Hollow-core optical fiber with nested structure

Abstract

The invention relates to the technical field of optical fiber communication, in particular to a hollow-core optical fiber of a nested structure. The hollow-core optical fiber with the nested structure comprises an outer cladding, a fiber core area located in the center of the optical fiber and a plurality of anti-resonance tube units, each anti-resonance tube unit is composed of a cladding tube and at least three nested tubes; the cladding tubes are arranged around the fiber core area in a radial distribution mode, and the outer cladding layer tightly surrounds the cladding tubes. The circle center point of each cladding tube is the same as that of the center nested tube in the cladding tube, and the outer nested tubes are arranged on the two sides of the center nested tube and symmetrically distributed with the center nested tube as the center, so that a negative curvature nested structure is formed. The cladding tube surrounds the fiber core to form an anti-resonant cavity for optical signals, light leakage to a cladding area is reduced, the anti-resonant effect is enhanced through the negative curvature structures of the cladding tube and the nested tube, the binding capacity of the optical signals in the fiber core is improved, and meanwhile the long-distance low-loss optical transmission characteristic is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber communication, and in particular to a hollow-core optical fiber with a nested structure. Background Art

[0002] With the rapid development of communication technology, fiber-optic communication has become an important infrastructure of the modern information society. Especially in long-distance, high-capacity communication networks, the transmission loss of optical fiber directly determines the performance and economic efficiency of the communication system.

[0003] Traditional fiber-optic communication technology primarily relies on solid-core optical fiber, which transmits optical signals through a doped silica glass core. Inherent issues such as material loss, nonlinear effects, and dispersion limit the potential for further reducing transmission loss and increasing transmission capacity. In particular, performance bottlenecks of traditional solid-core optical fiber are becoming increasingly prominent in applications such as high-power laser transmission, ultra-high-speed communications, and complex sensing, hindering the development of optical fiber technology.

[0004] The above content is only used to assist in understanding the technical solution of the present invention and does not constitute an admission that the above content is prior art. Summary of the Invention

[0005] The main purpose of the present invention is to provide a nested hollow-core optical fiber, aiming to reduce problems such as optical fiber transmission loss, nonlinear effects and dispersion, and to solve the technical problem that traditional optical fiber materials are prone to damage and performance degradation in high radiation and high temperature environments.

[0006] To achieve the above object, the present invention proposes a nested hollow-core optical fiber, which comprises: an outer cladding, a core region located at the center of the optical fiber, and a plurality of anti-resonance tube units;

[0007] Each of the anti-resonance tube units is composed of a cladding tube and at least three nested tubes, wherein the nested tubes include a central nested tube and at least two outer nested tubes;

[0008] The cladding tubes are arranged radially around the core region, and the outer cladding tightly surrounds the outside of each cladding tube;

[0009] The center point of each cladding tube is the same as that of the inner central nested tube, and the outer nested tubes are arranged on both sides of the central nested tube and are symmetrically distributed with the central nested tube as the center. The radius of each outer nested tube is the same, and the centers of each outer nested tube are arranged in parallel along the radial direction.

[0010] Optionally, the anti-resonance tube units are arranged around the fiber core region in a circular ring structure at equal distances and in equal orientations, and the number and angles of the anti-resonance tube units are adjusted according to the transmission performance of the optical fiber.

[0011] Optionally, a low refractive index material is filled between the core region and each of the nested tubes.

[0012] Optionally, the spacing between the nested tubes is set according to the operating wavelength of the optical fiber transmission.

[0013] Optionally, the coupling area of ​​each nested tube adopts a high temperature welding or polymer bonding interface.

[0014] Optionally, the outer cladding is made of a polymer composite material, and the inner surface of the outer cladding close to the core area is provided with a nano moisture-proof coating, a corrosion-resistant coating or a crack-resistant stress transfer layer, and the thickness and outer diameter of the outer cladding are set according to the mechanical strength of the optical fiber.

[0015] Optionally, the center of the central nested tube inside each anti-resonance tube unit and the center of each outer nested tube are located in different planes. When the number of the nested tubes in the anti-resonance tube unit is three, the center of the central nested tube and the center of each outer nested tube form a triangular arrangement.

[0016] Optionally, the center of the central nested tube inside each anti-resonance tube unit and the center of each outer nested tube are located in the same plane, and the size of the central nested tube is larger than that of the outer nested tube.

