LU508211B1 - Manufacturing hollow core fiber preforms - Google Patents

Manufacturing hollow core fiber preforms

Info

Publication number
LU508211B1
LU508211B1 LU508211A LU508211A LU508211B1 LU 508211 B1 LU508211 B1 LU 508211B1 LU 508211 A LU508211 A LU 508211A LU 508211 A LU508211 A LU 508211A LU 508211 B1 LU508211 B1 LU 508211B1
Authority
LU
Luxembourg
Prior art keywords
support assemblies
cylindrical shell
glass
glass capillary
hollow core
Prior art date
Application number
LU508211A
Other languages
French (fr)
Inventor
Abubakar Isa Adamu
Original Assignee
Microsoft Tech Licensing Llc
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 Microsoft Tech Licensing Llc filed Critical Microsoft Tech Licensing Llc
Priority to LU508211A priority Critical patent/LU508211B1/en
Priority to PCT/US2025/040685 priority patent/WO2026054917A1/en
Application granted granted Critical
Publication of LU508211B1 publication Critical patent/LU508211B1/en

Links

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
    • C03B37/01205—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
    • C03B37/012—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
    • C03B37/0126—Means for supporting, rotating, translating the rod, tube or preform
    • 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
    • C03B2203/14—Non-solid, i.e. hollow products, e.g. hollow clad or with core-clad interface
    • 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
    • C03B2203/14—Non-solid, i.e. hollow products, e.g. hollow clad or with core-clad interface
    • C03B2203/16—Hollow core
    • 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

Landscapes

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

Abstract

An apparatus for manufacturing hollow core fiber preforms is described. The apparatus comprises a first plurality of support assemblies, each of the first plurality of support assemblies comprising an outer cylindrical shell and inner cylindrical shell, each of the outer cylindrical shell and inner cylindrical shells having a longitudinal axis and the outer cylindrical shell of each of the first plurality of support assemblies comprising an arcuate opening running parallel to the longitudinal axis.

