Manufacturing method for hollow-core optical fiber preform, and hollow-core optical fiber preform

Abstract

The present disclosure relates to the technical field of optical fiber communications. Provided are a manufacturing method for a hollow-core optical fiber preform and a hollow-core optical fiber preform. The manufacturing method comprises: manufacturing an anti-resonance element, the anti-resonance element being a sealed tube and comprising a first curved surface and a first plane, or comprising a first curved surface and a second curved surface, and the second curved surface being an arc surface that protrudes outward from a fiber core of the anti-resonance element; manufacturing an anti-resonance assembly by means of using the anti-resonance element; and manufacturing a hollow-core optical fiber preform by means of using a plurality of anti-resonance assemblies and an outer cladding tube, the plurality of anti-resonance assemblies being arranged on the inner wall of the outer cladding tube.

Description

A method for preparing a hollow optical fiber preform and the hollow optical fiber preform

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to Chinese Patent Application No. 202410989756.7, filed in China on July 23, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of optical fiber communication technology, and in particular to a method for preparing a hollow optical fiber preform and the hollow optical fiber preform itself. Background Technology

[0004] Reducing the transmission loss of hollow-core optical fibers has always been a hot research topic in the industry. Currently, anti-resonant hollow-core fibers have been proposed, which can reduce transmission loss to 0.28 dB / km. The mechanism of hollow-core anti-resonant fibers is to utilize a cavity composed of air and high-refractive-index glass walls. When light passes through the high-refractive-index glass walls, anti-resonance is generated, confining the light field and allowing light to propagate within the fiber core. Different structures of hollow-core anti-resonant fibers have been proposed, such as nested hollow-core anti-resonant fibers, single-ring hollow-core anti-resonant fibers, integrated tube hollow-core anti-resonant fibers, and hybrid structure hollow-core anti-resonant fibers. However, the complex hollow core structure of these fibers leads to poor stability of the hollow-core fiber preform during fiber drawing. Summary of the Invention

[0005] The purpose of this technical solution is to provide a method for preparing hollow optical fiber preforms and a hollow optical fiber preform, so as to solve the problem of poor stability of hollow optical fiber preforms during optical fiber drawing in related technologies.

[0006] To achieve the above objectives, this disclosure provides a method for preparing a hollow optical fiber preform, comprising:

[0007] An anti-resonant element is prepared, wherein the anti-resonant element is a closed tube, including a first curved surface and a first plane, or including a first curved surface and a second curved surface, wherein the second curved surface is an arc surface protruding outward from the fiber core of the anti-resonant element;

[0008] An anti-resonant assembly is prepared using the aforementioned anti-resonant element;

[0009] Hollow-core optical fiber preforms are prepared using multiple anti-resonance components and an outer cladding tube, with the multiple anti-resonance components disposed on the inner wall of the outer cladding tube.

[0010] Optionally, in the method for preparing the hollow fiber preform, the preparation of the anti-resonant element includes:

[0011] The anti-resonant element is obtained by heating the first tube wall region along the axial direction of the first tubular structure, wherein the first tube wall region is a first plane or a second curved surface, and the second tube wall region of the first tubular structure other than the first tube wall region is a first curved surface.

[0012] The first tubular structure is either a circular tube or an elliptical tube.

[0013] Optionally, in the method for preparing the hollow fiber preform, the preparation of the anti-resonant element includes:

[0014] The second tubular structure is cut or corroded along the axial direction to obtain a third tube wall, wherein the third tube wall is a first curved surface;

[0015] The fourth tube wall is prepared by using a flat plate structure, wherein the fourth tube wall is a first plane, or the fifth tube wall is obtained by cutting or etching the third tubular structure along the axial direction, wherein the fifth tube wall is a second curved surface;

[0016] The third tube wall and the fourth tube wall, or the third tube wall and the fifth tube wall, are fused together to obtain an anti-resonant element;

[0017] Wherein, the diameter of the second tubular structure is smaller than the diameter of the third tubular structure; the second tubular structure is a circular tube or an elliptical tube; the third tubular structure is a circular tube or an elliptical tube.

