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WO2000010932A1 - Procedes et appareil de production de fibre optique - Google Patents

Procedes et appareil de production de fibre optique Download PDF

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Publication number
WO2000010932A1
WO2000010932A1 PCT/US1999/016177 US9916177W WO0010932A1 WO 2000010932 A1 WO2000010932 A1 WO 2000010932A1 US 9916177 W US9916177 W US 9916177W WO 0010932 A1 WO0010932 A1 WO 0010932A1
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WO
WIPO (PCT)
Prior art keywords
tube
feedstock
core
optical fiber
preform
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1999/016177
Other languages
English (en)
Inventor
Polly W. Chu
Rebecca Dahlman
Matthew J. Dejneka
John W. Solosky
Otis L. Wilson, Jr.
Kevin J. Yost
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Corning Inc
Original Assignee
Corning Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Corning Inc filed Critical Corning Inc
Priority to AU53166/99A priority Critical patent/AU5316699A/en
Publication of WO2000010932A1 publication Critical patent/WO2000010932A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
    • C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
    • C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
    • C03B37/02709—Polarisation maintaining fibres, e.g. PM, PANDA, bi-refringent optical fibres
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
    • C03B37/01211—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
    • C03B37/01211—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube
    • C03B37/01217—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube for making preforms of polarisation-maintaining optical fibres
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
    • C03B37/01211—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube
    • C03B37/0122—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube for making preforms of photonic crystal, microstructured or holey optical fibres
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
    • C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
    • C03B37/026—Drawing fibres reinforced with a metal wire or with other non-glass material
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
    • C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
    • C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
    • C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
    • C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
    • C03B37/02736—Means for supporting, rotating or feeding the tubes, rods, fibres or filaments to be drawn, e.g. fibre draw towers, preform alignment, butt-joining preforms or dummy parts during feeding
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
    • C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
    • C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
    • C03B37/02754—Solid fibres drawn from hollow preforms
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
    • C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
    • C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
    • C03B37/0279—Photonic crystal fibres or microstructured optical fibres other than holey optical fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
    • C03B2201/31—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with germanium
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
    • C03B2201/34—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with rare earth metals, i.e. with Sc, Y or lanthanides, e.g. for laser-amplifiers
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
    • C03B2201/34—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with rare earth metals, i.e. with Sc, Y or lanthanides, e.g. for laser-amplifiers
    • C03B2201/36—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with rare earth metals, i.e. with Sc, Y or lanthanides, e.g. for laser-amplifiers doped with rare earth metals and aluminium, e.g. Er-Al co-doped
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
    • C03B2201/40—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
    • C03B2201/54—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with beryllium, magnesium or alkaline earth metals
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
    • C03B2201/58—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with metals in non-oxide form, e.g. CdSe
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2203/00—Fibre product details, e.g. structure, shape
    • C03B2203/42—Photonic crystal fibres, e.g. fibres using the photonic bandgap PBG effect, microstructured or holey optical fibres

