Single-mode ultralow-loss hollow-core anti-resonance optical fiber

Abstract

The invention relates to a single-mode ultra-low-loss hollow-core anti-resonance optical fiber which comprises an outer cladding and an inner cladding, the inner cladding is composed of nested structure units, the nested structure units are arranged at intervals in the circumferential direction of the inner wall of the outer cladding and connected with the inner wall of the outer cladding, a fiber core is formed by a central cavity wrapped by the inner cladding, and the fiber core is connected with the inner wall of the inner cladding. Each nested structure unit comprises two or more layers of nested glass tubes with different radiuses, and is characterized in that an auxiliary inner cladding layer is arranged along the circumferential direction of the inner wall of the outer cladding layer and comprises an auxiliary nested structure unit; the auxiliary nested structure units and the nested structure units are arranged at intervals in a staggered mode in the circumferential direction of the inner wall of the outer cladding layer, the auxiliary nested structure units are connected with the inner wall of the outer cladding layer, and a circular mold releasing cavity tangent to the auxiliary nested structure units and the nested structure units on the two adjacent sides is formed between the auxiliary nested structure units and the nested structure units on the two adjacent sides. Through the change of the cladding structure, the high-order mode loss is improved while the fundamental mode loss is reduced, so that the low-loss transmission under a high-purity single mode is realized.

Description

Technical Field

[0001] The present invention relates to a single-mode ultra-low-loss hollow anti-resonant optical fiber, belonging to the technical fields of optical communication and transmission. Background Art

[0002] Hollow anti-resonant optical fibers have a unique microstructure design that can confine the transmitted light wave in an air core. They have important applications in fields such as the interaction between light and filling substances, nonlinear optics, gas detection, gas laser generation, and optical fluid technology. Due to their unique structure and light guiding mechanism, they can achieve ultra-low Rayleigh scattering, low nonlinear coefficients, and adjustable dispersion characteristics, and can provide a higher laser damage threshold, making them potentially applicable in high-power laser transmission, ultraviolet / mid-infrared light transmission, pulse compression, and optical soliton transmission. The ultra-low loss, low dispersion, low nonlinearity, and near-light-speed propagation speed of the air core enable the development of hollow fiber optical communication transmission and communication devices, laying a foundation for the construction and development of the next-generation ultra-large-capacity, low-latency, and high-speed optical communication system.

[0003] Even though hollow optical fibers have unique and significant advantages in design and application, due to their natural lack of high-order mode cut-off conditions, the high-order modes of hollow optical fibers cannot be effectively filtered out like those of solid-core single-mode optical fibers. This will greatly limit their application scenarios in short-distance transmission. Recent research work has shown that through reasonable structural design, the leakage loss of high-order modes can be improved to a certain extent, resulting in an approximately single-mode effect after a certain distance.

[0004] The currently commonly used method for filtering high-order modes is to select a high-attenuation cladding mode and make it highly phase-matched with the LP11 mode in the core through structural design, thereby effectively increasing the leakage loss of the LP11 mode. The key factors in this design method are: the original attenuation of the cladding mode and its degree of phase matching with the LP11 mode. Generally, the higher the attenuation of the cladding mode and the higher the degree of phase matching with the LP11 mode, the greater the increase in the leakage of the LP11 mode and the better the single-mode performance.

[0005] U.S. Patent US11733451B2 discloses a single-ring hollow anti-resonant optical fiber. This patent proposes to utilize the high-phase matching between the high-loss anti-resonant unit (ARE) mode and the core LP11 mode. This structure is very simple, has a low drawing difficulty, and can achieve an extremely high high-order mode suppression ratio. When the ratio of the cladding tube to the core size is about 0.68, a broadband highly single-mode effect can be achieved, and the attenuation of the LP11 mode can reach 10 2The order of dB / m. However, it is difficult to achieve ultra-low attenuation transmission with this structure. Currently, the lowest attenuation in the near-infrared band is 4.3 dB / km (1080 nm), and the attenuation is even higher in the communication band. Moreover, its anti-bending performance is poor, so it has no great advantage in many applications in the near-infrared band.

