Abstract: A method of making a glass article such as an optical waveguide preform is disclosed. The method comprises drawing a rod in at least two steps. In the first step an elongated, consolidated preform having an aperture therethrough is drawn to a reduced diameter preform. The second step involves drawing the reduced diameter preform into a rod, preferably at a lower temperature than the first step. The method substantially reduces the formation of inclusions in the glass article during drawing.

Abstract: A drawing apparatus 1 has a drawing furnace 11, a heating furnace 21, and a resin curing section 31. The drawing furnace 11 has a muffle tube 13 to which an He gas supply passage 15 from an He gas supply section 14 is connected so as to supply He gas. The optical fiber 3 drawn upon heating by the drawing furnace 11 is fed to the heating furnace 21, whereby a predetermined part of the optical fiber 3 is annealed at a predetermined cooling rate. The heating furnace 21 has a muffle tube 23 to which an N2 gas supply passage 25 from an N2 gas supply section 24 is connected so as to supply N2 gas. Thereafter, the optical fiber 3 is coated with a UV resin 39 by a coating die 38, and the UV resin 39 is cured in the resin curing section 31, whereby a coated optical fiber 4 is formed.

Abstract: A method for manufacturing an optical fiber comprises setting a heating condition for heating a glass rod, which is a parent material of the optical fiber, and an elongating speed of the glass rod based on a prescribed numerical value which changes with a progress of elongation of the glass rod; heating and elongating the glass rod to generate a preform based on the heating condition and the elongating speed which are set by the setting; and drawing the preform to a filament-like form by further heating the preform to generate the optical fiber.

Abstract: A method of fabricating an optical fiber incorporating a volatile constituent, involving: (a) providing a preform comprising a cladding glass having an axial aperture and a core glass arranged in the axial aperture, wherein the working temperature of the core glass lies below the working temperature of the cladding glass; and (b) drawing the preform into an optical fiber at a drawing temperature that lies between the working temperatures of the core and cladding glasses and above the softening temperature of the cladding glass, wherein the core glass prior to drawing includes a dioxide or higher oxide compound of the volatile constituent having a Gibbs free energy of disassociation into a monoxide compound of the volatile constituent that is negative at the drawing temperature, whereby the dioxide or higher oxide compound tends to disassociate into the monoxide compound during drawing. The volatile constituent may be Sn or Pb. The method may also be adapted for incorporating P as the volatile constituent.

Abstract: The present invention is directed to a silica forming feedstock and a method of making optical waveguides and optical waveguide preforms. The feedstock for use in the manufacturing of germanium doped silica glass products includes a siloxane and a germanium dopant component such as germanium alkoxide. The invention further relates to the manufacturing of optical waveguides and optical waveguide preforms using a fluid feedstock which includes a siloxane and germanium dopant component, preferably germanium alkoxide.

Abstract: An optical fiber preform 2 having a viscosity ratio R&eegr;=&eegr;0/&eegr;t of 2.5 or less between the core average viscosity &eegr;0 and the total average viscosity &eegr;t is prepared, and is drawn by a drawing furnace 11 so as to yield an optical fiber 3, which is then heated to a temperature within a predetermined range so as to be annealed by a heating furnace 21 disposed downstream the drawing furnace 11. Here, upon annealing in the heating furnace 21, the fictive temperature Tf within the optical fiber lowers, thereby reducing the Rayleigh scattering loss. At the same time, the viscosity ratio condition of R&eegr;≦2.5 restrains the stress from being concentrated into the core, thereby lowering the occurrence of structural asymmetry loss and the like. Hence, anoptical fiber which can reduce the transmission loss caused by the Rayleigh scattering loss and the like as a whole, and a method of making the same can be obtained.

Abstract: A method of fabricating a microstructured optical fiber is described in which a plurality of solid silica wafers are generated corresponding to longitudinally consecutive portions of the optical fiber, separately etched with void patterns in a lithographic process, and bonded together into a preform. The preform is then drawn to form the optical fiber. The lithographic process used to form the void patterns in the wafers may be any of several processes currently or prospectively used in VLSI fabrication. Such lithographic process may be used because the wafers comprise silica glass or other material common in VLSI devices and, in accordance with a preferred embodiment, are generated with thicknesses highly amenable to such fabrication methods. The wafers are preferably generated by creating a preliminary preform having the desired material refractive index profile using conventional preform fabrication methods, the wafers then being sliced from the preliminary preform.

