Hollow anti-resonance optical fiber with composite structure

Abstract

A composite structure hollow anti-resonance optical fiber disclosed by the present invention comprises an outer cladding layer, a doping layer and an anti-resonance layer which are sequentially arranged from outside to inside, the anti-resonance layer comprises a plurality of glass nested combination tubes which are uniformly distributed along the circumferential direction, are tangent to the doping layer and are arranged at intervals, and the plurality of glass nested combination tubes surround to form an air fiber core. The glass nested combined pipe comprises an outer nested pipe of a circular structure and an inner nested pipe of an oval structure arranged in the outer nested pipe. The short half axis of the inner nested pipe is arranged in the radial direction of the optical fiber, and the outer ring, away from the air fiber core, of the inner nested pipe is tangent to the inner ring, away from the air fiber core, of the outer nested pipe. According to the invention, a multi-layer nested structure is adopted, and the anti-resonance effect is optimized through the cooperation of the doping layer and the anti-resonance layer with a special structure.

Description

Technical Field

[0001] The invention relates to the field of optical fibers, and in particular to a hollow anti-resonant optical fiber with a composite structure. Background Art

[0002] Conventional solid-core optical fibers, such as step-index optical fibers, use materials with higher refractive indexes for the core and materials with lower refractive indexes for the cladding, so as to guide light through total reflection. The solid-core optical fibers that are widely used today have intrinsic defects such as nonlinearity of the core adapting to the matrix material, dispersion, photodamage, and UV, mid-infrared light blocking, which greatly limits their application in certain fields such as communication and data transmission. At the same time, traditional optical fibers have certain limitations in high-power transmission, high-sensitivity sensing, and broadband optical applications, especially in the process of high-power light beam transmission, where traditional optical fibers are prone to signal distortion due to nonlinear effects. With the increasing demand for higher bandwidth, faster transmission speeds, and longer transmission distances, existing optical fiber designs are difficult to meet these requirements, and a new type of optical fiber that can overcome these technical bottlenecks is urgently needed.

[0003] Hollow-core Anti-resonant Fiber (HC-ARF) was proposed to meet these challenges. This technology uses a hollow structure design, and the transmission of light in the core is mainly achieved through the antiresonance effect in the cladding, thereby greatly reducing the absorption and scattering losses of the optical fiber material to light. Compared with traditional solid-core optical fibers, hollow-core anti-resonant fibers have lower nonlinear effects, higher power capacity, and low loss characteristics over a wide spectral range. These characteristics make HC-ARF show significant advantages in applications such as high-power laser transmission, ultrafast optical pulse transmission, and optical sensing. In addition, the design of hollow-core anti-resonant fiber also provides flexibility and adjustability. By adjusting the core structure and anti-resonance bandwidth, efficient transmission of light in different wavelength ranges can be achieved. This flexibility not only makes it very useful in traditional optical communications, but also provides new possibilities for emerging quantum communications, terahertz transmission, and nonlinear optics.

[0004] However, current hollow-core antiresonant fibers usually use a single geometric structure to achieve their functions, which limits the performance of the fiber and has poor adaptability and performance in a variety of applications. Summary of the invention

[0005] The purpose of the present invention is to propose a composite structure hollow antiresonant optical fiber to address the deficiencies of the prior art, thereby providing high bandwidth, low loss and excellent optical performance in different application scenarios.

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] A composite hollow anti-resonant optical fiber comprises an outer cladding, a doping layer and an anti-resonant layer arranged in sequence from the outside to the inside, the anti-resonant layer comprises a plurality of glass nested composite tubes uniformly distributed along the circumferential direction and arranged in gaps tangent to the doping layer, a plurality of the glass nested composite tubes surround an air core, the glass nested composite tubes comprise an outer nested tube of a circular structure and an inner nested tube of an elliptical structure arranged inside the outer nested tube, the short semi-axis of the inner nested tube is arranged along the radial direction of the optical fiber, and the outer circle of the inner nested tube away from the air core is arranged tangent to the inner circle of the outer nested tube away from the air core.

