Abstract: A device including at least one gripping member, rotatably mounted about an axis Z-Z, adapted to hold at least one end of at least one elongated element for chemical vapour deposition for forming a preform. The device includes at least one burner being mobile along a direction substantially parallel to the axis Z-Z and adapted to deposit, on the elongated element, a chemical substance for forming a preform, and at least one suction element arranged on the opposite side of the burner on a portion of a wall of the device on the opposite side of the gripping member from the burner. At least one air suction member, mobile along direction Z, is provided with motion synchronous with respect to the burner. The wall with the air suction member has a pair of respective upper and lower tapes rigidly associated with the burner.

Abstract: A deposition system for depositing a chemical vapor onto a workpiece is disclosed, including a deposition chamber having a plurality of components for performing chemical vapor deposition on the workpiece. The deposition chamber includes an inner skin made of Hasteloy for sealing the plurality of components and the workpiece from the air surrounding the deposition system, and an outer skin that encloses the inner skin and is separated from the inner skin by an air gap. The outer skin includes vents that create a convection current in the air gap between the inner skin and outer skin of the deposition chamber. The deposition system also has a gas panel for regulating the flow of gases and vapors into the deposition chamber, and a computer for controlling operation of the gas panel and the components in the deposition chamber.

Abstract: A deposition system for depositing a chemical vapor onto a workpiece, including a deposition chamber having a plurality of components for performing chemical vapor deposition on the workpiece. The deposition chamber includes an inner skin made of Hasteloy for sealing the plurality of components and the workpiece from the air surrounding the deposition system, and an outer skin that encloses the inner skin and is separated from the inner skin by an air gap. The outer skin includes vents that create a convection current in the air gap between the inner skin and outer skin of the deposition chamber. The deposition system also has a gas panel for regulating the flow of gases and vapors into the deposition chamber, and a computer for controlling operation of the gas panel and the components in the deposition chamber.

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: 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: An Outside Vapor Deposition (OVD) apparatus for making an optical fiber preform with uniform deposition of silica particles through uniform heating to the overall length of the preform includes a mandrel having a predetermined length and driven to rotate and a burner for emitting a combustion gas together with a combustion gas toward the mandrel and burning the combustion gas to make silica particles to that the silica particles are deposited on a surface of the mandrel, wherein the burner has a length corresponding to the length of the mandrel and provides uniform temperature throughout the overall length of the mandrel at the same time.

Abstract: This invention provides a method for manufacturing an optical glass in order to prevent the deterioration of the burner used in the synthesis of glass particles that form the optical glass, and to obtain a stable quality optical glass. In this invention, the number of residual bubbles with a diameter of 0.3 mm and more is 0.005/cm3 or less per unit volume of the optical glass. Such optical glass is obtained by controlling the temperature of an end face of the burner for glass synthesis during the deposition of the glass particles by regulating the relationship of the flow velocity or the flow volume between an inflammable gas and a combustion-supporting gas.

Abstract: A method for deposition glass soot for making an optical fiber preform. A fuel and a glass precursor are flowed to a burner flame forming glass soot which is deposited onto a glass target. By first depositing an insulating layer of glass soot with a low velocity burner flame, the amount of water which may be adsorbed into the surface of the glass target can be reduced. Thereafter, the flame velocity may be increased to increase the deposition rate of the glass soot without significantly increasing the concentration of water incorporated into the glass target.

Abstract: There is provided a method for manufacturing an optical fiber base material. The method includes: connecting a dummy rod 3 to an end of a target formed of a quartz glass rod to form a rod with dummy, the target becoming the optical fiber base material by depositing thereon glass particles; forming a taper portion 10 of which a diameter of the dummy rod side is narrower than a diameter of the target side in a connecting portion between the dummy road being chucked and the target 5 when processing the rod with dummy to transparently vitrify it; and depositing glass particles on an outer circumference of the glass rod with dummy after the processing the dummy rod so as to cover the outer circumference of a large diameter side of the taper portion 10 and forming soot.

