Multi-core optical fiber based on a preform and method of forming

Abstract

A method for manufacturing optical fibers includes mounting a glass sleeve in a selective etching apparatus. The sleeve includes one or more axial through-holes, and the etching apparatus includes a first end cap having a central orifice disposed therethrough, the first end cap being attached to a first surface of the sleeve. The method further includes exposing the sleeve to an acid solution such that a first portion of the first surface is exposed to the acid solution while a second portion of the first surface is not exposed to the acid solution. When the sleeve is mounted in the selective etching apparatus, the first portion is adjacent to the central orifice, and when the sleeve is mounted in the selective etching apparatus, the second portion is covered by the first end cap.

Description

[0001] This application claims the priority benefit of U.S. Provisional Patent Application Serial No. 63 / 191,543, filed May 21, 2021, the contents of which are based and incorporated herein by reference in their entirety. Technical Field

[0002] This disclosure generally relates to rod-based multi-core optical fibers, and more specifically, to methods for forming rod-based multi-core optical fibers using a vacuum-based approach. Background Technology

[0003] Multi-core fiber increases transmission capacity in communication systems compared to single-core fiber. In multi-core fiber, multiple cores are surrounded by a single cladding, allowing light to propagate through each core. Multi-core fiber can be manufactured using an all-glass process, which uses a bulk cladding glass with one or more precisely formed axial holes. Each hole houses a preform, and the preform forms the core of the multi-core fiber.

[0004] All-glass processes are preferred over deposition-based processes (e.g., external vapor deposition (OVD)) that involve soot layering, sintering, and consolidation to transform soot into glass. With all-glass processes, the cladding glass can be precisely ground to a selected diameter, providing both precision and flexibility in the arrangement of various spacings, shapes, and the one or more axial holes when forming glass preforms.

[0005] However, the all-glass process is expensive and time-consuming. Precise hole drilling is time-consuming, requiring the formation of one or more preforms to define the selected refractive index distribution before being added to the cladding glass, and the entire structure needs to be consolidated in a furnace to form a solid glass preform. To manufacture sufficiently long glass preforms, it may be necessary to axially join the separate glass cladding segments, which involves precise alignment of the axial holes. The consolidation process typically requires special support fixtures to hold the glass cladding segments and preforms in the consolidation furnace to form the solid glass preform. The solid glass preform must then be removed from the support fixtures so that it can be moved from the consolidation furnace to a drawing furnace to be drawn into an optical fiber. Summary of the Invention

[0006] Typical all-glass processes are not only resource-intensive but also extremely time-consuming. More specifically, the entire process takes approximately two days to allow the cladding glass to cool completely between each step. Furthermore, the process involves a large number of steps. Embodiments of this disclosure reduce the number of steps and the resources involved in producing optical fibers from cladding glass. For example, embodiments of this disclosure reduce the number of steps, allowing the entire process to be performed in a single day. Moreover, embodiments of this disclosure do not require separate consolidation furnaces and drawing towers. Therefore, embodiments of this disclosure provide a more economical and resource-efficient process for producing optical fibers compared to typical processes.

[0007] The independent claims describe exemplary solutions to this objective. Various embodiments are defined in the dependent claims.

[0008] This disclosure includes aspects of a method for manufacturing optical fibers. The method includes mounting a glass sleeve in a selective etching apparatus, the sleeve including one or more axial through-holes, and the etching apparatus including a first end cap having a central orifice disposed therethrough, the first end cap being attached to a first surface of the sleeve. The method also includes exposing the sleeve to an acid solution such that a first portion of the first surface is exposed to the acid solution while a second portion of the first surface is not exposed to the acid solution. When the sleeve is mounted in the selective etching apparatus, the first portion is adjacent to the central orifice, and when the sleeve is mounted in the selective etching apparatus, the second portion is covered by the first end cap.

[0009] Aspects of this disclosure include methods for manufacturing optical fibers. The methods include forming a concave recess on a first surface of a glass sleeve, the concave recess being surrounded by a raised lip of the sleeve, and the sleeve including one or more axial through-holes. The methods also include inserting a glass preform core into each axial through-hole, and vacuum-sealing the sleeve with one or more additional glass assemblies to form an assembly.

[0010] Aspects of this disclosure include methods for manufacturing optical fibers. The methods include inserting a glass preform core into an axial through-hole in a glass sleeve, and simultaneously vacuum-sealing the sleeve with one or more additional glass assemblies to form an assembly, while drawing the assembly to form an optical fiber.

[0011] Although many different implementations are listed, implementations may exist alone or in any combination possible. Exemplary implementations are shown and described below. Attached Figure Description

[0012] Figure 1 This is a manufacturing process for multi-core optical fibers according to embodiments of the present disclosure;

[0013] Figure 2 Showing a sleeve having one or more axial through holes according to an embodiment of the present disclosure;

[0014] Figure 3 Showing a selective etching apparatus according to an embodiment of the present disclosure;

[0015] Figures 4A-4C This illustrates an implementation method according to the present disclosure. Figure 3 A partially enlarged view of the selective etching equipment;

[0016] Figures 5A-5D This illustrates an implementation method according to the present disclosure. Figure 3 Enlarged view of other parts of the selective etching equipment;

[0017] Figure 6 This is an implementation method based on the content of this disclosure. Figure 3 Another enlarged view of a portion of the selective etching equipment;

[0018] Figure 7 The schematic diagram shows the sleeve before, during and after the selective etching process according to an embodiment of the present disclosure;

[0019] Figure 8 The sleeve attached to the selective etching equipment is shown after the selective etching process.

