WO1997041076A1 - Procede de fabrication de fibres optiques - Google Patents

Procede de fabrication de fibres optiques Download PDF

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Publication number
WO1997041076A1
WO1997041076A1 PCT/US1997/006924 US9706924W WO9741076A1 WO 1997041076 A1 WO1997041076 A1 WO 1997041076A1 US 9706924 W US9706924 W US 9706924W WO 9741076 A1 WO9741076 A1 WO 9741076A1
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WO
WIPO (PCT)
Prior art keywords
fiber
tablets
core
adjacent
dispersion
Prior art date
Application number
PCT/US1997/006924
Other languages
English (en)
Inventor
George E. Berkey
Original Assignee
Corning Incorporated
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 Incorporated filed Critical Corning Incorporated
Priority to EP97927608A priority Critical patent/EP0835227A4/fr
Priority to AU32036/97A priority patent/AU733718C/en
Priority to BR9702176A priority patent/BR9702176A/pt
Priority to JP53904197A priority patent/JP3534192B2/ja
Publication of WO1997041076A1 publication Critical patent/WO1997041076A1/fr

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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
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/018—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
    • 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
    • G02B6/02214—Optical fibres with cladding with or without a coating tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
    • G02B6/02219—Characterised by the wavelength dispersion properties in the silica low loss window around 1550 nm, i.e. S, C, L and U bands from 1460-1675 nm
    • G02B6/02247—Dispersion varying along the longitudinal direction, e.g. dispersion managed fibre
    • 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
    • C03B37/01225—Means for changing or stabilising the shape, e.g. diameter, of tubes or rods in general, e.g. collapsing
    • C03B37/01248—Means for changing or stabilising the shape, e.g. diameter, of tubes or rods in general, e.g. collapsing by collapsing without drawing
    • 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
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/01446—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering
    • 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
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/01486—Means for supporting, rotating or translating the preforms being formed, e.g. lathes
    • C03B37/01493—Deposition substrates, e.g. targets, mandrels, start rods or tubes
    • 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
    • G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
    • 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
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • 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
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
    • G02B6/03644—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only arranged - + -
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2203/00—Fibre product details, e.g. structure, shape
    • C03B2203/10—Internal structure or shape details
    • C03B2203/18—Axial perturbations, e.g. in refractive index or composition
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2203/00—Fibre product details, e.g. structure, shape
    • C03B2203/36—Dispersion modified fibres, e.g. wavelength or polarisation shifted, flattened or compensating fibres (DSF, DFF, DCF)
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
    • Y02P40/57—Improving the yield, e-g- reduction of reject rates