[0008] Furthermore, a compensation tube tangentially arranged to the doping layer is provided between adjacent glass nested combined tubes.

[0009] Furthermore, the cross-section of the compensating tube is circular.

[0010] Furthermore, the number of the glass nested combined tubes is 4 to 8.

[0011] Furthermore, the inner diameter of the outer nested tube is 35-40 μm, the major axis of the inner nested tube is 25-30 μm, the minor axis is 15-20 μm, the inner diameter of the compensation tube is 15-20 μm, and the thickness of the outer nested tube, the inner nested tube and the compensation tube are all 0.2-1.5 μm, and the thickness is consistent to ensure the stability and uniformity of the entire structure.

[0012] Furthermore, the inner diameter of the outer cladding layer is 110-130 μm, and the thickness is 50-60 μm; the inner diameter of the doping layer is 100-110 μm, and the thickness is 5-10 μm.

[0013] Furthermore, the inner diameter of the outer nested tube is 1.4 to 1.6 times the long axis of the inner nested tube to ensure effective transmission of light and reduce reflection loss.

[0014] Furthermore, the short axis of the inner nested tube should be smaller than half of the inner diameter of the outer nested tube to ensure sufficient space to form an effective air core.

[0015] Furthermore, the gap between adjacent glass nested combined tubes and the compensating tube accounts for 10% to 20% of the diameter of the inner nested tube, thereby optimizing the propagation path of light and preventing light leakage.

[0016] Furthermore, the inner diameter of the compensation tube should have a size ratio of 1:1.5 to 1:2 to the short axis of the inner nested tube, so as to achieve better compensation in terms of anti-resonance effect.

[0017] Furthermore, the inner diameter of the outer cladding is about 110-130 μm and should match the inner diameter of the doping layer of 100-110 μm. It is recommended that the ratio of the inner diameter of the outer cladding to the inner diameter of the doping layer be 1:1 to 1.1:1 to ensure the effective structural stability of the optical fiber.

[0018] Furthermore, the anti-resonance layer is made of glass with a refractive index of 1.46 to 1.48.

[0019] Furthermore, the doping layer is a glass material based on silicon dioxide and is added with one or more doping materials of fluorine, germanium, phosphorus, boron or ytterbium, so that the refractive index of the doping layer reaches 1.42-1.48.

[0020] Furthermore, the material of the outer cladding is pure silicon dioxide or germanium-doped silicon dioxide, so that the refractive index of the outer cladding is 1.38-1.42.

[0021] Furthermore, the refractive index difference between the doping layer and the outer cladding layer is 0.02 to 0.08.

[0022] By adopting the above technical solution, the present invention has the following beneficial effects:

[0023] (1) The present invention adopts a multi-layer nested structure, and optimizes the anti-resonance effect by cooperating with a doping layer and an anti-resonance layer of a special structure. The glass nested composite tubes are evenly arranged along the circumference, which enhances the mechanical stability of the optical fiber and improves its ability to resist environmental disturbances, so that the optical fiber can still maintain good transmission performance under different environmental conditions. The inner nested tube of the elliptical structure is tangentially embedded in the outer nested tube of the circular structure, and the special structure of the inner nested tube is utilized to generate asymmetric photon restrictions in different directions, thereby better controlling the propagation path of photons and reducing light loss. The tangent point between the inner nested tube and the outer nested tube is close to the position of the doping layer, so that the light is mainly confined to the air core area. In addition, the inner nested tube is innovatively embedded in the outer nested tube of the circular structure. The short semi-axis of the inner nested tube is arranged along the radial direction of the optical fiber. First, the optical loss can be reduced. By adjusting the anti-resonance conditions of the inner and outer interfaces of the nested tube, the reflection loss of light in the radial direction can be minimized, which helps to improve the transmission efficiency of the optical fiber, especially in the anti-resonance optical fiber, effectively reducing the leakage of optical signals. Moreover, the hollow anti-resonance optical fiber is usually sensitive to bending, and the nested tube adopts a flat elliptical structure, and the short semi-axis is consistent with the radial direction, which can effectively suppress the mode mismatch and leakage caused by bending, reduce the bending loss of the optical fiber, and is suitable for applications requiring high bending performance; at the same time, the flat shape of the ellipse makes the structure have a directional distribution, and the short semi-axis in the radial direction can better withstand external mechanical stress. This setting improves the stability of the optical fiber under the action of external forces and enhances the stress resistance, which is particularly suitable for application scenarios requiring high mechanical stability; second, the mode field distribution can be optimized, and this geometric structure helps to control the mode field distribution in the optical fiber. Since the short semi-axis is arranged in the radial direction, the light field can be guided to be more effectively concentrated in the core area of ​​the hollow anti-resonance optical fiber, thereby improving the constraint ability of the mode field and improving the quality of optical transmission. This multi-layer structure can more effectively suppress light leakage from the fiber core and improve the transmission efficiency of optical fiber over a wide wavelength range, thereby providing high bandwidth, low loss and excellent optical performance in different application scenarios.

