1 &#x2003;&#x2003;(1).

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Sakura, Japan

Takakazu Gotoh