Azimuth-angle-controllable anti-resonance hollow-core optical fiber and preparation method thereof

Abstract

The invention relates to an azimuth-angle-controllable anti-resonance hollow-core optical fiber and a preparation method thereof.The azimuth-angle-controllable anti-resonance hollow-core optical fiber comprises an outer cladding and an inner cladding, the inner cladding is composed of nested structure units, and the nested structure units are arranged in the circumferential direction of the inner wall of the outer cladding at intervals to form an air fiber core in the middle of an inner cavity; a filling layer is arranged between the inner wall of the outer wrapping layer and the nested structure units, the filling layer is formed by tightly arranging capillary tubes around the inner wall of the outer wrapping layer, and the nested structure units are located at the adjacent positions of the capillary tubes of the filling layer, or between the capillary tubes and the capillary rods, or between the capillary rods. In the optical fiber drawing process, the size of the capillary tube of the filling layer is adjusted in real time through pressure regulation, so that the azimuth angle of the nested structure unit is adjusted, the azimuth angle deviation of the nested structure unit is conveniently controlled on line, each nested structure unit is finally and accurately positioned in the inner cladding layer, and the transmission loss of the hollow-core optical fiber is reduced.

Description

Technical Field

[0001] The invention relates to an azimuthally controllable anti-resonance hollow-core optical fiber and a preparation method thereof, and belongs to the technical field of optical fiber communication transmission. Background Art

[0002] Hollow-core microstructured optical fiber has the characteristics of simple structure, hollow-core single-mode light guiding, and wide transmission spectrum. It has important applications in the fields of interaction between light and filling materials, nonlinear optics, gas detection, gas laser generation, optofluidic technology, etc.; large air hole core light guiding has ultra-low Rayleigh scattering, low nonlinear coefficient, and adjustable dispersion, which can provide a higher laser damage threshold, making it 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 propagation speed of the air core close to the speed of light can realize the development of hollow-core optical fiber communication transmission and communication devices, laying the foundation for the construction and development of the next generation of ultra-large capacity, low latency, and high-speed optical communication systems.

[0003] Even though hollow-core optical fibers have great advantages in design and application, their transmission loss has always been higher than that of traditional quartz optical fibers. In recent years, it has been found that hollow-core optical fibers based on the anti-resonance principle can effectively reduce transmission loss under reasonable structural design, and have the potential to be used as ultra-long-distance communication optical fibers. Further reducing attenuation is an important topic in the field of hollow-core microstructure optical fiber manufacturing.

[0004] Although known hollow core antiresonant fibers, especially those with nested structural elements, can significantly reduce the attenuation of optical fibers, typical structures such as Figure 1 As shown in the figure (theoretical design structure, the azimuth angles of the antiresonance units are uniformly distributed, that is, θ1-1 = θ1-2 = θ1-3 = θ1-4 = θ1-5). However, in the manufacturing process of hollow-core antiresonance optical fiber, due to the inhomogeneity of raw materials, deviations in the stacking process of nested structural elements, and uneven distribution of thermal fields during the drawing process, the antiresonance structural elements of the drawn hollow-core antiresonance optical fiber will have structural inhomogeneities, especially the azimuth angles between the nested units will deviate, such as Figure 2 As shown in (θ1-1≠θ1-2≠θ1-3≠θ1-4≠θ1-5)). This geometric inhomogeneity will greatly affect the transmission loss of the hollow-core antiresonant fiber, such as Fig. 9 As shown, as the azimuth angle shifts further, the limiting loss of the optical fiber will increase.

[0005] There is no relevant description of online adjustment of azimuth angle in current domestic and foreign patents. Similar patents, such as CN115629444A, arrange a layer of support elements on the inner surface of the outer cladding in a specific manner, and use it as a reference to place a nested tubular element in the concave area formed by the two spaced support elements. This structure can ensure the uniform distribution of the nested tubular elements. On the one hand, it does not mention the adjustment of azimuth angle deviation, and on the other hand, its support structure has gaps, which makes it difficult to achieve uniform arrangement. Summary of the invention

[0006] The problem to be solved by the present invention is to provide an azimuthally controllable anti-resonant hollow-core optical fiber and a preparation method thereof in view of the deficiencies in the prior art, which can reduce the azimuth deviation by real-time adjusting the azimuth of the nested structural units during the optical fiber drawing process, thereby reducing the transmission loss of the hollow-core optical fiber.

[0007] The hollow core optical fiber technical solution adopted by the present invention to solve the above-mentioned problems is:

[0008] The invention comprises an outer cladding and an inner cladding, wherein the inner cladding is composed of nested structural units, and the nested structural units are arranged at intervals along the circumference of the inner wall of the outer cladding to form an air core in the middle of the inner cavity. The invention is characterized in that a filling layer is arranged between the inner wall of the outer cladding and the nested structural units, and the filling layer is composed of capillaries arranged closely around the inner wall of the outer cladding, or of capillaries and capillary rods (solid rods) arranged closely around the inner wall of the outer cladding, and the nested structural units are located at the adjacent parts of the filling layer capillaries and capillaries, or between the capillary and the capillary rod, or between the capillary rods.