Definitions

  • the invention is directed to a method for making an optical fiber having optical properties that systematically vary along its length. This method is particularly useful for making dispersion managed (DM) single-mode optical waveguide fibers.
  • DM dispersion managed
  • the potentially high bandwidth of single-mode optical fibers can be realized only if the system design is optimized so that the total dispersion is equal to zero or nearly equal to zero at the operating wavelength.
  • the term "dispersion” refers to pulse broadening and is expressed in p ⁇ /nm-km.
  • Dispersion Product refers to dispersion times length and is expressed in ps/nm.
  • Tne system can experience a loss due to four wave mixing.
  • Tnis loss occurs when the signal wavelength is at or near tne zero dispersion wavelength of the optical transmission fiber. This has necessitated the exploration of waveguide fiber designs which can minimize signal degradation that results from this non-linear waveguide effec;.
  • a dilemma arises in the design of a waveguide fiber to minimize four wave mixing while maintaining characteristics required for systems which have long spacing between regenerators. That is, m order to substantially eliminate four wave mixing, the waveguide fiber should not be operated near its zero of total dispersion, because four wave mixing occurs when waveguide dispersion is low, i.e., less than about 0.5 ps/nm-km.
  • signals having a wavelength away from the zero of total dispersion of the waveguide are degraded because of the presence of the total dispersion.
  • each individual fiber is made to be a self contained dispersion managed system.
  • Each waveguide fiber is interchangeable with any other waveguide fiber designed for that system link.
  • the cabled waveguide fibers all have essentially identical dispersion product characteristics, and there is no need to assign a particular set of cables to a particular part of the system. Power penalty due to four wave mixing is essentially eliminated, or reduced to a pre-selected level, while total link dispersion is held to a pre- selected value, which may be a value substantially equal to zero.
  • the dispersion of a DM fiber varies between a range of positive values and a range of negative values along the waveguide length.
  • the dispersion product, expressed as ps/nm, of a particular length, 1, is the product (D ps/nm-km * 1 km) .
  • a positive number of ps/nm will cancel an equal negative number of ps/nm.
  • the dispersion associated with a length 1_ may vary from point to point along 1,_. That is, the dispersion D lies within a pre-determined range of dispersions, but may vary from point to point along l x .
  • 1 1 is made up of segments dl, over which the associated total dispersion D d is essentially constant. Then the sum of products dl x * D, characterizes the dispersion product contribution of 1 1 . Note that, in the limit where dl x approaches zero, the sum of products dl, * D_ is simply the integral of dl, * D over the length 1,. If the dispersion is essentially constant over sub-length 1,, then the sum of products is simply 1, * D, .
  • the dispersion of the overall waveguide fiber length is managed by controlling the dispersion D 1 of each segment ⁇ l l f so that the sum of the products D ⁇ * dl, is equal to a pre-selected value over a wavelength range wherein signals may be multiplexed.
  • the wavelength range m the low attenuation window from about 1525 nm to 1565 nm may be advantageously chosen.
  • the sum of the dispersion products for the DM fiber would have to be targeted at zero over that range of wavelengths.
  • the D, magnitudes are held above 0.5 ps/nm-km to substantially prevent four wave mixing and below about 20 ps/nm-km so that overly large swings m the waveguide fiber parameters are not required.
  • the length over which a given total dispersion persists is generally greater than about 0.1 km. This lower length limit reduces the power penalty (see FIG. 5), and simplifies the manufacturing process.
  • the period of a DM single-mode waveguide is defined as a first length having a total dispersion which is within a first range, plus a second length having a dispersion which is in a second range, wherein the first and second ranges are of opposite sign, plus a transition length over which the dispersion makes a transition between the first and second range.
  • the dispersion m the central portions of the transition regions will be near zero for some finite length of fiber. This will result m some power penalty due to four wave mixing. The longer the transition regions are, the higher the power penalty. The transition regions should therefore be sufficiently sharp that the fiber power penalty does not cause the total system power penalty to exceed the allocated power penalty budget.
  • the DM fiber must be a unitary fiber that is formed by drawing a draw preform or draw blank that includes sections that will form the fiber sections of different dispersion. Such a unitary fiber does not include splices between separately drawn fiber sections, as each splice would introduce additional loss. Ideally, the total attenuation of the unitary fiber is no greater than the composite of the weighted attenuation of each of the serially disposed sections of which it is formed.
  • an object of the invention is to provide an optical fiber having distinctly different optical characteristics along its length and an improved method for making sucn a fiber. Another object is to provide a method for ma ⁇ ng optical fiber of the aforementioned type wherein the transition lengths between sections of different characteristics are very short. A further object is to provide a method for making fiber of the aforementioned type wherein the attenuation is sufficiently low for use as long distance transmission fiber. Another object is to provide a method for making low loss single-mode DM optical fiber having short transition lengths. Yet another object is to provide a method for making optical fibers exhibiting low polarization mode dispersion.