Description

MANUFACTURING HOLLOW CORE FIBER PREFORMS LUS08211
BACKGROUND
[0001] A hollow core fiber preform is typically a glass element that is used as the basis for creating a hollow core optical fiber. The hollow core fiber preforms are drawn in a fiber drawing tower to form optical fibers. The resulting optical fibers have a smaller diameter than the original fiber preforms, and the inner microstructure matches that of the original preform, albeit at a reduced scale.
Hollow core fiber preforms are typically manufactured by fusing together a plurality of glass tubes. This involves positioning the tubes that will form the structured inner cladding inside a tube that will form the tubular outer cladding and then applying heat along the outside of the tubular outer cladding at the point where the tubes are to be fused together. This involves multiple operations, e.g. to fuse each set of nested capillaries to the inner surface of the tubular outer cladding.
[0002] The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known methods and apparatus for manufacturing hollow core fiber preforms.
SUMMARY
[0003] The following presents a simplified summary of the disclosure to provide a basic understanding to the reader. This summary is not intended to identify key features or essential features of the claimed subject matter nor is it intended to be used to limit the scope of the claimed subject matter. Its sole purpose is to present a selection of concepts disclosed herein in a simplified form as a prelude to the more detailed description that is presented later.
[0004] A method for manufacturing hollow core fiber preforms is described.
The method comprises inserting each glass capillary tube of a first plurality of glass capillary tubes into a different one of a first plurality of support assemblies, each of the support assemblies in the first plurality of support assemblies comprising an outer cylindrical shell and inner cylindrical shell, each of the outer cylindrical shell and inner cylindrical shells having a longitudinal axis and the
Page 1 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 outer cylindrical shell of each of the first plurality of support assemblies LUS08211 comprising an arcuate opening running parallel to the longitudinal axis, wherein the glass capillary tubes are inserted between the outer cylindrical shell and inner cylindrical shell; assembling the first plurality of support assemblies into an outer glass cladding, such that each glass capillary tube is in contact with an inner surface of the outer glass cladding through the arcuate opening of the outer cylindrical shell, to form a preform assembly; heating the preform assembly to at least a glass transition temperature of the first plurality of glass capillary tubes; cooling the preform assembly to below the glass transition temperature; and removing the first plurality of support assemblies from the preform assembly, to form a hollow core fiber preform.
[0005] Many of the attendant features will be more readily appreciated as the same becomes better understood by reference to the following detailed description considered in connection with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
[0006] The present description will be better understood from the following detailed description read in light of the accompanying drawings, wherein:
FIGs. 1-3 show transverse cross-sectional views of three different examples of anti-resonant hollow core fibers.
FIG. 4 is a flowchart of a method for manufacturing hollow core fiber preforms, according to the present disclosure.
FIGs. 5A, 5B and 5C show physical examples of the formation of an assembly and hollow core fiber preform.
FIGs. 6A, 6B and 6C show formation of an assembly and hollow core fiber preform, according to an example with a nested internal structure.
FIGs. 7A and 7B show physical examples of an assembly and hollow core fiber preform, according to an example with a double-nested internal structure.
FIG. 8 shows an example assembly for making a hollow core fiber preform, with an end cap.
Page 2 of 41
UTILITY PATENT
MS Docket No. 502051-LU01
FIG. 9 shows an apparatus used for drawing hollow core optical fibers from LUS08211 a hollow core fiber preform.
Reference numerals are used throughout the description to designate parts in the accompanying drawings.
DETAILED DESCRIPTION
[0007] The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present examples are constructed or utilized. The description sets forth the functions of the examples and the sequence of operations for constructing and operating the examples. However, the same or equivalent functions and sequences may be accomplished by different examples.
[0008] FIGs. 1-3 show transverse cross-sectional views of three different examples of antiresonant hollow core fibers (ARFs). Light is guided in these fibers by an antiresonant optical effect. Each of the fibers 100, 200, 300 comprises a tubular outer cladding (or cladding) 102, a structured, inner, cladding comprising a plurality of tubular cladding capillaries 104, 204, 304 and a hollow core 106. The outer cladding 102 has a glass thickness that is typically much larger than that of the cladding capillaries 104, 204, 304. In the first example, shown in FIG. 1, the structured, inner, cladding comprises five capillaries 104 of the same cross- sectional size and shape, which are arranged inside the outer cladding 102 in a single ring so that the longitudinal axes of each cladding capillary 104 and of the outer cladding 102 are substantially parallel. Each cladding capillary 104 is in contact with (e.g. bonded to) the inner surface of the outer cladding 102 at an azimuthal location 108, such that the cladding capillaries 104 are evenly spaced around the inner circumference of the outer cladding 102 and are also spaced apart from each other by gaps 110 (i.e. such that there is no contact between neighbouring capillaries). In some designs of ARF, the cladding capillaries 104 may be positioned in contact with each other (in other words, not spaced apart as in
FIG. 1), but spacing to eliminate this contact can improve the fiber’s optical
Page 3 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 performance. The gaps 110 remove nodes that arise at the contact points between LUS08211 adjacent tubes, and which tend to cause undesirable resonances that result in high losses. Accordingly, fibers with spaced-apart cladding capillaries may be referred to as “nodeless antiresonant hollow core fibers”.
[0009] The arrangement of the cladding capillaries 104 in a ring around the inside of the tubular outer cladding 102 creates a central space, cavity, or void within the fiber, also with its longitudinal axis parallel to those of the outer cladding 102 and the cladding capillaries 104, which is the fiber’s hollow core 106.
The hollow core 106 is bounded by the inwardly facing parts of the outer surfaces of the cladding capillaries 104. This is the core boundary, and the material (glass or polymer, for example) of the capillary walls that make up this boundary provides the required antiresonance optical guidance effect or mechanism. The cladding capillaries 104 have a thickness, t, at the core boundary which defines the wavelength for which antiresonant optical guiding occurs in the ARF.
[0010] In the second example, shown in FIG. 2, each primary cladding capillary 104 has a secondary, smaller capillary 204 nested inside it, bonded to the inner surface of the primary cladding capillary 104, in this example at the same azimuthal location 108 as the point of bonding between the primary cladding capillary 104 and the outer cladding 102. These additional smaller capillaries 204 can reduce the optical loss. ARF designs of this type, with secondary capillaries, may be referred to as “nested antiresonant nodeless fibers” (NANFs) (TM).
[0011] The third example, shown in FIG. 3, has two smaller cladding capillaries 204, 304 nested inside each cladding capillary 104. As with the example shown in FIG. 2, each of the smaller capillaries 204, 304 is bonded to the inner surface of the immediately larger capillary at the same azimuthal location as the point of bonding between the primary cladding capillary 104 and the outer cladding 102. In this example, the smaller capillary 204 may be referred to as the secondary cladding capillary and the smallest capillary 304 may be referred to as the tertiary cladding capillary. The tertiary cladding capillary 304 is bonded to the inner surface of the secondary cladding capillary 204 and the secondary cladding capillary 204 1s bonded to the inner surface of the primary cladding capillary 104.
Page 4 of 41
UTILITY PATENT
MS Docket No. 502051-LU01
ARF designs of this type, with secondary and tertiary cladding capillaries may be LUS08211 referred to as “double-nested antiresonant nodeless fibers” (DNANFs). In yet further examples (not shown in the drawings) there may be a different configuration of cladding capillaries. For example, there may be smaller further capillaries, within the tertiary capillary 304 to provide further levels of nesting and/or there may be a plurality of secondary cladding capillaries within each primary cladding capillary, each secondary cladding capillary being bonded to the inner surface of the primary cladding capillary at a different azimuthal location and/or each primary cladding capillary may have an internal structure (e.g. one or more dividing walls). [001 2] A technique for manufacturing such antiresonant nodeless fibers (referred to herein as ‘hollow core optical fibers’), including the nested and double- nested variants, is to use a fiber preform (referred to herein as ‘hollow core fiber preform’). A hollow core fiber preform is drawn into a hollow core optical fiber, and in many cases, the preform has the same waveguide structure as the eventual hollow core optical fiber, albeit on a larger scale (i.e. the same arrangement of capillaries). The hollow core fiber preform is heated and drawn by a pulling system to elongate the hollow core fiber preform into hollow core optical fibers. In most cases, the preforms are drawn into canes, which are then drawn into fibers. In other cases, it is possible to draw a preform directly into a fiber. In other words, the hollow core fiber preform is a larger-scale version of the hollow core optical fiber.
The hollow core fiber preform has a larger diameter compared to the hollow core optical fiber, as the elongation/drawing process will cause a narrowing of the diameter of the preform during formation of the hollow core optical fiber.
[0013] Hollow core fiber preforms are typically manufactured by fusing together a plurality of glass tubes. This involves positioning the tubes that will form the structured inner cladding inside a tube that will form the tubular outer cladding and then applying heat along the outside of the tubular outer cladding at the points where the tubes are to be fused together. This typically involves multiple operations, e.g. to fuse each set of nested capillaries to the inner surface of the tubular outer cladding.
Page 5 of 41
UTILITY PATENT
MS Docket No. 502051-LU01
[0014] The hollow core fiber preforms fabricated using these conventional LUS08211 methods are usually limited in size. This is because the fusing of various glass parts is dependent entirely on heat transfer from the outside of the hollow core fiber preform, towards the center of the hollow core fiber preform in order to fuse the glass tubes together. This limits the diameter of a hollow core fiber preform (e.g. because the preform is a scaled-up version of the hollow core fiber and so if the diameter of the preform is increased, the thickness of the tubular outer cladding is increased). If the diameter of the preform is limited, then there is an upper limit to how much hollow core optical fiber can be drawn from a single preform. This limits the maximum length of a single piece of hollow core fiber and as a result may increase the number of splices that are required within a fiber link. This may result in the overall link losses being too high for long distance transmission.
[0015] There is also very limited control over the geometry of the fiber preform using conventional assembly methods. The internal structure of the hollow core fiber preform is often not precisely known, and it is difficult to modify the properties that affect the resulting hollow core fiber preform.
[0016] Described herein is a novel method and apparatus for manufacturing hollow core fiber preforms from a plurality of glass tubes, leading to increased yields, high precision, and greater control of geometry. The novel method presented is also applicable for a wide range of hollow core fiber preform configurations and whilst the examples shown and described below relate to ARFs as shown in FIGs. 1-3, this is by way of example only and the methods can be applied to other geometries of structured inner cladding formed from a plurality of glass tubes.
[0017] FIG. 4 1s a flowchart of a method 400 for manufacturing hollow core fiber preforms, according to the present disclosure. The method uses a first plurality of support assemblies. The support assemblies each comprise an inner cylindrical shell and an outer cylindrical shell. Both the inner and outer cylindrical shell have an axis running through the center of the shell, and hence through the center of the circular cross-sections of the cylindrical shells. This axis is referred to herein as the longitudinal axis of the inner and outer cylindrical shell, and by
Page 6 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 extension, the longitudinal axis of the support assembly. The inner cylindrical shell LUS08211 is arranged such that it is inside the outer cylindrical shell, configured such that the longitudinal axes of the outer shell and inner shell are parallel and overlapping. As the support assembly is comprised of an outer cylindrical shell, with another cylindrical shell nested within, the shape of the support assembly is correspondingly cylindrical.
[0018] Each glass capillary tube of a first plurality of glass capillary tubes is inserted into a different one of the first plurality of support assemblies 402. In various examples, a machine inserts a glass capillary tube into each of the first plurality of support assemblies. Alternatively, a human inserts a glass capillary tube into each of the first plurality of support assemblies. The glass capillary tubes may be high purity glass capillary tubes (e.g. off-the-shelf capillary tubes or specifically manufactured capillary tubes). As tubes, the glass capillary tubes have cylindrical shapes. They have an inner diameter, and an outer diameter. The glass capillary tubes are said to match each of the first plurality of support assemblies, with the inner diameter of the glass capillary tubes equal to the outer diameter of the inner cylindrical shells and the outer diameter of the glass capillary tubes equal to the inner diameter of the outer cylindrical shells. In other words, a glass capillary tube is insertable into the support assembly between the outer cylindrical shell and inner cylindrical shell of each support assembly and, when assembled, the glass capillary tube is in contact with both the inner and outer cylindrical shells.
[0019] A preform assembly is formed by assembling the first plurality of support assemblies (now containing the glass capillary tubes) into an outer glass cladding 404. In various examples, an outer glass cladding is a cylindrical glass shell, with an inner diameter greater than that of the first plurality of support assemblies, such that all the first plurality of support assemblies are insertable into the outer glass cladding. The inner diameter of the outer glass cladding may be sufficiently large such that all the first plurality of support assemblies are insertable into the outer glass cladding, with no physical contact between each of the first plurality of support assemblies. Each of the first plurality of support assemblies contains an arcuate opening in at least the outer cylindrical shell. The arcuate