[0017] Optionally, the nested hollow-core optical fiber is formed by an integrated process of preparing a silica-glass composite preform and drawing, and each of the anti-resonance tube units and the outer cladding are integrally sintered.

[0018] Optionally, the preform rod is located between the outer cladding and the anti-resonance tube unit.

[0019] The present invention provides a nested hollow-core optical fiber, comprising: an outer cladding, a core region located at the center of the optical fiber, and multiple antiresonant tube units; each antiresonant tube unit is composed of a cladding tube and at least three nested tubes; the cladding tubes are radially arranged around the core region, with the outer cladding tightly surrounding each cladding tube; one nested tube is disposed at the center axis of each cladding tube as a central nested tube, and the remaining nested tubes are evenly distributed on either side of the central nested tube as outer nested tubes; the outer nested tubes have the same radius, and the centers of the nested tubes are radially arranged parallel to form a negative curvature nested structure. By introducing negative curvature in geometric space, the cladding tubes surround the core to form an antiresonant cavity for the optical signal, reducing light leakage into the cladding region. The negative curvature structure of the cladding tubes and nested tubes enhances the antiresonance effect, improves the optical signal confinement within the core, and achieves long-distance, low-loss optical transmission characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0021] Figure 1 This is a schematic structural diagram of a first embodiment of a nested hollow-core optical fiber according to the present invention;

[0022] Figure 2 This is a schematic diagram of the first structure of the second embodiment of the nested hollow-core optical fiber of the present invention;

[0023] Figure 3 A second structural diagram of the second embodiment of the nested hollow-core optical fiber of the present invention;

[0024] Figure 4 This is a schematic diagram of the third structure of the second embodiment of the nested hollow-core optical fiber of the present invention;

[0025] Figure 5 This is a schematic diagram of the fourth structure of the second embodiment of the nested hollow-core optical fiber of the present invention;

[0026] Figure 6 This is a fifth structural diagram of the second embodiment of the nested hollow-core optical fiber of the present invention;

[0027] Figure 7 Schematic diagram of the structure of the third embodiment of the nested hollow-core optical fiber of the present invention.

[0028] Explanation of the accompanying drawings: 10, outer cladding; 20, core region; 30, antiresonance tube unit; 101, preform rod; 301, nested tube; 302, cladding tube; 3011, central nested tube; 3022, outer nested tube.

[0029] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0030] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0033] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] Traditional fiber-optic communication technology primarily relies on solid-core optical fiber, which transmits optical signals through a doped quartz glass core. Although solid-core optical fiber technology has matured significantly after decades of development and has been widely used in the communications field, inherent issues such as material loss, nonlinear effects, and dispersion limit the potential for further reducing transmission loss and increasing transmission capacity. In particular, in applications such as high-power laser transmission, ultra-high-speed communications, and complex sensing, the performance bottlenecks of traditional solid-core optical fiber have become increasingly prominent, hindering the development of optical fiber technology. Hollow-core optical fiber, due to its unique low loss, low nonlinear effects, and high-power transmission capabilities, has gradually become a research hotspot in the optical communications field. By forming an air core in the core region, hollow-core optical fiber allows optical signals to propagate primarily in air, significantly reducing material loss, nonlinear effects, and dispersion, exhibiting excellent transmission performance and becoming a key development direction for next-generation optical fiber technology.

[0035] Hollow-core fibers are mainly divided into two types: photonic crystal hollow-core fibers and antiresonant hollow-core fibers. Among them, antiresonant hollow-core fibers have gradually become a research hotspot due to their simple structure, relatively mature manufacturing process, ultra-low loss, and wide transmission window. Antiresonant hollow-core fibers are usually composed of multiple thin-walled glass tubes surrounding an air core, and light is confined to the core for transmission through the antiresonance effect. In recent years, with the proposal and application of multi-layer nested structures, the loss performance of antiresonant hollow-core fibers has been significantly optimized. For example, by introducing thin tubes into the cladding capillary to achieve a layered nested structure design, not only the antiresonance effect is enhanced, but also the leakage loss is effectively reduced, while improving the mode selectivity and high-order mode suppression performance.

