A method of forming an optical fiber preform includes the steps: igniting a burner having a fume tube assembly to produce a first spray size of silicon dioxide particles; depositing the silicon dioxide particles on a core cane to produce a soot blank; and adjusting an effective diameter of an aperture of the fume tube assembly to produce a second spray size of the silicon dioxide particles. The second spray size is larger than the first spray size.

According to some embodiments method for making an optical fiber preform comprises the steps of: (i) placing a plurality of rods with an outer surface having a coefficient of friction 0.02≦COF≦0.3 into an inner cavity of an apparatus; (ii) placing particulate glass material in the inner cavity between the rods and an inner wall of the mold cavity; and (iii) applying pressure against the particulate glass material to press the particulate glass material against the plurality of rods.

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±10% when a glass particle deposition layer of a portion satisfying a relation 0.5L≦R≦0.8L 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.].

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±10% when a glass particle deposition layer of a portion satisfying a relation 0.5 L≤R≤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.].

A method and an apparatus for producing a porous glass preform by using organosiloxane raw material is provided. The apparatus for producing the porous glass preform 12 according to the present embodiment is configured to mix organosiloxane in a liquid state being a raw material with a carrier gas in a vaporizer 6, heat this mixture to be vaporized, supply this vapor to a burner 13 as a gas raw material, and produce a porous glass preform by depositing a glass fine particle produced by combusting the gas raw material on a starting material, herein the apparatus for producing a porous glass preform includes a moisture removing apparatus 8 configured to remove moisture in the carrier gas and supply the vaporizer with the carrier gas.

A multiple tube burner for synthesizing a porous material includes three or more glass tubes are arranged coaxially with one another, the glass tubes having a substantially circular shape on a cross section perpendicular to a longitudinal direction. Out of the three or more glass tubes, a first glass tube and a second glass tube that is arranged on an outer side of the first glass tube are connected with each other on a gas introducing side, and a thickness near a joint portion of the second glass tube connected with the first glass tube is thicker than a thickness of the second glass tube on the gas spouting side.

To provide a fabrication method for a porous glass base material for optical fiber, the method including performing deposition of glass fine particles generated by using a burner for glass fine particle synthesis to form a porous glass base material, and heating this porous glass base material to be transformed into transparent glass to obtain a glass base material hardly containing any air bubbles. Provided is a fabrication method for a porous glass base material for optical fiber by depositing glass fine particles, which is generated in flame formed by ejecting a glass raw material gas and a combustible gas from a burner, on a rotating starting material, in which the burner continuously ejects inert gas for at least a predetermined period immediately after the end of the deposition of the glass fine particles.

Vaporizers and systems for vaporizing liquid precursor for forming glass optical fiber preforms are provided. The vaporizer includes an expansion chamber at least partially enclosed by a side wall, the expansion chamber comprising an upper end and a lower end with the side wall disposed between the upper end and the lower end. The vaporizer further includes a closed-loop liquid delivery conduit positioned in the expansion chamber proximate to the upper end of the expansion chamber, wherein the closed-loop liquid delivery conduit comprises a plurality of nozzles oriented to direct a spray of liquid precursor onto an inner surface of the side wall. Further, the vaporizer includes at least one supply conduit positioned proximate the upper end of the expansion chamber and coupled to the closed-loop liquid delivery conduit, and a vapor delivery outlet coupled to the expansion chamber and configured to direct vaporized liquid precursor from the expansion chamber.

An aspect of the present disclosure enables prediction of a refractive index profile of a transparent glass preform obtained in a production stage of a glass particulate deposit by a VAD method. The glass preform production apparatus includes a gas supply system, a burner, and a signal processing device. The signal processing device includes an imaging device that images a particle flow of glass fine particles, and a calculation unit. The calculation unit extracts, at any one or more time points during a period from the start of production to the end of production of the glass particulate deposit, image data representing a state of at least the flame or the particle flow from an image obtained by the imaging device, and regressively predicts a refractive index profile of the transparent glass preform serving as an objective variable from an explanatory variable including the image data.

A method and an apparatus for producing a porous glass preform by using organosiloxane raw material is provided. The apparatus for producing the porous glass preform 12 according to the present embodiment is configured to mix organosiloxane in a liquid state being a raw material with a carrier gas in a vaporizer 6, heat this mixture to be vaporized, supply this vapor to a burner 13 as a gas raw material, and produce a porous glass preform by depositing a glass fine particle produced by combusting the gas raw material on a starting material, herein the apparatus for producing a porous glass preform includes a moisture removing apparatus 8 configured to remove moisture in the carrier gas and supply the vaporizer with the carrier gas.