[0024] (2) The present invention can form effective anti-resonance conditions in multiple wavelength ranges by adding a compensation tube and cooperating with the glass nested combination tube, especially in achieving multi-wavelength anti-resonance conditions. The specific analysis is as follows:

[0025] Optimizing refractive index profile:

[0026] The compensating tube can form a specific refractive index distribution by adjusting its material and thickness to help achieve the anti-resonance effect. By cooperating with the glass nested combination tube, the propagation path and mode of light can be effectively controlled.

[0027] Enhance light transmission efficiency:

[0028] The compensating tube can reduce the scattering and reflection of light in the optical fiber, optimize the propagation characteristics of light, and improve the transmission efficiency. Especially when transmitting multi-wavelength signals, it can more effectively maintain the signal quality.

[0029] Reduce modal interference:

[0030] The design of the compensating tube helps to reduce interference between modes, especially in multimode optical fibers. Through effective structural design, better mode selectivity can be achieved and signal clarity can be improved.

[0031] Providing structural support:

[0032] The compensating tube provides structural support for the nested combined tubes, ensuring the mechanical strength and stability of the optical fiber in various environments and avoiding performance degradation due to external pressure or bending.

[0033] (3) The cross section of the compensating pipe of the present invention is circular, which has the following advantages:

[0034] Uniform optical properties:

[0035] The circular cross-section is symmetrical in all directions, which allows light to propagate in a uniform manner when passing through the compensating tube, reducing light distortion and scattering.

[0036] Simplify the manufacturing process:

[0037] The circular cross-section design is easier to implement in the production process, especially in large-scale production, reducing production costs and complexity.

[0038] Enhanced structural strength:

[0039] The circular structure performs better when subjected to internal and external pressure, and can effectively resist bending and compression forces, thereby improving the durability and stability of the optical fiber.

[0040] (4) The doping layer of the present invention can be doped with different materials to adjust the refractive index of each layer, and the width of the photonic band gap can be accurately controlled, so that the optical fiber can adapt to a wider wavelength range, thereby further optimizing the anti-resonance effect. By doping with different elements such as fluorine, germanium, phosphorus, etc., the optical properties of the optical fiber can be adjusted to have better transmission performance at a specific wavelength; at the same time, doping can reduce the loss of the optical fiber and improve the transmission efficiency of the signal, which is particularly important in high-power laser applications; doping elements can also improve the heat resistance of the optical fiber, enhance its stability in high-temperature environments, and extend the service life of the optical fiber; through doping, the nonlinear optical properties of the optical fiber can be controlled, thereby optimizing the laser amplification and optical transmission characteristics and improving the overall performance of the system; in summary, the optical fiber containing the doping layer can maintain a stable photonic band gap width under different experimental conditions (such as temperature changes, light intensity changes), thereby improving the adaptability and multi-wavelength transmission capability of the optical fiber.