[0018] Optionally, the method for preparing the hollow optical fiber preform includes fusing the third tube wall and the fourth tube wall, comprising:

[0019] The edge of the third pipe wall is fused to the edge of the fourth pipe wall, or the edge of the third pipe wall is fused to the surface of the fourth pipe wall.

[0020] Optionally, in the method for preparing the hollow-core optical fiber preform, the step of preparing the anti-resonant assembly using the anti-resonant element includes:

[0021] An anti-resonant assembly is prepared using at least two of the aforementioned anti-resonant elements, wherein the at least two anti-resonant elements have different dimensions; or...

[0022] An anti-resonant assembly is prepared using at least one first element and at least one of the anti-resonant elements, wherein the first element is a different element from the anti-resonant element, and at least one first element and at least one of the anti-resonant elements have different dimensions.

[0023] Optionally, in the method for preparing the hollow-core optical fiber preform, the step of preparing the anti-resonant assembly using at least two of the anti-resonant elements includes:

[0024] Prepare an anti-resonant component using one of the following methods:

[0025] The outer wall of the first plane in the first anti-resonant element is attached to the inner wall of the first plane in the second anti-resonant element;

[0026] The outer wall of the second curved surface in the first anti-resonant element is attached to the inner wall of the second curved surface in the second anti-resonant element;

[0027] The outer wall of the first plane in the first anti-resonant element is attached to the inner wall of the second curved surface in the second anti-resonant element;

[0028] The outer wall of the second curved surface in the first anti-resonant element is attached to the inner wall of the first plane in the second anti-resonant element;

[0029] The size of the first anti-resonant element is smaller than that of the second anti-resonant element.

[0030] Optionally, in the method for preparing the hollow optical fiber preform, the bonding area of ​​the first anti-resonant element and the second anti-resonant element includes a surface bonding area or a two-line bonding area.

[0031] Optionally, in the method for preparing the hollow optical fiber preform, the ratio of the product of the wall thickness and refractive index of the first anti-resonant element to the product of the wall thickness and refractive index of the second anti-resonant element is within a preset range, which is [0.9, 1.1].

[0032] Optionally, in the method for preparing the hollow optical fiber preform, the step of bonding the outer wall of the first plane in the first anti-resonant element with the inner wall of the first plane in the second anti-resonant element includes:

[0033] The outer wall of the first plane in the first anti-resonant element is bonded to the inner wall of the first plane in the second anti-resonant element by means of adhesive bonding or welding.

[0034] Optionally, the method for preparing the hollow fiber preform, wherein the preparation of the hollow fiber preform using multiple anti-resonant components and an outer cladding tube includes:

[0035] By using an adhesive or fusion splicing method, the outer wall of the first plane or the second curved surface of the outermost anti-resonant element in each anti-resonant assembly is bonded to the inner wall of the outer cladding tube to obtain a hollow fiber preform.

[0036] To achieve the above objectives, this disclosure also provides a hollow optical fiber preform, which is prepared using the hollow optical fiber preform preparation method described in any of the preceding embodiments.

[0037] The beneficial effects of the above-mentioned technical solution disclosed herein are as follows:

[0038] The method for fabricating hollow-core optical fiber preforms according to embodiments of this disclosure is used to fabricate anti-resonant elements. The anti-resonant element is a closed tube, including a first curved surface and a first flat surface, or including a first curved surface and a second curved surface, wherein the second curved surface is an arc surface convex outward from the fiber core of the anti-resonant element. Anti-resonant components are fabricated using the anti-resonant element. Hollow-core optical fiber preforms are fabricated using multiple anti-resonant components and an outer cladding tube, with the multiple anti-resonant components disposed on the inner wall of the outer cladding tube. Thus, the fabricated hollow-core optical fiber preform exhibits excellent stability during optical fiber drawing because the anti-resonant element is a closed tube and the anti-resonant components are closely fitted to the outer cladding tube. Furthermore, the fabrication process for the anti-resonant element has lower requirements, resulting in lower costs. Attached Figure Description