Abstract: In connection with drawing a fiber in a drawing portion of a drawing device having a refractory, oxide component, a method and apparatus provide an environment in the drawing portion that causes active oxidation of a refractory contaminant on a blank. The active oxidation of the refractory contaminant causes it to corrode away during drawing.

Abstract: The present invention provides an optical fiber and the like comprising a structure making it possible to realize optical communications with a higher speed and a larger capacity as compared with conventional optical transmission systems. The optical fiber according to the present invention is an optical fiber in which at least one first portion having a positive chromatic dispersion at a predetermined wavelength within a wavelength band in use and at least one second portion having a negative chromatic dispersion at the predetermined wavelength are arranged adjacent each other along the longitudinal direction thereof. In particular, the optical fiber comprises a polarization coupling structure for inducing coupling between polarization modes of propagating light. This polarization coupling structure randomly causes coupling between polarization modes of the propagating light, whereby polarization mode dispersion decreases at the predetermined wavelength.

Abstract: An optical fiber has a section of the first kind having a chromatic dispersion not less than a given positive value x and a negative chromatic dispersion slope at a given wavelength and a section of the second kind has a chromatic dispersion not more than −x and a positive chromatic dispersion slope at the same wavelength. Another optical fiber has a chromatic dispersion higher than a positive value x and a negative chromatic dispersion slope at a given wavelength band.

Abstract: The invention proposes to fabricate an optical fiber by drawing a preform including several layers, at least one of which has a different viscosity to the other layers at the drawing temperature. The drawing tension is varied during drawing to obtain a fiber having a constant diameter and a varying profile. The chromatic dispersion of the fiber can therefore vary along the fiber. The invention applies to the fabrication of dispersion managed fibers (DMF).

Abstract: An improved process for fabricating a refractory dielectric article, in particular silica optical fiber, is provided. The fabrication process involves joining of two elongated bodies—typically silica preforms—end-to-end by use of an isothermal plasma torch technique. A long preform made in this manner allows drawing of optical fiber with less down-time and waste than current processes. The plasma torch technique also produces low perturbations within the resultant preform, thereby increasing the amount of usable fiber.

Abstract: A wavelength selective optical fiber coupler having various applications in the field of optical communications is disclosed. The coupler is composed of dissimilar waveguides in close proximity. A light induced, permanent index of refraction grating is recorded in the coupler waist The grating filters and transfers energy within a particular range of wavelengths from a first waveguide to a second waveguide. Transversely asymmetric gratings provide an efficient means of energy transfer. The coupler can be used to combine or multiplex a plurality of lasers operating at slightly different wavelengths into a single fiber. Other embodiments such as a dispersion compensator and gain flattening filter are disclosed.

Abstract: The present invention relates to a rod-shaped preform for manufacturing an optical fibre therefrom, as well as to a method for manufacturing such a rod-shaped preform. The present invention furthermore relates to a method for manufacturing an optical fibre, wherein one end of a rod-shaped preform is subjected to a heat treatment, after which the thus softened end of the rod-shaped preform is subjected to a pulling force for the purpose of drawing an optical fibre therefrom.

Abstract: Our method of making high bandwidth silica-based multimode optical fiber comprises provision of a non-circular preform, and drawing fiber of chiral structure from the preform. The non-circular preform can be made by maintaining the inside of the tubular preform under reduced pressure during at least part of the collapse, resulting in a non-circular core and cladding. It can also be made by removal (e.g., by grinding or plasma etching) of appropriate portions of the preform, resulting in a circular core and non-circular cladding. In the latter case, fiber is drawn at a relatively high temperature such that, due to surface tension, the cladding assumes substantially circular shape and the core assumes a non-circular shape. The chiral structure is imposed on the fiber in any appropriate way, e.g., by twisting during fiber drawing the fiber alternately in clockwise and couterclockwise sense relative to the preform.

Abstract: A method for threading a lead end of a fiber through the drawing apparatus of a fiber draw process. A prethread filament is fed through the apparatus of a draw process. One end of the prethread filament is then attached to the lead end of the fiber and used to pull the fiber through the apparatus of the draw process.