Definitions

  • the present invention relates generally to improvements in optical fiber waveguides and their manufacture. More particularly, the present invention relates to novel methods and apparatus for forming optical fiber waveguides via filament in tube and stick in tube methods of fiberization.
  • Optical fiber waveguides have come to play an increasingly important role in communications.
  • a range of optical fiber types with regard to size, index profiles, operating wavelengths, materials, etc., must be available in order to fulfill many different system applications.
  • active devices such as amplifiers, lasers, switches and dispersion compensators.
  • optical fiber cables must be spliced together without excessive practical difficulties. It is important that these splicing techniques may be applied with ease in field locations where cable connection takes place. It is particularly important in many applications that a new fiber may be readily spliced to an existing fiber already in place. Put otherwise, removing all the existing fiber and replacing it with new fiber having different characteristics is often not an option.
  • Another method involves the insertion of a core material into a molten cladding material to create a preform.
  • the core insertion is performed rapidly so that the core does not soften or dissolve during the procedure.
  • the resultant preform is then drawn into optical fiber.
  • Flouride glasses, such as ZBLAN, manufactured in this fashion are not fusion spliceable to silica fibers, are prone to devitrification and have poor durability.
  • One of the more important methods employed in making soot used in the manufacture of low loss optical fiber is the chemical vapor deposition (CVD) process.
  • CVD chemical vapor deposition
  • relatively pure chemicals such as silicon tetrachloride
  • MCVD process is also a known CVD process.
  • a core cullet feedstock (having a particle size typically in the range of 100 - 5,000 urn) is introduced into a cladding structure.
  • the end of the core/cladding structure is heated in a furnace to near the softening temperature of the cladding and drawn into optical fiber.
  • This method overcomes some of the disadvantages of typical CVD processes, allowing the cladding composition to consist of pure SiO2 and the core composition to consist of multicomponent glasses.
  • the present invention provides methods and apparatus for producing a wide variety of optical fibers via filament in tube or stick in tube methods of fiberization.
  • the present invention comprises the steps of filling a glass tube with a glass filament or stick of the desired material and subsequent drawing or elongation of the glass tube at elevated temperatures.
  • the material within the tube melts at the draw temperature and fills the tube to form a continuous core.
  • the loose fitting feedstock can be automatically fed or melted down by gravity to maintain a constant depth of molten feedstock, yielding a homogeneous and reproducible product.
  • the feedstock can be comprised of a core material or a core/clad material.
  • the tube can be comprised of additional core material (e.g., which could be used to form the outer core region), core/clad material, or a cladding material.
  • additional core material e.g., which could be used to form the outer core region
  • core/clad material e.g., a cladding material
  • the present invention can be used to draw optical fiber directly (filament in tube) or can be used to make a core cane or a core clad cane which is then overcladded with additional material before being drawn into optical fiber (stick in tube).
  • the present invention allows almost any glass that can be produced by chemical (sol-gel, vapor deposition, etc.) or physical (batch and melt) techniques to be economically fabricated in the form of a continuous clad filament.
  • chemical sol-gel, vapor deposition, etc.
  • physical batch and melt
  • FIG. 1 is a cross sectional drawing of suitable apparatus for performing the filament in tube method of drawing optical fiber in accordance with the present invention
  • FIG. 2 is a cross sectional drawing of suitable apparatus for performing the stick in tube method of drawing optical fiber in accordance with the present invention
  • FIG. 3 illustrates suitable apparatus for overcladding an optical cane formed in accordance with the present invention which may then be drawn into optical fiber in accordance with the present invention
  • FIG. 4 is a graph showing loss as a function of wavelength for a 5 meter span of optical fiber produced in accordance with a filament-in-tube method of the present invention
  • FIG. 5 is a graph showing the refractive index profile of a core clad cane produced in accordance with the present invention.
  • FIG. 6 is a graph showing loss as a function of wavelength for a 5 meter span of optical fiber produced in accordance with a stick-in-tube-method of the present invention.
  • FIG. 7 is a graph showing the loss and mode field diameter as a function of fiber length for an optical fiber produced in accordance with the present invention.
  • the present invention provides methods and apparatus for producing a wide variety of optical fibers via filament in tube and stick in tube methods of fiberization as more fully discussed below.
  • a glass or crystalline stick of the desired core composition should be obtained. It does not matter if the stick has a round, square, or triangular, or some other different cross section, it need only fit within a cladding tube with which it is to be utilized. Unlike the weli known rod-in-tube method, the inventive method does not require the core to fit tightly and concentrically within the cladding tube, since the core filament melts to conform to the cladding walls.