Page 7 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 opening refers to a missing arcuate portion of each support assembly. In some LUS08211 examples, only the outer cylindrical shell comprises an arcuate opening. In other examples, both the outer cylindrical shell and inner cylindrical shell comprise an arcuate opening. The arcuate opening is an opening in the cylindrical shell running parallel to the longitudinal axis of the outer cylindrical shell of each of the first plurality of support assemblies.
[0020] Due to the outer cylindrical shell comprising this arcuate opening, the support assembly is also said to comprise an arcuate opening. As each of the first plurality of support assemblies comprises this arcuate opening, and not the glass capillary tubes, the arcuate opening allows access to the glass capillary tube inserted within the support assembly. The first plurality of support assemblies is assembled into the outer glass cladding, such that each glass capillary tube is in physical contact with the inner surface of the outer glass cladding through the arcuate opening in the outer cylindrical shell of the support assembly.
[0021] As the arcuate opening extends over the entire length of the support assembly, this means that if the arcuate opening is positioned adjacent to the outer glass cladding, the glass capillary tube within the support assembly is in contact with the outer glass cladding over its entire length. This arrangement is to allow for glass-to-glass contact between the glass capillary tube and an inner surface of the outer glass cladding. To secure the support assemblies in place in contact with the outer glass cladding, end caps may be used. The end caps are described herein, with reference to FIG. 8. In various examples, at least one end cap is placed at one end of the outer glass cladding to secure the first plurality of support assemblies in position in the outer glass cladding. The assembling of the first plurality of support assemblies (containing the glass capillary tubes) into the outer glass cladding and securing them in position using at least one end cap forms the preform assembly.
[0022] In various examples, the operations of 402 and 404 are swapped, such that the first plurality of support assemblies is assembled into the outer glass cladding, configured such that the arcuate opening of the support assemblies is facing (i.e. adjacent to) the inner surface of the outer glass cladding, prior to the
Page 8 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 glass capillary tubes being inserted into each of the support assemblies. This is LUS08211 described herein, with reference to FIG. 8.
[0023] Once the preform assembly is formed, the assembly 1s heated to above the glass transition temperature 406 of the glass capillary tubes and outer glass cladding. The preform assembly (the outer glass cladding, containing the first plurality of support assemblies in physical contact at the arcuate opening of the first plurality of support assemblies with the inner surface of the outer glass cladding, which may be secured in position by at least one end cap) is heated to at least the glass transition temperature. The glass transition temperature refers to the temperature at which the glass starts to soften (i.e., beginning of a transition from solid to liquid). In various examples, the assembly is heated in a furnace. In other examples, the assembly is heated by applying a high voltage to one or more of the support assemblies secured in position by end caps in the outer glass cladding (i.e. resistive heating). A high voltage, in the context of the present method, refers to any voltage that is sufficient to cause heating of the preform assembly to at least the glass transition temperature. The voltage may be applied to the support assemblies themselves or the end cap. In this way, the assembly itself acts like a furnace.
[0024] The first plurality of support assemblies is formed from a material that has a higher softening / melting temperature than the glass transition temperature of the glass capillary tubes and outer glass cladding (so that the support assemblies will not soften or deform during heating). Additionally, the material may have a higher coefficient of thermal expansion than the glass capillary tubes and outer glass cladding. This is so that during the heating, the first plurality of support assemblies will expand and separate from the glass capillary tubes and/or outer glass cladding, allowing for simplified removal of the support assemblies. In various examples, the first plurality of support assemblies is comprised of graphite. Graphite is a suitable material as it has a higher coefficient of thermal expansion than glass, and a higher melting temperature than glass.
Graphite 1s also an exfoliating material, which assists in the removal of the support assemblies, as described below. In other examples, the first plurality of support
Page 9 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 assemblies are ceramic. In other examples, the first plurality of support assemblies | -U508211 are metals with very high melting points. Examples of such metals include (but are not limited to) molybdenum or tungsten. In other examples, the first plurality of support assemblies are alloys. An example of a suitable alloy is a molybdenum- based alloy.
[0025] When heated, the glass of the capillary tubes and outer glass cladding will start to soften, allowing for fusion of the glass of the glass capillary tube and the glass of the outer glass cladding. The fusion occurs at the point of contact between the different glass structures (i.e., through the arcuate opening in the support assemblies). The dimensions over which fusion occurs is therefore controlled by the size of the arcuate opening and so the use of the described method provides a high degree of precision, control, and repeatability of the fusing of the glass capillary tubes to the outer glass cladding which cannot be achieved using conventional methods.
[0026] After heating, the preform assembly is cooled down to below the glass transition temperature 408. In various examples, the preform assembly is cooled down to room temperature. As the outer glass cladding and glass capillary tubes cool, they resolidify such that they are now connected at the glass contact points between the glass capillary tubes and the outer glass cladding (i.e. at the arcuate opening).
[0027] The first plurality of support assemblies (and the end caps) is removed from the preform assembly 410. In various examples, a machine removes the first plurality of support assemblies. In other examples, a human removes the first plurality of support assemblies. The removal of the support assemblies leaves behind a glass structure, with glass capillary tubes bonded to an outer glass cladding. This is a hollow core fiber preform, formed according to the disclosed method.
[0028] Once the hollow core fiber preform is formed, there is optional further processing to be performed 412. In various examples, the fiber preform is cleaned post-formation. In various examples, during removal of the first plurality of support assemblies, debris from the first plurality of support assemblies is left
Page 10 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 behind on the hollow core fiber preform. For example, where each of the first LUS08211 plurality of support assemblies is made of graphite, the top layer of the graphite may be left behind on the surface of the hollow core fiber preform, which occurs when the support assemblies are slid off during removal. This is because graphite is an exfoliating material, and this property makes it easier to remove the support assemblies from the preform assembly. There is also a chance that there is the presence of general contaminants, not related to the material composing the first plurality of support assemblies. Contaminants refers to inorganic and/or organic contaminants that were on the glass surface during initial assembly.
[0029] In various examples, the method further comprises etching the hollow core fiber preform with an etching solution comprising hydrofluoric acid (HF) and/or other acids to clean the hollow core fiber preform of at least one contaminant and/or debris originating from the first plurality of support assemblies.
Debris refers to any material left on the hollow core fiber preform from the first plurality of support assemblies, post-removal of the first plurality of support assemblies. HF dissolves silica which may free surface contaminants and debris so that they can be washed away. Other acids, such as nitric acid, may be used (in addition to, or instead of HF) to dissolve metallic contaminants. A second cleaning method is also available, using oxidization. In various examples, the method further comprises oxidizing the hollow core fiber preform, to clean the hollow core fiber preform of at least one contaminant and/or debris from the first plurality of support assemblies. Oxidizing the hollow core fiber preform comprises heating the hollow core fiber preform. In various examples, the hollow core fiber preform is heated to a very high temperature. The specific temperature used varies based on the size of the resulting preform. In various examples, the method further comprises etching the hollow core fiber preform with HF, and oxidization. In various examples, the optional further processing steps 412 also comprise drawing the hollow core fiber preform into hollow core optical fibers. This process is described in more detail herein, with reference to FIG. 9.
[0030] Using the described method enables fabrication of hollow core fiber preforms with dimensions that are larger than using conventional methods. For
Page 11 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 example, hollow core fiber preforms with diameters of over 40mm can be LUS08211 fabricated. This 1s related to the diameter of the outer glass cladding. In various examples, the outer glass cladding has a diameter equal to or greater than 40mm.
However, the method of using support assemblies may still be applied when the outer glass cladding 1s less than 40mm. The length of these preforms may, for example, be in a range of 1200-1300mm. However, the method also may manufacture preforms with lengths below 1200mm or greater than 1300mm.
Having a larger preform is advantageous as it enables longer continuous lengths of hollow core optical fibers to be drawn and hence reduces the number of splices that are required for long transmission links. As splices introduce losses, it reduces the overall loss of a long transmission link. Furthermore, the use of support assemblies with an arcuate opening allows for much greater control over the resulting optical fiber preform. By altering the dimensions of the support assemblies (such as their length, diameters, or size of the arcuate opening), or their positioning inside the outer glass cladding, there is much greater control on the structure of the final preform including the size of the region in which the glass capillary tubes, and outer glass cladding are fused. This 1s also currently a challenge with current methods. The use of the method described herein therefore increases the yield of the process of fabricating hollow core fiber preforms.
[0031] Whilst the method described above relates to the fabrication of a non- nested hollow core fiber, such as shown in FIG. 1, the method may be used to fabricate hollow core fiber preforms with the more complicated nested structures for hollow core optical fibers (as shown in FIG. 2 and FIG. 3), as described below, along with many other structures that are not illustrated. This is due to the ability to manufacture the support assemblies in any shape or size desired, leading to high control over the internal structure of the hollow core fiber preform.
[0032] FIGs. 5A, 5B and 5C show physical examples of the formation of an assembly and hollow core fiber preform using the method of FIG. 4, according to an example without an internal nesting structure (e.g. for a fiber as shown in FIG. 1).
Page 12 of 41
UTILITY PATENT
MS Docket No. 502051-LU01
[0033] FIG. SA is an example of the insertion of glass capillary tubes into LUS08211 the support assemblies, shown in cross section. The figure shows a support assembly 500A, a glass capillary tube 502A and the glass capillary tube inserted into the support assembly 504A (which may be referred to as the assembled support assembly). The cross-section of the support assembly 500A is circular, with an inner radius from the center 514A of the cross-section (which corresponds to the longitudinal axis of the support assembly 500A) to the inner cylindrical shell 510A of the support assembly, and outer radius from the center 514A of the cross- section to the outer cylindrical shell 512A. The outer cylindrical shell 512A comprises an arcuate opening 506A which extends along the entire length of the outer cylindrical shell 512A, parallel to the longitudinal axis of the support assembly, such that the arcuate opening is always visible when looking down the longitudinal axis.
[0034] In the example shown in FIG. 5A, only the outer cylindrical shell 512A comprises an arcuate opening 506A. In other examples, however, both the inner and outer cylindrical shells comprise arcuate openings and the angle subtended by the arcuate opening may be the same for the inner cylindrical shell 510A and outer cylindrical shell 512A or the angle subtended by the arcuate opening of the outer cylindrical shell may be larger than the angle subtended by the arcuate opening of the inner cylindrical shell (e.g. as shown in FIG. 6B). Where both the inner cylindrical shell and outer cylindrical shell have an arcuate opening, the two openings may be aligned (e.g. as shown in FIG. 6B). In the example with no nesting, at least the outer cylindrical shell has an arcuate opening to enable glass-to-glass contact between the glass capillary tube and inner surface of the outer glass cladding.
[0035] The cross section of a glass capillary tube 502A is also shown in FIG. 5A. The glass capillary tube is said to match the support assembly 500A, meaning the glass capillary tube 502A has inner and outer diameters such that it can be inserted into support assembly 500A (i.e. the inner and outer diameter of the glass capillary tube both have sizes between the inner diameter of the outer cylindrical shell 512A and outer diameter of the inner cylindrical shell 510A). In various
Page 13 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 examples, a glass capillary tube 502A is inserted into a support assembly 500A LUS08211 such the longitudinal axes of the support assembly and glass capillary tubes overlap. Although FIG. SA shows a visible gap between the glass capillary tube 502A and the support assembly 500A after insertion, this is to increase the clarity of the diagram only and when implemented, the glass capillary tube may be in contact with both the inner and outer cylindrical shells 510A, 512A or there may be a small gap (e.g. to accommodate manufacturing tolerances in the glass capillary tubes). In the examples where there is a small gap, the small gap may have a size in the range of 50-100um.