Abstract: An optical fiber making apparatus has a main pipe connected to the furnace core tube, two branch pipes branching from the main pipe, and a gas source, a valve and a flow meter connected to each of the branch pipes. The flows or compositions of the inert gases supplied from the gas sources into the furnace core tube are varied. This changes the amount of heat applied to the lower end of the optical fiber preform, without depending solely on the main heater, to adjust the draw tension and thereby change the local chromatic dispersion along the longitudinal direction of the optical fiber being manufactured.

Abstract: The specification describes a process and apparatus for collapsing preform tubes in Modified Chemical Vapor Deposition processes. The problem of bubble formation during tube collapse was found to be attributable to excess dopant vapor pressure emitted from the hot zone during the final stage of tube collapse. This excess pressure is controlled by cooling the tube in advance of the torch, thereby decreasing the viscosity of the dopant vapor and increasing its transport rate. This is found to reduce internal tube pressure and eliminate bubble formation in the collapsed preform.

Abstract: In the fiber-drawing method, a first preform is lowered along a fiber-drawing axis through a fiber-drawing oven so as to be heated and drawn down into an optical fiber, and a second preform is lowered along the fiber-drawing axis through the fiber-drawing oven so as to be heated and drawn down in turn after the first preform has been withdrawn. While the first preform is being drawn down into a fiber, the second preform is heated in a preheating oven disposed adjacent to the fiber-drawing oven so as to raise the second preform to a temperature which is slightly below the fiber-drawing temperature, and the preheated second preform is transferred quickly onto the fiber-drawing axis after the first preform has been withdrawn therefrom. This method contributes to increasing the capacity for producing optical fibers.

Abstract: A method for drawing a glass ingot into a rod having a given outer diameter is described. The method is characterized in that when the glass ingot is fed into a heating zone at a final tapered portion thereof, a temperature in the heating zone is decreased so that the final tapered portion is prevented from being drawn in excess owing to the heat from the heating zone.

Abstract: Glass compositions displaying decreased far infrared radiation transmission, high biosolubility, and excellent moisture resistance are capable of fiberization by the rotary process, and may be used to prepare thermal insulation products exhibiting high thermal insulation efficiency as reflected by low thermal index values. The insulation products also exhibit excellent stiffness and recovery properties.

Abstract: A method for manufacturing a glass preform from a metal sulfide chalcogenide glass to which a large amount of light emitting substances can be added includes steps of etching a surface made of the chalcogenide glass or oxychalcogenide glass of disc shape core and clad forming glass starting materials by an etchant including an acid and a compound reacting with a hydrogen chalcogenide, and forming the core forming glass starting material and the clad forming glass starting material into a united body serving as a glass preform. In a method for manufacturing a single-mode glass fiber using a preform method by drawing the glass preform whose outer round surface is made of a chalcogenide glass or oxychalcogenide glass, the outer round surface of the glass preform is etched using an etchant including an acid and a compound reacting with a hydrogen chalcogenide and then drawn into the glass fiber.

Abstract: The invention relates to coated optical fibers which are coated with a particular radiation-cured primary coating layer composition. The fibers which are coated comprises a glass core and a glass cladding layer. The core, for example may comprises silica doped with oxides of germanium or phosphorous and the cladding, a pure or doped silicate such as fluorosilicate. Alternatively, the fibers may comprises a polymerclad silica glass core. Examples of such claddings include organosiloxanes such as polydimethylsiloxane or a fluorinated acrylic polymer.

Abstract: Dehydroxylated, silica-containing, glass surfaces are known to be at least partially terminated by strained siloxane rings. According to the invention, a surface of this kind is exposed to a selected silane compound or mixture of silane compounds under reaction-promoting conditons. The ensuing reaction results in opening of the strained siloxane rings, and termination of surface atoms by chemical species, such as organic or organosilicon species, having desirable properties. These species can be chosen to provide qualities such as hydrophobicity, or improved coupling to a polymeric coating.

Abstract: Disclosed is a method of controlling the diameter of a glass rod drawn from a glass preform. The diameter control begins as soon as a glass gob begins to move away from a heated portion of the preform. The velocity of the gob is measured and furnace temperature adjusted to maintain gob velocity at a pre-selected target value. By starting diameter control at this early stage of the process, utilization of the preform is improved as is the utilization of the drawing equipment.