[0036] Existing ultra-low-loss anti-resonant hollow-core optical fibers usually use structural units with four or more tubes. This structure is ideal when designing a two-layer nested tube structure. However, in order to further reduce the loss, the number of anti-resonant layers needs to be increased. When designing a three-layer anti-resonant layer structure, several key problems arise due to insufficient air layer area: First, the air layer area is not enough to effectively filter out high-order modes, resulting in the fundamental mode and high-order mode losses differing by only about one order of magnitude, making it difficult to achieve good single-mode characteristics, and high-order modes are prone to crosstalk with the fundamental mode. Second, in order to achieve a higher high-order mode suppression ratio, the area of ​​certain air layers has to be reduced, which may cause the air layer to be in a resonant state, thereby increasing the confinement loss or bending loss. These problems indicate that existing technologies still need innovations in structural design and manufacturing processes to further break through performance bottlenecks.

[0037] The present invention proposes a nested hollow-core optical fiber, which is mainly used in ultra-long-distance optical communication systems, ultra-high-speed optical communication networks, optical fiber sensing systems, and high-power laser transmission fields. This optical fiber structure can be widely used in transoceanic communication cables, data center interconnection, quantum communication networks, precision optical fiber sensors, and medical laser transmission, meeting the urgent needs of future communication networks for low loss, high stability, and high-power transmission. Nested hollow-core optical fibers can also be used for optical fiber transmission in special environments, such as aerospace, military communications, nuclear radiation environments, and other special scenarios. Since the light transmission of the hollow-core optical fiber mainly occurs in the air core, the loss and nonlinear effects of the material itself are greatly reduced. Especially in the field of aerospace, traditional optical fiber materials are prone to damage and performance degradation in high-radiation and high-temperature environments, while the hollow-core optical fiber structure of the present invention can effectively avoid these problems and significantly improve the reliability and life of the communication system.

[0038] Reference Figure 1 , Figure 1 FIG. 1 is a schematic structural diagram of a first embodiment of a nested hollow-core optical fiber according to the present invention. Figure 1 As shown, in this embodiment, the nested hollow-core optical fiber includes: an outer cladding 10 , a core region 20 located at the center of the optical fiber, and a plurality of anti-resonance tube units 30 .

[0039] It should be noted that each of the anti-resonance tube units 30 is composed of a cladding tube 302 and at least three nested tubes 301, wherein the nested tubes 301 include a central nested tube 3011 and at least two outer nested tubes 3022; the cladding tubes 302 are arranged radially around the core region 20, and the outer cladding 10 tightly surrounds the outside of each of the cladding tubes 302; the center point of each of the cladding tubes 302 is the same as that of the central nested tube 3011 inside, and the outer nested tubes 3022 are arranged on both sides of the central nested tube 3011 and are symmetrically distributed with the central nested tube 3011 as the center. The radius of each of the outer nested tubes 3022 is the same, and the center of each of the outer nested tubes 3022 is arranged in parallel along the radial direction.

[0040] Furthermore, each of the anti-resonance tube units 30 is composed of at least three nested tubes 301 and a cladding tube 302 ; the cladding tubes 302 are arranged radially around the core region 20 , and the outer cladding 10 tightly surrounds each of the cladding tubes 302 .

[0041] It should be noted that a number of cladding tubes are arranged around the core area. These cladding tubes are evenly distributed around the core area, and the tubes are arranged at equal distances and in equal orientations to ensure the high symmetry and optical uniformity of the entire cross-section. With such a structural design, the core can obtain balanced anti-resonance effects from multiple directions to maximize the binding and constraint of the optical signal. In addition to the geometrically symmetrical structural characteristics, the number of cladding tube units also has a strong flexible adjustment capability. The number of cladding units can be reduced or increased for different applications to optimize the transmission performance. At the same time, the position layout, spacing and diameter of each resonant tube unit are strictly optimized. The high symmetry and regular distribution of the overall structure not only reduces the dependence on extremely high equipment precision during the preparation process, but also effectively improves the consistency of the dimensional parameters of the finished optical fiber, significantly enhancing its stability in subsequent use.

[0042] It should be understood that the fiber core is precisely positioned at the optical fiber's axial geometric center, with its size and position controlled through precision manufacturing processes to ensure strict alignment with the surrounding antiresonant tube unit structure. The axial alignment of the fiber core region and the antiresonant tube unit is achieved during the manufacturing process through rotary drawing and a laser intelligent positioning system, effectively reducing mode interference and transmission loss caused by center offset.

[0043] Furthermore, one nested tube 301 is provided on the central axis of each cladding tube 302 as a central nested tube 3011, and the remaining nested tubes 301 are evenly distributed on both sides of the central nested tube 3011 as outer nested tubes 3022. The radius of each outer nested tube 3022 is the same, and the centers of each nested tube 301 are arranged in parallel along the radial direction to form a negative curvature nested structure.