[0036] Once inserted, the assembled support assembly S04 A is produced. At the arcuate opening 508A of the support assembly 504A, the glass of the capillary tube 1s accessible parallel to the open arc mapped out by the arcuate opening. This enables the glass capillary tube to be put in physical contact with the inner surface of an outer glass cladding, despite being contained within the support assembly. As described above, when assembling the support assembly 504A into an outer glass cladding, the arcuate opening 508A of the support assembly is placed in contact with the inner surface of an outer glass cladding. The arc length of the arcuate opening is said to correspond to the fusal length. The fusal length refers to the length of the glass capillary tube that is fused to the inner surface of an outer glass cladding (i.e. the arc length of the arcuate opening). The fusal length affects various properties of the resulting hollow core optical fiber, formed from the hollow core fiber preform. Current methods have great difficulty in controlling fusal lengths, however, with the method presented, the support assemblies are fabricated with an arcuate opening of any desired size, allowing for significant control over quantities such as the fusal length.
[0037] FIG. 5B is an example of a preform assembly 500B, with a first plurality of support assemblies 502B, containing glass capillary tubes 504B assembled into an outer glass cladding 506B such that the arcuate opening of the support assemblies 508B is positioned adjacent to the inner surface of the outer glass cladding 506B, allowing for glass-to-glass contact between the glass capillary
Page 14 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 tubes 504B and inner surface of the outer glass cladding 506B through the arcuate LUS08211 opening.
[0038] The example described in FIG. 5A referred to the formation of a single support assembly containing a glass capillary tube. However, in various examples, a first plurality of support assemblies and glass capillary tubes are received, for the insertion of a single glass capillary tube into each support assembly. À glass capillary tube 504B 1s inserted into a support assembly 502B, but this process is repeated for a desired number of support assemblies (dependent on the desired hollow core fiber preform configuration), such that there is a first plurality. In various examples, such as the example shown in FIG. 5B, there are five support assemblies, each containing a glass capillary tube. In various examples that are not illustrated, there are more than five support assemblies (e.g. 6, 7, 8, etc.), each filled with a glass capillary tube. In other examples that are also not illustrated, there are less than five support assemblies (e.g. 4, 3, 2, etc), each filled with a glass capillary tube. In various examples, the only condition on the size of the first plurality of support assemblies is that they are inserted into the outer glass cladding. In other words, if the support assemblies fit inside the outer glass cladding (in an arrangement where they are placed into outer glass cladding such that the longitudinal axis of the support assembly is parallel to the longitudinal axis of the outer glass cladding), and the arcuate opening is placed in contact with the inner surface of the outer glass cladding, then any number of support assemblies is possible.
[0039] Furthermore, FIG. 5B shows each of the first plurality of support assemblies as having the same dimensions. This 1s not a requirement. It is entirely possible to have the first plurality of support assemblies as different sizes (i.e. one support assembly may have a larger cross-sectional diameter than another). The first plurality refers to the first support assemblies inserted without any nesting (only nested within the outer glass cladding) and the first plurality is not necessarily defined by dimension.
[0040] To accommodate for this, the diameter of both the glass capillary tubes and first plurality of support assemblies are varied, subject to need and
Page 15 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 requirement. In various examples, the scale of the support assemblies is determined LUS08211 by instructions provided to a machine that fabricates each of the first plurality of support assemblies. The machine that is used to fabricate the support assemblies is given instructions on dimensions, such as what diameters to manufacture the support assemblies as. This further highlights the advantages of the present disclosure, showing the high degree of control and precision allowed for manufacturing desired hollow core fiber preforms.
[0041] The two support assemblies at the top of the cross-section 510B are held in place, and do not fall under gravity, due to the action of at least one end cap. End caps are described in more detail herein, with reference to FIG. 8, but are not shown in this figure. Once the assembly 500B has been assembled, it is heated to at least the glass transition temperature and cooled down again, according to the method described in FIG. 4.
[0042] FIG. 5C shows an example hollow core fiber preform formed by the method described in FIG. 4, without nesting. This example preform is shown after the removal of the first plurality of support assemblies and at least one end cap (where an end cap is used). The figure shows a hollow core fiber preform 500C, an outer glass cladding 502C and glass capillary tubes 504C. The hollow core fiber preform 500C is entirely comprised of glass. The glass capillary tubes are now fused at points of contact 506C between the glass capillary tubes and outer glass cladding, because of consolidation (during the heating and cooling process). This hollow core fiber preform 500C is now optionally further processed, to clean the preform and draw it into canes which are then further drawn into hollow core optical fibers. It is also possible to draw the preform directly into hollow core optical fibers. This is described in more detail in FIG. 9.
[0043] To fabricate a nested hollow core fiber preform, the method of FIG. 4 is extended to also use a second plurality of support assemblies with smaller diameters than the first plurality of support assemblies and a corresponding second plurality of glass capillary tubes with smaller diameters than the first plurality of glass capillary tubes. The glass capillary tubes of the second plurality of glass capillary tubes form the secondary capillaries 204 (e.g. as shown in FIG. 2) when
Page 16 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 the preform is drawn into hollow core optical fiber. Where there is nesting, both the LUS08211 inner and outer cylindrical shells of the first plurality of support assemblies comprise an arcuate opening.
[0044] Similarly for double nesting (e.g. as shown in FIG. 3 above), the method of FIG. 4 is further extended to additionally use a third plurality of support assemblies with smaller diameters than both the first and second pluralities of support assemblies and a corresponding third plurality of glass capillary tubes with smaller diameters than both the first and second pluralities of glass capillary tubes.
The glass capillary tubes of the third plurality of glass capillary tubes form the tertiary capillaries 304 (e.g. as shown in FIG. 3) when the preform is drawn into hollow core optical fiber. Where there is double nesting, both the inner and outer cylindrical shells of the first and second pluralities of support assemblies comprise an arcuate opening.
[0045] Where a nested preform is to be fabricated, the method of FIG. 4 is extended by additionally comprising inserting a different glass capillary tube from the second plurality of glass capillary tubes into each of these second plurality of support assemblies and inserting one of the second plurality of support assemblies (now containing glass capillary tubes of the second plurality of glass capillary tubes) into each of the assembled first plurality of support assemblies. The arcuate opening of the second plurality of support assemblies is also arranged to be aligned with the arcuate opening of the first plurality support assemblies, and therefore the arcuate opening of the second plurality of support assemblies is directed at the inner surface of the outer glass cladding, as in 404. In various examples, a third plurality of support assemblies is included, with an even smaller diameter than the second plurality of support assemblies. By using the support assemblies with an arcuate opening, and using a variation in their diameter, many designs of hollow core fiber preform are possible, including the more complex nested and double nested structures. These are described in more detail herein, with reference to FIG. 6 and FIG. 7.
[0046] Hence, the method described also allows for greater control of internal structure of hollow core fiber preforms, including simplifying the creation
Page 17 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 of the more complex structures, such as the nested structures. Current methods also LUS08211 use a glass lathe, and a flame to fuse different glass segments to form the hollow core fiber preform. This limits control of hollow core fiber preform internal structure configurations, and yield of hollow core optical fibers, due to the limitation arising from the path the heat has to travel for effective fusing of glass.
The method described in FIG. 4 allows careful control over the assembly of the support assemblies, and provides uniform consolidation, significantly improving upon current methods for manufacture hollow core fiber preforms. Finally, by using high purity off-the-shelf glass capillary tubes, as opposed to sintering with silica powder, the problem of silica densification is avoided, creating uniform, high quality, clear hollow core fiber preforms.
[0047] FIGs. 6A, 6B and 6C show formation of an assembly and hollow core fiber preform, according to an example with a nested internal structure.
[0048] FIG. 6A shows an assembly 600A, formed by following the method described with reference to FIG. 4. The assembly 600A comprises an outer glass cladding 608A, containing a first plurality of support assemblies 602A wherein each of the first plurality of support assemblies contains a glass capillary tube 614A, as described previously (i.e. the glass capillary tube is inserted between an inner and outer cylindrical shell of each of the first plurality of support assemblies).
The assembly 600A differs from the previous example in that the assembly 600A further comprises an outer shell 612A and a second plurality of support assemblies 604A, with a glass capillary tube 616A inserted into each of the second plurality of support assemblies 604A. The glass capillary tubes 614A inserted into the first plurality of support assemblies are said to be glass capillary tubes of a first plurality of glass capillary tubes, while glass capillary tubes 616A inserted into the second plurality of support assemblies are said to be glass capillary tubes of a second plurality of glass capillary tubes. In various examples, the method further comprises inserting the outer glass cladding 608A into an outer shell 612A, to form the assembly. The arcuate opening of both the first plurality of support assemblies and second plurality of support assemblies, are aligned so as to be adjacent to an
Page 18 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 inner surface of outer glass cladding 608A as shown at 610A to enable glass to LUS08211 glass contact through the arcuate opening.
[0049] In various examples, the outer shell 612A 1s a large-scale support assembly. In various examples, the outer shell 612A is a cylindrical shell having an inner and outer diameter, with a greater inner diameter than the outer glass cladding 608A, such that the outer glass cladding 608A is inserted into the outer shell 612A. In various examples, the outer cladding is inserted into the outer shell in a way such that the longitudinal axis of the outer cladding and the longitudinal axis of the outer shell are parallel and overlapping. For both the outer shell and outer glass cladding, the longitudinal axis refers to the axis passing through the center of the cylinders and through the center of both circular cross-sections (i.e. along the length of the outer shell and outer glass cladding). In various examples, the outer shell 612A is comprised of a material with a higher coefficient of thermal expansion than glass, and a higher softening (and/or melting) temperature than glass. In various examples, the outer shell 612A is comprised of graphite. The role of the outer shell is like the first plurality of support assemblies, and they may be formed from the same material. In some examples, the outer shell may be formed from a different material from any of the support assemblies (e.g. using graphite support assemblies with a molybdenum-based alloy for the outer shell). The main parameter is that the outer shell withstands temperatures above the glass transition temperature. The outer shell 612A acts as support for the outer glass cladding.
During consolidation, the outer shell maintains the shape of the outer glass cladding. Whilst the example shown in FIG. 5B does not include an outer shell (such as that shown in FIG. 6A, at 612A), in other examples, it may additionally comprise an outer shell.
[0050] In various examples, the method further comprises inserting a glass capillary tube into each of the second plurality of support assemblies. Each of the second plurality of support assemblies 604A, comprises an inner cylindrical shell 618A and outer cylindrical shell 620A The outer diameter of the outer cylindrical shell of the each of the second support assembly is smaller than the inner diameter of each of the inner cylindrical shells of the first plurality of support assemblies.
Page 19 of 41
UTILITY PATENT
MS Docket No. 502051-LU01
The method further comprises inserting one of the second plurality of support LUS08211 assemblies 604A into each of the first plurality of support assemblies 602A. The glass capillary tubes inserted into the second plurality of support assemblies are said to match the second plurality of support assemblies. In other words, the glass capillary tubes of the second plurality of glass capillary tubes that are used to insert into the second plurality of support assemblies are inserted between an inner cylindrical shell and outer cylindrical shell of each of the second plurality of support assemblies. By extension, the glass capillary tubes that are inserted into the second plurality of support assemblies have a diameter that is smaller than the diameter of the glass capillary tubes that are inserted into the first plurality of support assemblies (i.e. the glass capillary tubes 616A and 614A are different).
[0051] FIG. 6B shows an example of an arrangement for assembling a nested structure, corresponding to assembly of any one of the interior structures shown in FIG. 6A.
[0052] One of a plurality of first support assemblies 600B is shown, with arcuate opening 602B. In various examples, such as that shown in FIG. 6B, the plurality of support assemblies is machined such that the angle subtended by the arcuate opening is not the same for the inner and outer cylindrical shells. In various examples, such as that shown in FIG. 6B, the angle subtended by the arcuate opening is smaller for the outer cylindrical shell. It is entirely possible to have a larger angle subtended by the arcuate opening of the outer cylindrical shell. The configuration of the arcuate opening 602B allows for greater support of a second support assembly that is inserted inside and helps prevent the second support assembly from rolling around inside. The arcuate opening 602B machined in this way also allows greater control of the amount of glass-to-glass contact between the glass capillary tube contained within a second support assembly and a glass capillary tube contained within a first support assembly.
[0053] One of a second plurality of support assemblies 620B is shown with an arcuate opening 622B. The second support assembly 620B is comprised of an inner and outer cylindrical shell. In various examples, such as the example in FIG. 6B, the outer cylindrical shell of the second support assembly comprises an arcuate
Page 20 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 opening. In other examples that are not illustrated, both the inner and outer LUS08211 cylindrical shell comprise an arcuate opening. In 604B, both the first and second support assemblies have a corresponding glass capillary tube inserted into them and then the second support assembly 1s arranged into the first support assembly.