[0006] Chinese Patent CN110515152B discloses a nested anti-resonant nodeless fiber (NANF) with a single nested tube structure and a double nested anti-resonant nodeless fiber (DNANF) with a double nested tube structure. By increasing the number of anti-resonant layers, the transmission loss of the fundamental mode is effectively reduced in these two structures. For the NANF fiber, its lowest attenuation has reached 0.22 dB / km, while the DNANF has even broken through the lowest attenuation record of traditional solid-core fibers and reached 0.11 dB / km. However, while achieving ultra-low attenuation, the loss of the LP11 mode is also at a relatively low level in the above two types of fibers. When the NANF structure achieves the best resonant leakage design for the LP11 mode, the theoretical LP11 attenuation is about 10 2 ~10 3 dB / km, and currently, the highest can reach 2.6 dB / m under actual manufacturing and placement conditions. The inherent attenuation of its cladding mode has been greatly reduced with the increase in the number of structure layers, so the LP11 mode attenuation cannot reach a high enough level. This situation is even more severe in the DNANF structure: First, the attenuation of the cladding mode in the DNANF structure is further reduced; second, there is not enough space in the cladding region of the DNANF structure to achieve sufficient phase matching between the LP11 mode and the cladding mode, and the theoretical attenuation of the LP11 mode is lower than 10 2 dB / km, which means that the DNANF fiber cannot effectively filter out high-order modes, seriously affecting the signal transmission quality. Summary of the Invention

[0007] The problem to be solved by the present invention is to provide a single-mode ultra-low-loss hollow anti-resonant fiber in view of the deficiencies of the above-mentioned existing technologies. By changing the cladding structure, while reducing the fundamental mode loss, the high-order mode loss is increased, so as to achieve low-loss transmission under high-purity single mode.

[0008] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows: It includes an outer cladding and an inner cladding. The inner cladding is composed of nested structural units. The nested structural units are arranged at intervals along the circumferential direction of the inner wall of the outer cladding and are in contact with the inner wall of the outer cladding. The central cavity covered by the inner cladding forms a core. The nested structural unit includes two or more nested glass tubes with different radii. It is characterized in that an auxiliary inner cladding is provided along the circumferential direction of the inner wall of the outer cladding. The auxiliary inner cladding includes auxiliary nested structural units. The auxiliary nested structural units are arranged at intervals in a staggered manner with the nested structural units along the circumferential direction of the inner wall of the outer cladding and are in contact with the inner wall of the outer cladding. A circular die-relief cavity that is tangent to all three is formed between the auxiliary nested structural unit and the nested structural units on both adjacent sides.

[0009] According to the above solution, the auxiliary nested structural unit includes one or more nested glass tubes with different radii.

[0010] According to the above solution, the nested glass tube includes an outer nested glass tube and an inner nested glass tube from the outside to the inside.

[0011] According to the above solution, there is one or more auxiliary nested structural units between two adjacent nested structural units.

[0012] According to the above solution, the auxiliary nested structural units are symmetrically arranged between two adjacent nested structural units, that is, the geometric center line of the auxiliary nested structural unit coincides with the geometric center lines of the two adjacent nested structural units.

[0013] According to the above solution, the inner cladding includes 3 to 5 nested structural units, and the auxiliary inner cladding correspondingly includes 3 to 5 auxiliary nested structural units.

[0014] According to the above solution, the nested structural units are evenly arranged at intervals along the circumferential direction of the inner wall of the outer cladding.

[0015] According to the above solution, the nested structural unit includes three nested glass tubes with different radii, including an outer nested glass tube, a first inner nested glass tube, and a second inner nested glass tube from the outside to the inside.

[0016] According to the above solution, both the outer cladding and its inner wall are circular.

