Composite hollow-core optical fiber and application thereof

Abstract

The invention belongs to the technical field of optical fibers, and discloses a composite hollow-core optical fiber and application thereof. The composite hollow-core optical fiber provided by the invention comprises an outer cladding, an inner cladding and a fiber core from outside to inside, the inner cladding is composed of an outer layer kagome lattice structure, an inner layer kagome lattice structure and a nested tube structure; the outer layer kagome lattice structure is composed of a plurality of regular hexagonal air holes and a plurality of regular triangular air holes; the inner layer kagome lattice structure is composed of a plurality of air holes with negative curvature and a plurality of regular triangle air holes. The nested tube structure comprises a plurality of unit nested tube structures, each unit nested tube structure is composed of a first tubular structure and a second tubular structure, the radius of the first tubular structure is larger than that of the second tubular structure, and the inner side of the first tubular structure is tangent to the outer side of the second tubular structure. According to the invention, the transmission loss of the hollow-core optical fiber can be reduced, and the hollow-core optical fiber is particularly suitable for VCSEL communication.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fibers, and more specifically, relates to a composite hollow-core optical fiber and an application thereof. Background Art

[0002] Hollow-core fiber is an important research direction in fiber optics. With its specific microstructure design, the light field can be confined in the air core, reducing the overlap between the light field and the quartz area. Compared with traditional solid-core fiber, hollow-core fiber overcomes intrinsic losses such as material and scattering, and can theoretically achieve ultra-low-loss light transmission; in addition, it also theoretically has the advantages of low latency, low dispersion, low nonlinearity, high optical damage threshold, anti-interference, and high flexibility in being able to be filled with liquid or gas, and has broad application prospects in the fields of high-power pulsed laser transmission, ultrafast optics, and nonlinear optics.

[0003] Although hollow-core optical fibers have developed rapidly, most of the current research on hollow-core optical fibers is concentrated in the band greater than 1000nm, and there are relatively few studies on the band less than 1000nm. In addition, the transmission loss in the band less than 1000nm in the existing research is relatively large.

[0004] VCSEL (Vertical-Cavity Surface-Emitting Laser) has low production cost and is the main light source for short-distance transmission in modern data centers and supercomputer systems. It produces a wavelength of 850nm. The transmission loss of light with a wavelength of 850nm is very large in solid-core optical fibers because Rayleigh scattering is very large in the 850nm band. Rayleigh scattering is mainly caused by the distribution of silicon atoms and oxygen atoms. Solid-core optical fibers are limited by the distribution of silicon atoms and oxygen atoms in glass materials, and have requirements for the transmission wavelength. They cannot meet the requirements of low-loss transmission of light with a wavelength of 850nm.

[0005] However, existing research on hollow-core optical fibers has shown that the transmission loss in the wavelength band below 1000nm is relatively large, so it is difficult to achieve low-loss transmission of light with a wavelength of 850nm, and it is not suitable for VCSEL communication.

[0006] How to reduce the transmission loss of hollow core optical fiber and make it suitable for VCSEL communication is a technical problem that is of concern in this field and needs to be solved. Summary of the invention

[0007] The present invention provides a composite hollow-core optical fiber and application thereof, thereby solving the problem in the prior art that the hollow-core optical fiber has large transmission loss and is difficult to be applied to VCSEL communication.

[0008] The present invention provides a composite hollow core optical fiber, comprising: an outer cladding, an inner cladding and a core from outside to inside;

[0009] The inner cladding is composed of an outer kagome lattice structure, an inner kagome lattice structure and a nested tube structure;

[0010] The outer kagome lattice structure is composed of a plurality of regular hexagonal air holes and a plurality of regular triangle air holes;

[0011] The inner kagome lattice structure is composed of a plurality of air holes with negative curvature and a plurality of equilateral triangular air holes;

[0012] The nested tube structure includes a plurality of unit nested tube structures, each of which is composed of a first tubular structure and a second tubular structure, the radius of the first tubular structure is greater than the radius of the second tubular structure, and the inner side of the first tubular structure is tangent to the outer side of the second tubular structure.

[0013] Preferably, the inner kagome lattice structure is composed of a plurality of first negative curvature structures, a plurality of second negative curvature structures and a plurality of equilateral triangular air holes; the first negative curvature structure and the second negative curvature structure are both evolved from regular hexagonal air holes, the first negative curvature structure is an air hole in which two sides of a regular hexagon evolve into circular arcs, and the second negative curvature structure is an air hole in which three sides of a regular hexagon evolve into circular arcs.