[0054] A second support assembly 610B (the same as second support assembly 620B) with an outer diameter smaller than that of the support assembly 606B receives a glass capillary tube 612B, which is inserted into the second support assembly. In various examples, the glass capillary tube 612B is inserted into the second support assembly in a way such that the longitudinal axis of the glass capillary tube 612B and the longitudinal axis of the second support assembly 610B are parallel and overlapping. The second support assembly 610B is inserted into the support assembly 606B (the same support assembly as first support assembly 600B), resulting in a new structure for the support assemblies shown in
FIG. 6B. In various examples, the second support assembly 610B is inserted into the support assembly 606B in a way such that the longitudinal axis of the second support assembly 610B and the longitudinal axis of the support assembly 606B are parallel.
[0055] The second support assembly 610B is arranged such that it sits in the arcuate opening of the support assembly 606B, and there is contact between the glass capillary tubes of both the first support assembly and the second support assembly (i.e. glass-to-glass contact between different glass capillary tubes 608B and 612B) through the arcuate openings in the support assemblies. The configuration of arcuate opening 602B helps in allowing second support assembly 610B to be supported. In various examples, a first plurality of these support assemblies (each further comprising a second support assembly) are formed by repeating this process. Next, the first plurality of support assemblies is assembled into an outer glass cladding, such that the arcuate opening of the second plurality of support assemblies is aligned with the arcuate opening of the first plurality of support assemblies. This allows for glass-to-glass contact between the outer glass cladding, and both glass capillary tubes, despite the desired nesting structure. This means that the use of the support assemblies allows for simplified production of
Page 21 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 more complex hollow core fiber preforms, such as nested structures, as the interior LUS08211 capillaries are now fused at the same point and fused by the same heating process.
The resulting assembly resembles that shown in FIG. 6A, once the first plurality of support assemblies is assembled into the outer glass cladding in the described configuration.
[0056] It is important to note that to allow glass-to-glass contact between glass capillary tubes 608B and 612B, both the outer and inner cylindrical shells of the first plurality of support assemblies comprise an arcuate opening, aligned such that they are parallel. The outer cylindrical shell of the second plurality of support shells also requires the arcuate opening for the glass-to-glass contact. In various examples, such as that shown in FIG. 6B, the inner cylindrical shell of the second plurality of support assemblies does not require an arcuate opening (shown at 614B). An alignment between the arcuate opening of the second support assembly and the arcuate opening of the first support assembly is shown at 618B, allowing for glass-to-glass contact between the different glass capillary tubes that have been inserted into each support assembly.
[0057] FIG. 6C shows an example hollow core fiber preform 600C formed by the method described previously, with a nested structure. This example preform is shown after the removal of the first plurality (and second plurality) of support assemblies and any number of end caps used. This preform 600C is formed by heating and cooling the assembly 600A shown in FIG. 6A. The hollow core fiber preform comprises an outer glass cladding 602C, an internal glass capillary 604C, a nested internal glass capillary 606C, wherein both the internal glass capillary 604C and nested internal glass capillary 606C for each of the plurality of support assemblies are fused to the outer glass cladding at the same point 608C (i.e. at the arcuate openings of the support assemblies). In various examples, the inner shell of the second plurality of support assemblies is replaced with a solid cylindrical core to form the nested structure.
[0058] FIGs. 7A and 7B show physical examples of an assembly and hollow core fiber preform, according to an example with a double-nested internal structure.
Page 22 of 41
UTILITY PATENT
MS Docket No. 502051-LU01
[0059] FIG. 7A shows an assembly 700A, comprising a double-nested LUS08211 internal structure and comprising the outer shell 702A. The assembly comprises the outer shell 702A, the outer glass cladding 704A, a first plurality of support assemblies 706A, each containing a glass capillary tube of a first plurality of glass capillary tubes 708A, a second plurality of support assemblies 710A, each containing a glass capillary tube of a second plurality of glass capillary tubes 712A, and a third plurality of support assemblies 714A, each containing a glass capillary tube of a third plurality of glass capillary tubes 716A. In various examples, the double-nested internal structure is formed by use of a third plurality of support assemblies, wherein each of the third plurality of support assemblies comprises an inner cylindrical shell 720A and outer cylindrical shell 722A, wherein the glass capillary tube of the third plurality of glass capillary tubes is inserted between the inner and outer cylindrical shells of each of the third plurality of support assemblies. By extension, the glass capillary tubes inserted into the third plurality of support assemblies have a smaller outer diameter than the inner diameter glass capillary tubes inserted into the first plurality of support assemblies 706A and the second plurality of support assemblies 710A (i.e. the glass capillary tubes 716A, 712A and 708A are all different from each other and have different diameters).
[0060] Similarly to the nesting described previously, the third plurality of support assemblies 714A (once inserted into the second plurality of support assemblies 710A, which in itself is inserted into a first plurality of support assemblies 706A) is arranged such that an arcuate opening of the third plurality of support assemblies 1s aligned with the arcuate opening of both the second plurality of support assemblies and the first plurality of support assemblies such that there is glass-to-glass contact between the glass capillary tubes 716A, 712A and 708A of the support assemblies and the inner surface of the outer glass cladding 704A.
[0061] It is important to note that to allow glass-to-glass contact between glass capillary tubes 716A, 712A and 708A, both the outer and inner cylindrical shells of the first plurality of support assemblies and the outer and inner cylindrical shells of the second plurality of support assemblies comprise an arcuate opening, aligned such that they are parallel. For contact with the glass capillary tubes of the
Page 23 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 third plurality, at least the outer cylindrical shell of the third plurality of support LUS08211 assemblies comprises an arcuate opening. As seen in FIG. 7A, the inner cylindrical shell of the third plurality does not have an arcuate opening, shown at 718A. The opening of the outer cylindrical shell of the third plurality of support assemblies is shown at 724A. In various examples, such as that shown in FIG. 7A, the inner cylindrical shell of the third plurality of support assemblies does not require an arcuate opening.
[0062] The assembly 700A is heated and cooled, with removal of all the support assemblies (first, second and third plurality) and outer shell 702A according to the method described previously. This forms a double-nested hollow core fiber preform.
[0063] FIG. 7B shows an example hollow core fiber preform 700B formed by the method described, with a double-nested internal structure. This example preform is shown after the removal of the first plurality (and second and third plurality) of support assemblies and at least one end cap. This preform 700B is formed by heating and cooling the assembly 700A shown in FIG. 7A, according to the method described in FIG. 4, and removing the outer shell 702A and plurality of support assemblies (all 706A, 710A, 714A).
[0064] The hollow core fiber preform 700B comprises an outer glass cladding 702B, a first plurality of internal capillaries 704B, a second plurality of internal capillaries (nested capillaries) 706B, and a third plurality of internal capillaries (double nested capillaries) 708B. One of the internal capillaries, nested capillaries, and double nested capillaries form groups of three that are fused to the outer glass cladding 702B at the same point (i.e. along a corresponding arc of the circular cross-section). In various examples that are not illustrated, the inner shell of the third plurality of support assemblies is replaced with a solid cylindrical core to form the double-nested structure.
[0065] FIG. 8 shows an example assembly for making a hollow core fiber preform, with an end cap 806. The assembly 800 comprises an outer glass cladding 802, a first plurality of support assemblies 804, and an end cap 806. In the configuration shown in FIG. 8, each of the first plurality of support assemblies 804
Page 24 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 are assembled into the outer glass cladding 802, configured such that an arcuate LUS08211 opening of each of the first plurality of support assemblies is in contact with an inner surface 812 of the outer glass cladding 802.
[0066] The outer glass cladding 802 has a diameter such that it fits all the first plurality of support assemblies inside. In various examples, each of the first plurality of support assemblies is inserted such that the longitudinal axis of the each of the first plurality of support assemblies and the longitudinal axis of the outer glass cladding are parallel. In various examples, the outer glass cladding is a support assembly, with a finite thickness. The thickness used in the apparatus (or method as described previously) is subject to the requirements of the resulting hollow core fiber preform and is therefore variable.
[0067] The assembly 800 also comprises end cap 806. For illustrative purposes, one end cap and one circular cross section is shown in FIG. 8, however, in various examples, a second end cap 1s used with respect to the other circular cross-section of the outer glass cladding (not shown in the figure) at the opposing end of the outer glass cladding. In various examples, the shape of the end cap corresponds to the cross-sectional shape of the outer glass cladding (i.e. as shown, a circular end cap for a circular cross-section, in the example of a cylindrical outer glass cladding). The end cap 806 secures the first plurality of support assemblies 804 in place, such that they do not move or fall under gravity when assembled into the outer glass cladding 802. In various examples, the diameter of the end caps is the same for all end caps used. In various examples, the diameter of the at least one end cap is equal to the outer diameter of the outer glass cladding. In various examples, the end caps are manufactured to feature a textured surface, e.g. engravings 808, corresponding to the outlines of the first plurality of support assemblies (or any of the plurality of support assemblies). In various examples, the width of an engraving is equal to the distance between the inner and outer cylindrical shells of each support assembly. In various examples, the engravings are manufactured by a machine. In various examples, the engravings are holes in the end cap. In various examples, the engravings are embossments / protrusions in the end cap. The engravings 808, or equivalent protrusions, are used to secure the
Page 25 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 first plurality of support assemblies in place slot into the engravings 808. By LUS08211 attaching an identical end cap at both ends of the outer glass cladding 810, the first plurality of support assemblies is secured strongly in place (i.e. in the example of a cylindrical outer glass cladding, attaching an end cap at each circular cross section of the outer glass cladding). In various examples, each of the first plurality of support assemblies are longer than the outer glass cladding such that the end cap secures onto the length of the first plurality of support assemblies that is partially outside of the outer glass cladding.
[0068] In various examples, a glass capillary tube 814 is inserted 816 into each of the first plurality of support assemblies 804 (in FIG. 8, one glass capillary tube is shown for illustrative purposes, however, there are multiple glass capillary tubes. The shape of the glass capillary tube is also simplified). As explained with respect to FIG. 4, it is entirely possible to assemble each of the first plurality of support assemblies into the outer glass cladding, with the arcuate opening in contact with an inner surface of the outer glass cladding prior to the insertion of the glass capillary tubes. In this example, the glass capillary tubes are inserted into each of the first plurality of support assemblies prior to positioning the at least one end cap on the cross sections of the outer glass cladding. The glass capillary tubes are inserted between the inner cylindrical shells 818 and outer cylindrical shells 820 of the support assemblies. This reordering is displayed in FIG. 8, where each of the first plurality of support assemblies are assembled into the outer glass cladding and configured such that the arcuate opening is in contact with the inner surface of the outer glass cladding. In various examples, such as those discussed previously, the glass capillary tubes are inserted into the first plurality of support assemblies prior to assembling the first plurality of support assemblies into the outer glass cladding.
[0069] The at least one end cap is configured to support a desired amount of nesting and capillaries. In other words, the end cap may be manufactured to support no nesting, single nesting, or double nesting. In various examples, the end cap is configured to hold a second plurality of support assemblies in place. In various examples, the end cap is configured to hold the second plurality of support
Page 26 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 assemblies in place using engravings corresponding to the outlines of the second LUS08211 plurality of support assemblies in the desired positions of the second plurality of support assemblies. In various examples, the end cap is configured to hold a third plurality of support assemblies in place. In various examples, the end cap 1s configured to hold the third plurality of support assemblies in place using engravings corresponding to the solid sections of the third plurality of support assemblies in the desired positions of the third plurality of support assemblies. In various examples, each of the second plurality of support assemblies are longer than the outer glass cladding such that the end cap secures onto the length of the second plurality of support assemblies that is partially outside of the outer glass cladding. In various examples, each of the third plurality of support assemblies are longer than the outer glass cladding such that the end cap secures onto the length of the third plurality of support assemblies that is partially outside of the outer glass cladding.
[0070] FIG. 9 shows an apparatus used for drawing hollow core optical fibers from a hollow core fiber preform. The apparatus 900 comprises a feeding unit 902, a hollow core fiber preform 904, a furnace 906, a diameter gauge 908, a coating cup 912, a cooling chamber 914, a pulley system 916 and a curing oven 918.