  • the tube bore need not be circular, but can be rectangular in shape for efficiently coupling the light from a stripe laser diode or to form a polarization maintaining fiber.
  • a typical high powered stripe laser diode emits a beam having essentially a 100 ⁇ m x 1 ⁇ m rectangular geometry. Accordingly, a beam having this geometry is more efficiently captured by a fiber formed in accordance with the present invention to have an identical or substantially similar core geometry to that of the laser beam.
  • the inventive method also does not require the core stick to be uniform in cross section and have a smooth surface, unlike prior rod-in-tube technology.
  • the core stick can be fabricated by conventional crucible melting and casting, drawing, sol-gel, or some other technique. The stick is then loaded into the cladding tube.
  • composition of the tube which becomes the fiber cladding is not limited and can range from pure SiO2 to multicomponent glasses.
  • the only requirement is that the core glass melt at or below the softening point of the cladding tube and that the thermal expansion difference between the core and clad not be so large as to shatter the resultant fiber upon cooling as addressed in greater detail below.
  • the cladding tube After the cladding tube is filled, it can be drawn down into fiber or canes for overcladding.
  • the filled tube is heated to soften the cladding glass for elongation.
  • the core stick As the cladding tube softens during the draw, the core stick will melt, fine (removal of bubbles), and conform to the walls of the cladding tube forming an interface determined by the inner surface of the cladding tube.
  • the ratio of the outer diameter (OD) to the inner diameter (ID) of the tube will be roughly the same as the fiber or cane OD/ID ratio although it can be controlled by the pressure (positive or negative) applied over the molten core relative to outside the cladding tube.
  • the draw temperature can also be used to control the core diameter as higher draw temperatures will lead to smaller core diameters for the same given fiber OD. This control represents a substantial advantage over conventional preforms where this ratio is fixed once the blank is fabricated.
  • the higher temperatures used to draw the cladding tube (2000°C for the case of pure SiO2 cladding) serve to homogenize the core melt and drive off detrimental water in the glass.
  • a vacuum can be applied to a centerline to enhance water removal and fining. Utilizing an open centerline during the first draw step allows for atmospheric control of the melt at the drawing temperature. Oxidizing as well as reducing atmospheres can be introduced above the melt to control the redox state of the core material or maintain reduced metallic cores or superconductors in a dielectric cladding. Multiple concentric or parallel cores may also be made by this method where one core may carry optical information and the other electrical information. The pressure above the core can also be controlled to regulate the core diameter. This type of process control is not available with any of the current preform fiberization methods.
  • Controlled glass composition and thermal history can also be used to generate graded index profiles. Since the core is molten and the cladding is softening, diffusional processes are relatively fast, so graded index profiles can be created in situ. With appropriate choice of cladding material, the fibers produced can be fusion spliced to conventional fibers making them quite practical in existing fiber networks and easing device manufacture.
  • the stick-in-tube method allows for complicated index profiles.
  • the first cladding tube could have a refractive index in between that of the core and the overclad tube to control the numerical aperture of the fiber or it could contain refractive index moats and rings inserted to engineer the dispersion of the fiber.
  • the first draw reduces the redial dimensions of the index profile by a factor of 6-8, and the second draw, reduces them down again by a factor of 400-500, so very fine structures can be achieved.
  • FIG. 1 is a cross sectional drawing of an apparatus 100 which may suitably be used for implementing the filament in tube method of drawing optical fiber in accordance with the present invention.
  • a cladding tube 112 having a 57mm OD and a 2mm ID in a preferred embodiment, with an inner wall 118 is purged with a drying gas, for example chlorine (CI2) or chlorine mixed with an inert gas, to remove unwanted moisture.
  • a drying gas for example chlorine (CI2) or chlorine mixed with an inert gas
  • a core feedstock or filament 110 having a 1.5 mm diameter in a preferred embodiment, is disposed within the cladding tube 112.
  • This feedstock or filament 110 is preferably an elongated monolithic rod of material, however, a plurality of elongated rods can be stacked one atop the other within the cladding tube 112 to form the feedstock. Using a plurality of rods is particularly well suited for the production of dispersion managed fiber.
  • the cladding tube 112 and the core filament 110 form a filled cladding tube with an open centerline 122 which is heated by a furnace 114, as described further below.
  • the furnace 114 is operated at a draw temperature which is at or above the melting temperature of the core filament 110, but only causes the cladding tube 112 to soften.