[0020] Figure 9 Another embodiment of the selective etching process according to the present disclosure is shown;

[0021] Figure 10A and 10B This illustrates the process of inserting the billet core into the sleeve according to an embodiment of the present disclosure;

[0022] Figure 10C Showing a cross-sectional view of the fiber core of the billet;

[0023] Figure 10D This shows a cross-sectional view of the sleeve into which the billet core is inserted;

[0024] Figure 11 Showing a cross-sectional view of a billet-cladding assembly located in a drawing tower furnace and connected to a vacuum system according to an embodiment of the present disclosure;

[0025] Figure 12 Displaying the internal channels of a billet-cladding assembly according to an embodiment of the present disclosure; and

[0026] Figure 13 An exemplary pulling system is shown schematically. Detailed Implementation

[0027] Additional features and advantages of this disclosure are set forth in the following detailed description, some of which will be readily understood by those skilled in the art from the description, or will be recognized by practicing this disclosure as described below and in the claims and drawings.

[0028] As used herein, the term "and / or" when used to list two or more items means that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as containing components A, B, and / or C, the composition may contain only A; only B; only C; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B, and C.

[0029] In this document, relational terms, such as first and second, top and bottom, are used only to distinguish one entity or behavior from another, and do not necessarily require or imply any actual such relationship or order between such entities or behaviors.

[0030] As used in this article, the expression “includes” includes the special case of the term “consisting of”, so for example, the expression “A includes B and C” should be understood to include the case of “A consists of B and C”.

[0031] As used in this document, the term "consolidation" refers to the selection of an assembly made of different glass components that are not bonded together, and the heating of the assembly to slightly above the softening point of the glass components, so that the glass components can flow and bond or seal together to form a monolithic glass assembly that maintains the general overall structure of the glass components, i.e., the basic shape of the glass components is not significantly changed.

[0032] The term "axial hole" or "axial through hole" refers to a hole that is parallel to the axial direction, that is, parallel to the central axis or centerline.

[0033] As used herein, the term "cylinder" refers to a three-dimensional shape formed by selecting a two-dimensional shape and projecting it along a third dimension perpendicular to a plane perpendicular to that two-dimensional shape. Therefore, the term "cylinder," as used herein, can have cross-sectional shapes other than circles.

[0034] Those skilled in the art will understand that the construction of the disclosure and other components is not limited to any specific material. Unless otherwise stated herein, other exemplary embodiments of the disclosure disclosed herein can be formed from a wide range of materials.

[0035] Importantly, it should be noted that the construction and arrangement of the elements of this disclosure shown in the exemplary embodiments are merely exemplary. While only some embodiments of this disclosure have been described in detail herein, those skilled in the art will readily understand that many modifications are possible (e.g., variations in the size, scale, structure, shape, and proportion of various elements, as well as parameter values, mounting arrangements, use of materials, colors, orientations, etc.) without substantially departing from the novelty and non-obvious teachings and advantages of the subject matter. For example, an element shown as integrally formed may be composed of multiple parts, or elements shown as multiple parts may be integrally formed; the operation of interfaces may be reversed or otherwise varied; the length or width of structures, and / or elements or connectors or other components of the system may be varied; and the nature or number of adjustment positions provided between elements may be altered. It should be noted that the elements and / or assemblies of the system may be constructed from an arbitrarily wide range of materials that provide sufficient strength or durability with an arbitrarily wide range of colors, textures, and combinations thereof. Therefore, all such modifications are intended to be included within the scope of this disclosure. Without departing from the spirit of this disclosure, other substitutions, improvements, changes, and omissions may be made to the design, operating conditions, and arrangements of various required and other exemplary embodiments.

[0036] Preferred embodiments of the present disclosure are described in detail below, examples of which are shown in the accompanying drawings. Wherever possible, the same reference numerals are used in all the drawings to denote the same or similar parts.

[0037] See now Figure 1 This illustrates an exemplary process 1 according to an embodiment of the present disclosure. Process 1 is a system for producing multi-core optical fibers. However, it is also contemplated that process 1 be used for producing single-core optical fibers. Figure 1 As shown, step 10 of process 1 includes forming holes in a glass sleeve. The size of each hole is adjusted to accommodate the preform core. Next, in step 20, a selective etching process is performed on the sleeve, which creates a recessed area at either end of the sleeve. This recessed area is later used in the vacuum sealing process to seal multiple glass assemblies together and provide a preform assembly. Then, in step 30, the preform core is inserted into the holes. In step 40, both the vacuum sealing and drawing processes are performed. Advantageously, step 40 of process 1 performs the drawing process concurrently with the vacuum sealing process. Each step of process 1 will be discussed in more detail below.

[0038] like Figure 2As shown, in step 10 of process 1, a hole 110 is formed in the sleeve 100. In some embodiments, the hole 110 is formed by precision drilling (e.g., diamond core drilling and / or ultrasonic-assisted core drilling). The sleeve 100 is a cylindrical glass body comprising a top surface 102 and a bottom surface 104. Furthermore, the sleeve 100 comprises silicon dioxide (e.g., pure silicon dioxide or doped silicon dioxide). Figure 2 As shown, sleeve 100 has a diameter D S and height H S In some implementations, the diameter D S The range is approximately 25mm to approximately 200mm or approximately 50mm to approximately 125mm, and the height H S The range is approximately 50 mm to approximately 2 m or approximately 75 mm to approximately 1 m. In one exemplary embodiment, the diameter D S It is approximately 70mm, while the height H S It is approximately 110 mm. Other diameters and heights will be apparent to those skilled in the art.

[0039] Each hole 110 is an axial through hole formed in the internal volume of the sleeve 100. Although Figure 2 The diagram shows four holes 110, but it is also conceivable that the sleeve 100 may include more or fewer holes 110. For example, the sleeve 100 may contain one or more holes, two or more holes, four or more holes, six or more holes, eight or more holes, ten or more holes, or twelve or more holes. Furthermore, the holes 110 may have a circular cross-sectional shape, such as... Figure 2 As shown. It is also considered that hole 110 may include other cross-sectional shapes, and one or more holes may have cross-sectional shapes different from one or more other holes.