[0071] The feeding unit 902 is configured to hold the hollow core fiber preform 904 and ensure it is aligned with the rest of the apparatus 900. In various examples, the hollow core fiber preform 904 is produced by the method described herein, and using the apparatus described herein, with reference to FIG. 4 and FIG. 8. In various examples, the hollow core fiber preform 904 does not have a nested structure. In various examples, the hollow core fiber preform 904 has a nested structure. In various examples, the hollow core fiber preform 904 has a double nested structure. While the figures have only illustrated a hollow core fiber preform without nesting, nesting, or double nesting, it is important to note that by manufacturing the support assemblies in any desired shape or size, then it is possible to create any desired configuration for the structure of the hollow core fiber preform.
Page 27 of 41
UTILITY PATENT
MS Docket No. 502051-LU01
[0072] The hollow core fiber preform 904 is fed into a furnace 906. In the LU508211 furnace 906, the hollow core fiber preform 904 is heated. In various examples, such as that shown in FIG. 9, only part of the hollow core fiber preform 904 is in in the furnace 906. The part of the hollow core fiber preform 904 is heated to at least the glass transition temperature, such that the part of the hollow core fiber preform 904 inside the furnace becomes soft. The soft part of the hollow core fiber preform is connected to a spool which is part of a pulley system 916. The pulley system pulls the now soft part of the hollow core fiber preform, which narrows the diameter as it is pulled and forms a hollow core optical fiber. The speed of the pulley system is adjusted to ensure the diameter of the resulting hollow core optical fiber is constant throughout its length.
[0073] In various examples, the apparatus 900 further comprises a diameter gauge 908. This acts to limit the diameter of the resulting hollow core optical fiber.
The size of the diameter gauge is adjusted such that the resulting hollow core optical fiber has a diameter configured to the requirements of the manufacturer of the hollow core optical fiber. In various examples, the apparatus 900 further comprises a coating cup 912. The coating cup 912 is used to apply a coating to the exterior of the hollow core optical fiber. Many uses of hollow core optical fibers require use of a coating, with some coatings used to reduce micro-bends in the hollow core optical fiber, which affect performance. Some hollow core optical fibers use multiple coating layers, such as the hollow core optical fibers used in telecommunications. In various examples, apparatus 900 further comprises at least one coating cup.
[0074] In various examples, the apparatus 900 further comprises a cooling chamber 914. As the furnace 906 heats part of the hollow core fiber preform 904 which is then drawn out of the furnace 906 once it is soft (by the pulley system 916), the drawn hollow core optical fiber is hot and soft. The cooling chamber 914 is used to draw heat from the hollow core optical fiber which cools it down and assists to solidify the final product. In various examples, the apparatus 900 further comprises a curing oven 918. The curing oven 918 is used to cure the coating. In various examples, the curing oven comprises at least one UV irradiator for curing
Page 28 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 the coating. In various examples, the resulting hollow core optical fiber is wound LUS08211 up on a spool. In various examples, there are a plurality of curing ovens and coating cups. In various examples, there are no curing ovens and coating cups. In various examples, the order of coating cup 912, cooling chamber 914 and curing oven 918 1s different. There are no strict requirements for the order of these components in the drawing mechanism.
[0075] The result of the apparatus 900 1s hollow core optical fibers, produced by drawing (e.g. elongating) the hollow core fiber preforms, manufactured by the method and apparatus disclosed within this application. As a result of being able to manufacture larger preforms using the method described in
FIG. 4, there 1s an increased yield of hollow core optical fiber.
[0076] Alternatively, or in addition to the other examples described herein, examples include any combination of the following:
[0077] Clause A: A method for manufacturing hollow core fiber preforms, the method comprising: inserting each glass capillary tube of a first plurality of glass capillary tubes into a different one of a first plurality of support assemblies, each of the support assemblies in the first plurality of support assemblies comprising an outer cylindrical shell and inner cylindrical shell, each of the outer cylindrical shell and inner cylindrical shell having a longitudinal axis and the outer cylindrical shell of each of the first plurality of support assemblies comprising an arcuate opening running parallel to the longitudinal axis, wherein the glass capillary tubes are inserted between the outer cylindrical shell and inner cylindrical shell; assembling the first plurality of support assemblies into an outer glass cladding, such that each glass capillary tube is in contact with an inner surface of the outer glass cladding through the arcuate opening of the outer cylindrical shell, to form a preform assembly; heating the preform assembly to at least a glass transition temperature of the first plurality of glass capillary tubes; cooling the preform assembly to below the glass transition temperature; and removing the first plurality of support assemblies from the preform assembly, to form a hollow core fiber preform.
Page 29 of 41
UTILITY PATENT
MS Docket No. 502051-LU01
[0078] Clause B: The method of clause A, wherein the preform assembly LUS08211 further comprises at least one end cap is positioned at an end of the outer glass cladding and the method further comprises removing the at least one end cap.
[0079] Clause C: The method of clause A or B, wherein the inner cylindrical shell of each of the first plurality of support assemblies comprises an arcuate opening and the method further comprising: inserting each glass capillary tube of a second plurality of glass capillary tubes into a different one of a second plurality of support assemblies, each of the support assemblies in the second plurality of support assemblies comprising an outer cylindrical shell and inner cylindrical shell, each of the outer cylindrical shell and inner cylindrical shell of the second plurality of support assemblies having a longitudinal axis and the outer cylindrical shell of each of the second plurality of support assemblies comprising an arcuate opening running parallel to the longitudinal axis, wherein the glass capillary tubes of the second plurality of glass capillary tubes are inserted between the outer cylindrical shell and inner cylindrical shell of the second plurality of support assemblies; inserting each of the second plurality of support assemblies into a different one of the first plurality of support assemblies prior to heating the preform assembly; and wherein removing the first plurality of support assemblies from the preform assembly to form a hollow core fiber preform further comprises removing the second plurality of support assemblies.
[0080] Clause D: The method of clause C, wherein the support assemblies of the second plurality of support assemblies are inserted into each of the first plurality of support assemblies such that the arcuate opening of the outer cylindrical shells of the second plurality of support assemblies is rotationally aligned with the arcuate openings of the outer cylindrical shell and the inner cylindrical shell of the first plurality of support assemblies.
[0081] Clause E: The method of clause C, wherein the inner cylindrical shell of each of the second plurality of support assemblies comprises an arcuate opening and the method further comprising; inserting each glass capillary tube of a third plurality of glass capillary tubes into a different one of a third plurality of support assemblies, each of the support assemblies in the third plurality of support
Page 30 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 assemblies comprising an outer cylindrical shell and inner cylindrical shell, each of LUS08211 the outer cylindrical shell and inner cylindrical shell of the third plurality of support assemblies having a longitudinal axis and the outer cylindrical shell of each of the third plurality of support assemblies comprising an arcuate opening running parallel to the longitudinal axis, wherein the glass capillary tubes of the third plurality of glass capillary tubes are inserted between the outer cylindrical shell and inner cylindrical shell of the third plurality of support assemblies; inserting each of the third plurality of support assemblies into a different one of the second plurality of support assemblies prior to heating the preform assembly; and wherein removing the first plurality of support assemblies from the preform assembly to form a hollow core fiber preform further comprises removing the third plurality of support assemblies.
[0082] Clause F: The method of clause E, wherein the support assemblies of the third plurality of support assemblies are inserted into each of the second plurality of support assemblies such that the arcuate opening of the outer cylindrical shells of the third plurality of support assemblies is rotationally aligned with the arcuate openings of the outer cylindrical shell and inner cylindrical shell of the first plurality of support assemblies, and the arcuate openings of the outer cylindrical shell and inner cylindrical shell of the second plurality of support assemblies.
[0083] Clause G: The method of any of clauses A-F, wherein each of the first plurality of support assemblies are comprised of a material with a higher coefficient of thermal expansion than the glass capillary tubes, and the material has a softening point higher than the glass transition temperature of the glass capillary tubes.
[0084] Clause H: The method of any of clauses A-G, wherein each of the first plurality of support assemblies is comprised of graphite.
[0085] Clause I: The method of any clauses A-H, wherein the method further comprises containing the preform assembly within an outer shell.
[0086] Clause J: The method of clause I, wherein the outer shell is made of graphite and has a cylindrical shell shape.
Page 31 of 41
UTILITY PATENT
MS Docket No. 502051-LU01
[0087] Clause K: The method of any of clauses A-J, wherein heating the LUS08211 preform assembly to at least the glass transition temperature of the glass capillary tubes comprises heating the assembly in a furnace to at least the glass transition temperature of the glass capillary tubes.
[0088] Clause L: The method of any of clauses A-K, wherein heating the preform assembly to at least the glass transition temperature of the glass capillary tubes comprises heating the assembly by applying a voltage to the support assemblies within the preform assembly.
[0089] Clause M: The method of any of clauses A-L, wherein the method further comprises etching the hollow core fiber preform with an etching solution comprising hydrofluoric acid, HF, to clean the hollow core fiber preform of at least one of: a contaminant; or debris from the first plurality of support assemblies.
[0090] Clause N: The method of any of clauses A-M, wherein the method further comprises oxidizing the hollow core fiber preform, to clean the hollow core fiber preform of at least one of: a contaminant; or debris from the first plurality of support assemblies.
[0091] Clause O: The method of any of clauses A-N, wherein the outer glass cladding has an outer diameter equal to or greater than 40mm.
[0092] Clause P: The method of any of clauses A-O, the method further comprising drawing the hollow core fiber preform into hollow core optical fibers.
[0093] Clause Q: An apparatus for manufacturing hollow core fiber preforms, the apparatus comprising: a first plurality of support assemblies, each of the first plurality of support assemblies comprising an outer cylindrical shell and inner cylindrical shell, each of the outer cylindrical shell and inner cylindrical shells having a longitudinal axis and the outer cylindrical shell of each of the first plurality of support assemblies comprising an arcuate opening running parallel to the longitudinal axis.
[0094] Clause R: The apparatus of clause Q, further comprising: a first plurality of glass capillary tubes, wherein each glass capillary tube of the first plurality of glass capillary tubes is inserted into a different one of the first plurality of support assemblies between the inner cylindrical shell and outer cylindrical
Page 32 of 41
UTILITY PATENT
MS Docket No. 502051-LU01 shell; an outer glass cladding; and at least one end cap, configured to secure each of LUS08211 the first plurality of support assemblies in position in the outer glass cladding.
[0095] Clause S: The apparatus of clause Q or R, wherein each of the first plurality of support assemblies is comprised of graphite.
[0096] Clause T: The apparatus of any of clauses Q-S, wherein the inner cylindrical shell of each of the first plurality of support assemblies comprises an arcuate opening and the apparatus further comprises: a second plurality of support assemblies, each of the second plurality of support assemblies comprising an outer cylindrical shell and inner cylindrical shell, each of the outer cylindrical shell and inner cylindrical shells of the second plurality of support assemblies having a longitudinal axis and the outer cylindrical shell of each of the second plurality of support assemblies comprising an arcuate opening running parallel to the longitudinal axis, and a second plurality of glass capillary tubes, wherein each glass capillary tube of the second plurality of glass capillary tubes is inserted into a different one of the second plurality of support assemblies between the inner cylindrical shell and outer cylindrical shell.
[0097] Clause U: The apparatus of clause T, wherein the inner cylindrical shell of each of the second plurality of support assemblies comprises an arcuate opening and the apparatus further comprises: a third plurality of support assemblies, each of the third plurality of support assemblies comprising an outer cylindrical shell and inner cylindrical shell, each of the outer cylindrical shell and inner cylindrical shells of the third plurality of support assemblies having a longitudinal axis and the outer cylindrical shell of each of the third plurality of support assemblies comprising an arcuate opening running parallel to the longitudinal axis, and a third plurality of glass capillary tubes, wherein each glass capillary tube of the third plurality of glass capillary tubes is inserted into a different one of the third plurality of support assemblies between the inner cylindrical shell and outer cylindrical shell.
[0098] Any range or device value given herein may be extended or altered without losing the effect sought, as will be apparent to the skilled person.
Page 33 of 41
UTILITY PATENT
MS Docket No. 502051-LU01
[0099] Although the subject matter has been described in language specific LUS08211 to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims 1s not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
[00100] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item refers to one or more of those items.
[00101] The operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought.
[00102] The term 'comprising' is used herein to mean including the method blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements.
[00103] It will be understood that the above description 1s given by way of example only and that various modifications may be made by those skilled in the art. The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this specification.
Page 34 of 41
UTILITY PATENT
MS Docket No. 502051-LU01

