Abstract: Provided is a method for producing an optical fiber having low attenuation and including a core that contains an alkali metal element. An optical fiber preform that includes a core part and a cladding part is drawn with a drawing apparatus 1 to form an optical fiber 30, the core part having an average concentration of an alkali metal element of 5 atomic ppm or more and the cladding part containing fluorine and chlorine. The optical fiber includes a glass portion and resin coating portion and the glass portion is under residual stress that is a compressive stress of 130 MPa or less. During the drawing, the time during which an individual position of the optical fiber preform is maintained at 1500° C. or higher is 110 minutes or less.

Abstract: An optical fiber manufacturing apparatus for manufacturing an optical fiber by drawing a optical fiber preform, including: a drawing furnace having therein a muffle tube into which the optical fiber preform is inserted and heating the optical fiber preform; and a first seal member which is disposed at an insert side of the drawing furnace so as to be coaxial with the drawing furnace and which seals the optical fiber preform inserted into an opening formed at the center thereof, wherein the first seal member includes a plurality of inner-circumference slits formed in the inner circumference thereof and a plurality of outer-circumference slits formed in the outer circumference thereof.

Abstract: In an optical fiber manufacturing method, the cooling device and the coating device are connected in an airtight manner and by preventing a cooling gas, flowing inside the cooling device, from flowing into the coating device by a meniscus of resin inside of the coating device, a flow of the cooling gas inside the cooling device is discharged to an outside of an upper end of the cooling device as an upward stream; helium gas as the cooling gas flows into a lower portion of the cooling device and carbon dioxide gas as the cooling gas which is separated from the helium gas flows into a side lower than a position where the helium gas flows in, during the forcible cooling; and a flow rate of the helium gas and a flow rate of the carbon dioxide gas are individually controlled.

Abstract: A method of processing an optical fiber includes introducing fiber that has passed a pulling mechanism to a shredding unit with an introducing unit. The introducing unit includes a movable unit including a notch configured to fit with a capstan roller included in the pulling mechanism, a sliding mechanism that attaches the movable unit slidably with respect to a main body of the introducing unit, and a restoring mechanism configured to restore the movable unit to an initial position when the movable unit has slid. The method includes shredding the fiber introduced by the introducing unit into fiber pieces, and suctioning, carrying, and collecting the fiber pieces. A method of drawing an optical fiber includes drawing the fiber while controlling a drawing speed, adjusting a diameter of the fiber to a diameter passable through a die, and arranging the die around the fiber having the diameter passable through the die.

Abstract: In one embodiment, an optical fiber cooling system includes a first cooling tube oriented substantially in parallel with and spaced apart from a second cooling tube such that an optical fiber pathway is positioned between the first cooling tube and the second cooling tube. The first cooling tube includes a plurality of cooling fluid outlets positioned along an axial length of the first cooling tube which are oriented to direct a flow of cooling fluid across the optical fiber pathway towards the second cooling tube. The second cooling tube includes a plurality of cooling fluid outlets positioned along an axial length of the second cooling tube which are oriented to direct a flow of cooling fluid across the optical fiber pathway towards the first cooling tube.

Abstract: The invention relates to a method for manufacturing an optical fiber, wherein a preform is placed in a draw tower, which draw tower comprises a furnace in which one end of a preform is heated, after which an optical fiber is drawn from the heated end, wherein the heating and/or cooling of the draw furnace takes place with a maximum temperature gradient of 15° C./minute.

Abstract: Drawing methods and drawing furnaces for drawing an optical fiber with small non-circularity by simple drawing system are provided. An optical fiber preform is received into a muffle tube and heated by a primary heater placed to surround the muffle tube. The optical fiber preform is heated such that a starting position of a meniscus portion is higher in its position than the top of the primary heater, wherein the meniscus portion is created at the bottom portion of the optical fiber preform.