Abstract: A process for producing a preform for a chalcogenide glass fiber which comprises inserting a cladding tube having contained therein a chalcogenide glass rod for core into a quartz tube having at its bottom a nozzle having an aperture smaller than the outer diameter of the cladding tube, locally heating the bottom of the quartz tube and pulling the cladding tube having contained the glass rod for core and a process for producing a chalcogenide glass fiber by heating and drawing the preform thus obtained, by which processes the devitrification of glass and the generation of bubbles in the core glass or at the core glass-cladding glass interface can be prevented and the adhesion between the core glass and the cladding glass can be improved. In particular, when the glass material for core does not contain Ge, a chalcogenide glass fiber having such a core-cladding structure that the transmission loss of the glass fiber when infrared light pass through the fiber is small and the mechanical strength is high.

Abstract: Glass compositions displaying decreased far infrared radiation transmission, high biosolubility, and excellent moisture resistance are capable of fiberization by the rotary process, and may be used to prepare thermal insulation products exhibiting high thermal insulation efficiency as reflected by low thermal index values.

Abstract: Fiber bow makes mass fusion splicing of optical fiber difficult and this is undesirable. We have found that fiber bow can be significantly reduced if the fiber that is being drawn from a heated optical fiber preform is caused to run through a tubular cooling chamber that extends from the draw furnace, the cooling chamber comprising a tube of inner diameter d.sub.1 <35 mm, preferably <20 mm. In a preferred embodiment the cooling chamber includes an upper cooling chamber of inner diameter d.sub.2 >d.sub.1, with a transition element providing a smooth transition between the two chambers. The cooling chamber desirably is free of turbulence-causing air leaks and/or geometrical features.

Abstract: In a drawing method and drawing apparatus according to the present invention, a forward end portion of an optical fiber glass preform is heated and melted while the glass preform is fed into a drawing furnace 3 so that an optical fiber is drawn, and the optical fiber glass preform is heated in a position just above the drawing furnace to make the surface of the glass preform clean.

Abstract: A method for manufacturing a glass fiber includes a process of drawing a starting glass material partially or entirely made of chalcogenide glass or oxychalcogenide glass, such as preform rod, rod-in-tube, or jacketing tube, into a glass fiber in an atmosphere containing sulfur. The concentration of the sulfur in the atmosphere is set at sulfur's vapor pressure or greater around the glass surface at a maximum temperature of the glass fiber while the glass fiber is drawn, thereby fabricating the glass fiber without forming substantially any crystallization on the glass surface.

Abstract: Optical fibers having novel refractive index profiles are disclosed. Optical fibers in accordance with the invention are especially useful for application in telecommunication applications such as networks. Processes for the preparation of optical fibers are also disclosed.

Abstract: Measurement of the delamination resistance of polymer coated optical fiber can provide valuable information for quality control and/or coating development, and a method of making polymer coated optical fiber that includes determination of the delamination resistance is disclosed. Also disclosed is apparatus that facilitates determination of the delamination resistance.

Abstract: To draw an optical fiber (10) from one end of a glass preform (9) which is heated to above the glass softening temperature at least in that area, a gas (21) flows around the preform (9) into a furnace space (16) during the drawing process and subsequent feeding of the preform. During the feeding, the areas that are adjacent to the drawing end of the preform (9) pass through gas zones in which the helium content of the furnace gas increases in the drawing direction.

Abstract: In accordance with the invention, a Ge-doped optical fiber having reduced Brillouin scattering loss is made by modulating the tension applied to the fiber during draw. The draw tension is modulated between a low range 10-50 g and a high in the range 150-250 g. The result is SBS suppression with no significant change to end-to-end fiber loss or dispersion factors.

Abstract: This invention provides a method of increasing adhesion of radiation-cured, inner primary coatings on glass optical fibers. A glass optical fiber drawing tower has a controllable variable amperage electron beam for exposing different sections of a glass optical fiber with different amperage levels of electron beam radiation. The different sections of the glass optical fiber after being exposed to the selected amperage levels of electron beam radiation are then coated with an inner primary coating composition which is finally cured by exposure to actinic radiation. Later formed sections of the same glass optical fiber can be exposed to different amperage levels of electron beam radiation and then coated and cured. The different sections of the glass optical fiber which have been coated with an inner primary coating using this method demonstrate correspondingly different degrees of coating adhesion. Reduced levels of adhesion promoter are required for inner primary coating compositions when using this method.