[0039] Figure 1 is a schematic flowchart of the method for preparing hollow optical fiber preform according to an embodiment of this disclosure;

[0040] Figure 2 is a schematic diagram of one of the anti-resonant elements described in the embodiments of this disclosure;

[0041] Figure 3 is a schematic diagram of the tubular structure described in an embodiment of this disclosure;

[0042] Figure 4 is a schematic diagram of the structure of the third pipe wall according to an embodiment of this disclosure;

[0043] Figure 5 is a schematic diagram of the flat plate structure described in an embodiment of this disclosure;

[0044] Figure 6 is a second schematic diagram of the anti-resonant element according to an embodiment of this disclosure;

[0045] Figure 7 is a third schematic diagram of the anti-resonant element according to an embodiment of this disclosure;

[0046] Figure 8 is a fourth schematic diagram of the anti-resonant element according to an embodiment of this disclosure;

[0047] Figure 9 is a fifth schematic diagram of the anti-resonant element according to an embodiment of this disclosure;

[0048] Figure 10 is a schematic diagram of one of the anti-resonance components described in the embodiments of this disclosure;

[0049] Figure 11 is a second schematic diagram of the anti-resonance component according to an embodiment of this disclosure;

[0050] Figure 12 is one of the bonding schematic diagrams of the anti-resonance component according to an embodiment of this disclosure;

[0051] Figure 13 is a second schematic diagram of the bonding of the anti-resonance component according to an embodiment of this disclosure;

[0052] Figure 14 is one of the structural schematic diagrams of the hollow optical fiber preform according to an embodiment of this disclosure;

[0053] Figure 15 is a second schematic diagram of the structure of the hollow optical fiber preform according to an embodiment of this disclosure;

[0054] Figure 16 is a third schematic diagram of the hollow optical fiber preform according to an embodiment of this disclosure;

[0055] Figure 17 is one of the bonding schematic diagrams of the hollow optical fiber preform according to an embodiment of this disclosure;

[0056] Figure 18 is a second schematic diagram of the bonding of the hollow optical fiber preform according to an embodiment of this disclosure. Detailed Implementation

[0057] To make the technical problems, technical solutions and advantages to be solved by this disclosure clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0058] Referring to Figure 1, which is a schematic flowchart of the method for preparing the hollow optical fiber preform according to an embodiment of this disclosure, the method includes the following steps:

[0059] Step 101: Prepare an anti-resonant element, which is a closed tube including a first curved surface and a first plane, or including a first curved surface and a second curved surface, wherein the second curved surface is an arc surface protruding outward from the fiber core of the anti-resonant element.

[0060] Optionally, the second curved surface is a circular arc or elliptical arc that protrudes outward from the fiber core of the anti-resonant element.

[0061] In this embodiment of the disclosure, since the first curved surface, the first plane and the second curved surface have lower requirements for the fabrication process, the anti-resonant element fabricated using the first curved surface, the first plane and the second curved surface also have lower requirements for the fabrication process, thereby reducing the fabrication cost of the anti-resonant element.

[0062] Step 102: Prepare an anti-resonant assembly using the aforementioned anti-resonant element.

[0063] In this embodiment of the disclosure, at least one of the aforementioned anti-resonant elements is used to prepare an anti-resonant assembly, and the anti-resonant assembly is a multilayer anti-resonant assembly.

[0064] Step 103: Prepare a hollow fiber preform using multiple anti-resonance components and an outer cladding tube, wherein the multiple anti-resonance components are disposed on the inner wall of the outer cladding tube.

[0065] In this embodiment, the anti-resonance component and the outer cladding tube have a high degree of adhesion, resulting in better stability of the hollow fiber preform prepared by the method described in this embodiment. Furthermore, the anti-resonance component is a closed tubular structure, exhibiting excellent stability during the fiber drawing process using the hollow fiber preform, making precise and repeatable production of hollow fibers easier.