[0041] (5) The present invention ensures effective reflection and transmission of optical signals and realizes effective coupling by controlling the refractive index difference between the doping layer and the outer cladding. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments and in conjunction with the accompanying drawings, wherein:

[0043] Figure 1 It is a structural schematic diagram of Example 1;

[0044] Figure 2 The effective refractive index curve of the composite structure hollow core antiresonant optical fiber of Example 1 varies with wavelength;

[0045] Figure 3 The limiting loss curve of the composite structure hollow core antiresonant optical fiber of Example 1 varies with wavelength;

[0046] Figure 4 is the bending loss curve of the composite structure hollow core antiresonant optical fiber of Example 1 as the bending radius changes;

[0047] Figure 5 1 is a high-order mode ratio curve of the hollow-core antiresonant optical fiber of Example 1 as the wavelength changes.

[0048] The reference numerals in the accompanying drawings are:

[0049] Outer cladding 1, doping layer 2, glass nested combined tube 3, outer nested tube 3-1, inner nested tube 3-2, air core 4, compensation tube 5. DETAILED DESCRIPTION

[0050] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0051] (Example 1)

[0052] like Figure 1The composite structure hollow antiresonant optical fiber shown includes an outer cladding 1, a doping layer 2 and an antiresonant layer arranged in sequence from the outside to the inside, wherein the antiresonant layer includes a plurality of glass nested composite tubes 3 uniformly distributed along the circumference and arranged at gaps tangent to the doping layer 2, and the plurality of glass nested composite tubes 3 surround and form an air core 4. The position distribution of the glass nested composite tubes 3 not only enhances the mechanical stability of the optical fiber, but also improves its ability to resist environmental disturbances, so that the optical fiber can still maintain good transmission performance under different environmental conditions. The glass nested composite tube 3 includes an outer nested tube 3-1 of a circular structure and an inner nested tube 3-2 of an elliptical structure arranged in the outer nested tube 3-1, and the short semi-axis of the inner nested tube 3-2 is arranged along the radial direction of the optical fiber, and the outer circle of the inner nested tube 3-2 away from the air core 4 is arranged tangent to the inner circle of the outer nested tube 3-1 away from the air core 4. By tangentially embedding the inner nested tube 3-2 of the elliptical structure into the outer nested tube 3-1 of the circular structure, the special structure of the inner nested tube is used to generate asymmetric photon restrictions in different directions, thereby better controlling the propagation path of photons and reducing light loss; and the tangent point between the inner nested tube 3-2 and the outer nested tube 3-1 is close to the position of the doping layer 2, thereby optimizing the reflection path so that the light is mainly confined to the air core area. In addition, the short semi-axis of the inner nested tube is innovatively set along the radial direction of the optical fiber; this multi-layer structure can more effectively suppress light leakage from the core and improve the transmission efficiency of the optical fiber in a wide wavelength range, thereby providing high bandwidth, low loss and excellent optical performance in different application scenarios.

[0053] Specifically, the number of glass nested combination tubes is 4 to 8. If the number of glass nested combination tubes is less than 4, the anti-resonance effect is insufficient. The small number of combination tubes cannot effectively achieve the anti-resonance effect, resulting in reduced transmission efficiency of the optical fiber, and the performance is not as expected. At the same time, the loss increases, and the light is more likely to be reflected and scattered during the propagation process, thereby increasing the loss. In addition, the flexibility is insufficient. Too few combination tubes limit the flexibility of the optical fiber design and cannot adapt to different application requirements and environments. If the number of glass nested combination tubes exceeds 8, the manufacturing complexity increases, the production difficulty increases, and the precision requirements in the manufacturing process are higher, resulting in increased costs. At the same time, the space utilization efficiency is low, and too many pipes occupy too much space, which leads to the overall structure of the optical fiber being not compact enough, affecting its applicability, and increasing the loss. Too many combination tubes increase the scattering inside the optical fiber, thereby increasing the loss of the optical signal and affecting the transmission performance.