Abstract: A glass body for optical fiber containing GeO.sub.2 --SiO.sub.2 glass in a core portion thereof, in which the GeO.sub.2 --SiO.sub.2 glass has an absorbance at 5.16 eV of at least 1/mm but not higher than 2.5/mm or in which concentration of Ge.sup.2+ contained in the GeO.sub.2 --SiO.sub.2 glass substantially lies within the range of 1.1.times.10.sup.-9 to 2.8.times.10.sup.-9 mol/mm.sup.3 as calculated by the following general equation:A=.epsilon..sub.5.16ev .multidot.C.sub.(Ge2+) .multidot.1wherein A is absorbance which is expressed by A=-log T (T being transmittance) and normalized per 1 mm of optical path length, C.sub.(Ge2+) is Ge.sup.2+ concentration, .epsilon..sub.5.16ev is absorption coefficient (1/mol/cm), and 1 is optical path length.

Abstract: The present invention relates to a method for precisely elongating a glass preform of an optical fiber body having a desired outer diameter. In this method, a predetermined part of the glass preform is elongated as tensile stress is applied to one end of the glass preform while a predetermined part of the glass preform is heated and softened successively from one end toward the other end of the glass preform. In this elongating operation, while the outer diameter of the softening portion of the glass preform is measured, the tensile stress is adjusted such that the outer diameter of the softening portion coincides with a preset value of the control outer diameter. In particular, this method is characterized in that the preset value of the control outer diameter is changed at least during a predetermined period until termination of elongation or during a predetermined period from the start of elongation.

Abstract: Optical fibers having novel refractive index profiles are disclosed. Optical fibers in accordance with the invention are especially useful for application in telecommunication applications such as networks. Processes for the preparation of optical fibers are also disclosed.

Abstract: A method for the controlled stretching of one or more optical fibers according to a desired profile and a device for its implementation. The method includes several steps. In these steps, a speed V.sub.e =dx.sub.e /dt of flow of the fiber entering the heating chamber is laid down, a relationship f of variation of the diameter D.sub.s of the fiber during exit from the heating chamber is chosen such that D.sub.s =f(x.sub.s) wherein x.sub.s represents the positions, variable in time, of a point on the fiber during exit from the heating chamber, successive stretching operations are performed on the fiber to modify, each time, the diameter D.sub.s of the fiber during exit from the heating chamber, so as to follow the profile defined by the relationship f of variation. The method has application to the making of optic fiber devices.

Abstract: A single mode optical fiber suitable for use in an amplified fiber optic system which includes an inner glass core doped with a rare earth element and an outer transparent glass cladding. The fiber exhibits a plurality of mode coupling sites formed at regular intervals along the length of the fiber which provides for a reduced DOP. The sites are formed by a twist at regular intervals along the fiber length by applying a torque to the fiber. The method of forming the fiber is also disclosed.

Abstract: A coated optical fiber comprising a light-transmitting fiber and a resin coating layer disposed on the outer periphery of the light-transmitting fiber is formed, an external flaw is imparted to the surface of the resin coating layer while running the coated optical fiber, and then the coated optical fiber is subjected to the measurement of a tensile breaking strength thereof. At this time, the fiber having a strength retention ratio R.sub.S =S.sub.A /S.sub.0 of 0.98 or more, wherein S.sub.A is the median value of the tensile breaking strength after the provision of the external flaw, and S.sub.0 is the median value of the tensile breaking strength before the provision of the external flaw, is selected as a non-defective product.

Abstract: A radiation resistant optical waveguide fiber doped with fluorine or drawn with low tension in the fiber. The fluorine doping is substantially constant across the core and a portion of the clad adjacent the core. The concentration of the fluorine is in the range of about 0.3 to 3.0 weight percent. The draw tension is less than or equal to about 5 grams (40 dynes/cm.sup.2) to achieve optimum radiation resistance. A synergy is found when fluorine and low draw tension are applied to a fiber. Improvement in radiation resistance is largely independent of fiber type and geometry. Further improvement in radiation resistance is found when germanium is doped in a portion of the clad adjacent the core.

Abstract: A glass preform for an optical fiber is effectively drawn by connecting dummy rods to both ends of the glass preform and connecting the dummy rods to fitting members.