[0066] The hollow fiber preform prepared by the method described in this embodiment is easy to fix during the fiber drawing process and has good stability. Moreover, the anti-resonance unit is prepared by using a closed tube, which has low process requirements and low cost.

[0067] In one embodiment, optionally, the fabrication of the anti-resonant element includes:

[0068] The anti-resonant element is obtained by heating the first tube wall region along the axial direction of the first tubular structure, wherein the first tube wall region is a first plane or a second curved surface, and the second tube wall region of the first tubular structure other than the first tube wall region is a first curved surface.

[0069] The first tubular structure is either a circular tube or an elliptical tube.

[0070] In this embodiment of the present disclosure, as shown in FIG2, the first tube wall region of the first tubular structure along the axial direction is heated, and the first tube wall region can be formed into a first plane or a second curved surface under the action of tension. The first tubular structure can adopt the tubular structure shown in FIG3.

[0071] Thus, an anti-resonant element can be prepared by generating tension in the first tube wall region through heating, with relatively low requirements for the preparation process.

[0072] In one embodiment, optionally, the fabrication of the anti-resonant element includes:

[0073] The second tubular structure is cut or corroded along the axial direction to obtain a third tube wall, wherein the third tube wall is a first curved surface;

[0074] The fourth tube wall is prepared by using a flat plate structure, wherein the fourth tube wall is a first plane, or the fifth tube wall is obtained by cutting or etching the third tubular structure along the axial direction, wherein the fifth tube wall is a second curved surface;

[0075] The third tube wall and the fourth tube wall, or the third tube wall and the fifth tube wall, are fused together to obtain an anti-resonant element;

[0076] Wherein, the diameter of the second tubular structure is smaller than the diameter of the third tubular structure; the second tubular structure is a circular tube or an elliptical tube; the third tubular structure is a circular tube or an elliptical tube.

[0077] In this embodiment of the disclosure, as shown in FIG4, the second tubular structure is fabricated into a third tube wall using a cutting or etching method. The third tube wall is a first curved surface and is a partial tube. The second tubular structure can also adopt the tubular structure shown in FIG3.

[0078] The fourth tube wall is prepared using a flat plate structure as shown in Figure 5, wherein the fourth tube wall is the first plane.

[0079] Alternatively, the third tubular structure can be fabricated into a fourth tubular wall using the same cutting or etching methods, wherein the fourth tubular wall is the second curved surface. The third tubular structure can also be the tubular structure shown in Figure 3.

[0080] By fusing the first curved surface and the first plane, or by fusing the first curved surface and the second curved surface, an anti-resonant element is obtained. Optionally, in one embodiment, fusing the third tube wall and the fourth tube wall includes:

[0081] The edge of the third pipe wall is fused to the edge of the fourth pipe wall, or the edge of the third pipe wall is fused to the surface of the fourth pipe wall.

[0082] It should be noted that when the third pipe wall and the fourth pipe wall are fused together, an edge alignment method can be used, as shown in Figure 6, where the fourth pipe wall is the first plane, and the edges of the third pipe wall and the fourth pipe wall are fused together accordingly; or, an edge misalignment method can be used, as shown in Figure 7, where the fourth pipe wall is the first plane, and the two ends of the third pipe wall and the surface of the fourth pipe wall are fused together.

[0083] Of course, when welding the third pipe wall and the fourth pipe wall, the edge alignment method can also be used, as shown in Figure 8, where the fourth pipe wall is a second curved surface, and the edges of the third pipe wall and the fourth pipe wall are welded together accordingly; or, the edge misalignment method can also be used, as shown in Figure 9, where the fourth pipe wall is a second curved surface, and the edges of the third pipe wall and the surface of the fourth pipe wall are welded together.

[0084] In summary, the anti-resonant element includes a first curved surface and a first flat surface, or includes a first curved surface and a second curved surface. The curved surface and the flat surface are relatively easy to manufacture and have low manufacturing costs. Moreover, the resulting anti-resonant element has a stable structure and is easy to fix.

