Abstract: Method of making a microstructured optical fiber. Silica glass based soot is deposited on a substrate to form at least a portion of an optical fiber preform by traversing a soot deposition burner with respect to said substrate at a burner traverse rate greater than 3 cm/sec, thereby depositing a layer of soot having a thickness less than 20 microns for each of a plurality of burner passes. At least a portion of the soot preform is then consolidated inside a furnace to remove greater than 50 percent of the air trapped in said soot preform, said consolidating taking place in a gaseous atmosphere containing krypton, nitrogen, or mixtures thereof under conditions which are effective to trap a portion of said gaseous atmosphere in said preform during said consolidation step, thereby forming a consolidated preform which when viewed in cross section will exhibit at least 50 voids therein.

Abstract: A multi-nozzle type burner is used for producing a porous glass preform, the burner having small variations in deposition efficiency with the burner tip being not burned even when axial shift occurs at the concentric multi-tube part of the burner. The present invention provides a burner for producing a porous glass preform with a concentric multi-tube structure, comprising a glass material gas jet port in a center, a plurality of gas jet ports concentrically disposed outside the glass material gas jet port, and small-diameter gas jet ports which are disposed in a line or a plurality of lines concentrically to the glass material gas jet port so as to be enclosed in one of the gas jet ports other than the gas jet ports in the center and at an outermost side, the small-diameter gas jet ports in the same line having an identical focal length.

Abstract: The present invention provides a method for producing a glass preform capable of improving the deposition efficiency of produced glass fine particles to a starting rod or a glass soot body. The method for manufacturing a glass preform includes controlling the temperature of SiCl4 used as a source gas to 100° C. or more, producing glass fine particles having an average outer diameter of 90 nm or more in a flame of a burner for producing glass fine particles, and depositing the glass fine particles on a starting glass rod 13.

Abstract: A known method for producing synthetic quartz glass comprises the method steps: providing a liquid SiO2 feedstock material, which contains octamethylcyclotetrasiloxane D4 as the main component, vaporizing the SiO2 feedstock material into a feedstock material vapor, converting the feedstock material vapor into SiO2 particles, depositing the SiO2 particles on a deposition surface while forming a porous SiO2 soot body, and vitrifying the SiO2 soot body while forming the synthetic quartz glass.

Abstract: A method for producing synthetic quartz glass comprises providing a liquid SiO2 feedstock material containing octamethylcyclotetrasiloxane D4, vaporizing the SiO2 feedstock material into vapor, converting the vapor into SiO2 particles, depositing the particles to form a porous SiO2 soot body, and vitrifying the soot body, forming the synthetic quartz glass. To produce cylindrical soot bodies with outer diameters above 300 mm and improved material homogeneity, the liquid feedstock material contains additional components comprising hexamethylcyclotrisiloxane D3 and the linear homolog thereof with a weight fraction mD3, decamethylcyclohexasiloxane D6 and the linear homolog thereof with a weight fraction mD6, and tetradecamethylcycloheptasiloxane D7 and/or hexadecamethylcyclooctasiloxane D8 and the linear homologs thereof with a weight fraction mD7+, wherein the weight ratio mD3/mD6 is between 0.5 and 500 and the weight fraction mD7+ is at least 20 wt. ppm.

Abstract: As a precursor to forming a glass sheet, a soot layer is formed on a deposition surface using a roll-to-roll glass soot deposition process. A soot layer-separating device is configured to bring a stream of gas into contact with at least a portion of a free surface of the soot layer. The impinging gas stream affects local thermal expansion stresses at the soot layer/deposition surface interface, which separates the soot layer from the deposition surface.

Abstract: A light diffusing optical fiber includes a core region and a cladding layer. The fiber is configured to scatter guided light away from the core and through an outer surface. A layer or region of the fiber includes material that converts scattered light to a longer wavelength, which is surrounded by a layer or region including material that blocks ultraviolet light.