[0044] It should be noted that the cladding tubes surrounding the core region are composed of three or more nested tubes arranged side by side, employing a multi-nested tube design to form a spatially symmetrical nested structure with negative curvature. This structure significantly enhances the antiresonant optical effect, improves mode field confinement, and suppresses leakage of non-targeted higher-order modes. The spacing between the nested tubes is controlled at submicron to micron levels, and customized geometry optimization is often performed based on the target operating wavelength (850nm, 1310nm, 1550nm, etc.) and application scenario.

[0045] It should be understood that a spatially symmetrically distributed nested structure of negative curvature generally refers to a geometric form with negative constant curvature, hierarchical symmetrical distribution, and layer-by-layer inclusion. Negative curvature is a basic geometric concept that describes the curvature properties of space or surfaces, such as a saddle surface (hyperboloid), where the neighborhood of any point is "concave inward." By introducing negative curvature in the geometric space, the cladding tube forms an anti-resonant cavity for the optical signal when surrounding the fiber core, effectively reducing the leakage of light into the cladding area. In terms of structural design, the central nested tube directly acts on the constraint of the fundamental mode, and the outer nested tubes, based on the principle of negative curvature, cooperate with the central nested tube to suppress the energy leakage of higher-order modes, so that the signal is transmitted only in the required mode with extremely low loss.

[0046] In this embodiment, a nested hollow-core optical fiber comprises an outer cladding, a core region located at the center of the fiber, and multiple antiresonant tube units. Each antiresonant tube unit is composed of a cladding tube and at least three nested tubes, including a central nested tube and at least two outer nested tubes. The cladding tubes are radially arranged around the core region, with the outer cladding tightly surrounding each cladding tube. Each cladding tube shares the same center point with the inner central nested tube. The outer nested tubes are symmetrically arranged on either side of the central nested tube, each having the same radius and radially parallel centers, forming a nested structure with negative curvature. By introducing negative curvature into the geometric space, the cladding tubes surround the core to form an antiresonant cavity for the optical signal, reducing light leakage into the cladding region. The negative curvature of the cladding tubes and nested tubes enhances the antiresonance effect, improves the optical signal confinement within the core, and achieves long-distance, low-loss optical transmission.

[0047] Reference Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the first structure of the second embodiment of the nested hollow-core optical fiber of the present invention. Figure 3 FIG2 is a schematic diagram of the second structure of the second embodiment of the nested hollow core optical fiber of the present invention. Figure 2 and Figure 3 As shown, in this embodiment, the same or similar contents as those in the first embodiment can be referred to the above introduction and will not be described in detail later.

[0048] It should be noted that parameters such as the number, radius (r1), distribution, wall thickness, and material refractive index of the nested tubes can all be simulated and modularly configured using software, allowing for flexible adjustments before and after fabrication. For broadband applications such as broadband supercontinuum and holographic displays, more layers of nested tubes can be used to achieve enhanced bandwidth and mode suppression. For narrow-linewidth, high-spectral-purity laser applications, the wall thickness and radius can be adjusted to suit specific transmission requirements.

[0049] It should be understood that each anti-resonance tube unit is an example of a geometric structure in which a central nested tube and two outer nested tubes are nested side by side and adjacent to each other. Five, seven or more nested tubes can also be used, and there is no specific limitation here. In order to ensure the formation of a spatially symmetrical negative curvature structure, the radius (r3) of the outer nested tubes is the same, and the radius (r2) of the middle nested tube can be modified according to the specific application scenario. That is, refer to Figure 1 The radius of the middle nested tube (r2) is greater than the radius of the outer nested tube (r3), Figure 2 The radius of the middle nested tube (r2) is smaller than the radius of the outer nested tube (r3) and Figure 3 The radius of the middle nested tube (r2) is equal to the radius of the outer nested tube (r3).