  • One aspect of the invention concerns a method of making an optical fiber preform.
  • the method comprises the following steps.
  • a coating of cladding glass particles is deposited on the outer surface of a cladding glass tube, and a plurality of tablets is inserted into the cladding glass tube.
  • At least one optical cnaracte ⁇ stic of at least one of the tablets m the tube is different than that of an adjacent tablet, and each tablet has at least a central region of core glass.
  • a centerline gas is flowed through the tube.
  • the centerline gas is selected from the group consisting of pure cnlonne and chlorine mixed with a diluent gas.
  • the coated assembly is heated to sinter the coating, thereby generating a radially-mwardly directed force that causes the tube to collapse onto and fuse to the tablets, and causing the cladding glass tube to shrink longitudinally, whereby adjacent tablets are urged toward one another and are fused to one another.
  • a further aspect of the invention concerns a unitary optical fiber that results from the above-described method.
  • the fiber comprises a plurality of serially disposed optical fiber sections, each fiber section having a glass cere and a glass outer cladding.
  • the core of a first fiber section is different from the core of each fiber section that is adjacent to the first section.
  • the cladding cf the first fiber section is identical to the cladding cf the adjacent fiber sections. Between each two adjacent fiber sections is a transition region, the length of which is less than 10 meters.
  • FIG. 1 is an illustration of total dispersion varying along the waveguide fiber length.
  • FIG. 2 shows how the zero dispersion of a waveguide fiber may vary to maintain total dispersion of the waveguide within a pre-selected range over a pre- determined wavelength window.
  • FIG. 3a is a chart illustrating the power penalty vs. input power for a system comprised of particular waveguide sub-lengths having a low total dispersion magnitude.
  • FIG. 3b is a chart illustrating the power penalty vs. input power for a system comprised of particular waveguide sub-lengths having a higher total dispersion magnitude.
  • FIG. 4 is a chart of total dispersion vs . power penalty.
  • FIG. 5 is a chart of dispersion variation period length vs. power penalty.
  • FIG. 6 is a chart of transition region length vs. power penalty.
  • FIG. 7 is a schematic representation of a process of making an optical fiber, adjacent sections of which have distinctly different characteristics.
  • FIG. 8 is an enlarged cross-sectional view of the tablets of FIG. 7.
  • FIG. 9 illustrates the application of a layer of cladding glass particles to a tube.
  • FIG. 10 is a cross-sectional view of the fused assembly resulting from the consolidation/fusion step illustrated in FIG. 7.
  • FIG. 11 is a partial cross-sectional view of a modification of the embodiment of FIG. 7.
  • FIGS. 12 and 13 are refractive index profiles of dispersion shifted optical fibers.
  • the total dispersion of a DM fiber is charted vs. waveguide length m FIG. 1.
  • the total dispersion is seen to alternate between positive values 2 and negative values 4.
  • FIG. 1 illustrates a plurality of sublengths exhibiting negative dispersion and a plurality of sublengths exhibiting positive dispersion, only one negative dispersion sublength and one positive dispersion sublength are required.
  • the spread in total dispersion values indicated by line 6 illustrates that total dispersion varies with the wavelength of light propagated.
  • the horizontal lines of the spread 6 represent total dispersion for a particular light wavelength.
  • the length of waveguide 8, characterized by a particular total dispersion is greater than about 0.1 km. There is essentially no upper limit on length 8 except one which may be inferred from the requirement that the sum of products, length x corresponding total dispersion, is equal to a pre-selected value.
  • FIG. 2 serves to illustrate design considerations for a DM single-mode waveguide fiber.
  • Lines 10, 12, 14 and 16 represent total dispersion for four individual waveguide fibers. Over the narrow wavelength range considered for each waveguide, i.e., about 30 nm, the dispersion may be approximated by a straight line as shown.
  • the wavelength range m which multiplexing is to be done is the range from 26 to 28. Any waveguide segment which has a zero dispersion wavelength m the range of 18 to 20 may be combined with a waveguide segment having a zero dispersion wavelength m the range 22 to 24, to yield a waveguide having a pre-selected total dispersion over the operating window 26 to 28.
  • the following example is based on FIG. 2.
  • the operating window Take the operating window to be 1540 n to 1565 nm.
  • the single-mode waveguide fiber has a dispersion slope of about 0.08 ps/nm 7 -km.
  • line 30 be the 0.5 ps/nm-km value and line 32 the 4 ps/nm-km value.
  • Apply the condition that the total dispersion within the operating window must be m the range of about 0.5 to A ps/nm-km.
  • a simple straight line calculation then yields zero dispersion wavelength range, 18 to 20, of 1515 nm to 1534 nm.
  • a similar calculation yields a zero dispersion wavelength range, 22 to 24, of 1570 nm to 1590 nm.
  • the magnitude of the total dispersion is about 0.5 ps/nm-km.
  • the sub-length for total dispersion of a given sign is 10 km.