[0017] According to the above solution, the nested glass tube includes circular nested glass tubes with different radii. Each circular nested glass tube is tangent to each other, and the outer nested glass tube is tangent to the inner wall of the cavity of the outer cladding.

[0018] According to the above solution, the nested glass tubes include arc nested glass tubes with different radii and circular nested glass tubes, wherein each arc nested glass tube intersects with the inner wall of the outer cladding or with the adjacent outer nested glass tube outside, and each circular nested glass tube is tangent to each other, or each circular nested glass tube is tangent to the inner wall of the outer cladding.

[0019] According to the above solution, the nested glass tubes include arc nested glass tubes with different radii, and each arc nested glass tube intersects with the inner wall of the outer cladding.

[0020] According to the above solution, the base materials of the outer cladding, the inner cladding and the auxiliary inner cladding are all pure silica glass.

[0021] According to the above solution, the single-side wall thicknesses of the inner and outer nested glass tubes that make up the nested structure unit and the auxiliary nested structure unit are the same or the difference is less than 20%.

[0022] According to the above solution, the single-side wall thicknesses of the inner and outer nested glass tubes and the outer cladding that make up the nested structure unit and the auxiliary nested structure unit are 0.3 to 1.5 μm.

[0023] According to the above solution, the nested structure unit includes three layers of nested glass tubes with different radii. The outer nested glass tube and the first inner nested glass tube are circular nested glass tubes with different radii, and support pads are arranged at the joint between the outer nested glass tube and the first inner nested glass tube.

[0024] According to the above solution, the number of the support pads is one or more, and they are distributed circumferentially.

[0025] According to the above solution, the cross section of the support pad is approximately circular, elliptical, rhombic or rectangular.

[0026] According to the above solution, the ratio of the diameter of the circular core to the diameter of the circular leakage mode cavity is 1:0.4 to 0.7.

[0027] According to the above solution, the ratio of the diameter of the circular core to the outer nested glass tube of the nested structure unit is 1:1.2 to 1.5.

[0028] According to the above solution, the ratio of the diameter of the outer nested glass tube to the first inner nested glass tube of the nested structure unit is 1:0.55 to 0.75.

[0029] According to the above solution, the ratio of the diameter of the first inner nested glass tube to the second inner nested glass tube of the nested structure unit is 1:0.4 to 0.7.

[0030] According to the above solution, the core region and other inner cavity regions of the outer cladding are filled with gas.

[0031] According to the above solution, the gas is argon, nitrogen, helium, air, or a mixture of multiple gases.

[0032] According to the above solution, the fundamental mode loss of the optical fiber is lower than 0.5 dB / km. Preferably, the fundamental mode loss of the optical fiber is lower than 0.15 dB / km.

[0033] According to the above solution, the loss of the high-order mode of the optical fiber is higher than 6 dB / m. Preferably, the attenuation of the high-order mode of the optical fiber is higher than 10 dB / m.

[0034] The beneficial effects of the present invention are as follows: 1. By setting a circular mode leakage cavity formed between the auxiliary inner cladding and the nested structural unit as a high-order mode resonance filtering unit, the cavity region is close to the outermost side of the microstructure, and the fundamental mode in the region has ultra-high attenuation. By further designing the phase matching between the mode in the air region and the high-order mode of the core, the high-order mode of the core leaks more efficiently, greatly improving the high-order mode attenuation and having excellent single-mode transmission performance; while achieving ultra-low loss transmission, the single-mode property of the hollow-core optical fiber can be greatly improved. 2. For the fundamental mode, the cladding of the present invention includes multiple layers of anti-resonant quartz walls and air layers, and the transmitted fundamental mode is effectively confined in the core, reducing the confinement loss and achieving ultra-low loss transmission. The optimized support pads can further reduce the optical fiber attenuation. 3. The single-mode performance of the present invention does not have wavelength selectivity, and highly single-mode transmission can be achieved within the working wavelength range. While reducing the fundamental mode loss, the high-order mode loss is increased, thereby achieving low-loss transmission under high-purity single-mode conditions, providing a transmission medium with excellent performance for fields such as high-speed communication, high-power transmission, gas lasers, and gas detection. Description of the Drawings

[0035] Figure 1 It is a radial cross-sectional structure diagram of Embodiment 1 of the present invention.