[0014] Preferably, the outer contour of the outer cladding is a circle, and the inner contour of the outer cladding is a regular hexagon;

[0015] The outer kagome lattice structure forms a regular hexagon, in which the regular hexagonal air holes and the regular triangular air holes are arranged in sequence, and two regular triangular air holes are arranged between two adjacent regular hexagonal air holes;

[0016] In the inner kagome lattice structure, a plurality of the first negative curvature structures are arranged at the vertex positions of the regular hexagon formed by the outer kagome lattice structure, a plurality of the second negative curvature structures are arranged between two of the first negative curvature structures, and the remaining area of ​​the inner kagome lattice structure is arranged with regular triangular air holes.

[0017] Preferably, the nested tube structure is supported and connected by the inner kagome lattice structure, and the outer side of the first tubular structure is tangent to the outer side of the second negative curvature structure.

[0018] Preferably, the nested tube structure is composed of six unit nested tube structures that are not in contact with each other, and the centers of the first tubular structure and the second tubular structure are both on the diagonal of a regular hexagon that serves as the inner contour of the outer cladding.

[0019] Preferably, the filling medium of the outer cladding is silica glass; the inner cladding is made of silica glass; and the medium of the core is air.

[0020] Preferably, all the air holes in the outer kagome lattice structure, the inner kagome lattice structure, the first tubular structure and the second tubular structure have the same wall thickness, and the wall thickness ranges from 0.55 μm to 0.65 μm;

[0021] The side length of the regular hexagonal air holes in the outer kagome lattice structure ranges from 7.7 μm to 8.7 μm;

[0022] The distance between two adjacent unit nested tube structures ranges from 2.05 μm to 3.05 μm;

[0023] The radius of the first tubular structure ranges from 11.95 μm to 12.95 μm, and the maximum distance between the inner diameter of the first tubular structure and the outer diameter of the second tubular structure ranges from 2.94 μm to 3.84 μm.

[0024] Preferably, the diameter of the circumscribed circle of the outer cladding is 170 μm to 250 μm;

[0025] The side length of the regular hexagon as the inner contour of the outer cladding layer ranges from 76.81 μm to 77.81 μm;

[0026] The radius of the fiber core ranges from 14.5 μm to 15.5 μm.

[0027] Preferably, when the wavelength range of the transmitted light is 800 nm to 890 nm, the loss of the composite hollow-core optical fiber is lower than 0.4 dB / km.

[0028] On the other hand, the present invention provides an application of the composite hollow core optical fiber as described above, wherein the composite hollow core optical fiber is applied to VCSEL communication.

[0029] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0030] The composite hollow-core optical fiber provided by the present invention comprises an outer cladding, an inner cladding and a core from the outside to the inside, wherein the inner cladding is composed of an outer kagome lattice structure, an inner kagome lattice structure and a nested tube structure, the outer kagome lattice structure is composed of a plurality of regular hexagonal air holes and a plurality of regular triangular air holes, the inner kagome lattice structure is composed of a plurality of air holes with negative curvature and a plurality of regular triangular air holes, the nested tube structure comprises a plurality of unit nested tube structures, each unit nested tube structure is composed of a first tubular structure and a second tubular structure, the radius of the first tubular structure is greater than the radius of the second tubular structure, and the inner side of the first tubular structure is tangent to the outer side of the second tubular structure. The present invention designs a hollow-core optical fiber by combining a kagome lattice and a nested tube, and the kagome lattice can impose secondary restrictions on the light leaked from the nested tube, thereby reducing the transmission loss. Wherein, the kagome lattice as the outer layer is composed of regular hexagonal air holes and regular triangle air holes with a certain thickness, and the kagome lattice as the inner layer is composed of special-shaped air holes and regular triangle air holes. The special-shaped air holes are evolved from the regular hexagonal air hole shape, and the partial edges of the regular hexagon are evolved into arc shapes, that is, they have a negative curvature structure. This design can further limit the transmission light, thereby further reducing the loss. The kagome lattice in the present invention is composed of regular hexagons (including the evolutionary structure of regular hexagons) and regular triangles as a whole, which can stabilize the structure of the optical fiber and is easy to process and manufacture. The present invention is also designed and optimized for a specific transmission wavelength less than 1000nm band. The composite hollow-core optical fiber provided by the present invention has a loss of less than 0.4dB / km when 800nm ​​to 890nm, and a loss of 0.3dB / km when the wavelength of the transmission light is 850nm, which is particularly suitable for VCSEL communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the cross-sectional structure of a composite hollow-core optical fiber provided in Example 1 of the present invention;