Abstract: The invention relates to a method for producing a silica glass tube which is characterized by depositing SiO2 particles on an elongate support that rotates about its longitudinal axis, thereby producing a porous with a cylindrical inner bore. Said blank is vertically aligned, suspended in a furnace using a suspension that engages with a constriction in the upper zone of the inner bore of the blank, and vitrified. The aim of the invention is to provided a method with which also heavy blanks can be secured safely and substantially without any danger of contaminations of the inner bore without using complicated securing devices. To this end, the constriction (6b) is generated by shaping the inner bore (7) when the SiO2 particles are deposited. For vitrification a suspension (8; 9; 10) is used that supports itself on the constriction (6b) and that otherwise projects into the cylindrical inner bore (7) without having any contact therewith.

Abstract: A known method for producing a cylindrical body uses a precipitation assembly (5) consisting of several precipitators (4), to which a parent substance is fed via medium supply lines (9), whereby the precipitation assembly (5) completes a closed trajectory (6) according to a predetermined displacement course, said trajectory comprising at least one precipitation path (8) that runs along the longitudinal axis (2) of the support. The aim of the invention is to provide an economical, reproducible, failsafe method based on said known procedure, which enables in particular the production of soot layers (3) on a support (1) at a high precipitation rate and nevertheless a high degree of uniformity. To achieve this, the displacement course (6) comprises a first loop (7a, 8) and a second loop (7b, 8), whereby the completion of the first loop (7a, 8) causes a right-hand torsion in the medium supply lines (9) and the completion of the second loop (7b, 8) causes a left-hand torsion in said lines (9).

Abstract: Method and burner for increasing the deposition rate of porous glass deposit in the manufacture of optical preforms, by modifying the cross-sectional shape of the flow of glass particles impacting onto a target preform. In particular, the cross-section of the flow of glass particles is modified by increasing the dimension of the flow from a circular cross-section to one having a major and minor axis in a direction substantially perpendicular to the longitudinal axis of the target preform.

Abstract: An apparatus for producing an optical fiber preform, having no seeds or bubbles at the central axis thereof and having no points at the central axis thereof where breaks may be initiated while drawing optical fiber therefrom, comprising bottom holding means 8 capable: of holding bottom end 9 of soot porous body 1 having centerline 10 consisting of mandrel 2; top holding means 11 capable of holding handle rod 3 of soot porous body 1; at least one pulling means 12 capable of holding and pulling mandrel 2 fitted in centerline 10 of soot porous body 1; at least one additional pulling means 13 capable of holding and pulling mandrel 2 when it is partly pulled out of centerline 10 of soot porous body 1 is provided. A mandrel pulling mechanism is also provided.

Abstract: To provide a method for producing a glass particle deposit and a method for producing a glass preform, in which outer diameter variation of the glass particle deposit can be reduced to thereby improve quality. A flow rate of clean gas (CG) introduced into a container potion 10 is limited to thereby prevent the outermost layer of a glass particle deposit 20 from being locally cooled and reduce variation in bulk density in the longitudinal direction of the glass particle deposit 20, that is, outer diameter variation and breakage.

Abstract: Methods, apparatus and precursors for producing substantially water-free silica soot, preforms and glass. The methods and apparatus make substantially water-free fused silica preforms or glass by removing water as a reaction product, removing water from the atmosphere, removing water from the transport process, or combinations thereof. In a first embodiment, substantially water-free soot, preforms or glass are achieved by using a hydrogen-free fuel, such as carbon monoxide, in the deposition process. In another embodiment, a soot producing burner has parameters that enable operation on a substantially hydrogen-free fuel. End burners, which minimize water production, are also described. Such water-free methods are useful in depositing fluorine-doped soot because of the low water present and the efficiency in which fluorine is incorporated. In another embodiment, glassy barrier layer methods and apparatus are described for minimizing dopant migration, especially fluorine.