  • the corresponding sub-length of the dispersion m curve 64 is 60 km.
  • the extra penalty results from the additional transitions through zero dispersion for the shorter, 10 km sub-length case.
  • An alternative statement is for the 10 km case, the phase separation of the signals, which is proportional to the oscillation sub-length, is not large enough to substantially prevent four wave mixing.
  • An "oscillation sub-length" is either the positive or negative dispersion sub-length of a period. Where there is no sign associated with oscillation sub-length, the positive and negative oscillation sub-lengths are taken as equal .
  • FIG. 3b shows the power penalty for a system identical to that shown in FIG. 3a, except that the sub-length is shorter, about 1 km, but the total dispersion magnitude is 1.5 ps/nm-km.
  • Causing the waveguide total dispersion to make wider positive to negative swings reduces power penalty significantly, from 0.6 dB to less than 0.2 dB.
  • the penalty difference of about 0.4 dB/120 km is large enough to be the difference between a functional and non-functional link, especially for long unregenerated links of 500 km or more.
  • FIG. 4 is interpreted m essentially the same manner as FIG. 3a an 3b.
  • Curve 68 shows power penalty charted vs. total dispersion magnitude.
  • the sub-length of the waveguide is chosen as about 1 km because the length of the shortest cables m general use is about 2 km.
  • the input power is 10 dBm.
  • the power penalty rises steeply when total dispersion magnitude falls below about 1.5 ps/nm-km.
  • System design is shown from another viewpoint m FIG.
  • Curve 70 represents power penalty vs. sub- length magnitude for a system having 8 channels with 200 GHz frequency separation and 10 dBm input power. The length is chosen to be 60 dispersion sub-lengths and the sub-length is allowed to vary. Lower power penalties result when the sub-length is above ' 2 km. But with the relatively large total dispersion magnitude, little is gained by lengthening the sub-length beyond 2 km. Note the generally lower four wave mixing penalty paid when the number of channels used is reduced to 4 as shown by curve 72.
  • core preforms can be prepared by any known process. Examples of processes that can be employed to make the core preforms are outside vapor deposition (OVD) , vapor axial deposition (VAD) , modified chemical vapor deposition (MCVD) wherein a core layer is formed inside a glass tube, and plasma chemical vapor deposition (PCVD) wherein the reaction within the tube is plasma induced.
  • ODD outside vapor deposition
  • VAD vapor axial deposition
  • MCVD modified chemical vapor deposition
  • PCVD plasma chemical vapor deposition
  • the core preform can consist entirely of core glass or it can consist of a core region and a cladding region.
  • the first and second preforms are cut into tablets 81 and 82, respectively.
  • the lengths of the tablets depend upon the specific type of fiber being made. In the process of making DM fibers, the lengths of the tablets 81 and 82 are selected to yield in the resultant optical fiber the desired sub-lengths.
  • the tablets can be made by the simple score and snap method. Tablet 81 has a core region 83 and a cladding region 84; tablet 82 has a core region 85 and a cladding region 86.
  • a tubular glass handle 92 having an annular enlargement 97 is fused to one end of an elongated glass tube 90.
  • Handle 92 is part of a ball joint type gas feed system of the type disclosed m U.S. patent 5,180,410.
  • Enlargement 97 is adapted to rest on a slotted base of a support tube (not shown) that suspends handle 92 in a consolidation furnace.
  • Tube 90 is heated and a dent 98 is formed near handle 92. Alternatively, that part of handle 92 adjacent tube 90 could be dented.
  • the assembly including tube 90 and handle 97 is inserted into a lathe (not shown) and rotated and translated with respect to burner 100 which deposits on tube 90 a layer 91 of cladding glass particles or soot (see FIG. 9) .
  • Coating 91 can be built up to a sufficient outside diameter (OD) that the resultant preform can be consolidated and drawn into an optical fiber having the desired optical characteristics.
  • Layer 91 can overlap handle 92 as shown in FIG. 7.
  • Tube 90 is oriented so that the end affixed to handle 92 is lower than the other end, and tablets 81 and 82 are alternately inserted into the upper end of tube 90. The tablets cannot fall beyond dent 98. Tube 90 is heated and a dent 99 is formed near that end opposite dent 98. When tube 90 is inverted, dent 99 prevents the tablets from falling from it.
  • Handle 92 is suspended from a support tube (not shown) which is lowered to insert assembly 94 into consolidation furnace muffle 95. While assembly 94 is heated m the consolidation furnace, a drying gas flows upwardly through the furnace (arrow 93) .
  • the drying gas conventionally comprises a mixture of chlorine and an inert gas such as helium.
  • a chlorine-containing gas stream (arrow 96) is flowed from tube 92 into tube 90.
  • gas stream 96 could contain a diluent such as helium, pure chlorine is preferred for cleaning purposes. Since the diameter of each of the tablets 81 and 82 is slightly smaller than the inner diameter of tube 90, the chlorine flows downwardly around the entire periphery of each of the tablets; it also flows or diffuses between adjacent tablets.
  • the chlorine then exhausts through the bottom of tube 90.
  • the chlorine functions as a hot chemical cleaning agent.
  • the temperature is below the consolidation temperature of soot coating 91 so that the space between tablets 81 and 82 and tube 90 remains open for a sufficient length of time for the required cleaning to occur.