[0032] Figure 2 A schematic diagram of a partially enlarged cross-section of a composite hollow-core optical fiber provided in Example 1 of the present invention;

[0033] Figure 3 A distribution diagram of an electric field mode in a composite hollow core optical fiber provided in Example 1 of the present invention;

[0034] Figure 4 A graph showing the variation of various losses of a composite hollow-core optical fiber with the transmission wavelength provided in Example 1 of the present invention;

[0035] Figure 5 A graph showing the variation of the total loss of a composite hollow-core optical fiber with the bending radius of the optical fiber provided in Example 1 of the present invention;

[0036] Figure 6 This is a graph showing the variation of the effective refractive index of a composite hollow-core optical fiber with wavelength provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0037] 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.

[0038] Embodiment 1:

[0039] Example 1 provides a composite hollow core optical fiber, see Figure 1 , including: an outer cladding 8, an inner cladding and a core 5 from the outside to the inside; the inner cladding is composed of an outer kagome lattice structure, an inner kagome lattice structure and a nested tube structure; the outer kagome lattice structure is composed of a plurality of regular hexagonal air holes 1 and a plurality of regular triangular air holes 6; the inner kagome lattice structure is composed of a plurality of air holes with negative curvature and a plurality of regular triangular air holes 6; the nested tube structure includes a plurality of unit nested tube structures, each of the unit nested tube structures is composed of a first tubular structure 4 and a second tubular structure 3, the radius of the first tubular structure 4 is greater than the radius of the second tubular structure 3, and the inner side of the first tubular structure 4 is tangent to the outer side of the second tubular structure 3.

[0040] The present invention adopts a structure combining kagome lattice and nested tube, which can effectively reduce the loss based on the anti-resonance principle. The inner cladding includes two layers of kagome lattice and one layer of nested tube structure, the kagome lattice as the outer layer is composed of regular hexagonal air holes 1 and regular triangular air holes 6 with a certain thickness, and the kagome lattice as the inner layer is composed of special-shaped air holes and regular triangular air holes 6. The special-shaped air holes are evolved from the regular hexagonal air hole 1, and some edges of the regular hexagon are evolved into arc shapes, that is, they have a negative curvature structure. This design can further limit the transmitted light, thereby further reducing the loss.

[0041] The design of the inner kagome lattice structure in the present invention can also be understood as first designing the inner kagome lattice structure to be a structure consisting of a regular hexagonal air hole 1 and a regular triangular air hole 6 with a certain thickness, and then designing part of the edge of the regular hexagonal air hole 1 close to the fiber core 5 to be an arc shape to obtain an air hole with a negative curvature.

[0042] The inner kagome lattice structure is composed of a plurality of first negative curvature structures 2, a plurality of second negative curvature structures 7, and a plurality of regular triangular air holes 6; the first negative curvature structure 2 and the second negative curvature structure 7 are both evolved from regular hexagonal air holes 1, the first negative curvature structure 2 is an air hole that evolves two sides of the regular hexagonal air hole 1 into arc-shaped air holes, and the second negative curvature structure 7 is an air hole that evolves three sides of the regular hexagonal air hole 1 into arc-shaped air holes. That is, the inner kagome lattice structure includes two negative curvature structures, one is a structure that evolves three sides of the regular hexagon into arc-shaped structures, and the other is a structure that evolves two sides of the regular hexagon into arc-shaped structures.

[0043] See also Figure 1 , Figure 2 , the air hole with negative curvature is evolved from the regular hexagonal air hole 1. Specifically, the geometric center of the regular hexagonal air hole 1 is the circle point, the side length of the regular hexagonal air hole 1 is the radius, and one of the vertices of the regular hexagonal air hole 1 is the starting point. After rotating by an angle α (for example, rotating by 180°), the two sides of the regular hexagon are evolved into arcs to form the first negative curvature structure 2. With the geometric center of the regular hexagonal air hole 1 as the center point, the side length of the regular hexagonal air hole 1 as the radius, and one of the vertices of the regular hexagonal air hole 1 as the starting point, the three sides of the regular hexagon are evolved into arcs to form the second negative curvature structure 7.