Abstract: This method for drawing a quartz glass optical component shortens the pulling process and minimizes loss of material. An end face of a quartz glass hollow cylinder forms a tapered end portion to an attachment piece of quartz glass having a bore. The inner bore of the hollow cylinder and the bore of the attachment piece are at least temporarily interconnected fluidically as a passage bore. A cleaning fluid is passed through the inner bore of the hollow cylinder and the passage bore. A core rod of quartz glass, which rests on a contact surface of the attachment piece, is inserted into the inner bore of the hollow cylinder, and the hollow cylinder is continuously supplied to a heating zone, heated therein so as to form a drawing bulb, and the component is continuously drawn therefrom.

Abstract: In a known method for producing a cylindrical glass body in a vertical drawing process, a glass blank is softened in a heating zone and drawn off as a glass strand by means of a draw-off device at a controlled drawing speed, the draw-off device comprising a first draw-off unit with rolling bodies rolling on the glass strand and being distributed around the circumference thereof, the rolling bodies being formed by a reference rolling body and at least one auxiliary rolling body, the drawing speed being controlled via the speed of the reference rolling body.

Abstract: The present invention provides a method of drawing a thermoelectrically active material in a glass cladding, comprising sealing off one end of a glass tube such that the tube has an open end and a closed end, introducing the thermoelectrically active material inside the glass tube and evacuating the tube by attaching the open end to a vacuum pump, heating a portion of the glass tube such that the glass partially melts and collapses under the vacuum such that the partially melted glass tube provides an ampoule containing the thermoelectric material to be used in a first drawing operation, introducing the ampoule containing the thermoelectric material into a heating device, increasing the temperature within the heating device such that the glass tube melts just enough for it to be drawn and drawing fibers of glass clad thermoelectrically active material.

Abstract: The present invention provides a method of drawing nanowires, comprising sealing off one end of a glass tube such that the tube has an open end and a closed end, introducing a nanowire material inside the glass tube and evacuating the tube by attaching the open end to a vacuum pump, heating a portion of the glass tube such that the glass partially melts under the vacuum such that the partially melted glass tube provides an ampoule containing the nanowire material to be used in a first drawing operation, introducing the ampoule containing the nanowire material into a heating device, increasing the temperature within the heating device such that the glass tube melts just enough for it to be drawn and drawing fibers of glass clad nanowire material. The invention further provides a method for bunching together such fibers and redrawing them one or more times to produce arrays of nanowires clad in glass.

Abstract: There is provided an elongating method of an optical fiber base material which can easily correct a distorted portion of an optical fiber base material with it being possible to elongate the optical fiber base material to reduce its diameter. According to such an elongating method, in an elongating process of elongating an optical fiber base material by heating the optical fiber base material in a heating furnace so that a diameter of the optical fiber base material is reduced, before the optical fiber base material is elongated from an end thereof, a distorted portion of the optical fiber base material is connected by being heated to be softened in the heating furnace. To do so, the optical fiber base material is attached to a hanging mechanism so as to be hung in an electric furnace, the distorted portion of the optical fiber base material is heated to be softened.

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: The present invention provides a method of fabricating rare earth doped preforms and optical fibers by a combination of modified chemical vapor deposition (MCVD) process and solution doping technique said MCVD process is used to develop matched or depressed clad structure inside a silica glass substrate tube followed by deposition of porous silica soot layer containing GeO2, P2O5 or such refractive index modifiers by the backward deposition method for formation of the core and presintering the deposited particulate layer by backward pass with flow of GeCl4 and/or corresponding dopant halides, soaking the porous soot layer into an alcoholic/aqueous solution of RE-salts containing codopants such as AlCl3 in definite proportion, drying, oxidation, dehydration and sintering of the RE containing porous deposit and by collapsing at a high temperature to produce the preform followed by drawing the fibers by known technique to produce fibers with suitable core-clad dimensions and geometry.

Abstract: A support pin—which is to be inserted into a pin insert hole formed in a seed rod provided at an upper end of a glass preform and suspends and supports the glass preform—is formed by coupling a pin main body having a flange section, a first shaft section, a second shaft section, and a male screw section with an auxiliary pin member having a flange section, a shaft section, and a female screw section. The first and second shaft sections of the pin main body and the shaft section of the auxiliary pin member are provided with claddings which are formed from synthetic resin and have elasticity. The support pin is formed so that the second shaft section of the pin main body covered with the cladding can be inserted into the pin insert hole formed in the seed rod.