[0040] The hole 110 has an open top end at the top surface 102 of the sleeve 100 and an open bottom end at the bottom surface 104 of the sleeve 100. Thus, each hole 110 forms a continuous opening from the top surface 102 to the bottom surface 104. In some embodiments, the hole 110 may have a diameter of about 2 mm to about 60 mm, or about 5 mm to about 45 mm, or about 10 mm to about 30 mm. It is also contemplated that one or more holes 110 may have a diameter different from one or more other holes.

[0041] The holes 110 can be spaced apart from each other at equal intervals. Furthermore, the holes 110 can be arranged and configured in any manner, as is known in the art.

[0042] In step 20 of process 1, a selective etching process is performed on the sleeve 100. Prior to the selective etching process, one or more surfaces of the sleeve 100 may be polished or finely ground. For example, the outer surface of the sleeve 100 may be polished or finely ground to obtain a precision diameter D. S And / or precision height H S As a supplement or alternative, the inner surface of the hole 110 may be polished or finely ground. Polishing or fine grinding of the top surface 102 and / or the bottom surface 104 is also considered to achieve a precise flatness. In some embodiments, the top and bottom surfaces 102, 104 are finely ground to obtain a surface roughness (RMS) of about 2 micrometers or less, or about 1 micrometer or less.

[0043] Selective etching etches only a portion of the sleeve 100 to provide recessed areas in the top surface 102 and / or bottom surface 104 of the sleeve 100. These recessed areas are used in the vacuum sealing step, as discussed further below. For selective etching, the etching apparatus 200 is first fixed to the sleeve 100. At this point, the sleeve 100 is a cylindrical element with flat and uniform top and bottom surfaces 102, 104. Therefore, at this stage, the sleeve 100 does not yet include recessed areas. Figure 3 As shown, when installed in the etching apparatus 200, the sleeve 100 is fixed between the first end cap 210 and the second end cap 220 of the apparatus 200. The first end cap 210 is connected to the top surface 102 of the sleeve 100, while the second end cap 220 is connected to the bottom surface 104 of the sleeve 100. As discussed further below, multiple rods 230 extend from the first end cap 210 to the second end cap 220 to secure the etching apparatus 200 on and around the sleeve 100.

[0044] The first and second end caps 210 and 220 can be flange elements, which helps to securely maintain the connection between the sleeve 100 and the etching equipment 200. The end caps 210 and 220 can be cylindrical elements with a central aperture extending from the top surface of the end cap to the bottom surface. Thus, the end caps 210 and 220 can be donut-shaped.

[0045] Figure 4A Showing the elevation view of the first end cap 210, and Figure 4B Show Passing Figure 4AThe diagram shows a cross-sectional view of the first end cap 210 of line AA. End cap 210 includes a central aperture 212 for alignment with sleeve 100. Additionally, end cap 210 includes a plurality of external apertures 214, each sized to accommodate a rod 230, as discussed further below. Both the central aperture 212 and the external apertures 214 extend through the entire length of the first end cap 210 from the first surface 211 to the second surface 213. The central aperture 212 has a diameter ranging from approximately 30 mm to approximately 60 mm, or approximately 40 mm to approximately 50 mm, or approximately 42 mm to approximately 48 mm. The diameter of the central aperture 212 is smaller than the diameter D of sleeve 100. S In some embodiments, the diameter of the central orifice 212 is larger than the diameter D of the sleeve 100. S Smaller than 5mm to about 10mm.

[0046] Furthermore, the diameter of the central aperture 212 is larger than the diameter of each of the outer apertures 214 (each of which ranges from approximately 10 mm to approximately 30 mm, or approximately 15 mm to approximately 25 mm, or approximately 18 mm to approximately 22 mm, or approximately 20 mm). However, the diameter of the outer apertures 214 may vary depending on the dimensions of the rod 230. The outer apertures 214 may be evenly spaced around the central aperture 212, such that the outer apertures 214 are radially outward relative to the central aperture 212.

[0047] The total outer diameter D of the first end cap 210 FEC The range can be approximately 120 mm to approximately 160 mm, or approximately 130 mm to approximately 150 mm, or approximately 140 mm. Furthermore, the first end cap 210 can have a height H within the following range: FEC (From the first surface 211 to the second surface 213): about 30 mm to about 50 mm, or about 35 mm to about 45 mm, or about 37 mm to about 39 mm, or about 39 mm. The first end cap 210 may also include a protrusion 215 extending radially outward from the first surface 211. Figure 4C show Figure 4B An enlarged view of section B shows the protrusion 215. The protrusion 215 can extend from the first surface 211 by a length of approximately 0.5 mm to approximately 1.5 mm, or approximately 0.75 mm to approximately 1.25 mm, or approximately 1 mm. Therefore, the maximum height of the first end cap 210 is the length (H) from the second surface 213 to the protrusion 215. FEC (Including the length of the protrusion 215). For example... Figure 4C As shown, the protrusion 215 marks the boundary of the central opening 212. Gaskets can be arranged around the protrusion 215 to secure the sleeve 100 to the first end cap 210, as discussed further below.

[0048] Figure 5A and 5B The first and second elevation views of the second end cap 220 are shown. Furthermore, Figure 5C Show Passing Figure 5A The image shows a cross-sectional view of the second end cap 220 of line CC. Similar to the first end cap 210, the second end cap 220 includes a central aperture 222 for alignment with the sleeve 100. Furthermore, the second end cap 220 includes a plurality of outer apertures 224, each sized to accommodate the rod 230, as discussed further below. Both the central aperture 222 and the outer apertures 224 extend through the entire length of the second end cap 220 from the first surface 221 to the second surface 223. Figure 5A The open ends of the openings 222 and 224 on the first surface 221 of the display end cap 220 are shown. Figure 5B The open ends of the openings 222 and 224 on the second surface 223 of the display end cap 220.

[0049] Similar to the first end cap 210, the center aperture 222 of the second end cap 220 has a diameter range of approximately 30 mm to approximately 60 mm, or approximately 40 mm to approximately 50 mm, or approximately 42 mm to approximately 48 mm. The diameter of the center aperture 222 is smaller than the diameter D of the sleeve 100. S In some embodiments, the diameter of the central orifice 222 is larger than the diameter D of the sleeve 100. S Smaller than 5mm to about 10mm.