[0054] This embodiment is provided with 5 glass nested combination tubes, and a compensation tube 5 tangentially arranged with the doping layer 2 is provided between adjacent glass nested combination tubes 3, which cooperates with the glass nested combination tubes 3 to form effective anti-resonance conditions in multiple wavelength ranges. The cross section of the compensation tube is circular. In order to ensure excellent anti-resonance effect, the inner diameter of the outer nested tube 3-1 is 35-40 μm, the long axis of the inner nested tube 3-2 is 25-30 μm, the short axis is 15-20 μm, the inner diameter of the compensation tube 5 is 15-20 μm, and the thickness of the outer nested tube, the inner nested tube and the compensation tube are all 0.2-1.5 μm. In this embodiment, the inner diameter of the outer nested tube 3-1 is 40 μm, the long axis of the inner nested tube 3-2 is 30 μm, the short axis is 15 μm, the inner diameter of the compensation tube is 15 μm, the thickness of the outer nested tube 3-1, the inner nested tube 3-2 and the compensation tube 5 are all 1 μm, and the material is glass material with a refractive index of 1.47.

[0055] The material of the outer cladding 1 is pure silica or germanium-doped silica, so that the refractive index of the outer cladding reaches 1.38 to 1.42. In this embodiment, the refractive index of the outer cladding is 1.4. The doping material of the doping layer 2 is one or more of fluorine, germanium, phosphorus, boron or ytterbium, so that the refractive index of the doping layer 2 reaches 1.42 to 1.48. By doping different materials to adjust the refractive index of each layer, the width of the photonic band gap can be accurately controlled, so that the optical fiber can adapt to a wider wavelength range, thereby further optimizing the anti-resonance effect. In this embodiment, the refractive index of the doping layer 2 is 1.45, and the refractive index difference between the doping layer 2 and the outer cladding 1 is 0.05. The inner diameter of the outer cladding 1 is 110 to 130 μm, and the thickness is 50 to 60 μm. The inner diameter of the doping layer 2 is 100 to 110 μm, and the thickness is 5 to 10 μm. In this embodiment, the inner diameter of the outer cladding layer is 120 μm and the thickness is 60 μm, and the inner diameter of the doping layer 2 is 110 μm and the thickness is 10 μm.

[0056] In the design of the composite structure hollow anti-resonant optical fiber of this embodiment, the refractive index of the anti-resonant layer plays a key role in the overall effect, and has a synergistic effect with the refractive index of the outer cladding and the doping layer. The main function of the anti-resonant layer is to limit the propagation path of photons in the core of the optical fiber by reflection to achieve the anti-resonance effect, thereby reducing the loss and scattering of light; the closer the refractive index of the anti-resonance layer is to the refractive index of the outer cladding of the optical fiber, the lower the transmission effect of low loss can be maintained in a wider wavelength range. The design refractive index of the anti-resonance layer of this embodiment is 1.47, which is lower than the refractive index of the doping layer and the outer cladding, making it easier for light to be reflected back into the hollow core in the doping layer, achieving effective light confinement, thereby reducing losses. The refractive index of the doping layer is 1.45, which is similar to the anti-resonance layer, which can increase the reflection of light in the doping layer and effectively reduce the leakage of light in the anti-resonance layer. The role of the doping layer is similar to that of the anti-resonance adjustment layer, which can improve the reflection effect of photons by fine-tuning the refractive index. The refractive index of the outer cladding is 1.42, which is relatively low. It forms a refractive index difference with the doped layer, making the reflection of light more concentrated, thereby further enhancing the confinement and propagation effect of light in the fiber core.

[0057] Through the precise distribution of the refractive index, the optical fiber can achieve excellent anti-resonance effect in different wavelength ranges. This synergistic effect of the refractive index is the basic condition for multi-wavelength low-loss transmission. In addition, the refractive index difference between the doping layer and the outer cladding can ensure stability and low nonlinear loss under high power conditions.

