The Furukawa Electric Co., Ltd.

Seiichi Shinada

Masaki Nakajima

Akihiro Kanao

Tatsuyuki Higashizawa

A manufacturing apparatus for an optical fiber porous preform includes a reaction chamber configured to accommodate a starting material; at least one main burner provided in the reaction chamber, the at least one main burner being configured to be supplied with a gas containing at least a source gas and a flammable gas, such that particulates are to be generated from reaction of the source gas and the flammable gas and deposited on the starting material; at least one auxiliary burner configured to be directed toward an end portion of the starting material on which the particulates are to be deposited; and an airflow guide provided such that at least part of the airflow guide is located across the at least one auxiliary burner from the starting material.

Manufacturing apparatus and manufacturing method for optical fiber porous preform

A method of manufacturing a porous glass preform includes depositing glass particles on an outer periphery of a target rod while a burner for synthesizing glass particles and the target rod that is rotating are relatively reciprocated, wherein V and r are gradually reduced while a variation in sweeping pitch P [mm] expressed as V/r is caused to be within a range of a central value&#xb1;10% when a glass particle deposition layer of a portion satisfying a relation 0.5 L&#x2264;R&#x2264;0.8 L is synthesized; where a final outer diameter of the manufactured porous glass preform for an optical fiber is L [mm], an outer diameter of a glass particle deposition body in the middle of the manufacture is R [mm], a rotating speed of the target rod is r [rpm], and a relative moving speed between the target rod and the burner is V [mm/min.].

Method of manufacturing porous glass preform for optical fiber

A method of manufacturing an optical fiber glass preform, the method comprising depositing glass particles on a base material, the glass particles being generated by glass making feedstock gas being supplied while a burner and the base material that is rotating are reciprocated relatively to each other, wherein when a portion corresponding to an outer diameter equal to or more than 0.80 L and equal to or less than L is deposited, wherein L represents a final outer diameter of a part of the optical fiber glass preform manufactured, the part being formed by the deposition of the glass particles, the deposition is performed under a first condition where an angle formed by a first line extending from a center O of a cross section of the base material to a rotational position rat which one round trip of the relative reciprocation starts and a second line extending from the center O to a rotational position rat which the one round trip of the relative reciprocation ends is an angle excluding 0&#xb0;, 120&#xb0;, 240&#xb0;, 72&#xb0;, 144&#xb0;, 216&#xb0;, and 288&#xb0;; or the deposition is performed under a second condition where the angle is 120&#xb0; or 240&#xb0;, thereby to deposit the glass particles to a thickness corresponding to a thickness equal to or less than 0.03 L; or the deposition is performed under a third condition where the angle is 72&#xb0;, 144&#xb0;, 216&#xb0;, or 288&#xb0;, thereby to deposit the glass particles to a thickness corresponding to a thickness equal to or less than 0.02 L; or the deposition is performed under a fourth condition where the angle is 0&#xb0;, thereby to deposit the glass particles to a thickness corresponding to a thickness equal to or less than 0.01 L.

Optical fiber glass preform manufacturing method

A production method of an optical fiber preform includes: forming a porous preform by depositing silica particles at an outer periphery of a core rod; and vitrifying the porous preform by conducting thermal treatment steps. At a first thermal treatment step that is an initial thermal treatment step of the thermal treatment steps, the porous preform is heated so that internal temperatures at two end portions in a longitudinal direction of the porous preform increase before an internal temperature of a center portion in the longitudinal direction increases.

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Tokyo, Japan

Seiichi Shinada