  • the chlorine cleaning step is more effective at high temperatures. It is preferred that the temperature of the cleaning step be at least 1000°C, since at lower temperatures, the duration of the step would be sufficiently long that the step would be undesirable for commercial purposes. Obviously, lower temperatures could be employed if processing time were not a concern.
  • the flow of hot chlorine between the tube 90 and tablets 81 and 82 is very beneficial m that it allows the surfaces of adjacent tablets and of tube and tablets to be brought together without the formation of seeds at their interface. Seeds include defects such as bubbles and impurities that can produce attenuation m the resultant optical fiber.
  • soot coating 91 shrinks radially, it exerts a force radially inwardly on tube 90. This urges tube 90 inwardly against tablets 81 and 82 to form a fused assembly 98 (see FIG. 10) m which the three regions 81, 90' and 91' are completely fused.
  • Region 90' is the collapsed tube, and region 91' is the sintered porous coating.
  • a relatively low density soot provides a greater inwardly directed force; however, t ⁇ e soot coating must be sufficiently dense to prevent cracking.
  • Regions 90' and 91' of fused assembly 98 function as cladding in the resultant optical fiber.
  • Assembly 98 can be used as a draw blank and can be drawn directly into an optical fiber.
  • Fused assembly 98 can optionally be provided with additional cladding prior to the fiber drawing step.
  • a coating of cladding soot can be deposited onto assembly 98 and then consolidated.
  • assembly 98 can be inserted into a cladding glass tube. If additional cladding were added, the diameters of the core regions of tablets 81 and 82 would have to be suitably adjusted.
  • the present method is simple to perform, and it enables the fusion to be carried out in a dry environment. The method is self aligning m that adjacent core canes of different diameter will be centered on the axis of the resultant draw blank when tube 90 collapses inwardly during the sintering of porous glass coating 91.
  • the method of this invention brings new degrees of freedom m the tailoring of fiber properties. It results in the formation of optical fibers having adjacent regions or lengths of disparate properties. Very abrupt transition regions connect the adjacent fiber lengths.
  • the attenuation of this fiber is identical to that of standard long distance telecommunication fiber, i.e. less than 0.25 dB/km and preferably less than 0.22 dB/km.
  • dents 98 and 99 are not formed in tube 90.
  • a short length 104 of glass capillary tubing is fused to one end of tube 90, and the glass handle is fused to the opposite end of tube 90. Tablets 81 and 82 are inserted through the handle and into tube 90. The tablets cannot fall beyond tube 104 since that tube has a relatively small bore.
  • tube 104 initially fuses to cut off the chlorine flow.
  • a dispersion managed fiber is formed from core preforms that are capable of forming single-mode optical fibers having different zero dispersion wavelengths.
  • the dispersion of a waveguide length can be changed by varying various waveguide parameters such as geometry, refractive index, refractive index profile, or composition. Any of a large number of refractive index profiles provide the required flexibility for adjusting waveguide dispersion and thereby varying the total dispersion.
  • refractive index profile which is useful for forming optical fibers having zero dispersion at predetermined wavelengths is that having a relatively high index central region surrounded by an annular region of depressed index which is in turn surrounded by an outer annular region of index higher than that of the depressed index region (see FIG. 12) .
  • the index profile of another embodiment includes an essentially constant index central portion having a refractive index substantially equal to the clad glass refractive index and an adjacent annular region of increased refractive index. 17
  • Optical fibers having this type of refractive index profile can be easily manufactured.
  • a simple DM fiber refractive index profile is the step index profile.
  • Two core preforms could be formed of the same core and cladding materials, the radius of one core region being larger than that of the other.
  • the draw blank is drawn to a fiber having lengths of a first core radius interspersed between lengths of a second core radius that is larger than the first radius.
  • a core diameter difference of about 5 " to 25 " is sufficient to produce the desired positive to negative dispersion variation.
  • a range of radii variation of 5 ° to 10 ° is, m general, sufficient for most applications.
  • the following example describes the formation of a single-mode DM fiber suitable for providing zero dispersion at 1545-1555 nm.
  • Two different core preforms were made by a method similar to that disclosed in U.S. patent 4,486,212 which is incorporated herein by reference. Briefly, the method of that patent includes the steps of (a) depositing glass particles on a mandrel to form a porous glass preform, (b) removing the mandrel and consolidating the porous preform to form a dry, sintered preform, (c) stretching the sintered preform and closing the axial aperture therein.
  • the core preform included a central region of core glass surrounded by a thin layer of cladding glass.
  • Both of the core preforms had core refractive index profiles of the type shown in FIG. 12.
  • the first core preform was such that if it were provided with cladding and drawn into a single-mode fiber having a 125 ⁇ m OD, it would exhibit zero dispersion at 1520 nm.
  • the second preform is such that if it were similarly formed into a 125 ⁇ m OD single-mode fiber, its zero dispersion wavelength would be 1570 nm.