Abstract: On the basis of a known process for the production of a preform for an optical fiber for optical data transmission technology, the productivity of the process for the production of complex refractive index profiles is to be improved by providing a quartz glass substrate tube which exhibits different doping in radial direction, introducing a core glass made of synthetic quartz glass into the substrate tube and covering the substrate tube with a jacket tube. A substrate tube suitable therefor is also being provided which tube requires less core glass material for the production of the preform, whether during the internal deposition or for the core glass rod in the rod-in-tube technique.

Abstract: The present invention provides an optical fiber preform manufacturing method and a burner apparatus employed for this method. In this manufacturing method, when glass particles are synthesized in an oxy-hydrogen flame emitted from a burner to form a porous optical fiber preform by depositing glass particles in the radial direction of a starting member, the relationship between the flow rate vm (m/sec) of a source material gas or a mixed gas of the source material gas and an additive gas discharged from the burner, and the flow rate vs (m/sec) of an inert gas is such that ?0.06 vm+1.4?vs??0.02 vm+1.8, and vs?0.40, while the relationship between the flow volume Vm (1/min) of the source material gas discharged from the burner and the flow volume Vs (1/min) of the inert gas is such that Vs/Vm?0.2.

Abstract: An apparatus for manufacturing a glass base material, which is a base material of an optical fiber, comprising: a base rod, around and along which said glass base material is formed; a burner that hydrolyzes and accumulates a gas material, which is a base material of said glass base material, around and along said base rod; a first burner-moving-unit that moves said burner in a direction parallel with a longitudinal direction of said base rod; and a second burner-moving-unit that moves said first burner-moving-unit in a same moving direction of said first burner-moving-unit.

Abstract: A GRIN fiber lens is fabricated by the steps of providing a graded index glass preform, thinning the graded index preform to remove a sufficient thickness of the graded glass to establish a desired ?n, and drawing a graded index optical fiber from the thinned graded index preform. Thinning, in this context, refers to removal of graded index glass from the outside of the graded index preform so as to reduce its outer diameter. The thinning thus changes ?n which is the refractive index difference between the center of the preform and its outer surface. The graded index preform can be provided by MCVD deposition followed by removal of the starting tube glass, by OVD deposition, by VAD, or by ion exchange fabrication. The thinned graded index preform is advantageously annealed before drawing in order to minimize ripple. And, in a variation of the process, an overcladding can be applied over the thinned graded preform before draw for further adjustment or control of the ?n.

Abstract: A method is disclosed for the manufacture of optical fiber preforms using plasma enhanced chemical vapor deposition (PECVD). The invention consists of a cylindrical reactor in which material such as flourine-doped silica glass is deposited on a cylindrical silica rod. A furnace for regulating reactor temperature encases the reactor. A microwave generator coupled with a resonator and an H10 waveguide delivers microwave energy to the reactor, producing simultaneously symmetrical excitations in the E010 mode and a plasma surface wave in E01 mode located at the surface of the rod. A microwave plasma is scanned along the length of the rod through a slit in the reactor to deposit a homogeneous film of a desired thickness. The benefits of the present invention over the prior art include increased absorption of delivered power, and the ability to uniformly deposit films such as flourine-doped silica on rods with diameters of up to 30–35 mm and thus produce optical fiber preforms with diameters greater than 40 mm.

Abstract: The invention provides a low cost method of manufacturing high capacity preforms by chemical vapor deposition. More particularly, there is described a method of manufacturing an optical fiber preform, which method comprises the steps of providing a substrate tube of silica doped with sufficient chlorine to obtain an OH concentration of less than 100 ppb and doped with sufficient fluorine proportional to the chlorine doping to obtain a refractive index that is lower than that of a natural silica, depositing inner cladding and an optical core inside the substrate tube, collapsing the substrate tube to form a primary preform, and depositing outer cladding of said natural silica on the resulting primary preform. The invention is applicable to manufacturing optical fibers.