[0085] In one embodiment, optionally, the fabrication of the anti-resonant assembly using the anti-resonant element includes:

[0086] An anti-resonant assembly is prepared using at least two of the aforementioned anti-resonant elements, wherein the at least two anti-resonant elements have different dimensions; or...

[0087] An anti-resonant assembly is prepared using at least one first element and at least one of the anti-resonant elements, wherein the first element is a different element from the anti-resonant element, and at least one first element and at least one of the anti-resonant elements have different dimensions.

[0088] In this embodiment of the disclosure, a multilayer anti-resonant assembly is prepared by using at least two of the aforementioned anti-resonant elements, or by using at least one first element and at least one of the aforementioned anti-resonant elements.

[0089] The first element may be an anti-resonant element other than the anti-resonant element described in the embodiments of this disclosure.

[0090] For example, as shown in Figures 10 and 11, an anti-resonant assembly is prepared using two of the aforementioned anti-resonant elements, and the two anti-resonant elements have different sizes.

[0091] In one embodiment, optionally, the step of fabricating the anti-resonant assembly using at least two of the anti-resonant elements includes:

[0092] Prepare an anti-resonant component using one of the following methods:

[0093] The outer wall of the first plane in the first anti-resonant element is attached to the inner wall of the first plane in the second anti-resonant element;

[0094] The outer wall of the second curved surface in the first anti-resonant element is attached to the inner wall of the second curved surface in the second anti-resonant element;

[0095] The outer wall of the first plane in the first anti-resonant element is attached to the inner wall of the second curved surface in the second anti-resonant element;

[0096] The outer wall of the second curved surface in the first anti-resonant element is attached to the inner wall of the first plane in the second anti-resonant element;

[0097] The size of the first anti-resonant element is smaller than that of the second anti-resonant element.

[0098] In this embodiment, the first anti-resonant element is nested inside the second anti-resonant element. Both the first and second anti-resonant elements are fabricated using a first curved surface, and can also be fabricated using a first plane or a second curved surface. If both the first and second anti-resonant elements are fabricated using a first curved surface and a first plane, their first planes are correspondingly attached; if both the first and second anti-resonant elements are fabricated using a first curved surface and a second curved surface, their first curved surfaces are correspondingly attached; if the first anti-resonant element is fabricated using a first curved surface and a first plane, and the second anti-resonant element is fabricated using a first curved surface and a second curved surface, then the first plane in the first anti-resonant element and the second curved surface in the second anti-resonant element are correspondingly attached; if the first anti-resonant element is fabricated using a first curved surface and a second curved surface, and the second anti-resonant element is fabricated using a first curved surface and a first plane, then the second curved surface in the first anti-resonant element and the first plane in the second anti-resonant element are correspondingly attached.

[0099] In one embodiment, the bonding area between the first anti-resonant element and the second anti-resonant element may include a surface bonding area or a two-line bonding area.

[0100] For example, the contact area between the outer wall of the first plane in the first anti-resonant element and the first plane in the second anti-resonant element is a surface-contact area.

[0101] For example, the contact area between the outer wall of the first plane in the first anti-resonant element and the inner wall of the second curved surface in the second anti-resonant element is a contact area between two lines.

[0102] In this embodiment of the disclosure, the product of the wall thickness and refractive index of the first anti-resonant element can be equal to, less than, or greater than the product of the wall thickness and refractive index of the second anti-resonant element. It should be noted that if the product of the wall thickness and refractive index of the first anti-resonant element is not equal to the product of the wall thickness and refractive index of the second anti-resonant element, then the ratio of the product of the wall thickness and refractive index of the first anti-resonant element to the product of the wall thickness and refractive index of the second anti-resonant element, or the ratio of the product of the wall thickness and refractive index of the second anti-resonant element to the product of the wall thickness and refractive index of the first anti-resonant element, is within a preset range, which is [0.9, 1.1].

[0103] Optionally, the wall thickness of the first anti-resonant element is equal to the wall thickness of the second anti-resonant element.

[0104] Optionally, the refractive index of the first anti-resonant element is equal to the refractive index of the second anti-resonant element.