  • the core filament 110 will melt at the draw temperature forming a core melt 120 contained within the cladding tube 112. It is presently preferred that the draw temperature is at or above the liquidus temperature of the core filament to eliminate crystals in core melt 120.
  • melt means that the core filament 110 flows and fills or deforms to the interior of the cladding tube 112 so that a filled cladding structure results.
  • the core preferably exhibits a viscosity of less than 106 poise, more preferably 104 poise, most preferably 1000 poise or less, and the cladding structure maintains a viscosity sufficient for the cladding to substantially retain its internal shape.
  • the cladding tube 112 exhibits a viscosity greater than 107.6 poise.
  • An optical fiber 116 is then drawn. While melting, the core filament 110 will preferably fine and conform to the interior wall 118 of the cladding tube 112, forming an interface determined by the inner surface 118, and completely filling the interior of the cladding tube 112.
  • a glass cladding material 112 has a viscosity of about 107.6 poise. For SiO2, this occurs at a temperature of about 2000°C.
  • the cladding material should be selected so that at the temperature at which the core material is filling the interior of the cladding tube it has a viscosity greater than 107 poise, and preferably greater than 107.6, and most preferably greater than 108.
  • a core 120 such as 69.86 mole % silica (SiO2), 18.63 mole % aluminum oxide (AI2O3), 4.66 mole % sodium oxide (Na2O), and 6.85 mole % lanthanum fluoride (La2F6) will have a viscosity of approximately 10 poise, seven orders of magnitude less than the cladding 112.
  • the core 120 might suitably have a viscosity less than or equal to about 104.5 poise.
  • a typical rod in tube process would typically employ both core and cladding material having substantially the same viscosity.
  • the core filament 110 can be produced in any shape (round, square, triangular, etc.) and via any method (conventional crucible melting and casting, drawing, sol-gel, etc.). The only physical requirement is that the core filament 110 fit within the inner walls of the cladding tube 112. Thus, less rigid process controls are required during the manufacture of the core filament 110. Moreover, the loose fitting core filament 110 may be automatically fed down or dropped down as its bottom is melted to maintain a constant depth of molten. core 120, yielding a homogeneous and reproducible optical fiber 116.
  • the core filament 110 has a melting temperature, as defined above, which is below the softening temperature of the cladding 112, and the thermal expansion difference between the core filament 110 and the cladding 112 is not so large as to shatter the fiber 116 when it is cooled.
  • the composition of the cladding 112 is preferably silicate glass, but it will be appreciated by those skilled in the art, that the composition of cladding 112 is essentially not limited and can range from pure SiO2 to multicomponent glasses.
  • FIG. 2 is a cross sectional drawing of an apparatus 200 which may suitably be employed for performing the stick in tube method of drawing optical fiber in accordance with the present invention.
  • a one meter long SiO2 cladding tube 212 (55 mm in outer diameter and 6 mm in inner diameter) is purged with drying gas to remove unwanted moisture.
  • a 5 mm diameter core stick 210 is disposed or placed within the cladding tube 212 to form a filled cladding tube.
  • the filled cladding tube is heated by a furnace 214 to 1700° C to soften the cladding tube 212 in preparation for elongation.
  • the core stick 210 melts, and a 6 mm outer diameter optical cane 216 is then drawn in a standard manner. While melting, the core stick 210 will fine and conform to the interior walls of the cladding tube 212, forming an interface determined by the inner surface of the cladding tube 212.
  • the cladding material 212 preferably has a viscosity of approximately 108 poise at a draw temperature of 1700°C and the core stick 210 will have a viscosity of approximately 104 poise or less at the draw temperature.
  • overcladding tube 220 is then placed within an overcladding tube 220.
  • the filled overcladding tube 220 is heated by a furnace 222 to soften the overcladding tube 220 in preparation for elongation.
  • the overcladding tube 220 softens, the cane 216 will soften, and an optical fiber 224 is drawn.
  • a core glass of molar composition 70.0 SiO2 - 11.25 AI2O3 - 7.5 Ta2O5 - 10 CaO - 2 CaF2 - .05 Er2O3 was batched from high purity powders, mixed, calcined at 400°C for 12 hours to dry the batch, and then melted in a covered high purity silica crucible at 1650°C for 4 hours.
  • the melt was stirred with a fused silica rod to promote homogeneity, then cooled to 1500°C and drawn up into a 4-5 mm diameter stick from the melt.
  • the 5 mm diameter stick of core glass was then inserted into a meter long 55 mm outer diameter (OD), consolidated, SiO2 blank previously manufactured using the outside vapor deposition process with a 6 mm inner diameter (ID).
  • the tube was purged with dry He gas to remove unwanted moisture and heated to 1800°C to soften the SiO2 blank and drawn down into a 6 mm diameter core/clad cane which was flame cut into 1 meter long pieces.
  • a 1 meter long piece was then mounted on a CVD lathe and overclad with SiO2 soot to obtain the desired clad diameter/core diameter ratio of 32:1.
  • the overclad cane was then consolidated between 1440 and 1500° to form a monolithic SiO2 blank with a core. This blank was then heated to 1950-2000° in a graphite resistance furnace and drawn into standard 125 micron diameter fiber at a rate of 2 m/s.