Abstract: The specification describes a technique for drawing circular core multimode optical fiber using twist during draw to increase fiber bandwidth.

Abstract: A microporous structure can be formed from ductile material such as glass into an axially extended outer wall surrounding a plurality of singular micro-passages surrounded by the outer wall to provide an open area that extends continuously over the length of the outer wall. The diameter of the micro-passages will usually not exceed 25 &mgr;m and are more in range of from 0.5 to 5 &mgr;m. The structure is particularly useful as frits for the containment of packing in capillaries for chromatograph applications and more generally as flow restrictors. Continuous open diameters of the micro-passages have a relatively straight flow path that reduces pressure drop relative to the random arrangement of other frits while still providing the desired containment.

Abstract: The glass base material drawing apparatus for heating and drawing a glass base material has a storage unit for storing the glass base material having an opening unit that is opened along the longitudinal direction of the storage unit when the glass base material is placed inside the storage unit, a heating unit for heating the glass base material that has been stored inside the storage unit via the opening unit, and a pull-out unit for pulling out the glass base material heated by the heating unit. The opening unit may be opened in such a manner that the glass base material is moved from a side direction of the storage unit into the interior of the storage unit. A main axis for supporting the glass base material is connected to the glass base material. The storage unit may have a penetration hole through which the main axis is inserted when the opening unit is closed.

Abstract: A method for making gradient refractive index optical components includes mixing a molten basic material (11) with a refractive index modifying material (21) in continuously changing proportions. The mixture is changed into a plurality of semi-molten fibers (41), and the fibers are rolled to form a continuous plate (51). The plate has a continuously changing refractive index along a lengthwise direction thereof. The plate is wound around a spindle (57) to obtain a wound preformed rod (58). The preformed rod is integrally fused by local heating, and drawn to form a draw (61) having a predetermined diameter. The draw is cut into pieces. Each piece can then be made into an optical component having a continuously changing refractive index in a radial direction. The method allows precise control of all steps, and such control is achieved with relative ease throughout.

Abstract: An optical fiber for maximizing residual mechanical stress and an optical fiber grating fabricating method using the optical fiber are provided. The optical fiber includes a core formed of silica, for propagating light, and a cladding formed of boron-doped silica, surrounding the core. Alternatively, the optical fiber includes a core formed of phosphorous-doped silica and a cladding formed of silica, surrounding the core.

Abstract: The present invention relates to an optical fiber fabrication method by which an optical fiber having an objective chromatic dispersion characteristic can be obtained readily. In an optical fiber fabrication method, a cutoff wavelength is measured in an optical fiber with a fixed length obtained by first drawing a part of an optical fiber preform. A target glass diameter for yielding an objective chromatic dispersion characteristic is then determined based on the cutoff wavelength thus measured. Then the rest of the optical fiber preform is drawn so that the glass diameter becomes the target glass diameter thus determined, thereby fabricating the optical fiber.

Abstract: A method for welding a dummy tube to a quartz glass tube for use as an optical fiber preform, comprising chamfering the inner edge portion of the dummy tube and/or the quartz glass tube for use as the optical fiber preform before welding the quartz glass tube for use as the optical fiber preform with the dummy tube, and then melt welding them together.

Abstract: A method for removing contaminants from an aqueous process stream containing ammonium ions and phenol-formaldehyde resin, such as the process stream of a fiberglass insulation manufacturer. One aspect of the method includes mixing sodium hydroxide with the aqueous stream so that the sodium hydroxide combines with the ammonium ions and liberates free ammonia. Another aspect of the method includes mixing calcium hydroxide with the aqueous stream so that the calcium hydroxide combines with the phenol-formaldehyde resin to form calcium phenate. The liberated free ammonia is captured and scrubbed, while the solid calcium phenate is easily removed by filters. The aqueous process stream is then clean enough to be reused.