[0036] Figure 2 It is the LP01 mode loss spectrum of Embodiment 1 of the present invention.

[0037] Figure 3 It is the LP11 mode loss spectrum of Embodiment 1 of the present invention.

[0038] Figure 4 It is a radial cross-sectional structure diagram of Embodiment 2 of the present invention.

[0039] Figure 5 It is a radial cross-sectional structure diagram of Embodiment 3 of the present invention.

[0040] Figure 6 It is the LP01 mode loss spectrum of Embodiment 3 of the present invention.

[0041] Figure 7 It is a radial cross-sectional structure diagram of Embodiment 4 of the present invention.

[0042] Figure 8 It is the radial cross-sectional structure diagram of Embodiment 5 of the present invention.

[0043] Figure 9 It is the radial cross-sectional structure diagram of Embodiment 6 of the present invention.

[0044] Figure 10 It is the radial cross-sectional structure diagram of Embodiment 7 of the present invention.

[0045] Figure 11 It is the radial cross-sectional structure diagram of Embodiment 8 of the present invention. Detailed implementation manners

[0046] The present invention will be further described in detail below in conjunction with the embodiments of the present invention and the accompanying drawings.

[0047] Embodiment 1: As Figure 1As shown, it is a single-mode, low-loss hollow anti-resonant optical fiber, including an outer cladding 1 and an inner cladding. The inner cladding is composed of 4 nested structural units. The nested structural units are evenly spaced along the circumferential direction of the inner wall of the outer cladding and are in contact with the inner wall of the outer cladding. The nested structural unit includes 3 circular nested glass tubes with different radii. From the outside to the inside, it includes a circular outer nested glass tube 201, a circular first inner nested glass tube 202, and a circular second inner nested glass tube 203. The outer nested glass tube is tangent to the inner wall of the cavity of the outer cladding, and each circular nested glass tube is tangent to the same point. A (equivalent) circular core cavity 4 that is tangent to each nested structural unit is formed at the center covered by the 4 nested structural units. An auxiliary inner cladding is provided along the circumferential direction of the inner wall of the outer cladding. The auxiliary inner cladding includes 4 auxiliary nested structural units. The auxiliary nested structural units are arranged in an alternating and spaced manner along the circumferential direction of the inner wall of the outer cladding with the nested structural units. The auxiliary nested structural units are symmetrically arranged between two adjacent nested structural units, that is, the geometric midline of the auxiliary nested structural unit coincides with the geometric midlines of two adjacent nested structural units. The auxiliary nested structural unit includes 1 layer of circular nested glass tube 301, that is, it is composed of 1 circular outer nested glass tube and is tangent to the inner wall of the outer cladding. A (equivalent) circular mode leakage cavity 5 that is tangent to the three of them is formed between the auxiliary nested structural unit and the nested structural units on both adjacent sides. 4 symmetrically distributed circular mode leakage cavities are formed in the entire cavity of the outer cladding. The diameter ratio of the circular core to the circular mode leakage cavity is 1:0.4 - 0.7. The diameter ratio of the circular core to the outer nested glass tube of the nested structural unit is 1:1.2 - 1.5. The diameter ratio of the outer nested glass tube to the first inner nested glass tube of the nested structural unit is 1:0.55 - 0.75. The diameter ratio of the first inner nested glass tube to the second inner nested glass tube of the nested structural unit is 1:0.4 - 0.7. The base materials of the outer cladding, the inner cladding, and the auxiliary inner cladding are all pure silica glass. The single-side wall thicknesses of the inner and outer nested glass tubes that make up all the nested structural units and the auxiliary nested structural units are the same or approximately the same. The core region and other inner cavity regions of the outer cladding are filled with gas.