Abstract: An apparatus for manufacturing a glass-base-material, which is a base material of an optical fiber, includes a driving unit that drives a glass rod around an axis of the glass rod; a burner for accumulating glass soot around outside surface of the glass rod, which is driven by the driving unit, to form the glass-base-material; a weight-deducting unit, on which the driving unit is mounted, for deducting a predetermined weight from a total weight of the driving unit and the glass-base-material formed by the burner; and a measuring unit provided under the weight-deducting unit for measuring the total weight, from which the predetermined weight is deducted by the weight-deducting unit.

Abstract: An apparatus for manufacturing a glass-base-material, which is a base material of an optical fiber, includes a driving unit that drives a glass rod around an axis of the glass rod; a burner for accumulating glass soot around outside surface of the glass rod, which is driven by the driving unit, to form the glass-base-material; a weight-deducting unit, on which the driving unit is mounted, for deducting a predetermined weight from a total weight of the driving unit and the glass-base-material formed by the burner; and a measuring unit provided under the weight-deducting unit for measuring the total weight, from which the predetermined weight is deducted by the weight-deducting unit.

Abstract: The specification describes a VAD method for producing optical fiber preforms by depositing soot onto a solid core rod. The solid core rod preferably has a uniform composition, doped or undoped, suitable for the center core region of the preform. The primary cladding layer, and additional cladding layers if desired, are produced by depositing soot on the center core rod. The surface of the center core rod is treated with an etchant torch that traverses the center core rod in front of the soot deposition torch. This produces a clean interface between the core and primary cladding. This soot-on-center-core-rod method allows the production of sharp index profiles by reducing the diffusion of dopants into and out of the center core portion of the preform that occurs in soot-on-soot processes.

Abstract: The specification describes a VAD method for dynamically controlling the growth rate of both the core soot and the cladding soot in response to separate growth monitors.

Abstract: A plurality of glass particles synthesizing burners are arranged at a predetermined burner interval opposite to a rotating starting rod. The starting rod and the glass particles synthesizing burners are relatively parallely reciprocally moved, and the soot deposition is conducted. A reciprocating speed v(mm/minute), axis rotating speed r (rpm), and burner interval L (mm) are set so that a value A expressed by the expression A=(r/v)×L is in a range 40?A?8.

Abstract: A method for producing an optical fiber preform is provided in which the variation of the outer diameter in the longitudinal direction is minimized and a target quantity of glass is accumulated as a whole. Based on a predetermined relationship between three variables: the outer diameter of a starting rod being a first variable, the outer diameter of an optical fiber preform a second variable, and the timing for ending the glass particles depositing process a third variable, the starting rod and burners are subjected to relative reciprocating movement so as to deposit glass particles on the starting rod until the timing for ending the depositing process, and then the resulting deposit body is vitrified. The third variable may be the traverse velocity, the glass particles deposition time, or the weight of a soot glass deposit body.

Abstract: The method of fabricating an optical waveguide fiber from a preform having a centerline aperture which includes reducing the pressure in the centerline aperture, then increasing the pressure in the centerline aperture to a pressure in order to improve uniformity, circularity, and/or symmetry around the centerline aperture region.

Abstract: An optical device having an optical circuit integrated on a side of a substrate having a column of substrate material. The column of substrate material preferably includes a cylindrical portion having a circular cross-section. The optical device preferably includes an optical waveguide that is wound around the cylindrical portion of the substrate. The waveguide is defined by a core region in a layer of optically transparent material on the side of the column. The core region can be generated by altering the index of refraction of the transparent material. The core region can also be generated by depositing a patterned layer of a second optically transparent material. The optical device can also include active devices such as fiber amplifiers, semiconductor lasers, and optical sampling devices. The optical device is preferably constructed by rotating the substrate while depositing optically transparent materials and/or various semiconductor materials on the substrate.