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: An induction furnace capable of drawing large diameter preforms of up to 130 mm is described. The induction furnace has top and bottom chimneys surrounding the entire preform during operation of the furnace with an inert conditioning gas which is introduced into the top chimney and flows downward through the furnace body and bottom chimney without significant turbulence. A distributor ring inside the top chimney redirects flow from a circumferential direction to a downward direction. The top chimney also includes a resilient seal to releasably hold the top of the preform. The bottom chimney has a smoothly decreasing cross-sectional area preventing turbulence at the furnace exit. The furnace insulation is preferably a rigid self-supporting graphite cylinder. A method of drawing large diameter preforms either to an optical fiber or to a preform of smaller diameter using such a furnace is also described.

Abstract: A drawing apparatus 1 has a drawing furnace 11 for heating and drawing an optical fiber preform 2, and a carbon heater 13 is disposed in this drawing furnace 11. The carbon heater 13 has a heating portion the length of which in a drawing direction is set to not less than 280 mm. The carbon heater 13 heats the preform so that a maximum temperature on the surface of the optical fiber preform 2 in the drawing furnace 11 becomes below 1800° C. The optical fiber preform 2 is drawn in a state in which the temperature of the muffle tube 12 of the drawing furnace 11 is kept below 1800° C., so that atomic arrangement in the optical fiber preform 2 becomes relatively aligned in a state of reduced randomness of atomic arrangement. This permits the optical fiber 3 to be drawn as reflecting the reduced randomness state of atomic arrangement, whereby the optical fiber 3 can be obtained with reduced Rayleigh scattering intensity and lowered transmission loss.

Abstract: An apparatus and method for drawing low loss fluoride glass fibers from a preform. A stream of reactive gas is passed around the preform and fiber so as to prevent moisture and oxygen contamination of the fiber while the fiber is being drawn. The apparatus includes an insulating vessel which surrounds a heating chamber in which the fiber is drawn, and a very narrow heating zone within the chamber for preventing crystallization of the drawn fiber.

Abstract: An optical fiber drawing furnace capable of the prevention of entry of an ambient gas into an inner space thereof both effectively and economically, provided with a lower gas introduction portion through which inert gas is introduced into the inner space of the optical fiber drawing furnace, a chamber separated by a lower partition, and a bottom cover. The lower partition is arranged immediately below the lower gas introduction portion and has a first hole through which the chamber and the inner space are communicated. The bottom cover has a second hole through which the chamber and the atmosphere are communicated. An optical fiber is passed through the first and second holes. A controller detects a differential pressure between a pressure P1 in the inner space and a pressure P2 in the chamber and controls the suction flow by a pump for evacuating the gas in the chamber to maintain P1>P2.

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: In order to provide a crystallized glass which can be shaped by the redraw forming and a method of manufacturing a crystallized glass article by the redraw forming, the crystallized glass contains precipitated crystals with a maximum grain size not greater than 5 .mu.m and a glass phase at a ratio of 10 to 85 vol %, and has a softening point lower than a melting point of a predominant precipitated crystal, and a property such that crystallization does not progress even when heated at a temperature higher than the softening point. In order to manufacture the crystallized glass article formed by the redrawing, the above-described crystallized glass is preformed and then subjected to the drawing while being heated to a temperature higher than the softening point.

Abstract: A fiber laser 10 with square inner cladding 12, 29 may have a single core 11 codoped either with Ytterbium or Erbium or with Thulium and Holmium at a ratio of at least 10:1 operating in a single mode to provide eye-safe radiation with wavelengths above 1.5 micron. The single core laser has a pump clad cross sectional area about 2(10).sup.3 greater than the cross sectional area of the core. A multi-core laser has a plurality of single mode cores 28 doped with any rare earth ions, the cores equally spaced by at least two core diameters in an isometric array, in a cavity having a finesse of greater than ten, to produce a single, very bright phase-locked beam in the fundamental supermode. A method starts with hexagonal cladded-core rods 35, 36 in an isometric array, which are then fused and drawn down.

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).