Abstract: A mass production method and apparatus of hermetic coating optical fiber where a bare fiber drawn from a preform is hermetically coated by CVD method in a reactor vessel, wherein a liquid flushes solid particles or by-products sticking to the reactor inner wall. The liquid may be supplied continuously or intermittently, to flush carbon particles generated during carbon coating process. The invention enables to produce a long hermetic coating optical fiber without choking the reactor, and improves a yield rate and productivity.

Abstract: A transparent glass preform for an optical fiber is produced by heating a glass soot preform to remove gas from the soot preform at a temperature at which the soot preform is not vitrified under reduced pressure, and then heating the preform at a temperature at which the preform is vitrified under reduced pressure, whereby the transparent glass preform containing no or little bubbles and having a uniform outer diameter is produced.

Abstract: A mass production method of hermetic coating optical fiber where a bare fiber drawn from a preform is hermetically coated by CVD method in a reactor vessel, wherein a liquid flushes solid particles or by-products sticking to the reactor inner wall. The liquid may be supplied continuously or intermittently, to flush carbon particles generated during carbon coating process. The invention enables to produce a long hermetic coating optical fiber without choking the reactor, and improves a yield rate and productivity.

Abstract: A glass soot deposit is produced at a high deposition rate by blowing a gaseous glass-forming raw material together with a fuel gas from a combustion burner in a closed muffle, hydrolyzing the glass-forming raw material in a flame to generate glass soot, and depositing the glass soot on a tip end or a peripheral surface of a starting member which is rotated to form a glass soot deposit, in which a lowest surface temperature of the muffle tube is maintained at 50.degree. C. or higher and an average surface temperature of the muffle is maintained in a range between 50.degree. C. and 150.degree. C., whereby corrosion of the muffle is prevented.

Abstract: The invention is a method for producing a porous preform for use in the fabrication of an optical fiber at least two burners synthesize glass soot particles, one of which generates a double-layer flame and one of which is used for forming a core part of the preform. The method comprises the steps of supplying SiCl.sub.4 and optionally GeCl.sub.4 to the inner flame of the double-layer flame, and only SiCl.sub.4 to an outer flame of the double-layer flame to flame hydrolyze the supplied compounds and synthesize glass soot particles. Compounds SiCl.sub.4 and GeCl.sub.4 as glass-forming raw materials are supplied to the burner for forming the core part of the preform by depositing the generated glass soot particles on the lower end of a rotating starting member. The generated porous preform comprises a core part containing at least partly GeO.sub.2, and a surface having a low concentration of GeO.sub.2 which reduces cracking or peeling.

Abstract: A glass preform for use in the fabrication of an optical fiber having a reduced transmission loss is produced by synthesizing a soot preform by a vapor synthesis method and consolidating the soot preform in an electric furnace to obtain a glass preform, wherein an intermediate body consisting of a core portion and an inner part of a cladding portion is consolidated under atmospheric pressure and an outer part of the cladding portion which surrounds a periphery of the intermediated body is consolidated under reduced pressure or in vacuo.

Abstract: A glass article is produced at a high production rate and a high yield by jetting a glass-forming raw material from a multi-port burner, synthesizing glass soot through hydrolysis of the glass-forming raw material, depositing the glass soot to form a soot preform and heating and vitrifying the soot preform to produce a transparent glass article, wherein the glass-forming raw material is vaporized by heating it at a temperature higher than its boiling point and directly supplied to the burner, the vaporized glass-forming raw material and a fuel gas for synthesizing glass soot are supplied to an inner port of the multi-port burner and a fuel gas for heating a formed preform is supplied to an outer port of the multi-port burner, and a molar ratio of water generated by a reaction of the fuel gas for synthesizing glass soot to the glass-foring raw material is from to 2 to 3.

Abstract: A glass preform for use in the fabrication of an optical fiber having little bubbles is produced by a method comprising depositing glass soot on a periphery of a starting glass rod to form a porous glass preform, heating and sintering the porous glass preform in a helium atmosphere to consolidate the porous glass preform and then heating the sintered glass in an atmosphere containing an inert gas except helium having partial pressure of the inert gas of not lower than 0.8 atm. to obtain a transparent glass preform.

Abstract: A raw material supplying device having a gas tight tank for receiving a material to be gasified by heating; a heater for heating the raw material within the tank and a plurality of pipes for conveying a plurality of streams of gas in parallel to each other to a plurality of ports of a reaction apparatus, and a process for using the raw material supplying device. The raw material supplying device can be used in a system for manufacturing glass fibers in which the ends of the plurality of pipes are connected to the gas feed ports of at least one multi-layer burner.

Abstract: A rod-in-tube method for producing a glass preform for use in the fabrication of an optical fiber, which comprises steps of inserting a glass rod constituting a core material in a glass tube constituting a cladding material, heating the rod-tube composite by an outer heating source with introducing, in the gap between the rod and the tube, a gaseous mixture containing a silicon halogenide, a fluorine-containing compound and oxygen gas in which a ratio of silicon and fluorine (Si/F) is larger than 1/300 and smaller than 1/5, and heating and fusing the composite at a temperature not lower than 1,900.degree. C. with filling the gap by a gaseous mixture comprising a halogen-containing compound and oxygen gas; from which glass preform, an optical fiber with low attenuation of light transmission, particularly in a long wavelength range, is fabricated.

Abstract: A method for producing a glass preform for an optical fiber comprising jetting SiCl.sub.4 as a glass-forming raw material and an insert gas from a first nozzle of a multi-nozzle burner and, as another glass-forming raw material, at least one hydrogen-containing silicon compound with larger oxidation or hydrolysis reaction heat than that of SiCl.sub.4 selected from the group consisting of SiHCl.sub.3, SiH.sub.2 Cl.sub.2, SiH.sub.3 Cl and SiH.sub.4 from a second nozzle surrounding the first nozzle, flame hydrolyzing or oxidizing the glass-forming raw materials to synthesize glass soot particles, depositing the glass soot particles on a starting member to form a porous soot preform with a controlled bulk density distribution and heating and sintering the soot preform to obtain a transparent glass preform, by which a large glass preform is stably produced without cracking.

Abstract: A method for producing a glass preform for an optical fiber by means at least two burners, comprising jetting a glass raw material containing SiCl.sub.4 from the first center burner and a hydrogen-containing silicon compound with larger reaction heat than SiCl.sub.4 from at least one second burner, flame hydrolyzing the glas raw material to synthesizing fine glass particles, depositing the fine glass particles on a starting member to form a porous soot preform and heating and sintering the soot preform to obtain a transparent glass preform, by which a large preform is stably produced and a bulk density of the preform is easily controlled.

Abstract: A rod-in-tube method for producing a glass preform for use in the fabrication of an optical fiber, which comprises steps of inserting a glass rod as a core material in a glass tube as a cladding material, fusing and closing one end of the cladding material, filling a gap between the core and cladding materials with an atmosphere containing at least one gaseous halogen-containing compound and then heating the core and cladding materials at a temperature not lower than 1,900.degree. C. to collapse the gap between them and to fuse them together, from which glass preform, an optical fiber with low attenuation of light transmission is fabricated.