Abstract: A method and apparatus for forming a glass article such as an optical fiber having a substantially matching viscosity across an interface associated with a first section and a second section of the optical fiber is disclosed herein. The first section has a first halogen concentration and the second section has a second halogen concentration. At least one of a partial pressure of the second halogen provided to a substrate tube and a temperature of the substrate tube is configured to affect the concentration of the second halogen in the second section. Optical fiber embodiments are also included.

Abstract: A method of making an optical waveguide preform includes forming a preform including a first portion and a second radial portion, wherein the second portion includes a dopant, and wherein the first portion exhibits a density greater than the second portion. The method further includes stripping at least a portion of the dopant from the second portion. In a preferred embodiment, the stripped dopant has migrated in a previous processing step.

Abstract: Three or more glass particle synthesizing burners are arranged to be opposed to a rotating glass rod. The glass rod and the glass particle synthesizing burners are reciprocated in parallel and relatively to deposit glass particles synthesized by the burners on the surface of the glass rod, thereby producing a soot body. The glass particle synthesizing conditions of the burners arranged at both ends are changed to have a greater deposition amount of glass particles per unit time in part or all of its movement range than other burners.

Abstract: In a known method for producing an SiO2 blank, SiO2 particles are formed in a burner flame assigned to a deposition burner and are deposited under the effect of an electrical field on a deposition surface of a carrier rotating about its longitudinal axis, said at least one deposition burner being reciprocated in a predetermined sequence of movement along the developing blank between turn-around points. Starting from said method, in order to obtain blanks of a predetermined, in particular axially homogeneous, density and mass distribution, it is suggested according to the invention that the geometrical shape of the burner flame should be varied by the electrical field in dependence upon the position of the deposition burner during the sequence of movement.

Abstract: An Outside Vapor Deposition (OVD) apparatus for making an optical fiber perform with uniform deposition of silica particles through uniform heating to the overall length of the preform includes a mandrel having a predetermined length and driven to rotate and a burner for emitting a combustion gas toward the mandrel and burning the combustion gas to make silica particles to that the silica particles are deposited on a surface of the mandrel, wherein the burner has a length corresponding to the length of the mandrel and provides uniform temperature throughout the overall length of the mandrel at the same time.

Abstract: A method for producing an optical fiber preform. Glass soot particles are formed by jetting and combusting a gaseous glass-forming material and a fuel gas from a burner in the presence of oxygen. The glass soot particles are deposited on a deposition rod while rotating the deposition rod about its axis and reciprocating the burner in parallel to the deposition rod so as to form the preform and varying at least one of the translation velocity of the burner and the rotation velocity of the rod so as to obtain a predetermined radial soot density distribution in the preform.

Abstract: A method for fabricating a GRIN fiber includes forming a tube of silica-glass having a tubular core and a concentric tubular cladding adjacent and external to the tubular core. The core has a dopant density with a radially graded profile. The method includes partially collapsing the tube by applying heat thereto. The partially collapsed tube has a central channel. The method includes passing a glass etchant through the central canal to remove an internal layer of silica glass, and then, collapsing the etched tube to a rod-like preform.

Abstract: Disclosed is an optical fiber article for receiving pump radiation of a first wavelength for amplifying or generating radiation of a second wavelength. The optical fiber article includes a core for propagating light of the second wavelength. The core has a first index of refraction and includes a rare earth material. A cladding surrounds the core and has a second index of refraction that is less than the first index of refraction. The outer circumference of the cladding can include a plurality of sections, where the plurality of sections includes at least one substantially straight section and one inwardly curved section. The optical fiber article can also include at least one outer layer surrounding the cladding, where the index of refraction of the outer layer is less than the second refractive index. Methods for producing the optical fiber article are also disclosed, as well as methods for providing a preform for drawing such an optical fiber article.