[0050] Furthermore, the diameter of the central aperture 222 is larger than the diameter of each of the outer apertures 224 (each of which ranges from approximately 10 mm to approximately 30 mm, or approximately 15 mm to approximately 25 mm, or approximately 18 mm to approximately 22 mm, or approximately 20 mm). However, the diameter of the outer apertures 224 may vary depending on the dimensions of the rod 230. The outer apertures 224 may be evenly spaced around the central aperture 222, such that the outer apertures 224 are radially outward relative to the central aperture 222.

[0051] The second surface 223 of the second end cap 220 may include a plurality of indentations 227, such that each outer aperture 224 is centered within the indentation 227. Therefore, the opening of each outer aperture 224 is formed on the indentation 227. As discussed further below, the indentation 227 helps to secure the rod 230 to the etching apparatus 200.

[0052] The total diameter D of the second end cap 220 SECThe range can be approximately 120 mm to approximately 160 mm, or approximately 130 mm to approximately 150 mm, or approximately 140 mm. Therefore, the first and second end caps 210 and 220 can have the same total diameter. Furthermore, the second end cap 220 can have a height H within the following range... SEC (From the first surface 221 to the second surface 223): approximately 40 mm to approximately 60 mm, or approximately 45 mm to approximately 55 mm, or approximately 50 mm. Therefore, the second end cap 220 has a height H. SEC The height H can be greater than that of the first end cap 210. FEC .

[0053] The second end cap 220 may also include a protrusion 225 extending radially outward from the first surface 221. Figure 5D show Figure 5C An enlarged view of section D shows the protrusion 225. The protrusion 225 can extend from the first surface 221 by a length of approximately 0.5 mm to approximately 1.5 mm, or approximately 0.75 mm to approximately 1.25 mm, or approximately 1 mm. Therefore, the maximum height of the second end cap is the length (H) from the second surface 223 to the protrusion 225. SEC (Including the 225mm length of the protrusion). For example... Figure 5D As shown, the protrusion 225 marks the boundary of the central opening 222. Gaskets can be arranged around the protrusion 225 to secure the sleeve 100 to the second end cap 220. Figure 5A This shows a gasket 240 fixed to the first surface 221 of the second end cap 220. A protrusion 225 helps to firmly hold the gasket 240 to the first surface 221. In some embodiments, the protrusion 225 forms a press fit with the gasket 240. Although... Figure 4A Not shown, but the gasket 240 may also be attached to the first surface 211 of the first end cap 210 in the same manner as described with reference to the second end cap 220.

[0054] Figure 6 The illustration shows a gasket 240 attached between the sleeve 100 and the first end cap 210. When the sleeve 100 is secured to the etching apparatus 200, the gasket 240 is positioned between the first end cap 210 and the sleeve 100. Therefore, the gasket 240 provides clearance so that the first end cap 210 does not directly contact the sleeve 100. This advantageously helps prevent the first end cap 210 from applying pressure to the sleeve 100. Figure 6 As shown, the gasket 240 overlaps the sleeve 100 in the radial width direction of the sleeve 100, with an overlap length of approximately 1 mm or less, or approximately 0.5 mm or less, or approximately 0.25 mm or less. Although this document is for... Figure 6 The gasket 240 is disclosed with reference to the first end cap 210, but the gasket 240 can serve the same function for the second end cap 220.

[0055] See you again Figure 3 The rods 230 are secured to the first and second end caps 210 by extending through (and within) the outer orifices 214 and 224. Thus, when the etching apparatus 200 is assembled, the rods 230 extend in the orifices 214 and 224 such that they protrude outwards from both the first and second surfaces 211 and 213 of the first end cap 210, and from both the first and second surfaces 221 and 223 of the second end cap 220. Nuts 232 can be secured around the protruding ends of each rod 230 to maintain each rod 230 in place within the etching apparatus 200b. Furthermore, a recess 227 on the second end cap 220 provides a further means of securing the nuts 232 to the rods 230. More specifically, the recess 227 reduces any relative displacement between the rods 230 and the end caps 210 and 220. It is also noted that the sleeve 100 keeps the first and second end caps 210, 220 fixed so that they cannot move toward each other.

[0056] In an alternative embodiment, the second end cap 220 does not use a nut 232 to secure the rod 230 to the end cap. Instead, in this embodiment, the rod 230 is welded to the second cap 220. Thus, the rod 230 and the second cap 230 form a single, integral element. In other embodiments, the first and second end caps 210, 220 are held and secured to the rod solely by friction.

[0057] When the etching equipment 200 is assembled and installed onto the sleeve 100, the rod 230 is radially spaced from the sleeve 100. For example, the rod 230 is approximately 15 mm apart from the outer diameter of the sleeve 100. Furthermore, the rod 230 can be radially spaced from adjacent rods, such as... Figure 3 As shown. The distance between each 230 rod can be approximately 36mm.

[0058] In addition, such as Figure 3 As shown, the etching apparatus 200 also includes a fastening element 250, which can be formed into a U-shape to be hung on a hook. The fastening element 250 is used to suspend the etching apparatus 200 on the hook inside the etching tank. It is also contemplated that the fastening element 250 may include different... Figure 3 Other shapes and constructions are shown.

[0059] Once the sleeve 100 is installed in the etching apparatus 200 and the apparatus is placed in the etching tank, the sleeve 100 is etched and exposed to an acid solution. In some embodiments, the acid solution comprises hydrofluoric acid (HF), which may be diluted with deionized water. As a supplement or alternative, the acid solution comprises nitric acid (HNO3) or sulfuric acid (H2SO4). Exemplary acid solutions include: (i) 10 vol% hydrofluoric acid and 15 vol% nitric acid; (ii) 5 vol% hydrofluoric acid and 7.5 vol% nitric acid; or (iii) 2.5 vol% hydrofluoric acid and 3.75 vol% nitric acid.