Claims (20)

CLAIMS LU508211 What is claimed is:
1. A method (400) for manufacturing hollow core fiber preforms, the method comprising: inserting (402) each glass capillary tube (502A) of a first plurality of glass capillary tubes into a different one of a first plurality of support assemblies (504A), each of the support assemblies in the first plurality of support assemblies comprising an outer cylindrical shell (512A) and inner cylindrical shell (510A), each of the outer cylindrical shell and inner cylindrical shell having a longitudinal axis and the outer cylindrical shell of each of the first plurality of support assemblies comprising an arcuate opening (506A) running parallel to the longitudinal axis, wherein the glass capillary tubes are inserted between the outer cylindrical shell and inner cylindrical shell; assembling (404) the first plurality of support assemblies into an outer glass cladding (506B), such that each glass capillary tube is in contact with an inner surface of the outer glass cladding (508B) through the arcuate opening of the outer cylindrical shell, to form a preform assembly; heating the preform assembly to at least a glass transition temperature of the first plurality of glass capillary tubes (406); cooling the preform assembly to below the glass transition temperature (408); and removing the first plurality of support assemblies from the preform assembly, to form a hollow core fiber preform (410).
2. The method of claim 1, wherein the preform assembly further comprises at least one end cap (806) is positioned at an end of the outer glass cladding and the method further comprises removing the at least one end cap.
3. The method of claim 1 or 2, wherein the inner cylindrical shell of each of the first plurality of support assemblies comprises an arcuate opening (602B) and the method further comprising: Page 35 of 41 UTILITY PATENT MS Docket No. 502051-LU01 inserting each glass capillary tube of a second plurality of glass capillary LUS08211 tubes (616A) into a different one of a second plurality of support assemblies (604A), each of the support assemblies in the second plurality of support assemblies comprising an outer cylindrical shell (620A) and inner cylindrical shell (618A), each of the outer cylindrical shell and inner cylindrical shell of the second plurality of support assemblies having a longitudinal axis and the outer cylindrical shell of each of the second plurality of support assemblies comprising an arcuate opening (618B) running parallel to the longitudinal axis, wherein the glass capillary tubes of the second plurality of glass capillary tubes are inserted between the outer cylindrical shell and inner cylindrical shell of the second plurality of support assemblies; inserting each of the second plurality of support assemblies into a different one of the first plurality of support assemblies prior to heating the preform assembly; and wherein removing the first plurality of support assemblies from the preform assembly to form a hollow core fiber preform further comprises removing the second plurality of support assemblies.
4. The method of claim 3, wherein the support assemblies of the second plurality of support assemblies are inserted into each of the first plurality of support assemblies such that the arcuate opening of the outer cylindrical shells of the second plurality of support assemblies is rotationally aligned with the arcuate openings of the outer cylindrical shell and the inner cylindrical shell of the first plurality of support assemblies.
5. The method of claim 3, wherein the inner cylindrical shell of each of the second plurality of support assemblies comprises an arcuate opening and the method further comprising; inserting each glass capillary tube (716A) of a third plurality of glass capillary tubes into a different one of a third plurality of support assemblies (714A), each of the support assemblies in the third plurality of support assemblies Page 36 of 41 UTILITY PATENT MS Docket No. 502051-LU01 comprising an outer cylindrical shell (722A) and inner cylindrical shell (720A), LUS08211 each of the outer cylindrical shell and inner cylindrical shell of the third plurality of support assemblies having a longitudinal axis and the outer cylindrical shell of each of the third plurality of support assemblies comprising an arcuate opening running parallel to the longitudinal axis, wherein the glass capillary tubes of the third plurality of glass capillary tubes are inserted between the outer cylindrical shell and inner cylindrical shell of the third plurality of support assemblies; inserting each of the third plurality of support assemblies into a different one of the second plurality of support assemblies prior to heating the preform assembly; and wherein removing the first plurality of support assemblies from the preform assembly to form a hollow core fiber preform further comprises removing the third plurality of support assemblies.
6. The method of claim 5, wherein the support assemblies of the third plurality of support assemblies are inserted into each of the second plurality of support assemblies such that the arcuate opening of the outer cylindrical shells of the third plurality of support assemblies is rotationally aligned with the arcuate openings of the outer cylindrical shell and inner cylindrical shell of the first plurality of support assemblies, and the arcuate openings of the outer cylindrical shell and inner cylindrical shell of the second plurality of support assemblies.
7. The method of any preceding claim, wherein each of the first plurality of support assemblies (504A) are comprised of a material with a higher coefficient of thermal expansion than the glass capillary tubes, and the material has a softening point higher than the glass transition temperature of the glass capillary tubes.
8. The method of any preceding claim, wherein each of the first plurality of support assemblies (504A) is comprised of graphite. Page 37 of 41 UTILITY PATENT MS Docket No. 502051-LU01
9. The method of any preceding claim, wherein the method further comprises containing the preform assembly within an outer shell (612A).
10. The method of claim 9, wherein the outer shell (612A) is made of graphite and has a cylindrical shell shape.
11. The method of any preceding claim, wherein heating the preform assembly (406) to at least the glass transition temperature of the glass capillary tubes comprises heating the assembly in a furnace to at least the glass transition temperature of the glass capillary tubes.
12. The method of any of claims 1 to 10, wherein heating the preform assembly (406) to at least the glass transition temperature of the glass capillary tubes comprises heating the assembly by applying a voltage to the support assemblies within the preform assembly.
13. The method of any preceding claim, wherein the method further comprises (412) etching the hollow core fiber preform with an etching solution comprising hydrofluoric acid, HF, to clean the hollow core fiber preform of at least one of: a contaminant; or debris from the first plurality of support assemblies.
14. The method of any preceding claim, wherein the method further comprises (412) oxidizing the hollow core fiber preform, to clean the hollow core fiber preform of at least one of: a contaminant; or Page 38 of 41 UTILITY PATENT MS Docket No. 502051-LU01 debris from the first plurality of support assemblies. LUS08211
15. The method of any preceding claim, the method further comprising (412) drawing the hollow core fiber preform into hollow core optical fibers (900).
16. An apparatus for manufacturing hollow core fiber preforms, the apparatus comprising: a first plurality of support assemblies (504A), each of the first plurality of support assemblies comprising an outer cylindrical shell (512A) and inner cylindrical shell (510A), each of the outer cylindrical shell and inner cylindrical shells having a longitudinal axis and the outer cylindrical shell of each of the first plurality of support assemblies comprising an arcuate opening (506A) running parallel to the longitudinal axis.
17. The apparatus of claim 16, further comprising: a first plurality of glass capillary tubes, wherein each glass capillary tube (502A) of the first plurality of glass capillary tubes is inserted into a different one of the first plurality of support assemblies between the inner cylindrical shell and outer cylindrical shell; an outer glass cladding (506B); and at least one end cap (806), configured to secure each of the first plurality of support assemblies in position in the outer glass cladding.
18. The apparatus of claim 16, wherein each of the first plurality of support assemblies is comprised of graphite.
19. The apparatus of claim 16, wherein the inner cylindrical shell of each of the first plurality of support assemblies comprises an arcuate opening and the apparatus further comprises: Page 39 of 41 UTILITY PATENT MS Docket No. 502051-LU01 a second plurality of support assemblies (604A), each of the second plurality LUS08211 of support assemblies comprising an outer cylindrical shell (620A) and inner cylindrical shell (618A), each of the outer cylindrical shell and inner cylindrical shells of the second plurality of support assemblies having a longitudinal axis and the outer cylindrical shell of each of the second plurality of support assemblies comprising an arcuate opening running parallel to the longitudinal axis, and a second plurality of glass capillary tubes, wherein each glass capillary tube of the second plurality of glass capillary tubes is inserted into a different one of the second plurality of support assemblies between the inner cylindrical shell and outer cylindrical shell.
20. The apparatus of claim 19, wherein the inner cylindrical shell of each of the second plurality of support assemblies comprises an arcuate opening and the apparatus further comprises: a third plurality of support assemblies, each of the third plurality of support assemblies comprising an outer cylindrical shell and inner cylindrical shell, each of the outer cylindrical shell and inner cylindrical shells of the third plurality of support assemblies having a longitudinal axis and the outer cylindrical shell of each of the third plurality of support assemblies comprising an arcuate opening running parallel to the longitudinal axis, and a third plurality of glass capillary tubes, wherein each glass capillary tube of the third plurality of glass capillary tubes is inserted into a different one of the third plurality of support assemblies between the inner cylindrical shell and outer cylindrical shell. Page 40 of 41 UTILITY PATENT MS Docket No. 502051-LU01
LU508211A 2024-09-09 2024-09-09 Manufacturing hollow core fiber preforms LU508211B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
LU508211A LU508211B1 (en) 2024-09-09 2024-09-09 Manufacturing hollow core fiber preforms
PCT/US2025/040685 WO2026054917A1 (en) 2024-09-09 2025-08-05 Method and apparatus for manufacturing hollow core fiber preforms