Abstract: A silica glass member manufacturing method of the present invention includes the steps of making a silicon compound react in oxyhydrogen flame using a burner having a multi-tubular structure to obtain fine silica glass particles, depositing the fine silica glass particles on a support rotating and placed to oppose the burner to obtain a silica glass ingot with a temperature distribution in at least one plane perpendicular to a rotational axis of the silica glass ingot, the temperature distribution being symmetrical with respect to the rotational axis and having a maximal value between a center and a peripheral portion of the plane, and obtaining a distribution of signed birefringence values on the basis of birefringence values and directions of phase advance axes measured at a plurality of points in the plane perpendicular to the rotational axis of the silica glass ingot and cutting, from the silica glass ingot, a silica glass member whose signed birefringence values monotonously increase from the center to t

Abstract: A method and apparatus for making optical fiber preforms using simultaneous plasma deposition on the inside and outside surface of a starting tube. A starting tubular member is rotated, CFOT chemicals are selectively injected into the plasma torch, and CFIT chemicals are selectively injected to flow through the hollow of the tube. The plasma torch is traversed along the tubular member to simultaneously deposit soot on the inside and outside surface. The soot on one or both surfaces may be consolidated into a silica layer as it is deposited. The plasma torch is traversed again to deposit additional soot, and/or consolidate previously deposited soot, on one or both surfaces. The process is repeated until a predetermined amount of silica is formed on the tubular member. The tubular member is then collapsed. Optionally, additional plasma deposition is performed during or after the collapsing.

Abstract: A glass tube for use in an optical fiber preform is produced by applying a first soot on an end face of a starting member to form an elongated, porous cylindrical soot core having a first density, and applying a second soot including SiO2 on the periphery of the soot core to form a porous soot cladding having a second density greater than that of the soot core at the periphery of the core. The core and the cladding are later heated together at a temperature sufficient for sintering to form a core glass and a cladding glass. Because the soot core collapses at a greater rate than the soot cladding during sintering, the core glass separates or delaminates radially from the cladding glass. The core glass is then removed from the surrounding cladding glass, and the latter is treated to provide a high purity glass tube suitable for use as part of an optical fiber preform.

Abstract: To provide a method for producing a glass particle deposit and a method for producing a glass preform, in which outer diameter variation of the glass particle deposit can be reduced to thereby improve quality. A flow rate of clean gas (CG) introduced into a container potion 10 is limited to thereby prevent the outermost layer of a glass particle deposit 20 from being locally cooled and reduce variation in bulk density in the longitudinal direction of the glass particle deposit 20, that is, outer diameter variation and breakage.

Abstract: The present invention relates to a method of making a glass tube. In the method, a diameter expanding member is inserted through a hole in a tubular glass blank so as to expand the diameter of the hole while the temperature of the glass blank is controlled to be more than or equal to the softening point. The tubular glass blank may be a purchased product or a self-made product. In the above-mentioned method of making a glass tube, the diameter of the hole in the glass blank may be expanded while at least the rear end of the diameter expanding member is supported. The diameter of the hole in the glass blank may be expanded while both ends of the diameter-expanding member are supported. The present invention also relates to an apparatus for manufacturing a glass tube.

Abstract: A process is disclosed for making a cylindrical glass preform by outside vapor deposition. Initially, a glass soot stream is directed from a deposition burner to a tapered mandrel, as the mandrel rotates about its longitudinal axis and as the burner reciprocates longitudinally along the mandrel. Mounted at opposite ends of the mandrel are a tubular glass handle and a glass tube having a closed end. After deposition has been completed, the mandrel is removed, leaving a porous glass preform with a central aperture and with the glass handle and the glass tube located at its opposite ends. The porous preform then is dehydrated and sintered into a dense glass preform, which is placed in an elongation machine that heats the end of the preform carrying the closed glass tube, while a vacuum is drawn from the central aperture via the handle. This collapses the aperture and elongates the preform into a solid glass rod.