[0050] Furthermore, the nested hollow-core optical fiber has extremely high parameter adjustability and application scalability. For the actual design of the optical fiber structure, the number of nested tubes and cladding tubes can be freely adjusted according to variables such as the working wavelength, target bandwidth, and application environment, and the actual radius, absolute thickness, tube distribution method and relative spacing of each tube can be flexibly set for different signal windows (such as the common 850nm, 1310nm and 1550nm, etc.), so as to obtain different optical suppression capabilities and mode field coverage characteristics. The highly symmetrical nature of the nested hollow-core optical fiber in the structure is greatly adapted to the current mainstream various types of optical fiber taper processes, preform rods and automated drawing production methods. For special working conditions such as high power, laser output, extreme low temperature or strong corrosion, the structural thickness of some areas can be increased, the cladding coating can be enhanced, and the refractive index change of the material can be optimized according to actual needs, so as to further improve the overall protection and specific functional performance of the new nested optical fiber and ensure compatibility with complex application scenarios.

[0051] Reference Figure 4 and Figure 5 , Figure 4 Fig. 3 is a third structural schematic diagram of the nested structure hollow core fiber second embodiment of the present application, Figure 5 Fig. 4 is a fourth structural schematic diagram of the nested structure hollow core fiber second embodiment of the present application. The center of the center nested tube inside each of the anti-resonance tube units can be located at different planes from the center of each of the outer nested tubes. When the number of the nested tubes in the anti-resonance tube units is three, the center of the center nested tube and the center of each of the outer nested tubes form a triangular arrangement. Meanwhile, referring to Figures 1 to 3 , the center of the center nested tube inside each of the anti-resonance tube units is located at the same plane as the center of each of the outer nested tubes.

[0052] Referring to Figure 6 , Figure 6 Fig. 5 is a fifth structural schematic diagram of the nested structure hollow core fiber second embodiment of the present application. The cladding tube can be arranged in a semi-circular structure. In the distribution mode of the cladding tube, both the classic hexagonal and circular full-symmetry arrangement can be used to achieve full-direction balanced anti-resonance, and the elliptical, dense or multi-block arrangement can be used according to specific application requirements to further realize differentiated structure optimization.

[0053] It should be understood that the outer cladding closely surrounds the cladding tube, and the cladding tube of the entire fiber structure is distributed radially around the core region. The number of units, the arrangement mode and the angle of each unit can be designed to ensure that the mode field is stably and uniformly distributed in the transverse direction, greatly reducing the mode coupling and performance fluctuations caused by external disturbances. At the same time, the number, spatial layout, filler rod type and pre-protective layer of the cladding tube and the nested tube can be increased or reduced according to the required communication window, infrared laser band, high-power low-loss, etc. Through parameter adjustment, the optimal adaptation to specific requirements such as different polarization, mode, dispersion, etc. can be realized. Due to the anti-resonance enhancement effect, the nested structure hollow core fiber can greatly eliminate non-target modes and high-order modes. Under the combination adjustment of the parameters of each unit (such as the number of rings, wall thickness, spacing, etc.), single-mode or fundamental mode high-fidelity stable transmission can be realized, polarization mode dispersion can be suppressed, mode coupling loss can be reduced, and signal purity and transmission distance can be effectively improved. It is especially suitable for the technical frontier fields of ultra-long distance low-loss communication, high-coherence laser transmission, high-power all-optical interconnection, etc.

[0054] In this embodiment, by introducing negative curvature in the geometric space, the cladding tubes form an antiresonant cavity for the optical signal when surrounding the fiber core, effectively reducing light leakage into the cladding region. In terms of structural design, the middle nested tube directly constrains the fundamental mode, while the outer nested tubes, based on the principle of negative curvature, collaborate with the central tube to suppress energy leakage in higher-order modes, allowing the signal to be transmitted only in the desired mode with extremely low loss. To ensure maximum structural performance, the radius, spacing, and thickness parameters of each nested tube are determined through a combination of theoretical calculations and simulation optimization to match the antiresonance peak position at different wavelengths and provide the optimal mode field distribution for the target operating band. This nested structure forms a multi-stage antiresonant cavity, broadening the low-loss operating bandwidth and suppressing high-order mode coupling. This significantly improves the fundamental mode energy localization and signal fidelity throughout the entire fiber, reducing channel loss caused by high-order mode leakage or dispersion.

[0055] Reference Figure 7 , Figure 7 This is a schematic structural diagram of a third embodiment of a nested hollow-core optical fiber according to the present invention. This third embodiment of a nested hollow-core optical fiber according to the present invention is proposed based on the above embodiments. For the same or similar contents as those in the above embodiments, please refer to the above description and will not be further elaborated.