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
LU508211A LU508211B1 (en) 2024-09-09 2024-09-09 Manufacturing hollow core fiber preforms

Publications (1)

Publication Number Publication Date
LU508211B1 true LU508211B1 (en) 2026-03-09

Family

ID=92711209

Family Applications (1)

Application Number Title Priority Date Filing Date
LU508211A LU508211B1 (en) 2024-09-09 2024-09-09 Manufacturing hollow core fiber preforms

Country Status (2)

Country Link
LU (1) LU508211B1 (en)
WO (1) WO2026054917A1 (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115072983A (en) * 2022-06-10 2022-09-20 武汉长盈通光电技术股份有限公司 Preparation method of hollow anti-resonance optical fiber intermediate prefabricated rod
US20220356108A1 (en) * 2019-07-17 2022-11-10 Heraeus Quarzglas Gmbh & Co. Kg Methods for producing a hollow-core fiber and for producing a preform for a hollow-core fiber

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220356108A1 (en) * 2019-07-17 2022-11-10 Heraeus Quarzglas Gmbh & Co. Kg Methods for producing a hollow-core fiber and for producing a preform for a hollow-core fiber
CN115072983A (en) * 2022-06-10 2022-09-20 武汉长盈通光电技术股份有限公司 Preparation method of hollow anti-resonance optical fiber intermediate prefabricated rod

Also Published As

Publication number Publication date
WO2026054917A1 (en) 2026-03-12

Similar Documents

Publication Publication Date Title
EP3959553B1 (en) Antiresonant hollow core fibre, preform therefor and method of fabrication
JP5038435B2 (en) Synthetic quartz glass hollow cylinder manufacturing method and thick hollow cylinder by the manufacturing method
EP1740511B1 (en) Preform for photonic crystal fibre and method of fabricating it
CN120698696A (en) Method for manufacturing hollow core optical fiber and hollow core optical fiber preform
EP3686167B1 (en) Preform for producing an optical glass component
EP3180293B1 (en) Method for forming a quartz glass optical component and system
US11649185B2 (en) Automated large outside diameter preform tipping process and resulting glass preforms
LU508211B1 (en) Manufacturing hollow core fiber preforms
CN101987778B (en) A method for manufacturing a primary preform for optical fibres
JP6681306B2 (en) Method for manufacturing base material for multicore fiber, and method for manufacturing multicore fiber using the same
US11130702B2 (en) Optical fiber manufacturing method
EP4105185B1 (en) Method for manufacturing a preform for a multi-core optical fiber and a multi-core optical fiber
US11242276B2 (en) Method for producing a glass-fibre preform with a core of a polygonal core cross section
JP6824233B2 (en) Method for forming quartz glass products and quartz glass optical members
RU2552590C1 (en) Photon-crystal chalcogenide fibre and method of its production
US10464837B2 (en) Method for inserting a core rod into an outer cladding tube with spacer
WO2026014334A1 (en) Preform to be processed into hollow-core optical fiber, method for manufacturing preform to be processed into hollow-core optical fiber, and method for manufacturing hollow-core optical fiber
JP2026034409A (en) Method for fabricating antiresonant hollow-core fibers
CN117623619A (en) Preparation method of deposition layer with multiple refractive index, deposition tube and optical fiber preparation method