[0044] The outer contour of the outer cladding 8 is circular, and the inner contour of the outer cladding 8 is a regular hexagon. That is, the outer cladding 8 is a columnar structure with a circular outer contour and a regular hexagonal inner contour, and wraps the inner cladding and the core 5.

[0045] The outer kagome lattice structure forms a regular hexagon. In the outer kagome lattice structure, regular hexagonal air holes 1 and regular triangular air holes 6 are arranged in sequence, and two regular triangular air holes 6 are arranged between two adjacent regular hexagonal air holes 1.

[0046] In the inner kagome lattice structure, a plurality of the first negative curvature structures 2 are arranged at the vertex positions of the regular hexagon formed by the outer kagome lattice structure, a plurality of the second negative curvature structures 7 are arranged between two of the first negative curvature structures 2, and the remaining area of ​​the inner kagome lattice structure is arranged with regular triangular air holes 6.

[0047] That is, the inner envelope is composed of a kagome lattice consisting of a regular hexagonal air hole 1 with a certain thickness, an equilateral triangular air hole 6, the first negative curvature structure 2 and the second negative curvature structure 7, and a nested tube consisting of the first tubular structure 4 and the second tubular structure 3 with a certain thickness. Taking the example that the inner kagome lattice structure includes six of the first negative curvature structures 2, the kagome lattice is composed of two layers, the outer layer is composed of regular hexagonal air holes 1 and equilateral triangular air holes 6 arranged in sequence, and two equilateral triangular air holes 6 are provided in the gap between two adjacent regular hexagonal air holes 1 (which can be understood as the upper and lower gap areas); the inner layer is composed of equilateral triangular air holes 6, the first negative curvature structure 2 and the second negative curvature structure 7, the six first negative curvature structures 2 are arranged at the six vertices of the large regular hexagon formed by the outer layer, and the second negative curvature structures 7 are arranged in pairs at the two ends. In the middle of the first negative curvature structure 2, the rest of the positions are equilateral triangular air holes 6, and in the gap between two adjacent negative curvature structures away from the fiber core 5 (including the gap between the first negative curvature structure 2 and the second negative curvature structure 7, and the gap between the two second negative curvature structures 7) there is an equilateral triangular air hole 6. It can be understood that one side of the equilateral triangular air hole 6 in the inner kagome lattice structure coincides with the side length of the air hole in the outer kagome lattice structure, and no equilateral triangular air hole 6 is set in the gap between two adjacent negative curvature structures close to the fiber core 5.

[0048] The second tubular structure 3 is nested in the first tubular structure 4, and the first tubular structure 4 and the second tubular structure 3 are tangent to each other on the side of the second tubular structure 3 close to the outer cladding 8. For example, the nested tubular structure is composed of six non-contacting unit nested tubular structures, and the centers of the first tubular structure 4 and the second tubular structure 3 are both on the diagonal of the regular hexagon that is the inner contour of the outer cladding 8. The nested tubular structure is supported and connected by the inner layer kagome lattice structure, and the outer side of the first tubular structure 4 is tangent to the outer side of the second negative curvature structure 7.

[0049] The filling medium of the outer cladding 8 is silica glass, that is, the outer cladding 8 is a silica glass matrix. The inner cladding is made of silica glass, and the refractive index n of the silica glass is 1.4565 to 1.4504.

[0050] The fiber core 5 is a circular area formed by the outer sides of a plurality of the first tubular structures 4. The fiber core 5 is located in the central area of ​​the composite hollow-core optical fiber. The medium of the fiber core 5 is air for transmitting light, and the refractive index of air is 1.

[0051] The parameter design of the composite hollow core optical fiber provided by the present invention is described below.

[0052] See also Figure 1 , all the air holes in the outer kagome lattice structure, the inner kagome lattice structure (including the regular hexagonal air hole 1, the regular triangle air hole 6, the first negative curvature structure 2, the second negative curvature structure 7), and the first tubular structure 4 and the second tubular structure 3 have the same wall thickness t, and the value range of the wall thickness t is 0.55 μm to 0.65 μm. That is, the thickness of all silica glass walls in the composite hollow core optical fiber is consistent.

[0053] Specifically, the wall thickness t is calculated using the following formula:

[0054]

[0055] Where λ is the central wavelength of the transmitted light, n is the refractive index of silica glass, and m is a positive integer.

[0056] In the present invention, when the value of m is 2 and the value range of λ is set to 800 nm to 890 nm, the range of t is obtained to be 0.55 μm to 0.65 μm.