Abstract: Provided is a porous glass matrix producing burner 10, wherein a third gas jetting opening 17, which is the most outward one of a plurality of gas jetting openings, is clogged by a clogging member 19, and one line or plural lines of gas jetting holes 20 are provided in the clogging member 19 concentrically with respect to the center line of a glass material gas jetting port 11. Hence, there are provided a porous glass matrix producing burner that can have the cross-sectional area of its most outward gas jetting opening changed and can have the flow rate and linear velocity of a combustion improving gas adjusted to thereby suppress diffusion of the combustion improving gas and a combustible gas and improve deposition efficiency, and a porous glass matrix producing method using the porous glass matrix producing burner.

Abstract: Provided is a method for manufacturing an optical fiber preform using a combustion burner. The method includes at least one of: a step ? of, when a mode is changed from a deposition mode to a non-deposition mode, changing a gas discharged from a combustion gas port of the burner from a combustion gas to a purge gas, while maintaining a pilot light and a flow rate of a supporting gas from supporting gas discharge nozzles of the burner so that the nozzle tip does not glow; and a step ? of, when the mode is changed from the non-deposition mode to the deposition mode, changing a gas discharged from the combustion gas port from a purge gas to a combustion gas, while maintaining a pilot light and the flow rate of the supporting gas so that the nozzle tip does not glow.

Abstract: A method for manufacturing an optical fiber base material includes producing glass fine particles through a hydrolysis of a glass material gas in a flame created by an oxidizing gas and a combustible gas.

Abstract: A method and device for manufacturing a preform for optical fibers through chemical deposition on a substrate for deposition arranged vertically is described, comprising a chemical deposition chamber including at least one gripping member rotatably mounted about an axis Z-Z and adapted to hold at least one end of at least one elongated element constituting a substrate for chemical deposition for the formation of a preform for optical fibers. The chamber includes, moreover, at least one burner which is mobile along a direction Z substantially parallel to said axis Z-Z and adapted to deposit, on said at least one elongated element, a chemical substance for the formation of a preform and at least one suction element for collecting exhaust chemical substances, said at least one suction element being arranged on the opposite side to said at least one burner with respect to said axis Z-Z and being mobile along said direction Z.

Abstract: The present invention relates to an optical fiber preform fabricating method that makes it possible to implement a reduction in iron impurities at a low cost. The optical fiber preform fabricating method comprises a glass synthesis step for forming a glass region constituting at least a part of the core area of the optical fiber. The glass synthesis step includes a deposition step of depositing glass particles containing the Al-element inside the glass pipe by means of chemical vapor deposition, and a consolidation step of obtaining a transparent glass body from the glass soot body thus obtained. In other words, the deposition step synthesizes glass particles on the inside wall of a glass pipe by feeding raw material gas, in which the content ratio (O/Al) of the O-element and Al-element is 20 or less, into the glass pipe. Furthermore, the consolidation step obtains a transparent glass body from the glass soot body by heating the glass soot body.

Abstract: A glass base material producing method produces a glass base material through fixing, deposition, pullout, consolidation, and collapse steps in sequence, while the fixing step inserts and fixes a starting bar 11 into a seed rod pipe 12 such that a leading end part 11a of the starting bar 11 projects from one end 12a of the seed rod pipe 12, thereby making a starting rod 10. The starting rod 10 made in the fixing step Si yields a level difference of at least 0.1 mm but not exceeding 0.5 mm at the one end 12a of the seed rod pipe 12. Fine glass particles are deposited on the seed rod pipe in the deposition step in an axial range of at least 50 mm from a position where the level difference exists.

Abstract: A process for producing a porous quartz glass body containing hydrolyzing a metal dopant precursor and an SiO2 precursor in a flame of a burner to form glass fine particles, and depositing and growing the formed glass fine particles on a base material, in which the burner has at least two nozzles, and in which a mixed gas containing (A) a metal dopant precursor gas, (B) an SiO2 precursor gas, (C) one gas of H2 and O2, and (D) one or more gases selected from the group consisting of a rare gas, N2, CO2, a hydrogen halide and H2O, with a proportion of the gas (D) being from 5 to 70 mol %; and (E) the other gas of H2 and O2 of (C), are fed into different nozzles of the burner from each other.