[0009] According to the above scheme, the nested structural unit includes 2 or more layers of nested glass tubes with different radii, including outer nested glass tubes and inner nested glass tubes.

[0010] According to the above scheme, the number of the nested structural units is 3 to 10.

[0011] According to the above scheme, the cross sections of the capillary tube, capillary rod and inner and outer nested glass tubes are all circular.

[0012] According to the above scheme, the outer nested glass tubes of the nested structural units located adjacent to the filling layers are tangent to the adjacent capillaries, or capillaries and capillary rods, or capillary rods and capillary rods.

[0013] According to the above solution, the number of capillary rods in the filling layer is twice or more than twice the number of anti-resonance units.

[0014] According to the above solution, the capillary rods in the filling layer are all tangent to the inner wall of the outer cladding layer, and the nested structural units are arranged at intervals along the circumferential direction of the inner surface of the filling layer.

[0015] According to the above solution, the diameter of the inner cladding is greater than or equal to 80 μm.

[0016] According to the above scheme, the azimuthal angle deviation of the nested structural units in the inner cladding is ≤10°, preferably ≤5°, and more preferably ≤2°.

[0017] According to the above solution, the transmission loss of the hollow core optical fiber is ≤0.5dB / km, and more preferably ≤0.2dB / km.

[0018] According to the above scheme, in the nested structural unit, at least one inner nested glass tube of at least one layer of inner nested glass tubes is deflected to one side relative to its adjacent outer nested glass tube, and the deflection angle is 5-55°.

[0019] According to the above scheme, the nested structural unit includes 3 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. The first inner nested glass tube is deflected to one side relative to the outer nested glass tube and / or the second inner nested glass tube is deflected to one side relative to the first inner nested glass tube.

[0020] According to the above scheme, the first inner nested glass tube is deflected to one side relative to the outer nested glass tube, that is, the line connecting the center of curvature (center of circle) of the first inner nested glass tube and the center of curvature (center of circle) of the outer nested glass tube forms a deflection angle with the extension line of the line connecting the center of curvature (center of circle) of the outer nested glass tube and the geometric center of the fiber core.

[0021] According to the above scheme, the second inner nested glass tube is deflected to one side relative to the first inner nested glass tube, that is, the line connecting the center of curvature (center of circle) of the second inner nested glass tube and the center of curvature (center of circle) of the first inner nested glass tube and the extended line connecting the center of curvature (center of circle) of the first inner nested glass tube and the center of curvature (center of circle) of the outer nested glass tube form a deflection angle.

[0022] According to the above scheme, all the inner nested glass tubes in one layer of the inner nested glass tubes are deflected to the same side relative to their adjacent outer nested glass tubes, and the deflection angles are the same or substantially the same.

[0023] According to the above scheme, the ratio of the outer diameter of the outer nested glass tube to the first inner nested glass tube is 1:0.5-0.65, and the ratio of the outer diameter of the first inner nested glass tube to the second inner nested glass tube is 1:0.3-0.5.

[0024] The technical solution of the hollow core optical fiber preparation method of the present invention is:

[0025] Preparation of nested structural unit prefabricated parts: using tubes, sheets, rods through cutting, grinding, welding to make nested structural unit prefabricated parts with 2 or more layers.

[0026] Preparation of filling layer preforms: Drawing a mother tube or mother rod into a capillary tube or capillary rod of the required diameter in a high-temperature wire drawing furnace. The capillary tube and capillary rod are cut, polished and welded to form a filling layer preform.

[0027] Preparation of optical fiber preform: stacking and assembling the obtained filling layer preform and the nested structural unit preform in a glass sleeve, wherein the filling layer is composed of capillary tubes arranged closely around the inner wall of the outer cladding, or is composed of capillary tubes and capillary rods arranged closely around the inner wall of the outer cladding, and the nested structural unit preform is located at the adjacent position between the filling layer capillary tube and the capillary tube, or the capillary tube and the capillary rod, or the capillary rod and the capillary rod, and the hollow core optical fiber preform with the filling layer is made by welding and bonding.

[0028] Drawing hollow-core optical fiber: Place the hollow-core optical fiber preform in an optical fiber drawing furnace and directly draw it into a hollow-core optical fiber, or first draw it into an intermediate preform, and then put it into a glass sleeve to draw it into a hollow-core optical fiber. During the drawing process, the size of the filling layer capillary is adjusted by adjusting the pressure of the filling layer capillary piece, thereby adjusting the azimuth angle of the nested structural unit.