[0105] In one embodiment, optionally, the step of fitting the outer wall of the first plane in the first anti-resonant element to the inner wall of the first plane in the second anti-resonant element includes:

[0106] The outer wall of the first plane in the first anti-resonant element is bonded to the inner wall of the first plane in the second anti-resonant element by means of adhesive bonding or welding.

[0107] It should be noted that when the contact area between the outer wall of the first plane in the first anti-resonant element and the inner wall of the first plane in the second anti-resonant element is a surface-fitting area, the surface-fitting area can be bonded by adhesive bonding or welding at at least two lines (as shown by the dotted lines in Figure 12), and the surface-fitting area can be kept consistent in the longitudinal direction; or, the surface-fitting area can be bonded by adhesive bonding or welding at at least one surface (as shown by the shaded area in Figure 13), and the surface-fitting area can be kept consistent in the longitudinal direction.

[0108] When the contact area between the outer wall of the first plane in the first anti-resonant element and the inner wall of the first plane in the second anti-resonant element is a two-line contact area, the two lines are bonded together by adhesive bonding or welding, and kept consistent in the longitudinal direction.

[0109] It should also be noted that the embodiments disclosed herein use adhesive bonding or welding to prepare the anti-resonance components, which is simple in process and low in cost.

[0110] It is understandable that one of the following methods can be used to fabricate an anti-resonant component:

[0111] The outer wall of the first plane in the first anti-resonant element is bonded to the inner wall of the first plane in the second anti-resonant element by means of adhesive bonding or welding.

[0112] The outer wall of the second curved surface in the first anti-resonant element is bonded to the inner wall of the second curved surface in the second anti-resonant element by means of adhesive bonding or welding.

[0113] The outer wall of the first plane in the first anti-resonant element is bonded to the inner wall of the second curved surface in the second anti-resonant element by means of adhesive bonding or welding.

[0114] The outer wall of the second curved surface in the first anti-resonant element is bonded to the inner wall of the first plane in the second anti-resonant element by means of adhesive bonding or welding.

[0115] In one embodiment, optionally, the fabrication of the hollow fiber preform using multiple anti-resonant components and an outer cladding tube includes:

[0116] By using an adhesive or fusion splicing method, the outer wall of the first plane or the second curved surface of the outermost anti-resonant element in each anti-resonant assembly is bonded to the inner wall of the outer cladding tube to obtain a hollow fiber preform.

[0117] In this embodiment of the disclosure, as shown in Figures 14 and 15, a plurality of the anti-resonance components are disposed at equal intervals on the inner wall of the outer cladding tube.

[0118] Optionally, the hollow fiber preform includes at least three of the anti-resonant components.

[0119] It should be noted that the outer wall of the first plane of the outermost anti-resonance element in each anti-resonance assembly and the inner wall of the outer cladding tube are two-line bonding areas. These two lines are bonded together using adhesive bonding or welding, and are kept consistent in the longitudinal direction.

[0120] The outer wall of the second curved surface of the outermost anti-resonant element in each anti-resonant assembly (as shown in Figure 16) and the inner wall of the outer cladding tube are in contact with a surface-fitting area. The surface-fitting area can be bonded by adhesive bonding or welding at at least two lines (as shown by the dotted lines in Figure 17) and kept consistent in the longitudinal direction; or, the surface-fitting area can be bonded by adhesive bonding or welding at at least one surface (as shown by the shaded area in Figure 18) and kept consistent in the longitudinal direction.

[0121] This disclosure also provides a hollow optical fiber preform, which is prepared using the hollow optical fiber preform preparation method described in any of the preceding embodiments.

[0122] The above description represents the preferred embodiments of this disclosure. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles described herein, and these improvements and modifications should also be considered within the scope of protection of this disclosure.

Claims

1. A method for preparing a hollow-core optical fiber preform, comprising: preparing an anti-resonant element, the anti-resonant element being a closed tube comprising a first curved surface and a first flat surface, or comprising a first curved surface and a second curved surface, the second curved surface being an arc surface protruding outward from a core of the anti-resonant element; preparing an anti-resonant assembly using the anti-resonant element; preparing a hollow-core optical fiber preform using a plurality of the anti-resonant assemblies and an outer cladding tube, the plurality of the anti-resonant assemblies being arranged on an inner wall of the outer cladding tube.