Abstract: The invention relates to a method for producing a blank mold from synthetic quartz glass by using a plasma-assisted deposition method, according to which a hydrogen-free media flow containing a glass starting material and a carrier gas is fed to a multi-nozzle deposition burner. The glass starting material is introduced into a plasma zone by the deposition burner and is oxidized therein while forming SiO2 particles, and the SiO2 particles are deposited on a deposition surface while being directly vitrified. In order to increase the deposition efficiency, the invention provides that the deposition burner (1) focuses the media flow toward the plasma zone (4) by. A multi-nozzle plasma burner, which is suited for carrying out the method and which is provided with a media nozzle for feeding a media flow to the plasma zone, is characterized in that the media nozzle (7) is designed so that it is focussed toward the plasma zone (4). The focussing is effected by a tapering (6) of the media nozzle (7).

Abstract: A deterministic methodology is provided for designing optical fibers that support field-flattened, ring-like higher order modes. The effective and group indices of its modes can be tuned by adjusting the widths of the guide's field-flattened layers or the average index of certain groups of layers. The approach outlined here provides a path to designing fibers that simultaneously have large mode areas and large separations between the propagation constants of its modes.

Abstract: A manufacturing method for a porous silica body including: a step of arranging a plurality of burners around an optical fiber core rod; and a deposition step of depositing a plurality of soot layers on an outer peripheral surface of the optical fiber core rod by the burners, wherein the deposition step comprises forming each of the plurality of soot layers by one of the burners, and depositing each soot layer to satisfy 0.2?x?0.5 and 0.1?y?4.0x2?3.8x+1.3 where x (g/cm3) is the average bulk density and y (mm) is the deposition thickness, and so that the maximum value of the bulk density of the soot layers becomes 0.6 g/cm3 or less.

Abstract: Provided is a method for manufacturing glass preforms which is suitable for making an optical fiber having a less transmission loss in the wavelength band of 1.38 ?m. The glass-preform manufacturing method of the present invention enables making a glass preform through a fixing step, a deposition step, an extraction step, a vitrification step, and a collapsing step in the named order. At the vitrification step, a glass soot body 13 with an integral tubular handle 12 is put in a heating furnace 22 in which He gas and Cl2 gas are introduced, so that it is heated with a heater 23. Thus, a consolidated glass pipe 14 is produced. A dry gas is introduced in the heating furnace 22 upon production of the consolidated glass pipe 14, and the consolidated glass pipe 14 is cooled under the conditions where the humidity of atmosphere around the outer circumference of the consolidated glass pipe 14 is maintained at 0.1% or less.

Abstract: Provided is a method for manufacturing glass preforms with high yield. In the glass-preform manufacturing method according to the present invention, a glass preform is produced through a fixing step, a deposition step, an extraction step, a vitrification step, and a collapsing step in the enumerated order. At the deposition step, the mean density of the glass soot body deposited on the circumference of the tubular handle 12 is made higher than the mean density of the glass soot body deposited on the circumference of the starting mandrel 11. It is preferable that the longitudinal variation in the mean density of a glass soot body deposited from the start of deposition to the tenth layer of glass particles within the range of ±50 mm from the boundary position between the starting mandrel and the tubular handle be 0.01 g/cc/mm or less.

Abstract: The method of manufacturing porous glass base material for optical fiber includes that flame-hydrolyzing raw materials for glass in oxyhydrogen flame, depositing the generated glass fine particles on a rotating target to form porous glass base material, dehydrating and sintering the porous glass base material to transform into clear glass. The method features, in terms of the surface temperature of said porous glass base material, which changes as the burner used for depositing glass fine particle is moved relatively to said target, the temperature difference between the surface temperature of the porous glass base material touching the burner flame Ta and the surface temperature of the porous glass base material before touching the flame Tb, that is Ta?Tb, is adjusted to be within the range from 200 to 700 degrees centigrade.

Abstract: A known method for producing a cylinder of quartz glass comprises a soot depositing process, in which SiO2 particles are deposited on an elongate carrier rotating about an axis of rotation with formation of a porous, hollow-cylindrical soot body, and a sintering process in which the soot body comprising an inner bore with inner wall, a longitudinal axis, an upper end and a lower end is held suspended in vertical orientation in a furnace, a holding element being provided for holding purposes, which projects from the upper end into the inner bore of the soot body and acts on a bearing provided in the inner bore.

