A method of producing soot, including: combusting a first fuel stream and a first oxidizer at a burner face; combusting a second fuel stream and a second oxidizer at the burner face, wherein the second fuel stream and the second oxidizer are premixed in advance of the burner face and a second equivalence ratio of the second fuel stream and the second oxidizer is less than about 1; and combusting a silicon-containing fuel into a plurality of soot particles, wherein the second fuel stream and the second oxidizer are combusted between the first fuel stream and the silicon-containing fuel. Applying this method of producing soot to deposit a preform suitable for the manufacture of optical fibers.

In order to improve the yield of an optical fiber base material, provided is a manufacturing apparatus for manufacturing an optical fiber base material by forming a soot deposition body on a surface of a target rod, including a main burner that generates glass microparticles to be deposited on the target rod while moving in a longitudinal direction of the target rod; a pair of side burners that are arranged outside a movement range of the main burner and heat both ends of the soot deposition body formed on the surface of the target rod; and a shielding member that prevents the glass microparticles generated by the main burner from being deposited on the target rod farther outward than a segment of the target rod sandwiched by the pair of side burners.

The invention provides a production method for a glass particulate deposit M which includes a deposition step where a starting rod 111 and a burner 222 for production of glass particles 130 are installed in a reactor 102, a glass source material is introduced into the burner 222, the glass source material is subjected to flame thermal decomposition in the flame formed by the burner 222 to thereby form glass particles 130, and the formed glass particles 130 are deposited on the starting rod 111 to produce a glass particulate deposit M. In the deposition step of the production method, at least two ejecting ports 231 are provided per one burner 222 for ejecting the glass source material from the burner 222, and a flow rate of the glass source material jetting out through one glass source material ejecting port 231 is from 4 m/s to 60 m/s.

This burner for producing a fine glass particle deposited body is provided with a metallic gas-feed pipe that forms a burner body, and a cover for covering the gas-feed pipe, wherein: the gas-feed pipe and the cover are integrally formed; the gas-feed pipe has connected thereto a piping through which material gas, oxyhydrogen gas, and seal gas are supplied; and the cover covers, in the axial direction of the burner over a prescribed length and in a given constant outer diameter, the gas-feed pipe and a connection part of the piping connected to a lateral surface of the gas-feed pipe.

A method of producing soot, including: combusting a first fuel stream and a first oxidizer at a burner face; combusting a second fuel stream and a second oxidizer at the burner face, wherein the second fuel stream and the second oxidizer are premixed in advance of the burner face and a second equivalence ratio of the second fuel stream and the second oxidizer is less than about 1; and combusting a silicon-containing fuel into a plurality of soot particles, wherein the second fuel stream and the second oxidizer are combusted between the first fuel stream and the silicon-containing fuel. Applying this method of producing soot to deposit a preform suitable for the manufacture of optical fibers.

A torch for fabricating optical fiber preforms may include a body having a surface and two or more slit-shaped orifices oriented parallel or substantially parallel to each other along the surface. The torch body may further include two or more conduits connected to corresponding orifices. The torch may be used by orienting it relative to a preform substrate, and simultaneously emitting two or more gases from corresponding orifices toward the surface of the preform substrate, such that the gases are involved in a reaction to form a soot.

In order to improve the yield of an optical fiber base material, provided is a manufacturing apparatus for manufacturing an optical fiber base material by forming a soot deposition body on a surface of a target rod, including a main burner that generates glass microparticles to be deposited on the target rod while moving in a longitudinal direction of the target rod; a pair of side burners that are arranged outside a movement range of the main burner and heat both ends of the soot deposition body formed on the surface of the target rod; and a shielding member that prevents the glass microparticles generated by the main burner from being deposited on the target rod farther outward than a segment of the target rod sandwiched by the pair of side burners.

A method for producing an optical fiber includes stabilizing a burner flame using a multi-nozzle burner. The multi-nozzle burner includes a raw material gas ejection port in a central part for ejecting a raw material gas. The multi-nozzle burner includes a seal gas ejection port on an outer side of the raw material gas ejection port for ejecting a seal gas. The multi-nozzle burner includes a combustible gas ejection port on an outer side of the seal gas ejection port for ejecting a combustible gas. The multi-nozzle burner includes a plurality of small diameter combustion supporting gas ejection ports surrounding the seal gas ejection port in the combustible gas ejection port for ejecting a combustion supporting gas. A gas flow rate of the raw material gas ejection port is V1 and a gas flow rate of the seal gas ejection port is V2, and 1>V2/V1>0.05.

A glass particle deposit producing method capable of preventing the variation in the outside diameter of a glass particle deposit and enhancing the yield of a glass raw material is provided. A glass particle deposit is produced by mounting a starting rod 11 and a glass particle generating burner 22 inside a reaction vessel 2, introducing a glass raw material into the burner 22, subjecting the glass raw material to a flame decomposition reaction inside a flame formed by the burner 22 to generate glass particles, and depositing the generated glass particles on the starting rod 11. At this time, the dispersion angle of the glass raw material jetted from the burner 22 with respect to the center axis of the burner 22 is set to the range of 5 to 70 degrees.

Titania-doped quartz glass is manufactured by mixing a silicon-providing reactant gas and a titanium-providing reactant gas, preheating the reactant gas mixture at 200-400 C., and subjecting the mixture to oxidation or flame hydrolysis. A substrate of the glass is free of concave defects having a volume of at least 30,000 nm.sup.3 in an effective region of the EUV light-reflecting surface and is suited for use in the EUV lithography.