[0057] The side length h of the regular hexagonal air hole 1 in the outer kagome lattice structure ranges from 7.7 μm to 8.7 μm. Correspondingly, the side length of the regular triangular air hole 6 in the outer kagome lattice structure and the side length of the regular triangular air hole 6 in the inner kagome lattice structure are both h.

[0058] The distance g between two adjacent unit nested tube structures ranges from 2.05 μm to 3.05 μm.

[0059] The radius b of the first tubular structure 4 ranges from 11.95 μm to 12.95 μm, and the maximum distance d between the inner diameter of the first tubular structure 4 and the outer diameter of the second tubular structure 3 ranges from 2.94 μm to 3.84 μm.

[0060] The diameter of the circumscribed circle of the outer cladding 8 is 170 μm to 250 μm.

[0061] The side length 2c of the regular hexagon as the inner contour of the outer cladding 8 ranges from 76.81 μm to 77.81 μm. It can also be understood that the kagome lattice forms a large regular hexagon, that is, the inner cladding is a regular hexagon with a side length of 76.81 μm to 77.81 μm.

[0062] The radius a of the fiber core 5 ranges from 14.5 μm to 15.5 μm.

[0063] The composite hollow-core optical fiber provided by the present invention has good tuning characteristics, and the loss can be further reduced by further optimizing the optical fiber structural parameters.

[0064] The performance of the composite hollow core optical fiber provided by the present invention is described below.

[0065] The distribution of the electric field mode in the composite hollow core optical fiber provided by the present invention is as follows: Figure 3 As shown, including the two-dimensional diagram and the three-dimensional diagram of the distribution of the electric field mode in the fiber core, it can be seen that the composite hollow core optical fiber can well confine the light in the fiber core.

[0066] The total loss (the sum of the restriction loss and the surface scattering loss) of the composite hollow core optical fiber provided by the present invention, the restriction loss, and the surface scattering loss are shown in the figure as a function of the transmission wavelength. Figure 4 As shown, it can be seen that the composite hollow-core optical fiber has very low loss. Specifically, when the wavelength range of the transmitted light is 800nm ​​to 890nm, the total loss of the composite hollow-core optical fiber is less than 0.4dB / km, and the lowest total loss of 0.26dB / km is achieved at 860nm. When the transmission wavelength is 850nm, the total loss is as low as 0.3dB / km. That is, the composite hollow-core optical fiber provided by the present invention can achieve low-loss transmission of light with a wavelength of 850nm.

[0067] The total loss of the composite hollow core optical fiber provided by the present invention varies with the bending radius of the optical fiber. Figure 5 As shown, when the bending radius is greater than 9 cm, the transmission loss change rate is basically stable, and it can be seen that the composite hollow-core optical fiber has good anti-bending performance.

[0068] The effective refractive index of the composite hollow core optical fiber provided by the present invention varies with wavelength as follows: Figure 6 As shown, it can be seen that the effective transmission of the fundamental mode in the composite hollow-core optical fiber decreases with the increase of the transmission wavelength, and the effective refractive index of light when transmitting in the core is close to the refractive index of air 1.

[0069] It can be seen that in the 800nm ​​to 890nm band, the composite hollow-core optical fiber provided in Example 1 has lower transmission loss and good anti-bending performance, and can achieve low-loss transmission.

[0070] In addition, because the composite hollow-core optical fiber provided in Example 1 is a hollow-core optical fiber, the light is confined to the core by the principle of anti-resonance, thereby greatly reducing the direct contact between light and the optical fiber material, making the optical fiber less likely to be burned, that is, the damage threshold is high.

[0071] In summary, the composite hollow-core optical fiber provided in Example 1 has the characteristics of low-loss transmission, wide spectral bandwidth (800nm ​​to 890nm), small bending loss, and high damage threshold.

[0072] Embodiment 2:

[0073] Embodiment 2 provides an application of the composite hollow core optical fiber as described in Embodiment 1, wherein the composite hollow core optical fiber is applied to VCSEL communication.

[0074] Compared with solid core optical fiber, the core of the composite hollow core optical fiber provided by the present invention is air, which can avoid the interaction between signal light and silicon atoms and oxygen atoms. In addition, the present invention reduces the loss of optical fiber by specially designing the inner cladding of the hollow core optical fiber and optimizing the optical fiber parameters for the wavelength band less than 1000nm, especially the specific transmission wavelength of 850nm.