Abstract: In a known process for producing a quartz glass cylinder, a porous soot tube, which is sintered to form the quartz glass cylinder, is produced by depositing SiO2 particles on an outer cylindrical surface of a support, which rotates about the longitudinal axis thereof and has a layer of silicon carbide (SiC layer). In order on this basis to specify a support having a high resistance to fracture, which firstly can easily be removed and which secondly presents a low risk of contamination for the soot body, the invention proposes that the SiC layer is treated at a high temperature in an oxygen-containing atmosphere before the SiO2 particles are deposited, in such a manner that an SiO2 protective layer having a thickness of at least 0.1 ?m is produced by oxidation.

Abstract: A method of making a fused silica article that is loaded with hydrogen. A fused silica glass near net shape part is provided and is loaded with a molecular hydrogen in a range from about 0.1×1017 molecules/cm3 up to about 1×1019 molecules/cm3. The thinner shape of the near net shape part enables the shape to be loaded more quickly than previous methods. A fused silica article loaded with hydrogen using the method is also described.

Abstract: A method for forming a silica glass blank includes generating soot using an array of soot producing burners, directing the soot along a first direction onto a bait, collecting the soot on the bait, imparting relative oscillatory motion having a repeat period between the array of soot producing burners and the bait along a second direction orthogonal to the first direction while collecting the soot, and offsetting the relative oscillatory motion by a selected distance along the second direction after each repeat period.

Abstract: A method of manufacturing a cylindrical glass optical waveguide preform having a low water content centerline region, for use in the manufacture of optical waveguide fiber, is disclosed. The centerline region of the glass optical waveguide preform has a water content sufficiently low such that an optical waveguide fiber producible from the glass optical waveguide preform of the present invention exhibits an optical attenuation of less than about 0.35 dB/km, and preferably less than about 0.31 dB/km, at a measured wavelength of 1380 nm. Method of manufacture of a porous core mandrel used in the manufacture of such a glass optical waveguide preform is also disclosed.

Abstract: Provided are a manufacturing method of an optical fiber base material and an optical fiber base material manufactured in the manufacturing method, the manufacturing method including: a process of combining at least two core base materials 70 by fusion-bonding to produce a single core base material; a process of fusion-bonding a pair of dummy glass rods 61 and 62 at both ends of the core base material 70 to produce a starting glass rod; a process of depositing, at an outer surface of the starting glass rod, glass particles generated by flame hydrolysis, to produce a porous base material 80; and a process of sintering and vitrifying, into transparent glass, the porous base material 80, to produce an optical fiber base material 310 that includes a core portion and a clad portion.

Abstract: Core rod sections useable for production of finished optical fiber preforms are fabricated by inserting one or more core body pieces axially end-to-end inside a glass cylinder, thereby defining joints between adjacent ones of the inserted pieces. The cylinder is mounted with the contained core body pieces in the region of a furnace. The glass cylinder and core body pieces are heated together in the furnace, thereby elongating the cylinder and the core body pieces contained in the cylinder, and the cylinder collapses to form a finished core rod. Core rod sections are cut from the finished core rod at positions that coincide with the joints between the core body pieces. One or more of the cut core rod sections are useable for the production of optical fiber preforms.

Abstract: Method for overcladding an optical fiber preform with a given target diameter (D0) of the final preform includes providing a primary preform to be overcladded, and successively depositing first overcladding layers by projecting and vitrifying silica particles on the primary preform moving in relative translation with a plasma torch. Each first overcladding layer has a given uniform thickness (d) and is deposited at a given, constant silica particle flow rate and at a given, constant translation speed. The method also includes the detection of a preform diameter (D1) greater than a given threshold (S) and the deposition of a final overcladding layer having the remaining required thickness (D0?D1) at a constant silica particle flow rate and at a reduced translation speed. The inventive method enables a preform to be overcladded efficiently with improved yield and high quality.