[0048] Example 1: The specific structural parameters are as follows: the diameter of the circular core is 28 μm; the outer diameter of the outer nested glass tube is 40 μm, the outer diameter of the first inner nested glass tube is 30 μm, and the ratio to the outer diameter of the outer nested glass tube is 0.75; the outer diameter of the second inner nested glass tube is 16 μm, and the inner diameter of the outer cladding is 105 μm. The auxiliary nested structure unit includes 1 layer of circular nested glass tube 301 with an outer diameter of 7.6 μm. The distance between the outer nested glass tubes of any two adjacent nested structure units is more than 8 μm, making the structure of the optical fiber more stable and easier to draw during the drawing process. In this example, the single-side wall thickness of the inner and outer nested glass tubes is 1.1 μm. When the second resonance working band is extended to 1310 nm, the wall thickness of each should be 0.95 μm; when using the first anti-resonance window as the communication working band, the wall thickness of each should be 0.5 μm. The present invention has a reasonable and preparable cladding wall shape, an optimized best size combination, and an innovative leakage mode cavity design, which comprehensively produce the following technical effects: significantly improving the leakage loss of the LP11 mode, reducing the transmission loss of the fundamental mode, and ultimately effectively improving the single-mode performance of the optical fiber. As Figure 2 shown, this example can achieve ultra-low attenuation transmission of less than 0.1 dB / km within a bandwidth of about 400 nm. As Figure 3 shown, in this example, the attenuation of the LP11 mode has a leakage loss higher than 10 dB / m within the light guiding band and is close to 100 dB / m within a wide band, enabling high-performance single-mode transmission.

[0049] Example 2: As Figure 4 shown, the main difference between this example and Example 1 is that the nested structure unit includes 3 layers of arc nested glass tubes and circular nested glass tubes with different radii. From the outside to the inside, it includes an arc outer nested glass tube 201, a circular first inner nested glass tube 202, and a circular second inner nested glass tube 203. Among them, the arc outer nested glass tube intersects with the inner wall of the outer cladding, and each circular inner nested glass tube is tangent to each other and tangent to the inner wall of the outer cladding at the same point. This example has a circular core cavity 4 with the same diameter as that in Example 1, but the inner diameter of the outer cladding 1 is smaller. The ratio of the diameter of the circular core to the diameter of the circular leakage mode cavity is 1:0.5 - 0.7, and the ratio of the diameter of the circular core of the nested structure unit to the diameter of the outer nested glass tube is 1:1.2 - 1.5. Other structures are basically the same as those in Example 1.

[0050] Example 3: As Figure 5 、 6As shown, the difference from Embodiment 1 is that the nested structure unit includes three circular nested glass tubes with different radii. From the outside to the inside, it includes a circular outer nested glass tube 201, a circular first inner nested glass tube 202, and a circular second inner nested glass tube 203. The outer nested glass tube is tangent to the inner cavity wall of the outer cladding. Each circular nested glass tube is tangent to the same point. At the junction between the outer nested glass tube and the first inner nested glass tube, a support pad 204 is installed. There is 1 support pad, and the cross-section of the support pad is approximately elliptical. Among them, the first inner nested glass tube and the second inner nested glass tube are both externally tangent to the inner tangent point of the support pad, and the outer nested glass tube and the inner cavity wall of the outer cladding are both internally tangent to the outer tangent point of the support pad. And the inner tangent point and the outer tangent point are located on the same radial line. This structure makes the outer nested glass tube and the first inner nested glass tube seem to be equally spaced. The specific structural parameters are as follows: the diameter of the circular core is 28μm; the outer diameter of the outer nested glass tube is 42μm, the outer diameter of the first inner nested glass tube is 27.3μm, and the ratio to the outer diameter of the outer nested glass tube is 0.65; the outer diameter of the second inner nested glass tube is 12μm, and the inner diameter of the outer cladding is 110μm. In this embodiment, the support pad is a solid-core ellipse with a major axis of 9μm and a minor axis of 4μm, and the material is pure silica glass. The auxiliary nested structure unit includes one layer of circular nested glass tube 301 with an outer diameter of 8.2μm. The distance between the outer nested glass tubes of any two adjacent nested structure units is more than 8μm, making the structure of the optical fiber more stable and easier to draw during the drawing process. In this embodiment, the single-side wall thickness of the inner and outer nested glass tubes is 1.1μm. When the second resonance working band is extended to 1310nm, the wall thickness of each should be 0.95μm; when using the first anti-resonance window as the communication working band, the wall thickness of each should be 0.5μm.