[0075] Based on the description of Example 1, it can be seen that the composite hollow-core optical fiber provided by the present invention has a loss as low as 0.3 dB / km when the transmission wavelength is 850 nm.

[0076] In summary, the composite hollow core optical fiber provided by the present invention can be combined with a VCSEL light source to achieve low-loss transmission. The present invention can achieve low-loss transmission of light with a wavelength of 850nm, which is of great significance.

[0077] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A composite hollow core optical fiber, characterized in that: include: From outside to inside, the outer cladding, inner cladding and core; The inner cladding is composed of an outer kagome lattice structure, an inner kagome lattice structure and a nested tube structure; The outer kagome lattice structure is composed of a plurality of regular hexagonal air holes and a plurality of regular triangle air holes; The inner kagome lattice structure is composed of a plurality of air holes with negative curvature and a plurality of equilateral triangular air holes; The nested tube structure includes a plurality of unit nested tube structures, each of which is composed of a first tubular structure and a second tubular structure, the radius of the first tubular structure is greater than the radius of the second tubular structure, and the inner side of the first tubular structure is tangent to the outer side of the second tubular structure.

2. The composite hollow core optical fiber according to claim 1, characterized in that: The inner kagome lattice structure is composed of multiple first negative curvature structures, multiple second negative curvature structures and multiple regular triangular air holes; the first negative curvature structure and the second negative curvature structure are both evolved from regular hexagonal air holes, the first negative curvature structure is an air hole evolved from two sides of a regular hexagon to a circular arc, and the second negative curvature structure is an air hole evolved from three sides of a regular hexagon to a circular arc.

3. The composite hollow core optical fiber according to claim 2, characterized in that: The outer contour of the outer cladding is a circle, and the inner contour of the outer cladding is a regular hexagon; The outer kagome lattice structure forms a regular hexagon, in which the regular hexagonal air holes and the regular triangular air holes are arranged in sequence, and two regular triangular air holes are arranged between two adjacent regular hexagonal air holes; In the inner kagome lattice structure, a plurality of the first negative curvature structures are arranged at the vertex positions of the regular hexagon formed by the outer kagome lattice structure, a plurality of the second negative curvature structures are arranged between two of the first negative curvature structures, and the remaining area of ​​the inner kagome lattice structure is arranged with regular triangular air holes.

4. The composite hollow core optical fiber according to claim 2, characterized in that: The nested tube structure is supported and connected by the inner kagome lattice structure, and the outer side of the first tubular structure is tangent to the outer side of the second negative curvature structure.

5. The composite hollow core optical fiber according to claim 3, characterized in that: The nested tube structure is composed of six mutually non-contacting unit nested tube structures, and the centers of the first tubular structure and the second tubular structure are both on the diagonal of a regular hexagon serving as the inner contour of the outer cladding.

6. The composite hollow core optical fiber according to claim 1, characterized in that: The filling medium of the outer cladding is silica glass; the inner cladding is made of silica glass; and the medium of the core is air.

7. The composite hollow core optical fiber according to claim 1, characterized in that: The outer kagome lattice structure, all the air holes in the inner kagome lattice structure, the first tubular structure and the second tubular structure have the same wall thickness, and the wall thickness ranges from 0.55 μm to 0.65 μm; The side length of the regular hexagonal air holes in the outer kagome lattice structure ranges from 7.7 μm to 8.7 μm; The distance between two adjacent unit nested tube structures ranges from 2.05 μm to 3.05 μm; The radius of the first tubular structure ranges from 11.95 μm to 12.95 μm, and the maximum distance between the inner diameter of the first tubular structure and the outer diameter of the second tubular structure ranges from 2.94 μm to 3.84 μm.

8. The composite hollow core optical fiber according to claim 3, characterized in that: The diameter of the circumscribed circle of the outer cladding is 170 μm to 250 μm; The side length of the regular hexagon as the inner contour of the outer cladding ranges from 76.81 μm to 77.81 μm; The radius of the fiber core ranges from 14.5 μm to 15.5 μm.

9. The composite hollow core optical fiber according to claim 1, characterized in that: When the wavelength range of the transmitted light is 800nm ​​to 890nm, the loss of the composite hollow-core optical fiber is lower than 0.4dB / km.

10. A use of the composite hollow core optical fiber according to any one of claims 1 to 9, characterized in that: The composite hollow core optical fiber is applied to VCSEL communication.

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