Abstract: A method of producing an optical fiber preform includes preparing a glass preform that has a hole extending in a longitudinal direction formed on one end of the glass preform in such a manner that a length of the hole is equal to or less than half of an entire length of the glass preform, synthesizing a porous glass preform by depositing glass particles on an outer circumference of the glass preform having the hole formed on the end, and sintering the porous glass preform after arranging the porous glass preform in such a manner that the end having the hole formed thereon points downward and the hole is open to the air.

Abstract: A method and apparatus for making an optical fiber preform. The apparatus has an outer wall and an inner wall. The outer wall surrounds the inner wall and the inner wall surrounds an inner cavity of the apparatus. A core rod is deposited in the inner cavity after which particulate glass material, such as glass soot, is deposited in the inner cavity around the core rod. The core rod has at least 10 percent of the final cladding soot already applied thereto. A radially inward pressure is applied against the particulate glass material to pressurize the particulate glass material against the core rod.

Abstract: An optical fiber preform manufacturing apparatus includes a booth, a reaction chamber disposed inside the booth, a target member disposed within the reaction chamber, a burner that deposits glass particles on the target member, a partition plate that partitions the internal space of the booth into a first space where the reaction chamber and the burner are disposed and a second space, and that has a plurality of through holes that allows the first space and the second space to communicate with each other, an air supply unit that supplies clean air into the first space; and an exhaust unit that discharges air within the second space.

Abstract: The present invention provides a burner for manufacturing a porous glass base material that has small-diameter gas discharge ports and that achieves uniform linear velocity at the gas discharge ports, a uniform reaction, and a stable flame, and improved deposition efficiency.

Abstract: Method for manufacturing an optical fiber perform, which forms a glass fine particle deposition portion composed of glass fine particles on a glass rod, and suspends the glass fine particle deposition vertically into a heating furnace to heat, and transparentize, the glass fine particle deposition. The method comprises the following steps: forming a hazy portion before heating, by causing a surface portion of the glass rod to sublime and adhere to at least a portion of a region closer to one end of the glass rod than a region of the glass rod where the deposition portion is formed; forming the deposition portion by depositing the glass fine particles on the glass rod; and transparentizing the deposition portion by heating the glass fine particle deposition in a state where the proximal end of the glass rod where the hazy portion is formed is suspended vertically into the heating furnace.

Abstract: The invention relates to a method for manufacturing a final optical fiber preform by overcladding, said method comprising the steps of providing a primary preform; positioning said primary preform within at least one tube, wherein the at least one tube partly covers the primary preform to create a zone to be overcladded, being an overclad zone, which overclad zone is located on the primary preform outside the at least one tube; injecting a gas into the annular space between the primary preform and the at least one tube under overpressure relative to the pressure outside the at least one tube; overcladding the primary preform in the overclad zone with an overcladding material using an overcladding device. The invention also relates to an apparatus for carrying out the method. The invention allows overcladding a primary preform at low cost while maximally limiting the incorporation of impurities into the silica overclad.

Abstract: According to an embodiment of the invention a method of manufacturing optical fiber cane comprises the steps of: (i) providing a core rod manufactured of relatively low viscosity glass; (ii) depositing SiO2 based soot around the core rod to form a soot preform, the soot being of relatively high viscosity material such that the softening point of the low viscosity glass is at least 200° C. lower than the viscosity of the high viscosity outer core region; and (iii) consolidating the soot of the soot preform by exposure to hot zone at temperatures of 1000° C.-1600° C. The soot is consolidated by heating the outer portion of the soot preform at a relatively fast heating rate, the heating rate being sufficient to densify the soot, so as to render the densified material with enough rigidity to confine the heated core rod and to prevent the heated core rod from puddling.

Abstract: A fused silica glass and a fused silica article having a combined concentration of at least one of OH and OD of up to about 50 ppm. The fused silica glass is formed by drying a fused silica soot blank or preform in an inert atmosphere containing a drying agent, followed by removal of residual drying agent from the dried soot blank by heating the dried soot blank in an atmosphere comprising an inert gas and of oxygen.

Abstract: There is provided a manufacturing apparatus of a porous glass base material which can prevent soot from being formed on an upper surface (ceiling) of the process chamber, and reduce the amount of soot that comes off the upper surface and falls. A manufacturing apparatus of a porous glass base material 4 deposits glass particles produced by subjecting a material gas to flame hydrolysis, onto a starting member 1 placed vertically. Here, a plurality of gas inlets 5 are provided in one or more lateral walls of a process chamber including a burner 2 for the deposition therein, in upper portions of the lateral walls and along a ceiling of the process chamber.