Abstract: A method for doping silica soot with fluorine during laydown, including providing a bait rod, and providing a burner, wherein the burner emits a reactant flame. The method also including providing at least one first gas-feed separate from the burner, wherein the gas-feed supplies a first jet of fluorine-based gases, and depositing a layer of silica soot on the bait rod by vaporizing a silica producing gas within the reactant flame of the burner. The method further including supplying the first jet of fluorine-based gases to the silica soot deposited on to the bait rod via the first gas-feed subsequent to vaporizing at least a portion of the silica producing gas within the reactant flame of the burner.

Abstract: A plurality of glass particle synthesizing burners are disposed opposite to a rotating starting rod. The starting rod and the glass particle synthesizing burners are relatively reciprocally moved to each other in parallel to the axial direction, so that glass particles synthesized by the burners are sequentially deposited on the surface of the starting rod. The movement is stopped and restarted repeatedly once or more than once during one reciprocal movement.

Abstract: The method is designed to be implemented in an installation provided with means enabling a preform held between two points by supporting end-pieces to be rotated and to be moved in translation. Heater means for heating the preform by means of a plasma torch are associated with material supply means, so as to enable the preform to be manufactured in layers. Preform/torch relative displacements, with or without material being supplied, lead either to a new layer of material being deposited on the preform, or to the most recent layer deposited being glazed. Said method interposes a one-ended reduction in layer length, starting from one of the intermediate layers, while a succession of concentric layers are being deposited on the preform in a manner such that the lengths of the layers are progressively reduced so that the preform tapers towards it ends. The one-ended reduction leads to a limitation of the thickness of a determined segment at the level of the layer deposited immediately prior to the reduction.

Abstract: A double-clad optical fiber includes a core, a multimode inner cladding disposed about the core, and a second cladding layer disposed about the inner cladding. The core includes an active material for absorbing pump radiation received by the inner cladding. The multimode inner cladding includes truncated regions including a first material, where the first material has an index of refraction that is different than the material of the inner cladding that surrounds said truncated regions, for promoting the scattering of pump radiation propagating in the multimode inner cladding for increasing the absorption of the pump radiation by the active material of the core. The truncated regions can include voids that are empty or that comprise a gas. Particles can be distributed in a soot and/or voids formed in the soot, where the soot can be deposited via Outside Vapor Deposition for forming the truncated regions in an optical fiber drawn from a preform.

Abstract: The invention relates to a method for producing a silica glass tube which is characterized by depositing SiO2 particles on an elongate support that rotates about its longitudinal axis, thereby producing a porous with a cylindrical inner bore. Said blank is vertically aligned, suspended in a furnace using a suspension that engages with a constriction in the upper zone of the inner bore of the blank, and vitrified. The aim of the invention is to provided a method with which also heavy blanks can be secured safely and substantially without any danger of contaminations of the inner bore without using complicated securing devices. To this end, the constriction (6b) is generated by shaping the inner bore (7) when the SiO2 particles are deposited. For vitrification a suspension (8; 9; 10) is used that supports itself on the constriction (6b) and that otherwise projects into the cylindrical inner bore (7) without having any contact therewith.

Abstract: A method of fabricating an optical fiber preform is disclosed which includes a step of outside deposition of silica possibly doped with at least one dopant by injecting at least one substance in the form of silica or a precursor of silica in the vicinity of a heating area created by a heating system during at least one pass of an injector system and the heating system along a longitudinal axis of the preform during which the relative positions of the injector and heating systems ore adjusted so that silica is deposited in the heated area regardless of the position of the heating system.

Abstract: This invention relates to the production of high purity fused silica glass through oxidation or flame hydrolysis of a vaporizable silicon-containing compound. More particularly, this invention is directed to the use of vaporizable, halide-free compounds in said production. In the preferred practice, a polymethylsiloxane comprises said vaporizable, halide-free compound.