  • the core preforms were stretched to diameters of 7 mm and 7.1 mm.
  • the first and second stretched preforms were scored and snapped to form tablets 81 and 82 of substantially equal length.
  • Tablets 81 had core regions 83 and cladding regions 84; tablets 82 had core regions 85 and cladding regions 86.
  • a one meter length of silica tube 90 was employed; it had an inside diameter (ID) of 7.5 mm and an O.D. of 9 mm.
  • ID inside diameter
  • O.D. O.D.
  • the technique described m conjunction with FIG. 7 was employed to load tablets 81 and 82 into tube 90.
  • Coating 91 was built up to a sufficient OD that the resultant preform could be consolidated and drawn into a 125 ⁇ m OD single-mode fiber.
  • the resultant assembly 94 was suspended in a consolidation furnace. While assembly 94 was rotated at 1 rpm, it was lowered into consolidation furnace muffle 95 at a rate of 5 mm per minute. A gas mixture (arrow 93) comprising 50 seem chlorine and 40 slpm helium flowed upwardly through the muffle. A centerline flow of 0.3 slpm chlorine flowed downwardly around tablets 81 and 82 and exhausted from the bottom of tube 90. The maximum temperature m the consolidation furnace was about 1450°C. As assembly 94 moved downwardly into the furnace, the centerline chlorine flow chemically cleaned the surfaces of tablets 81 and 82 and the inner surface of tube 90.
  • draw blanks formed by this process were drawn to form DM optical fibers having an OD of 125 ⁇ m.
  • Single-mode DM optical fibers made by this process have been drawn without upsets; attenuation has typically been 0.21 dB/km. This is the same attenuation that would have been exhibited by a single-mode dispersion shifted optical fiber drawn from a preform formed by overcladdmg one of the 7 mm core canes.
  • the zero dispersion wavelength was determined by the total lengths of each kind of core m the fiber.
  • the zero dispersion wavelength of the fiber could be changed by cutting off a portion at one end of the fiber, thus changing the ratio of the lengths of each kind of core m the fiber.
  • the oscillation sub-lengths and the period are controlled by the lengths of the core preform tablets. Fibers having oscillation sub-lengths of 1.2 to 2.5 km were drawn.
  • the method of the invention has been specifically described in connection with the manufacture of DM smgle- mode optical fibers, and a description of a method of making such a fiber is set forth m the preceding specific example. However, it can be employed to make many other types of optical fibers having optical properties that systematically vary along the fiber's length. In each instance, the fiber can be made by inserting the appropriate tablets into a tube and processing the tube as described above.
  • Spontaneous B ⁇ lluom Scattering can be minimized by providing a fiber with alternate lengths that exhibit significantly different values of ⁇ , wherein ⁇ is defined as
  • n 5 and n 2 are the refractive indices of the core and cladding, respectively.
  • One of the types of tablets that is used to make the fiber preform exhibits a given ⁇ , and the other type of tablet exhibits a significantly different value of ⁇ .
  • the ⁇ -value of a fiber core can be controlled by controlling the amount of a dopant in the core or by changing the composition of the core, i.e. by adding other dopants to the core. Numerous dopants including oxides of tantalum, aluminum, boron can be employed for the purpose of changing refractive index and other properties such as viscosity.
  • a fiber that provides a filtering function could be made by alternately disposing m a tube a plurality of tablets that are capable of forming optical fiber having a filtering function and a plurality of tablets that are capable of forming standard, non-fllte ⁇ ng optical fiber.
  • a fiber could include relatively short sections, the cores of which are doped with active dopant ions capable of producing stimulated emission of light when pumped with light of suitable wavelength.
  • Dopant ions of a rare earth such as erbium are particularly suitable for this purpose.
  • a fiber having sections of erbium-doped core located at spaced intervals along its length could be made by employing relatively long tablets of standard, erbium-free core and relatively short tablets of erbium-doped core.
  • a fiber where the core systematically decreases m size such as that employed in Sola ton fibers could be made by inserting into the tube a plurality of tablets, each having a core diameter smaller than the previous one or each having a core diameter larger than the previous one.
  • some other core characteristic that affects dispersion could be varied in the tablets so that the dispersion of the resultant fiber monotonically decreased from one end of the fiber to the other.
  • a single core preform could be used to form all tablets.
  • a single preform is formed such that its core has an azimuthally asymmetrical refractive index profile.
  • the core could be slightly out of round, i.e. the core cross-sectional shape of the core is an ellipse having a major axis and a minor axis (see U.S. patent 5,149,349) .
  • the fiber could contain stress rods on opposite sides of the core as disclosed in U.S. patent 5,152,818.
  • An elliptical core fiber can be formed as follows. Tablets are severed from the preform.
  • a cladding glass tube is provided with a coating of cladding glass soot.
  • the tablets are inserted into the cladding glass tube such that the major axis of the elliptical core of one tablet is rotated with respect to the major axes the cores of adjacent tablets.
  • the resultant draw blank is drawn into an optical fiber having low polarization mode dispersion.