Abstract: A method of manufacturing a cylindrical glass optical waveguide preform having a low water content centerline region, for use in the manufacture of optical waveguide fiber, is disclosed. The centerline region of the glass optical waveguide preform has a water content sufficiently low such that an optical waveguide fiber producible from the glass optical waveguide preform of the present invention exhibits an optical attenuation of less than about 0.35 dB/km, and preferably less than about 0.31 dB/km, at a measured wavelength of 1380 nm. Method of manufacture of a porous core mandrel used in the manufacture of such a glass optical waveguide preform is also disclosed.

Abstract: An apparatus for measuring the weight of a preform for optical fibers during a chemical deposition process for the formation of a preform is disclosed. The apparatus has at least one elastic constraint associated with at least one end portion of an elongated element made of a chemical deposition substrate for the formation of the preform, a device for inducing an oscillation, for example axial, on said elongated element, a device for detecting the frequency of oscillation of said elongated element, and a device for calculating the weight of the preform according to the detected frequency of oscillation. Advantageously, the device allows the realisation of a method for measuring the weight of the preform wherein the errors in measurement caused by thermal drift effects, by the axial distribution of the masses on the preform and by loads which are different from the mass of the preform in formation are reduced to below the required precision in measurement.

Abstract: Optical fiber preforms can comprise a glass preform structure with an inner cavity. A powder can be placed within the inner cavity having an average primary particle size of less than about one micron. The powder can be in the form of an unagglomerated particles or a powder coating with a degree of agglomeration or hard fusing ranging from none to significant amounts as long as the primary particles are visible in a micrograph. Powders can be placed within a preform structure by forming a slurry with a dispersion of submicron/nanoscale particles within a cavity within the preform. In other embodiments, a powder coating is formed within a preform structure by depositing the powder coating directly from a reaction product stream. The formation of the powder coating can be formed within the reaction chamber or outside of the reaction chamber by flowing the product particle stream through a conduit leading to the preform structure. In additional embodiments, a powder coating is placed on an insert, e.g.

Abstract: The improved plasma torch for making synthetic silica includes use of nitrogen screen gas from outer quartz tubing to provide active environment isolation. In addition, the present induction plasma torch includes a ring disk for more compact but complete environmental protection (360 degree coverage). It also includes offsetting and switching the position of the chemical injection nozzles for allowing improved deposition in both directions, when operated in a horizontal mode. Further, the present induction plasma torch maintains laminar flow for the injected chemicals and the middle quartz tube is provided with a concave section for increasing the average enthalpy of plasma jet, thus improving the efficiency of the plasma torch. In addition, it may utilize more plasma gas inlets. It also includes chemical injection nozzles having a downward angular inclination.

Abstract: An optical fiber preform is fabricated by inserting a number of core body pieces end-to-end inside a glass cylinder, wherein the pieces may have a cladding-to-core diameter (D/d) ratio within the range of one to four. The cylinder with the inserted core body pieces is mounted vertically on a furnace and heated so that the cylinder becomes elongated and its outside diameter collapses to form a core rod from which core rod sections with D/d ratios greater than five, can be cut. A soot overcladding is deposited on the circumference of a core rod section until the diameter of the deposited soot builds to a determined value. The core rod section with the deposited soot overcladding is consolidated to obtain a finished optical fiber preform. The preform preferably has a D/d ratio of about 15 or more, and an optical fiber may be drawn directly from the preform.

Abstract: Fused silica injected or created by pyrolysis of SiCl4 are introduced in a powder state into a vacuum chamber. Pluralities of jet streams of fused silica are directed towards a plurality of heated substrates. The particles attach on the substrates and form shaped bodies of fused silica called preforms. For uniformity the substrates are rotated. Dopant is be added in order to alter the index of refraction of the fused silica. Prepared soot preforms are vitrified in situ. Particles are heated, surface softened and agglomerated in mass and are collected in a heated crucible and are softened and flowed through a heated lower throat. The material is processed into quartz plates and rods for wafer processing and optical windows.