  • the resultant fiber having an Er-doped core is suitable for use as an optical amplifier.
  • FIG. 3 is a drawing of an apparatus 300 used for overcladding an optical cane via an alternative CVD process and then drawing an optical fiber in accordance with the present invention.
  • a cane 216 produced by the embodiment of the present invention shown in FIG. 2, is cut into 1 meter long pieces.
  • the cut cane 216 is then mounted on a CVD lathe 332 and overclad with SiO2 to obtain the desired ratio between the clad diameter and the core diameter, forming an overclad optical cane 330.
  • the overclad cane 330 is then consolidated at a temperature between 1400° C and 1500° C to form a monolithic SiO2 blank 336.
  • An end of the monolithic blank 336 is then heated in a furnace 338 to a draw temperature of 1950-2000° C and drawn into standard 125 micron diameter optical fiber 340.
  • FIG. 4 is a graph 400 showing loss as a function of wavelength for a 5 meter span of an optical fiber produced in accordance with the present invention.
  • the low loss optical fiber (0.07 dB/m at 1310 nm) exhibits the same loss per meter, beginning to end, over a 2000 meter span.
  • the core of the optical fiber was successfully doped with Erbium ions, Er3+, as evidenced by the adsorption bands at 980 and 1500 nm. Additionally, Er3+ fluorescence was observed from the optical fiber when 980 nm laser light was pumped into the fiber.
  • FIG. 5 is a graph 500 showing the refractive index profile of a core clad cane produced in accordance with the present invention.
  • the observed maximum delta of 6.7562 % is significantly higher than that seen for typical CVD produced fiber.
  • the cane was subsequently overclad and drawn into
  • fiber manufactured in accordance with the present invention shows an improvement of at least an order of magnitude.
  • utilizing SiO2 as the cladding material allowed the resultant optical fiber to be fusion spliced using conventional fusion splicers. Splice losses of less than 0.5 dB have been made to SMF-28 optical fiber, and splice losses of less than 0.2 dB have been made to CS-980 optical fiber.
  • FIG. 6 is a graph 600 showing loss as a function of wavelength for a 5 meter span of optical fiber produced in accordance with the present invention.
  • the multi-component core in this case was surrounded by a ring of SiO2 doped with germanium oxide (GeO2).
  • GeO2 germanium oxide
  • FIG. 7 is a graph 700 showing the loss and mode field diameter as a function of fiber length for an optical fiber produced in accordance with the present invention. Minimal variations in loss and mode field diameter for varying lengths are noted.
  • the method of the present invention has a variety of advantages.
  • the method of the invention opens up a large range of compositions.for fiberization that have not previously been attainable through conventional CVD techniques which have been employed to make optical fiber.
  • New compositions with high rare earth solubility, improved gain flatness and improved optical properties can be readily fabricated into fiber form.
  • the method also accommodates large differences in thermal expansion between the core filament 110 or core stick 210, and cladding material 112 or cladding material 212, since the core 110, 210 is not rigidly bonded to the clad 112, 212 until the core filament 110 or core stick 210 is in fiber form when the stress due to thermal expansion mismatch are much smaller than in a rigid monolithic preform of greater size, as these stress forces vary inversely with the square of the radius of the fiber, preform or the like. Accordingly, very large numerical aperture fibers for use as efficient couplers and lasers can be produced by the method of the present invention. The method also allows for atmospheric control of the core melt 120,
  • the ratio of the OD to the inner diameter (ID) of the tube will be roughly the same as the optical fiber OD to ID ratio although, as stated, it can be controlled by positive or negative pressure applied over the molten core 120, 220 relative to outside the cladding tube 112 or cladding tube 212, respectively. Additionally, the high temperatures used to draw the optical fiber 116, 216 serve to homogenize the core melt 120, 220 and drive off detrimental water present in the core melt 120, 220.
  • a core feedstock such as core feedstock 110
  • the core feedstock could conceivably be hollow, or be divided into several large blocks.
  • the term feedstock is intended to encompass a thin filament, a thicker stick, a plurality of elongated filaments bundled for insertion into the tube, or elongated filaments or sticks stacked axially one on top of the other for insertion into the tube, or the like, which will properly feed down upon melting.
  • feedstock as defined herein preferably is not powder or cullet.
  • the feedstock can be formed from a core material alone or from a core material having a cladding material disposed thereon. Either of these embodiments can then be disposed within a tube formed from cladding material.
  • the tube can be formed from core material or cladding material.
  • optical fiber should be construed as encompassing any fiber or fiber component employed in applications including but not limited to optical waveguides, single mode fibers, multi-mode fibers, amplifiers, electro-optical fibers, couplers, lasers, or the like.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Manufacturing & Machinery (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacture, Treatment Of Glass Fibers (AREA)
  • Glass Compositions (AREA)