[0051] The present invention has a reasonable and preparable cladding wall shape, an optimized best size combination, and an optimal quartz pad size, which comprehensively produce the following technical effects: significantly improving the leakage loss of the LP11 mode, reducing the transmission loss of the fundamental mode, and ultimately effectively enhancing the single-mode performance of the optical fiber; the distance between any two adjacent nested structure units is more than 8μm, greatly reducing the drawing difficulty and facilitating large-scale and long-distance production. Introducing a quartz support pad can further reduce the attenuation of the optical fiber and at the same time improve the leakage efficiency of the leakage mode cavity for the high-order modes of the core. As Figure 6 shown, this embodiment can achieve ultra-low attenuation transmission below 0.1dB / km within a bandwidth of about 400nm.

[0052] Embodiment 4: As Figure 7 shown, the difference between Embodiment 4 and Embodiment 3 lies in the shape of the support pad. In this embodiment, the cross-section of the support pad is a solid-core circle with a diameter of 5μm.

[0053] Embodiment 5: As Figure 8As shown, the difference between Example 5 and Example 3 lies in the shape of the support cushion block. In this example, the cross-section of the support cushion block is a solid rectangle.

[0054] Example 6: As Figure 9 shown, to increase the structural stability, on the basis of Example 4, Example 6 increases the number of solid circular support cushion blocks to 2, and the 2 support cushion blocks are symmetrically arranged on both sides of the inner nested glass tube.

[0055] Example 7: As Figure 10 shown, to increase the structural stability, on the basis of Example 5, Example 7 increases the number of rectangular support cushion blocks to 2, and the 2 support cushion blocks are symmetrically arranged on both sides of the inner nested glass tube.

[0056] Example 8: As Figure 11 shown, to increase the structural stability, on the basis of Example 5, Example 8 increases the number of rectangular support cushion blocks to 3.

Claims

1. A single-mode ultra-low loss hollow-core antiresonant optical fiber, comprising an outer cladding and an inner cladding, wherein the inner cladding is composed of nested structural units, the nested structural units are arranged at intervals along the circumference of the inner wall of the outer cladding and connected to the inner wall of the outer cladding, the central cavity covered by the inner cladding forms a fiber core, and the nested structural units include two or more layers of nested glass tubes with different radii, characterized in that An auxiliary inner cladding is provided along the circumference of the inner wall of the outer cladding, and the auxiliary inner cladding includes auxiliary nested structural units. The auxiliary nested structural units are arranged alternately with the nested structural units along the circumference of the inner wall of the outer cladding and connected to the inner wall of the outer cladding. A circular mold release cavity tangent to the three is formed between the auxiliary nested structural units and the nested structural units on the adjacent two sides.

2. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1, characterized in that The auxiliary nested structural unit comprises one or more layers of nested glass tubes with different radii.

3. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The nested glass tubes include an outer nested glass tube and an inner nested glass tube from the outside to the inside.

4. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The number of the auxiliary nested structural units located between two adjacent nested structural units is one or more.

5. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The auxiliary nested structural units are symmetrically arranged between two adjacent nested structural units, that is, the geometric center line of the auxiliary nested structural unit coincides with the geometric center line of the two adjacent nested structural units.

6. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The inner cladding layer includes 3 to 5 nested structural units, and the auxiliary inner cladding layer correspondingly includes 3 to 5 auxiliary nested structural units.

7. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 6, characterized in that The nested structural units are evenly spaced along the circumference of the inner wall of the outer cladding.

8. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The nested structural unit comprises three layers of nested glass tubes with different radii, including an outer nested glass tube, a first inner nested glass tube and a second inner nested glass tube from the outside to the inside.

9. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The outer cladding and the inner wall are both circular.

10. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The nested glass tubes include circular nested glass tubes with different radii, each circular nested glass tube is tangent to another, and the outer nested glass tube is tangent to the inner cavity wall of the outer cladding.

11. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The nested glass tubes include arc nested glass tubes and circular nested glass tubes with different radii, wherein each arc nested glass tube intersects with the inner wall of the outer cladding or with the adjacent outer nested glass tube, each circular nested glass tube is tangent to each circular nested glass tube, or each circular nested glass tube is tangent to the inner wall of the outer cladding.

12. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The nested glass tubes include arc-shaped nested glass tubes with different radii, and each arc-shaped nested glass tube intersects with the inner wall of the outer cladding.

13. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The base materials of the outer cladding, inner cladding and auxiliary inner cladding are all pure quartz glass.

14. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 3, characterized in that The single-side wall thickness of the inner and outer nested glass tubes constituting the nested structural unit and the auxiliary nested structural unit is consistent or the difference is less than 20%.

15. The single-mode ultra-low loss hollow-core anti-resonant optical fiber according to claim 3, characterized in that The single-side wall thickness of the inner and outer nested glass tubes constituting the nested structural unit and the auxiliary nested structural unit is 0.3 to 1.5 μm.

16. The single-mode ultra-low loss hollow-core anti-resonant optical fiber according to claim 8, characterized in that The nested structural unit comprises three layers of nested glass tubes with different radii. The outer nested glass tube and the first inner nested glass tube are circular nested glass tubes with different radii. A support pad is installed at the joint between the outer nested glass tube and the first inner nested glass tube.

17. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 16, characterized in that The supporting pad is one or more and is distributed along the circumferential direction; the cross section of the supporting pad is approximately circular, elliptical, diamond or rectangular.

18. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 1 or 2, characterized in that The ratio of the diameter of the circular fiber core to the diameter of the circular mold release cavity is 1:0.4-0.

7.

19. The single-mode ultra-low loss hollow-core antiresonant optical fiber according to claim 3, characterized in that The ratio of the diameter of the circular fiber core to the outer nested glass tube of the nested structural unit is 1:1.2-1.

5.

20. The single-mode ultra-low loss hollow-core anti-resonant optical fiber according to claim 3, characterized in that The ratio of the diameters of the outer nested glass tube and the first inner nested glass tube of the nested structural unit is 1:0.55-0.

75.

21. The single-mode ultra-low loss hollow-core anti-resonant optical fiber according to claim 3, characterized in that The ratio of the diameters of the first inner nested glass tube and the second inner nested glass tube of the nested structural unit is 1:0.4-0.

7.

22. The single-mode ultra-low loss hollow-core anti-resonant optical fiber according to claim 1 or 2, characterized in that The core region and other hollow regions in the outer cladding are filled with gas; the gas is argon, nitrogen, helium, air or a mixture of multiple gases.

23. The single-mode ultra-low loss hollow-core anti-resonant optical fiber according to claim 1 or 2, characterized in that The fundamental mode loss of the optical fiber is lower than 0.5 dB / km.

24. The single-mode ultra-low loss hollow-core anti-resonant optical fiber according to claim 18, characterized in that The optical fiber fundamental mode loss is lower than 0.1 dB / km.

25. The single-mode ultra-low loss hollow-core anti-resonant optical fiber according to claim 1 or 2, characterized in that The optical fiber high-order mode loss is higher than 6dB / m.

26. The single-mode ultra-low loss hollow-core anti-resonant optical fiber according to claim 18, characterized in that The optical fiber high-order mode attenuation is higher than 10dB / m.

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