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  • General Chemical & Material Sciences (AREA)
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  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)

Abstract

On fabrique une préforme (94) pour la production d'une fibre optique en déposant de la suie de silice (91) autour d'un tube (90). On place des pièces présentant différentes compositions de verre (81, 82) dans l'alèsage du tube. On procède au frittage, à la fusion de la préforme et on provoque son affaissement. On obtient une ébauche d'étirage que l'on peut étirer pour former une fibre optique monomode, à faibles pertes et à gestion de dispersion.
PCT/US1997/006924 1996-04-29 1997-04-21 Procede de fabrication de fibres optiques WO1997041076A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP97927608A EP0835227A4 (fr) 1996-04-29 1997-04-21 Procede de fabrication de fibres optiques
AU32036/97A AU733718C (en) 1996-04-29 1997-04-21 Method of making optical fibers
BR9702176A BR9702176A (pt) 1996-04-29 1997-04-21 Processo para fabricação de fibras ópticas
JP53904197A JP3534192B2 (ja) 1996-04-29 1997-04-21 光ファイバの製造方法

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US1643596P 1996-04-29 1996-04-29
US60/016,435 1996-04-29

Publications (1)

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WO1997041076A1 true WO1997041076A1 (fr) 1997-11-06

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EP (1) EP0835227A4 (fr)
JP (1) JP3534192B2 (fr)
KR (1) KR19990028560A (fr)
CN (1) CN1109661C (fr)
AU (1) AU733718C (fr)
BR (1) BR9702176A (fr)
CA (1) CA2220416A1 (fr)
RU (1) RU2169710C2 (fr)
TW (1) TW342457B (fr)
WO (1) WO1997041076A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6640038B2 (en) 2000-05-31 2003-10-28 Corning Incorporated Dispersion managed fibers having reduced sensitivity to manufacturing variabilities
RU2647207C1 (ru) * 2016-12-23 2018-03-14 Федеральное государственное бюджетное образовательное учреждение высшего образования - Российский химико-технологический университет имени Д.И. Менделеева (РХТУ им. Д.И. Менделеева) Способ получения одномодового волновода