Abstract: The invention starts from a known method for producing a glass body, comprising forming a cylindrical blank by successive deposition of a plurality of material layers on the outer surface of a substrate body which is rotating about its longitudinal axis, by using an arrangement of a plurality of depositors which are directed onto the substrate body and which are fed via supply lines with process media for material layer deposition and which are moved without a reversing movement relative to the longitudinal axis of the substrate body. Starting therefrom, to provide a method for producing a glass body of high homogeneity that can be realized in a constructionally simple way, the invention suggests that the movement of the depositor arrangement along the longitudinal axis of the substrate body should be accompanied by a displacement of the substrate body.

Abstract: A method for manufacturing a preform having a core and a multilayer clad, includes covering a circumference of a rod including at least the core and an inner clad layer with a first tube including at least a high viscosity clad layer, and unifying the rod and the first tube by heating and contracting the first tube.

Abstract: A method of producing a glass-particle-deposited body that has a small diameter variation and the like resulting from alteration of the deposition condition is offered. When the glass-particle-deposited body is produced, a burner row constituted by placing a plurality of burners is moved relative to a starting member, and glass particles ejected from the burners are deposited on the starting member. In the method of producing a glass-particle-deposited body, alteration of the deposition condition is performed during the course of the deposition of the glass particles on the starting member. The method of producing a glass-particle-deposited body has a feature in that the alteration of the deposition condition is performed at least twice and that the burner positions along the length of the starting member at which the deposition condition is altered are placed at intervals shorter than the intervals between burners.

Abstract: A method for manufacturing an optical fiber preform of the invention is a method for manufacturing an optical fiber preform, which forms a deposition portion composed of glass fine particles on a glass rod so as to form a glass fine particle deposition, and suspends the glass fine particle deposition vertically into a heating furnace to heat the glass fine particle deposition to transparentize the deposition portion, the method comprising: a step of forming a hazy portion, by causing a surface portion of the glass rod to sublime and adhere to at least a portion of a region closer to one end of the glass rod than a region of the glass rod where the deposition portion is formed, before said heating; a step of forming the deposition portion by depositing the glass fine particles on the glass rod; and a step of transparentizing the deposition portion by heating the glass fine particle deposition in a state where the proximal end of the glass rod where the hazy portion is formed is held and the glass fine particle

Abstract: A method for preparing doped oxide material, in which method substantially all the reactants forming the oxide material are brought to a vaporous reduced form in the gas phase and after this to react with each other in order to form oxide particles. The reactants in vaporous and reduced form are mixed together to a gas flow of reactants, which gas flow is further condensated fast in such a manner that substantially all the component parts of the reactants reach a supersaturated state substantially simultaneously by forming oxide particles in such a manner that there is no time to reach chemical phase balances.

Abstract: A method of fabricating an optical fiber preform, capable of depositing glass particles with high deposition rate without reducing deposition efficiency and fabricating an optical fiber preform having little bubbles using a burner having a simple structure, is provided. In the invention, a mixed gas of a glass raw material gas with a combustion assisting gas is ejected from an annular nozzle of a burner having a coaxially multiple tube structure, and a burnable gas is ejected from an inner nozzle located inside the annular nozzle. Alternatively, a mixed gas of a glass raw material gas with a burnable gas may be ejected from an annular nozzle, and a combustion assisting gas is ejected from an inner nozzle located inside the annular nozzle. In each case of the above, the burnable gas and the combustion assisting gas, respectively, are ejected from outer nozzles located outside the annular nozzle.

Abstract: Device and method for chemical deposition on an elongated member of vitreous material in which a rotating gripping member causes a first end portion of the elongated member to rotate. The second end portion of the elongated member is borne by a pair of supporting members which are axially spaced apart (L1) and are capable of permitting angular rotational movement and axial sliding of the second end portion. Each supporting member also applies a radial constraint preventing the second end portion from moving away from the axis of rotation, thus forcing the second portion and the elongated member to lie with a longitudinal axis coaxial with the axis of rotation. Any curvature of the elongated member is corrected and recovered in this way.