[0060] In some embodiments, a surfactant is added to the acid solution. The surfactant can be any suitable surfactant that is dissolved in the acid solution and does not react with the acid in the solution. For example, the surfactant can be a fluorinated surfactant, such as: FS-50 or FS-54. The surfactant concentration in the acid solution (in mL surfactant / L acid solution) may be: about 1, about 1.1, about 1.2, about 1.3, about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9 or about 2 or greater.

[0061] The sleeve 100 may be exposed to the acid solution for a total duration of about 10 hours to about 5 minutes, or about 15 minutes to about 30 minutes (i.e., the total etching time). When the sleeve 100 is exposed to the acid solution, the solution temperature may be about 25°C to about 35°C. In some embodiments, when the sleeve 100 is exposed to the acid solution, the acid solution may be subjected to ultrasonic vibration.

[0062] During the selective etching process, when the sleeve 100 is installed within the etching apparatus 200 and exposed to the acid solution, the acid solution is able to contact only a specific portion of the sleeve 100. More specifically, referring to the first end cap 210, the acid solution is able to flow in the central orifice 212 and contact a portion of the top surface 102 of the sleeve. This portion is smaller than the entire top surface 102. Furthermore, as discussed above, the diameter of the central orifice 212 of the first end cap 210 is smaller than the diameter D of the sleeve 100. S Therefore, at least a portion of the top surface 102 of the sleeve 100 is covered by the first end cap 210. More specifically, and as... Figure 7 As shown, during the etching process, the radially outer portion of the top surface 102 is covered by the first end cap 210. Therefore, during the etching process, the acid solution does not contact this radially outer portion of the sleeve 100, and thus this radially outer portion is not etched by the acid solution during the etching process. Only the central portion of the top surface 102 (the portion of the top surface 102 exposed through the central aperture 212) is etched during the etching process. Furthermore, as... Figure 7As shown, after the etching process, this forms a recess 120 surrounded by a raised lip 130 on the top surface 102. The central portion of the top surface 102 (the portion of the top surface 102 exposed through the central aperture 212) forms the recess 120 after the etching process, and the radially outer portion of the top surface 102 (the portion of the top surface 102 covered by the first end cap 210) forms the raised lip 120 after the etching process.

[0063] Furthermore, the selective etching process discussed above is also applicable to the second end cap 220. During the etching process, the acid solution can flow in the central orifice 222 of the second end cap 220 and contact a portion of the bottom surface 104 of the sleeve. This portion is smaller than the entire bottom surface 104. Similar to the first end cap 210, the diameter of the central orifice 222 of the second end cap 220 is smaller than the diameter D of the sleeve 100. S Therefore, at least a portion of the bottom surface 104 of the sleeve 100 is covered by the second end cap 220. The radially outer portion of the bottom surface 104 is covered by the second end cap 220. Therefore, during the etching process, the acid solution does not come into contact with this radially outer portion of the sleeve 100, and thus this radially outer portion is not etched by the acid solution during the etching process. Therefore, only the central portion of the bottom surface 104 (the portion of the bottom surface 104 exposed through the central aperture 222) is etched during the etching process. This forms a recess 120 surrounded by the raised lip 130 on the top surface after the etching process (similar to the situation described above with reference to the first end cap 21).

[0064] Therefore, the etching process disclosed above exposes the top surface 102 (first surface) of the sleeve 100 to the acid solution, thus exposing the first portion of the top surface 102 to the acid solution while the second portion of the top surface 102 remains unexposed. Similarly, the etching process disclosed above exposes the bottom surface 104 (second surface) of the sleeve 100 to the acid solution, thus exposing the first portion of the bottom surface 104 to the acid solution while the second portion of the bottom surface 104 remains unexposed. It should be noted that in... Figure 7 In the middle, for clarity, the first end cap 210 is shown in partial cross-section.

[0065] The shape and size of the recess 120 depend on the etching time of the acid solution. In some embodiments, the recess 120 (on the top surface 102 and / or bottom surface 104 of the sleeve 100) has a maximum depth of approximately 20 micrometers or more, or approximately 40 micrometers or more, or approximately 60 micrometers or more, or approximately 80 micrometers or more, or approximately 100 micrometers or more. Alternatively, the recess 120 may have a maximum depth of approximately 10 mm or less, or approximately 7 mm or less, or approximately 5 mm or less, or approximately 4 mm or less, or approximately 3 mm or less, or approximately 2 mm or less, or approximately 1 mm or less. In some embodiments, the maximum depth of the recess 120 is in the range of approximately 40 micrometers to approximately 5 mm, or approximately 6 micrometers to approximately 4 mm.

[0066] Furthermore, the recess 120 has a diameter range of approximately 30 mm to approximately 60 mm, or approximately 40 mm to approximately 50 mm, or approximately 42 mm to approximately 48 mm. In some embodiments, the diameter of the recess 120 is the same as the diameter of the orifice 212 and / or the orifice 222. Therefore, in the width direction of the sleeve 100, the raised lip 130 has a length range of approximately 2.5 mm to approximately 10 mm, or approximately 3 mm to approximately 5 mm. In some embodiments, such as Figure 8 As shown, the recess 120 (on the top surface 102 and / or bottom surface 104 of the sleeve 100) has a recessed shape. As discussed further below, this recessed shape provides an advantage during the vacuum sealing process. The recessed shape can be, for example, spherical or elliptical. Although... Figure 7 and 8 The recess 120 is shown to have a circular cross-sectional shape, but it is also considered that the recess 120 may have other cross-sectional shapes, such as square or rectangular.

[0067] As discussed above, the raised lip 130 is not etched during the selective timing process. Therefore, the raised lip 130 forms the polished surfaces of the top surface 102 and / or bottom surface 104 of the sleeve 100.