[0058] Taking the wavelength of 1550nm as the working wavelength, the structure of this embodiment is simulated by finite element method. The outer diameter of the outer cladding 1 is 230μm, the inner diameter is 120μm, and the thickness of the outer cladding is 55μm; the outer diameter of the doping layer 2 is 120μm, the inner diameter is 100μm, and the thickness is 10μm. Among them, the inner diameter of the circular outer nested tube is 36μm; the major axis of the elliptical inner nested tube is 28μm, and the minor axis is 16μm; the inner diameter of the circular compensation tube is 16μm.

[0059] See also Figure 2 The effective refractive index of the hollow core antiresonant optical fiber provided by the present invention is close to 1, that is, the transmission refractive index in the hollow core is close to 1. Figure 3 , at 1550nm, the fundamental mode confinement loss of hollow core antiresonant fiber is less than 0.005dB / km. Figure 4 The bending loss measured by the bending test with a bending radius of 20 cm is less than 0.06 dB / km, that is, the present invention has low fundamental mode loss at the working wavelength and low bending loss at the working wavelength.

[0060] In addition, see Figure 3The limiting loss corresponding to the transmission wavelength of 1300~1700nm is less than 0.011dB / km, and the transmission wavelength with limiting loss less than 0.01dB / km (the part <1300nm) actually has broadband low-loss transmission characteristics in the range greater than 1300~1700nm.

[0061] See also Figure 5 The high-order mode ratio of the hollow-core antiresonant fiber (the high-order mode ratio is the ratio of the fundamental mode loss to the minimum loss of the high-order mode) is greater than 100, and it has good single-mode characteristics.

[0062] (Comparative Example 1)

[0063] The structure of this embodiment is the same as that of Embodiment 1, except that the refractive index of the antiresonance layer is 1.47, the refractive index of the outer cladding layer 1 is 1.35, the refractive index of the doping layer 2 is 1.4, and the refractive index difference between the outer cladding layer 1 and the doping layer 2 is 0.05.

[0064] (Comparative Example 2)

[0065] The structure of this embodiment is the same as that of Embodiment 1, except that the refractive index of the antiresonance layer is 1.47, the refractive index of the outer cladding layer 1 is 1.35, the refractive index of the doping layer 2 is 1.5, and the refractive index difference between the outer cladding layer 1 and the doping layer 2 is 0.15.

[0066] (Comparative Example 3)

[0067] The structure of this embodiment is the same as that of Embodiment 1, except that the refractive index of the antiresonance layer is 1.47, the refractive index of the outer cladding layer 1 is 1.35, the refractive index of the doping layer 2 is 1.42, and the refractive index difference between the outer cladding layer 1 and the doping layer 2 is 0.07.

[0068] (Comparative Example 4)

[0069] The structure of this embodiment is the same as that of Embodiment 1, except that the refractive index of the antiresonance layer is 1.47, the refractive index of the outer cladding 1 is 1.45, the refractive index of the doping layer 2 is 1.5, and the refractive index difference between the outer cladding 1 and the doping layer 2 is 0.05.

[0070] (Comparative Example 5)

[0071] The structure of this embodiment is the same as that of Embodiment 1, except that the refractive index of the antiresonance layer is 1.47, the refractive index of the outer cladding layer 1 is 1.45, the refractive index of the doping layer 2 is 1.47, and the refractive index difference between the outer cladding layer 1 and the doping layer 2 is 0.02.

[0072] (Comparative Example 6)

[0073] The structure of this embodiment is the same as that of Embodiment 1, except that the refractive index of the antiresonance layer is 1.47, the refractive index of the outer cladding layer 1 is 1.45, the refractive index of the doping layer 2 is 1.4, and the refractive index difference between the outer cladding layer 1 and the doping layer 2 is -0.05.