[0056] It should be noted that nested hollow-core optical fibers can be produced using an integrated process for preparing and drawing a silica-glass composite preform 101, or conventional optical fiber drawing techniques. The integrated drawing process utilizes precision CNC drilling and laser-assisted forming to produce a multi-ring tube assembly with strictly controlled parameters such as ring number, radius, and wall thickness. Each antiresonant tube unit is integrally sintered with the outer cladding, and high-temperature plasma or specialized environmental treatment is used to eliminate internal stresses in the structure and prevent temporal degradation caused by thermal and mechanical stresses.

[0057] It should be understood that the preform 101 is located between the outer cladding 10 and the antiresonance tube unit 30, and the type and size (d) of the preform can also be adjusted. A silica-glass composite preform is composed of high-purity silica or doped silica glass combined with low-refractive-index glass. Its structure can be a coaxial "core-cladding" composite, used to produce optical fibers with specific optical properties (such as low loss, high bending strength, and transmission at specific wavelengths).

[0058] In this embodiment, each nested ring coupling zone is welded together at high temperature to form a single unit, suppressing micro-displacement and interfacial cracks. During batch production, all parameters can be standardized to ensure structural consistency and repeatable performance, greatly promoting industrial application and the feasibility of large-scale promotion. For specialized applications, it can be combined with online three-dimensional photon microscopy and an automatic quality feedback system to achieve full-process intelligent monitoring, meeting the high-standard and differentiated optical fiber requirements of future new optical communications and quantum information interconnection.

[0059] Furthermore, other low-refractive-index or high-temperature-resistant glass materials can be used instead of traditional SiO2 cladding materials to meet the needs of higher power or harsh environments (such as aerospace or nuclear radiation). At the same time, the air core filling medium can be changed.

[0060] The above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the scope of protection of the present invention.

[0061] Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0062] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0063] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A nested hollow-core optical fiber, characterized in that: The nested hollow-core optical fiber comprises: an outer cladding, a core region located at the center of the optical fiber, and a plurality of anti-resonance tube units; Each of the anti-resonance tube units is composed of a cladding tube and at least three nested tubes, wherein the nested tubes include a central nested tube and at least two outer nested tubes; The cladding tubes are arranged radially around the core region, and the outer cladding tightly surrounds the outside of each cladding tube; The center point of each cladding tube is the same as that of the inner central nested tube, and each outer nested tube is arranged on both sides of the central nested tube and is symmetrically distributed with the central nested tube as the center. The radius of each outer nested tube is the same, and the center of each outer nested tube is arranged in parallel along the radial direction.

2. The nested hollow-core optical fiber according to claim 1, wherein: The anti-resonance tube units are arranged around the fiber core region in a circular ring structure at equal distances and in equal directions. The number and angles of the anti-resonance tube units are adjusted according to the transmission performance of the optical fiber.

3. The nested hollow-core optical fiber according to claim 2, wherein: The space between the fiber core region and each of the nested tubes is filled with a low refractive index material.

4. The nested hollow-core optical fiber according to claim 3, wherein: The spacing between the nested tubes is set according to the working wavelength of the optical fiber transmission.

5. The nested hollow-core optical fiber according to claim 4, wherein: The coupling area of ​​each nested tube adopts high temperature welding or polymer bonding interface.

6. The nested hollow-core optical fiber according to claim 5, wherein: The outer cladding is made of a polymer composite material, and the inner surface of the outer cladding close to the core area is provided with a nano moisture-proof coating, a corrosion-resistant coating or a crack-resistant stress transfer layer. The thickness and outer diameter of the outer cladding are set according to the mechanical strength of the optical fiber.

7. The nested hollow-core optical fiber according to claim 1, wherein: The center of the central nested tube inside each anti-resonance tube unit and the center of each outer nested tube are located in different planes. When there are three nested tubes in the anti-resonance tube unit, the center of the central nested tube and the centers of each outer nested tube form a triangular arrangement.

8. The nested hollow-core optical fiber according to claim 1, wherein: The center of the central nested tube inside each of the anti-resonance tube units is located in the same plane as the center of each of the outer nested tubes, and the size of the central nested tube is larger than that of the outer nested tubes.

9. The nested hollow-core optical fiber according to claim 8, wherein: The nested hollow-core optical fiber is formed by an integrated process of preparing a silica-glass composite preform and drawing a wire, and each of the anti-resonance tube units and the outer cladding are integrally sintered.

10. The nested hollow-core optical fiber according to claim 9, wherein: The preform rod is located between the outer cladding and the anti-resonance tube unit.

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