[0068] In the selective etching process step 20 of process 1, the sleeve 100 is selectively etched to create the recess 120. Furthermore, the selective etching process advantageously provides pickling, which removes contaminants from the sleeve 100 and polishes the surfaces on the sleeve 100. Therefore, separate pickling and polishing steps are unnecessary. Instead, with the process disclosed herein, the selective etching process combines these steps into one. It should be noted that a longer etching time (as discussed above) can be used when only the top and bottom surfaces 102, 104 are etched, rather than when the entire sleeve 100 (except for the portion covered by the first and second end caps 210, 220) is etched.

[0069] like Figure 9 As shown, the assembled prefabricated assembly 300 includes a handle 310, a sleeve 100, and a nose cone 320, each of which is made of glass. These components are sealed together during a vacuum sealing process, as discussed further below. The selective etching process described above discloses selective etching of the top surface 102 and bottom surface 104 of the sleeve 100 to form a recess 120 and a raised lip 130 on the sleeve 100. However, in an alternative embodiment, the bottom surface of the handle 310 and the top surface of the nose cone 320 are selectively etched. In these embodiments, the sleeve 100 is not selectively etched. Therefore, the recess and raised lip are formed on the handle 310 and the nose cone 320, but not on the sleeve 100. In some embodiments, the recesses formed on the handle 310 and / or the nose cone 320 have a recessed shape (as discussed above). In these embodiments where the handle 310 and nose cone 320 are etched, a longer etching time, such as about 10 hours, can be used. Other embodiments are also contemplated where selective etching is performed on only one of the handle 310 and nose cone 320. Therefore, in such an embodiment, one of the top surface 102 and bottom surface 104 of the sleeve 100 is also etched.

[0070] See you again Figure 1 After the selective etching process is completed, in step 30 of process 1, the blank core is inserted into the hole 110 of the sleeve 100. Figure 10A The billet 140 is operably arranged relative to the hole 110 of the sleeve 100 during the formation of the billet-cladding assembly 150. Figure 10B The image shows an exemplary assembled billet-wrapping assembly 150, while Figure 10C A cross-sectional view of a blank 140 is shown. Each blank 140 is formed of a glass body, which includes a core segment 142 and an inner cladding segment 144 surrounding the core segment 142. Furthermore, the inner cladding segment 144 may include one or more inner cladding portions with different refractive indices. It is also contemplated in some embodiments that the glass body of the blank 140 consists only of the core segment 142 (without a cladding segment). A sleeve 100 surrounds each blank 140 during the formation of the blank-cladding assembly 150 into a preform and then into an optical fiber. Therefore, the sleeve 100 forms the outer cladding segment in the drawn optical fiber.

[0071] Figure 10D yes Figure 10B Cross-sectional view of the billet-cladding assembly 150. (See figure) Figure 10D As shown, in some embodiments, the diameter D of each billet 140 is... CSlightly smaller than the diameter D of the corresponding hole 110 into which the blank 140 is inserted. H Therefore, a gap G is provided between the billet 140 and the hole 110, which allows for convenient sliding of the billet 140 within the hole 110. More specifically, a gap G is provided between the outer surface of the billet 140 and the inner surface of the hole 110. In some embodiments, the gap G has a length of approximately 2 mm or less, or approximately 1.5 mm or less, or approximately 1 mm or less, or approximately 0.75 mm or less, or approximately 0.5 mm or less, or approximately 0.25 mm or less. Alternatively, the length of the gap G may be approximately 0.1 mm or more, or approximately 0.2 mm or more, or approximately 0.4 mm or more, or approximately 0.6 mm or more, or approximately 0.8 mm or more, or approximately 1 mm or more. In some embodiments, the length of the gap G ranges from approximately 0.1 mm to approximately 1 mm, or from approximately 0.2 mm to approximately 0.8 mm. It should also be noted that the length of the gap G is a function of the dimensions of the sleeve 100. Having a smaller diameter D S The smaller sleeve 100 requires a smaller gap length G.

[0072] Next, in Figure 1 In process 1, after the blank 140 is inserted into the sleeve 100 to form the blank-cladding assembly 150, a vacuum sealing and drawing process is performed in step 40. This vacuum sealing and drawing process is performed to produce a preform and to draw the preform into an optical fiber. First, the handle 310, the sleeve 100 (in which the blank 14 is inserted), and the nose cone 320 are assembled in a stacked configuration. When in the stacked configuration, the handle 310 is arranged longitudinally above the sleeve 100, and the sleeve 100 is arranged longitudinally above the nose cone 320. In some embodiments, the stacked configuration may also include multiple sleeves. Figure 11 This illustrates an exemplary stacked configuration with four sleeves 110 arranged between the handle 310 and the nose cone 320. In this embodiment, each billet 140 can pass through all four sleeves 110. Therefore, all four sleeves share the same billet 140. Figure 11 As shown, when in stacked configuration, handle 310 contacts the topmost sleeve 110, and each sleeve 110 directly contacts the adjacent sleeve 100. Furthermore, the bottommost sleeve 100 directly contacts the nose cone 320. It should also be noted that handle 310, sleeves (multiple sleeves) 110, and nose cone 320 are cleaned (e.g., acid-washed and then rinsed with deionized water) before being assembled into a stacked configuration.

[0073] In addition, such as Figure 11As shown, the stacked form is connected to the vacuum system 400, so that the stacked form and the vacuum system 400 together comprise the prefabrication system 500. The vacuum system 400 also includes a conduit 410 that supports the stacked form and provides an airflow connection between the vacuum system 400 and the stacked form. As discussed further below, the vacuum system 400 uses pneumatic pressure to seal the handle 310, sleeves (multiple sleeves) 110, and nose cone 320 together in the stacked form.