[0074] Taking the wavelength of 1550nm as the working wavelength, the structures of Comparative Examples 1 to Comparative Examples 6 were simulated using finite element method. The results are shown in the following table, where the bending loss performance is the result under the bending radius of 20cm:

[0075] Effective refractive index Limit loss dB / km Bending loss dB / km Comparative Example 1 0.99952 0.0049 0.46 Comparative Example 2 1.02952 0.0229 0.68 Comparative Example 3 1.00952 0.0085 0.52 Comparative Example 4 1.01952 0.0178 0.74 Comparative Example 5 0.99952 0.0121 0.58 Comparative Example 6 1.03952 0.0532 0.92

[0076] The present invention adopts a multi-layer nested structure, and optimizes the anti-resonance effect and enhances the mechanical stability of the optical fiber through the cooperation of the doping layer and the anti-resonance layer of the special structure, so that the optical fiber can still maintain good transmission performance under different environmental conditions, reduce light loss, improve the transmission efficiency of the optical fiber, and reduce the bending loss of the optical fiber. Through the precise distribution setting of the refractive index, the optical fiber can achieve excellent anti-resonance effect in different wavelength ranges. The synergistic effect of the refractive index is the basic condition for multi-wavelength low-loss transmission. In addition, the refractive index difference between the doping layer and the outer cladding can ensure stability and low nonlinear loss under high power conditions.

[0077] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite hollow antiresonant optical fiber, characterized in that: The invention comprises an outer cladding, a doping layer and an anti-resonance layer which are arranged in sequence from the outside to the inside. The anti-resonance layer comprises a plurality of glass nested combined tubes which are evenly distributed along the circumference and tangent to the doping layer. The plurality of glass nested combined tubes surround an air core. The glass nested combined tubes comprise an outer nested tube with a circular structure and an inner nested tube with an elliptical structure which is arranged inside the outer nested tube. The short semi-axis of the inner nested tube is arranged along the radial direction of the optical fiber and the outer circle of the inner nested tube away from the air core is arranged tangent to the inner circle of the outer nested tube away from the air core.

2. The composite structure hollow-core antiresonant optical fiber according to claim 1, characterized in that: A compensation tube tangentially arranged with the doping layer is arranged between adjacent glass nested combined tubes.

3. The composite structure hollow-core antiresonant optical fiber according to claim 2, characterized in that: The cross section of the compensating tube is circular.

4. The composite structure hollow-core antiresonant optical fiber according to claim 3, characterized in that: The number of the glass nested combined tubes is 4 to 8.

5. The composite structure hollow-core antiresonant optical fiber according to claim 3, characterized in that: The inner diameter of the outer nested tube is 35-40 μm, the major axis of the inner nested tube is 25-30 μm, the minor axis is 15-20 μm, the inner diameter of the compensation tube is 15-20 μm, and the thickness of the outer nested tube, the inner nested tube and the compensation tube are all 0.2-1.5 μm.

6. The composite structure hollow-core antiresonant optical fiber according to claim 3, characterized in that: The inner diameter of the outer cladding layer is 110-130 μm, and the thickness is 50-60 μm. The inner diameter of the doping layer is 100-110 μm, and the thickness is 5-10 μm.

7. The composite structure hollow-core antiresonant optical fiber according to claim 1, characterized in that: The anti-resonance layer is made of glass with a refractive index of 1.46-1.

48.

8. The composite structure hollow-core antiresonant optical fiber according to claim 1, characterized in that: The doping layer is a glass material based on silicon dioxide and is added with one or more of fluorine, germanium, phosphorus, boron or ytterbium, so that the refractive index of the doping layer reaches 1.42-1.

48.

9. The composite structure hollow-core antiresonant optical fiber according to claim 1, characterized in that: The material of the outer cladding is pure silicon dioxide or germanium-doped silicon dioxide, so that the refractive index of the outer cladding is 1.38-1.

42.

10. The composite structure hollow-core antiresonant optical fiber according to claim 1, characterized in that: The refractive index difference between the doping layer and the outer cladding layer is 0.02-0.08.

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