2. The method of making a hollow-core optical fiber preform according to claim 1, wherein, The preparing of the anti-resonant element comprises: heating a first tube wall region of a first tubular structure in an axial direction to obtain the anti-resonant element, the first tube wall region being the first flat surface or the second curved surface, a second tube wall region of the first tubular structure other than the first tube wall region being the first curved surface; wherein the first tubular structure is a circular tube or an elliptical tube.

3. The method of making a hollow-core optical fiber preform according to claim 1, wherein, The preparing of the anti-resonant element comprises: cutting or etching a second tubular structure in an axial direction to obtain a third tube wall, the third tube wall being the first curved surface; preparing a fourth tube wall using a flat plate structure, the fourth tube wall being the first flat surface, or cutting or etching a third tubular structure in an axial direction to obtain a fifth tube wall, the fifth tube wall being the second curved surface; fusing the third tube wall and the fourth tube wall, or fusing the third tube wall and the fifth tube wall to obtain the anti-resonant element; wherein a tube diameter of the second tubular structure is smaller than a tube diameter of the third tubular structure; the second tubular structure is a circular tube or an elliptical tube; and the third tubular structure is a circular tube or an elliptical tube.

4. The method of making a hollow-core optical fiber preform according to claim 3, wherein, The fusing of the third tube wall and the fourth tube wall comprises: fusing an edge of the third tube wall with an edge of the fourth tube wall, or fusing an edge of the third tube wall with a surface of the fourth tube wall.

5. The method of making a hollow-core optical fiber preform according to claim 1, wherein, The preparing of the anti-resonant assembly using the anti-resonant element comprises: preparing the anti-resonant assembly using at least two anti-resonant elements, the at least two anti-resonant elements being different in size; or preparing the anti-resonant assembly using at least one first element and at least one anti-resonant element, the first element being different from the anti-resonant element, the at least one first element and the at least one anti-resonant element being different in size.

6. The method of making a hollow-core optical fiber preform according to claim 5, wherein, The preparing of the anti-resonant assembly using at least two anti-resonant elements comprises: preparing the anti-resonant assembly using one of the following: adhering an outer wall of a first flat surface in a first anti-resonant element to an inner wall of a first flat surface in a second anti-resonant element; adhering an outer wall of a second curved surface in a first anti-resonant element to an inner wall of a second curved surface in a second anti-resonant element; adhering an outer wall of a first flat surface in a first anti-resonant element to an inner wall of a second curved surface in a second anti-resonant element; adhering an outer wall of a second curved surface in a first anti-resonant element to an inner wall of a first flat surface in a second anti-resonant element; wherein the first anti-resonant element is smaller in size than the second anti-resonant element.

7. The method of making a hollow-core optical fiber preform according to claim 6, wherein, The adhering region of the first anti-resonant element and the second anti-resonant element comprises a surface adhering region or two line adhering regions.

8. The method of making a hollow-core optical fiber preform according to claim 6, wherein, The first flat surface outer wall in the first anti-resonance element is attached to the first flat surface inner wall in the second anti-resonance element, including: The first flat surface outer wall in the first anti-resonance element is attached to the first flat surface inner wall in the second anti-resonance element by means of adhesion or fusion.

9. The method of making a hollow-core optical fiber preform according to claim 1, wherein, The hollow-core optical fiber preform is prepared by using the plurality of anti-resonance assemblies and the outer cladding tube, including: The outer wall of the first flat surface or the second curved surface of the outermost anti-resonance element in each anti-resonance assembly is attached to the inner wall of the outer cladding tube by means of adhesion or fusion to obtain the hollow-core optical fiber preform. 10.A hollow-core optical fiber preform prepared by using the preparation method of the hollow-core optical fiber preform according to any one of claims 1 to 9.

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