[0074] Figure 12 show Figure 11 A partial cross-sectional view of part A of the prefabricated system 500, showing two sleeves 100 in a stacked configuration. The top sleeve 100 is connected to the handle 310. Note that the nose cone 320 is not shown in this partial view. Figure 12 As shown, a first recess 120 on the bottom surface of the topmost sleeve 10 connects to a second recess 120 on the top surface of the adjacent sleeve 100. Furthermore, all the recesses 120 on the plurality of sleeves 100 are connected together, having a space formed by the gap G (between the sleeve 100 and the billet 140), and are connected to a channel via a conduit 410 to form a continuous internal channel 420. This channel 420 is substantially sealed due to the contact between the sufficiently smooth glass surfaces of the handle 310, the sleeves (plural sleeves) 100, and the nose cone 320. Although Figure 12 Not shown, but channel 420 extends through the entire stack and down to nose cone 320. Furthermore, channel 420 is connected to vacuum system 400 to provide a pneumatic flow path.

[0075] When activated, the vacuum system 400 draws air from channel 420 and enters the vacuum system 400, such as... Figure 12 The airflow line B is shown. Because channel 420 is essentially sealed, vacuum suction creates a significant pressure difference ΔP between channel 420 and the surrounding environment 430 around the prefabricated system 500. This pressure difference ΔP causes the handle 310, sleeves (multiple sleeves) 100, and nose cone 320 to be compressed and sealed together when longitudinally oriented in a stacked configuration. Therefore, these components are compressed and sealed together against gravity. In this example, the pressure difference ΔP between the vacuum system 400 and the normal ambient pressure at sea level is approximately equal to the pressure difference ΔP between the vacuum system 400 and the normal ambient pressure at sea level in diameter D. S An axial compressive force of 98.5 kg is provided on a typical assembly with a maximum diameter of 122 mm and channel 420 having a maximum diameter of 112 mm. In other embodiments, the pressure differential ΔP can be approximately 100 kg, the exact value depending on the weight of the individual components of the prefabricated assembly 500 and the dimensions of the various segments of channel 420, as will be apparent to those skilled in the art.

[0076] Vacuum suction of vacuum system 400 forms a billet-cladding assembly 150 held together by vacuum (“vacuum holding”). Therefore, handle 310, sleeves (multiple sleeves) 100, and nose cone 320 are compressed and sealed together, and passage 420 is eliminated. When handle 310, sleeves (multiple sleeves) 100, and nose cone 320 are compressed and sealed together, (when having...) Figure 8 The recess 120 in the recessed configuration shown deforms because the glass components first seal onto the radially outer portion of the recess 120, followed by the central portion. Therefore, the sealing of the glass components (handle 310, sleeves (multiple sleeves) 100, and nose cone 320) begins at the radially outer end of the recess 120 and then moves radially inward until the glass components are sealed together. This results in a stronger bond between the glass components compared to when the recess 120 is in a non-recessed shape. Conversely, when using a non-recessed shape, the glass components are sealed together simultaneously at both the radially outer and central portions of the recess.

[0077] It is also noted that in some embodiments, the recess 120 is formed on the handle 310 and / or the nose cone 320 instead of on the sleeve 100, as referenced above. Figure 9 As discussed above. In these embodiments, the channel 420 is formed by the recess 120 on the handle 310 and / or the nose cone, and the components are sealed together, similar to the description above. Figure 12 The situation described above.

[0078] In conventional sealing and drawing processes, the preform-cladding assembly is first vacuum-sealed and then consolidated in a consolidation furnace at approximately 1100°C in a chlorine atmosphere. This consolidation step bonds the glass components of the preform-cladding assembly together. After the consolidation step, the assembly is annealed at a temperature of approximately 1400°C to approximately 1500°C. After the annealing step, the assembly is now a preform, which is moved from the consolidation furnace to a drawing tower furnace for drawing the preform into optical fibers. Therefore, in conventional processes, the preform assembly is first vacuum-sealed, and then it is moved to a drawing tower furnace for drawing into optical fibers. Embodiments of this disclosure combine these two steps by simultaneously vacuum-sealing the assembly during the drawing process. Furthermore, embodiments of this disclosure do not have separate consolidation and annealing steps as in conventional processes. Therefore, embodiments of this disclosure reduce the total number of steps, which requires less time and saves money. In addition, in conventional processes, the glass assembly must be cooled and relaxed between steps (e.g., annealing and drawing steps). Due to inherent stresses arising from non-uniform heating or cooling of large glass sheets, each cooling step introduces a potential risk of failure. Embodiments of this disclosure reduce the number of steps and thus lower the potential for such inherent stresses in the glass. Furthermore, embodiments of this disclosure eliminate the need to move the preform from the consolidation furnace to the drawing tower furnace, a process that could result in scratches or chipping. Also, embodiments of this disclosure do not require two separate consolidation furnaces and drawing tower furnaces.

[0079] As disclosed above, the embodiments of this disclosure simultaneously perform a vacuum sealing process and a drawing process. Therefore, in the vacuum sealing process disclosed above, the billet-cladding assembly 150 is arranged in the drawing tower furnace 520 and is heated by a lower heater 510. Figure 11 As shown, the lower heater 510 creates a hot zone 515 in the furnace, which has the following temperature ranges: about 1500°C or higher, or about 1600°C or higher, or about 1700°C or higher, or about 1800°C or higher, or about 1900°C or higher, or about 2000°C or higher. In some embodiments, the temperature range of the hot zone 515 is about 1600°C to about 2200°C, or about 1800°C to about 2100°C. The temperature of the hot zone 515 is sufficient to consolidate the billet-cladding assembly 150 (thereby bonding the glass components together) and to heat the billet-cladding assembly 150 to its glass melting temperature (for the drawing step). It should be noted that the temperature of the hot zone 515 is higher than that of conventional consolidation furnaces, as discussed above.

[0080] When arranged in furnace 520, as the billet-cladding assembly 150 is consumed and drawn into optical fiber, the billet-cladding assembly 150 slowly descends toward the lower heater 510. Furthermore, as the billet-cladding assembly 150 slowly descends toward the lower heater 510, the vacuum sealing process disclosed above is performed simultaneously. Therefore, vacuum suction from vacuum system 400 is performed while the billet-cladding assembly 150 is consumed and drawn into optical fiber. Furnace 520 may contain one or more inert gases in addition to the billet-cladding assembly 500.