Abstract

La charge d'alimentation (110) est insérée dans un tube (112). La charge d'alimentation (110) est fondue (120) dans le tube (112) et ensuite étirée en une fibre (116).
PCT/US1999/016177 1998-08-25 1999-07-16 Procedes et appareil de production de fibre optique Ceased WO2000010932A1 (fr)

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US9787698P 1998-08-25 1998-08-25
US60/097,876 1998-08-25

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EP1139518A1 (fr) * 2000-03-30 2001-10-04 Optical Technologies Italia S.p.A. Fibre optique active dotée de terres rares
EP1207140A1 (fr) * 2000-11-20 2002-05-22 Lucent Technologies Inc. Procédé de fabrication d élements à fibre optique electrocommandables
US6587633B2 (en) 2000-03-30 2003-07-01 Corning Oti, Inc. Active optical fibre doped with rare earth elements
US8639078B2 (en) 2011-12-19 2014-01-28 Olympus Corporation Optical fiber manufacturing method, optical fiber and endoscope
CN112062463A (zh) * 2020-09-29 2020-12-11 山西能源学院 一种液闪用玻璃微孔阵列制备方法
EP3918387A4 (fr) * 2019-01-29 2022-10-12 Sterlite Technologies Limited Préforme de fibre optique et son procédé de fabrication
US12401424B2 (en) 2023-10-27 2025-08-26 Attotude, Inc. Fiber-coupled Terahertz transceiver system

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EP1199286A1 (fr) * 2000-10-18 2002-04-24 The University Of Southampton Fibres et préformes optiques comprenant des constituants volatils et procédé de fabrication la fibre
WO2005019889A1 (fr) * 2003-08-21 2005-03-03 Federalnoe Gosudarstvennoe Unitarnoe Predpyatie 'vserossiysky Nauchny Tsentr 'gosudarstvenny Optichesky Institut Im. S.I.Vavilova' (Fgup Goi) Fibre electro-optique monomode et son procede de fabrication
DE102005034594B4 (de) * 2005-07-20 2008-09-25 J-Fiber Gmbh Verfahren zur Herstellung von Glasfaserpreformen mit einem großen Kerndurchmesser
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EP1139518A1 (fr) * 2000-03-30 2001-10-04 Optical Technologies Italia S.p.A. Fibre optique active dotée de terres rares
WO2001076024A1 (fr) * 2000-03-30 2001-10-11 Optical Technologies Italia S.P.A. Fibre optique active dopees d'element de terre rare
US6587633B2 (en) 2000-03-30 2003-07-01 Corning Oti, Inc. Active optical fibre doped with rare earth elements
EP1207140A1 (fr) * 2000-11-20 2002-05-22 Lucent Technologies Inc. Procédé de fabrication d élements à fibre optique electrocommandables
US8639078B2 (en) 2011-12-19 2014-01-28 Olympus Corporation Optical fiber manufacturing method, optical fiber and endoscope
EP3918387A4 (fr) * 2019-01-29 2022-10-12 Sterlite Technologies Limited Préforme de fibre optique et son procédé de fabrication
CN112062463A (zh) * 2020-09-29 2020-12-11 山西能源学院 一种液闪用玻璃微孔阵列制备方法
US12401424B2 (en) 2023-10-27 2025-08-26 Attotude, Inc. Fiber-coupled Terahertz transceiver system

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AU5316699A (en) 2000-03-14
CN1324334A (zh) 2001-11-28
WO2000027773A1 (fr) 2000-05-18
AU3096600A (en) 2000-05-29
ID29631A (id) 2001-09-06
ZA200101616B (en) 2001-09-17
TW440718B (en) 2001-06-16
CA2341713A1 (fr) 2000-05-18
EP1108233A1 (fr) 2001-06-20
KR20010082180A (ko) 2001-08-29

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