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JP2005263555A (ja) * 2004-03-18 2005-09-29 Shin Etsu Chem Co Ltd 多孔質ガラス母材の製造方法及び光ファイバ用ガラス母材
CN1300023C (zh) * 2004-08-16 2007-02-14 华南理工大学 一种玻璃光纤预制棒的制备方法
CN102245522B (zh) * 2008-12-19 2015-10-07 株式会社藤仓 光纤线的制造方法
JP5544354B2 (ja) 2009-04-16 2014-07-09 株式会社フジクラ 光ファイバ素線の製造方法
RU2537450C1 (ru) * 2013-09-27 2015-01-10 Российская Федерация, от имени которой выступает Министерство промышленности и торговли Российской Федерации (Минпромторг России) Способ изготовления заготовок для волоконных световодов на основе кварцевого стекла, легированного азотом
RU2552279C1 (ru) * 2014-02-25 2015-06-10 Федеральное государственное бюджетное учреждение науки Институт радиотехники и электроники им. В.А. Котельникова Российской академии наук Способ изготовления оптического волокна с эллиптической сердцевиной
CN108254827B (zh) * 2018-01-16 2021-05-04 江苏睿赛光电科技有限公司 一种有源无源一体化的光纤及其制备方法
CN110455320B (zh) * 2019-08-07 2021-06-01 深圳大学 一种光纤传感器及其制作方法
CN113121104B (zh) * 2019-12-31 2024-06-25 武汉光谷长盈通计量有限公司 一种光纤预制棒及制备光纤预制棒和光纤的方法

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GB1448080A (en) * 1975-04-10 1976-09-02 Standard Telephones Cables Ltd Optical fibre transducer
US4212660A (en) * 1979-03-22 1980-07-15 Corning Glass Works Method for making multiple mode waveguide having cylindrical perturbations
US5618325A (en) * 1993-07-06 1997-04-08 Alcatel Fibres Optiques Method of manufacturing a multi-component glass cylindrical part in the form of a tube and/or rod

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JPS55158146A (en) * 1979-05-29 1980-12-09 Fujitsu Ltd Manufacture of optical fiber
JPH0316930A (ja) * 1989-06-13 1991-01-24 Fujikura Ltd 複雑屈折率分布を有する光ファイバの製造方法
CA2161939A1 (fr) * 1994-12-20 1996-06-21 George E. Berkey Procede de fabrication de fibres optiques comportant une zone a indice de refraction reduit
AU693329B2 (en) * 1995-04-13 1998-06-25 Corning Incorporated Dispersion managed optical waveguide

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GB1448080A (en) * 1975-04-10 1976-09-02 Standard Telephones Cables Ltd Optical fibre transducer
US4212660A (en) * 1979-03-22 1980-07-15 Corning Glass Works Method for making multiple mode waveguide having cylindrical perturbations
US5618325A (en) * 1993-07-06 1997-04-08 Alcatel Fibres Optiques Method of manufacturing a multi-component glass cylindrical part in the form of a tube and/or rod

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See also references of EP0835227A4 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6640038B2 (en) 2000-05-31 2003-10-28 Corning Incorporated Dispersion managed fibers having reduced sensitivity to manufacturing variabilities
RU2647207C1 (ru) * 2016-12-23 2018-03-14 Федеральное государственное бюджетное образовательное учреждение высшего образования - Российский химико-технологический университет имени Д.И. Менделеева (РХТУ им. Д.И. Менделеева) Способ получения одномодового волновода

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EP0835227A4 (fr) 1998-08-19
AU733718B2 (en) 2001-05-24
KR19990028560A (ko) 1999-04-15
RU2169710C2 (ru) 2001-06-27
AU3203697A (en) 1997-11-19
JP3534192B2 (ja) 2004-06-07
AU733718C (en) 2003-03-20
CA2220416A1 (fr) 1997-11-06
CN1189812A (zh) 1998-08-05
BR9702176A (pt) 1999-03-02
CN1109661C (zh) 2003-05-28
TW342457B (en) 1998-10-11
JPH11513968A (ja) 1999-11-30
EP0835227A1 (fr) 1998-04-15

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