[0081] Figure 13 This illustration shows a drawing system 600 for drawing optical fibers according to an embodiment disclosed herein. The exemplary drawing system 600 includes a furnace 520, as discussed above. Furthermore, the drawing system 600 includes non-contact measurement sensors 610, 615 for measuring the dimensions (e.g., diameter control) of the drawn (bare) optical fiber 620 exiting the furnace 520. A cooling workstation 630 is located downstream of the measurement sensors 610, 615 and is configured to cool the bare optical fiber 620. A coating workstation 640 is located downstream of the cooling workstation 630 and is configured to deposit a protective coating 645 on the bare optical fiber 620 to form a coated optical fiber 625. A tensioning device 650 is located downstream of the coating workstation 640. The tensioning device 650 has a surface 655 for pulling (drawing) the coated optical fiber 625. A set of guide wheels 660 having corresponding surfaces 665 are located downstream of the tensioning device 650. The guide wheel 660 serves to guide the coated optical fiber 625 to the optical fiber spool (“spool”) 670 for storage of the coated optical fiber 625. Embodiments of this disclosure can be used to form single-core or multi-core optical fibers.

[0082] Although various embodiments have been described herein, they are given by way of example only and are not intended to be limiting. It should be noted that, based on the teachings and guidance set forth herein, the aim is to include adjustments and modifications within the meaning and equivalence of the disclosed embodiments. Therefore, it will be apparent to those skilled in the art that various modifications and variations in form and detail can be made to the embodiments disclosed herein without departing from the spirit and scope of this disclosure. The elements of the embodiments presented herein are not necessarily mutually exclusive, but can be interchanged to meet various needs, as will be understood by those skilled in the art.

[0083] It should be understood that the phrases and terms used herein are descriptive and not limiting. The breadth and scope of this disclosure should not be limited to any of the exemplary embodiments described above, but only to the following claims and their equivalents.

Claims

1. A method for manufacturing optical fibers, the method comprising: Install the glass sleeve in the selective etching equipment. The sleeve includes one or more axial through holes, and The etching apparatus includes a first end cap having a central orifice disposed therethrough, the first end cap being attached to a first surface of a sleeve; as well as The sleeve is exposed to an acid solution, so that a first portion of the first surface is exposed to the acid solution while a second portion of the first surface is not exposed to the acid solution, wherein exposing the sleeve to the acid solution creates a recessed depression in the first portion of the sleeve; When the sleeve is installed in a selective etching apparatus, the first portion is adjacent to the central aperture, and When the sleeve is installed in a selective etching apparatus, the second part is covered by the first end cap.

2. The method as described in claim 1, wherein, The recess is surrounded by the raised lip of the sleeve, which is the second part of the sleeve.

3. The method of claim 1, further comprising inserting a glass preform core into each of the one or more axial through holes.

4. The method of claim 3 further includes a gap between the billet core and the axial through hole, the gap having a diameter of 1 mm or less.

5. The method of claim 3, further comprising attaching a sleeve in which the blank core is inserted to a glass handle and a glass nose cone to form an assembly.

6. The method of claim 5, wherein the assembly includes an internal channel formed by a recess.

7. The method of claim 6, further comprising exposing the assembly to a vacuum sealing process, wherein, The vacuum system generates a vacuum suction through the channel.

8. The method of claim 7, wherein, Vacuum sealing process is carried out in the drawing tower furnace.

9. The method of claim 7, further comprising simultaneously drawing optical fibers from the assembly while exposing the assembly to the vacuum sealing process.

10. The method according to any one of claims 1-9, wherein, The depression has a depth of 40 micrometers or more.

11. The method according to any one of claims 1-9, wherein, The depression has a depth of 10 mm or less.

12. The method according to any one of claims 1-9, wherein, The depressions range in depth from 40 micrometers to 5 mm.

13. The method of any one of claims 1-9, further comprising forming a second recess on the second surface of the sleeve.

14. The method according to any one of claims 1-9, wherein, Acidic solutions include hydrofluoric acid.

15. A method for manufacturing optical fibers, the method comprising: A recessed depression is formed on a first surface of the glass sleeve, the recessed depression being surrounded by a raised lip of the sleeve, and the sleeve including one or more axial through holes. Insert the glass blank rod core into each axial through hole; as well as The sleeve is vacuum-sealed with one or more additional glass components to form an assembly.

16. The method of claim 15, further comprising vacuum sealing the sleeve to form the assembly while drawing the assembly to form the optical fiber.

17. The method of claim 15, further comprising vacuum sealing the sleeve in the drawing tower furnace.

18. The method according to any one of claims 15-17, wherein, The depression has a depth of 40 micrometers or more.

19. The method according to any one of claims 15-17, wherein, The depression has a depth of 10 mm or less.

20. The method according to any one of claims 15-17, wherein, The depressions range in depth from 40 micrometers to 5 mm.

21. The method of any one of claims 15-17, further comprising forming a second recessed depression on the second surface of the sleeve.

22. The method of any one of claims 15-17, further comprising a gap between the billet core and the axial through hole, said gap having a diameter of 1 mm or less.

23. A method for manufacturing optical fibers, the method comprising: A recessed depression is formed on the first surface of the glass sleeve; Insert the glass blank rod core into the axial through hole on the glass sleeve; as well as While drawing the assembly to form the optical fiber, the sleeve is simultaneously vacuum-sealed with one or more additional glass assemblies to form the assembly.

24. The method of claim 23, further comprising vacuum sealing the sleeve in the drawing tower furnace.

25. The method of claim 23 or 24, wherein, The assembly includes a sleeve, a glass handle, and a glass nose cone.

26. The method of claim 25, wherein, The assembly includes internal channels, and a vacuum seal creates a vacuum suction through the internal channels.

27. The method of claim 26, wherein, The internal channel forms the internal connection between the sleeve, handle, and nose cone.

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