Abstract: In accordance with the invention, an optical fiber is made by the steps of providing an optical fiber preform having a longitudinal axis, rotating the preform about the axis, directing onto the preform a plasma torch which is reciprocated over a limited region parallel to the axis to define a heated region, and drawing a fiber from the heated region. Apparatus for making optical fiber comprises a rotatable mount for securing one end of a preform and rotating it about a vertical axis, a plasma torch for heating a drawing region on the preform, a positioning stage for moving the torch parallel to the vertical axis in a reciprocating manner, and a fiber drawing apparatus for drawing a fiber from the heated region of the preform.

Abstract: A capstan belt (80) is mounted on a pair of pulleys (82,83) for engagement with the surface of a draw capstan (75), the capstan belt (80) being driven for rotation on the pair of pulleys (82,83) by rotational movement of the capstan (75). A coated optical fiber (35) is drawn between the capstan (75) and the capstan belt (80). At least a surface of the capstan belt (80) is manufactured of a very low modulus material which easily deforms when contacting the coated optical fiber (35) such that the belt material deforms rather than the coating on the fiber during contact between the belt and the coated fiber. An idler belt (78) may surround the capstan (75) and an idler pulley (79), at least the surface of the idler belt (78) being manufactured of the same or similar material as the capstan belt (80). The belt material has a modulus of elasticity in the range of 10 to 200 PSI (0.07 to 1.38 MPa) at 10% strain and 200 to 5000 PSI (1.38 to 34.5 MPa) at 100% strain.

Abstract: A furnace and method for drawing an optical fiber is provided. The furnace included a furnace core chamber in which a preform is inserted into the chamber through the upper end thereof and a drawn optical fiber is pulled out of the chamber through an opening positioned at the lower end thereof. The furnace also includes a gas-supply means for introducing an inert gas into the furnace core chamber to thus establish an inert gas atmosphere within the chamber, and a heater for heating the preform so that the lower part of the preform is molten and drawn into the optical fiber, which is positioned around the outer periphery of the furnace core chamber. The furnace further includes an inner furnace core tube, which is positioned within the furnace core chamber and which has a cylindrical part whose lower part is communicated to the opening of the furnace core chamber and a funnel-like part which is positioned on the upper end of the cylindrical part.

Abstract: A method and apparatus are provided for drawing a self-aligned core fiber free of surface contamination and inserting the core fiber into a cladding material to make an optical fiber preform. Single or multi-mode optical fibers having high quality core-clad interfaces can be directly drawn from the preforms described herein.

Abstract: A system for controlling the drawing of a hermetically-coated optical waveguide fiber from a preform is provided in which two measurements of fiber diameter are made and combined into an overall control signal. The first measurement is made on bare fiber in the region of the preform's root using an interference technique. The second measurement is made after the hermetic coating has been applied using a shadow technique. The first measurement provides high speed, high accuracy data needed for process control and defect detection. It is, however, subject to error due to fluctuations in the root with tractor speed. The second measurement reduces the effects of such error on the overall control signal.

Abstract: A method for manufacturing an optical fiber (11), wherein the fiber (11) is drawn from one end of a preform (9) which is heated to above the glass softening temperature. The preform (9) is surronded by a protective gas (14) whose flow direction corresponds to the fiber drawing direction. The flow of the gas surrounding the preform (9) in the drawing area (10) is stabilized by an additional flushing gas (16).

Abstract: Disclosed is a polarization-splitting fiber coupler capable of stably executing a polarization separation/coupling and a method of stably manufacturing the polarization-splitting fiber coupler at a low cost. The method comprises the steps of (1) arranging a plurality of non-polarization fibers in parallel so that the side surfaces thereof come into contact to each other; (2) heating and fusing a portion of the arranged non-polarization fibers by controlling a heating temperature and a heating time so that the cross section of the fused portion thereof has an aspect ratio of 1.85-1.95; (3) thereafter, forming a fused/drawn portion by drawing the fused portion while keeping the aspect ratio after lowering the heating temperature; and (4) connecting polarization-maintaining fibers to the respective ends of the fused/drawn portion, respectively. Further, a portion of the connected polarization-maintaining fiber is heated and drawn to a taper-shape to provide the heated-fused portion with a polarizer function.