[0029] According to the above scheme, the nested structural unit preforms, filling layer preforms, and glass sleeves are made of pure silica glass and / or doped quartz glass (doped with one or more elements such as germanium, fluorine, chlorine, boron, aluminum, etc.), or plastic materials, etc.

[0030] According to the above solution, the number of the nested structural unit prefabricated parts is 3 to 10.

[0031] According to the above scheme, the outer nested glass tubes of the nested structural unit preforms located adjacent to the filling layer are tangent to the adjacent capillary tube members and capillary tube members, or capillary tube members and capillary rod members, or capillary rod members and capillary rod members.

[0032] According to the above solution, the number of capillary rods in the filling layer is twice or more than twice the number of the nested structural unit preforms.

[0033] According to the above scheme, during the optical fiber drawing process, the filling layer will undergo deformation (adhesion, extrusion, collapse, melting, etc.).

[0034] The beneficial effects of the present invention are as follows: 1. By adding a filling area composed of a capillary and a capillary rod between the sleeve of the preform rod and the nested structure (anti-resonance) unit, the nested structure unit is located at the junction of the filling layer capillary and the rod. During the optical fiber drawing process, the size of the filling layer capillary can be adjusted in real time by adjusting the voltage to adjust the azimuth of the nested structure unit, which is convenient for online control of the azimuth deviation of the nested structure unit, so that each nested structure unit is finally accurately positioned in the inner cladding, thereby reducing the transmission loss of the hollow core optical fiber. 2. The present invention significantly improves the leakage loss of the LP11 mode through the change of the cladding structure, with a reasonable and manufacturable nested structure unit shape, an optimized nested size combination and a deflection of the inner nested glass tube, and has little effect on the fundamental mode performance. The fundamental mode loss of the optical fiber is 0.05-0.5dB / km. Further, the fundamental mode loss of the optical fiber is lower than 0.15dB / km, which effectively improves the single-mode performance of the optical fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the structure of a hollow-core optical fiber under ideal conditions.

[0036] Figure 2 It is a schematic diagram of the azimuth deviation of the hollow core optical fiber under actual conditions.

[0037] Figure 3 It is a schematic diagram of a radial cross-section of a hollow-core optical fiber according to Embodiment 1 of the present invention.

[0038] Figure 4 It is a schematic diagram of a radial cross-section of a hollow-core optical fiber according to Embodiment 2 of the present invention.

[0039] Figure 5 It is a schematic diagram of the radial cross-section of the hollow-core optical fiber in Example 3 of the present invention.

[0040] Figure 6 It is a schematic diagram of the radial cross-section of the hollow-core optical fiber according to embodiment 4 of the present invention.

[0041] Figure 7 It is a schematic diagram of the radial cross-section of the hollow-core optical fiber according to embodiment 5 of the present invention.

[0042] Figure 8 It is a schematic diagram of the radial cross-section of the hollow-core optical fiber according to Example 6 of the present invention.

[0043] Fig. 9 This is a simulation result diagram of the effect of the azimuth angle offset of the hollow-core fiber antiresonance unit on the limiting loss. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below with reference to the embodiments.

[0045] First, let's introduce the ideal hollow-core optical fiber structure. Figure 1As shown, it includes an outer cladding C1 and an inner cladding, and the inner cladding is composed of nested structural units E1. There may be 5 nested structural units, which are arranged at intervals along the circumference of the inner wall of the outer cladding to form an air core in the middle of the inner cavity. In an ideal state, the spacings g1-1, g1-2, g1-3, g1-4, and g1-5 of each nested structural unit are equal, and the azimuth angles θ1-1, θ1-2, θ1-3, θ1-4, and θ1-5 of each nested structural unit are also equal, that is, each nested structural unit is evenly distributed along the circumference. However, in the actual manufacturing process, the spacings and azimuth angles of each nested structural unit will be offset and changed, so that the spacings g2-1, g2-2, g2-3, g2-4, and g2-5 of each nested structural unit are not equal, and the azimuth angles θ1-1, θ1-2, θ1-3, θ1-4, and θ1-5 of each nested structural unit are also not equal. Figure 2 As shown in Figure 2, this geometric inhomogeneity will greatly affect the transmission loss of hollow-core antiresonant fibers. Fig. 9 As shown, as the azimuth angle shifts further, the limiting loss of the optical fiber will increase.

[0046] The present invention is further described in detail below with reference to the embodiments.

[0047] Example 1: Figure 3 As shown, the outer cladding C3 of the hollow-core optical fiber is made of quartz, and its outer diameter after drawing is 246μm and the inner diameter is 140μm. The filling layer is composed of 15 capillaries T3 arranged closely around the inner wall of the outer cladding and tangent to the inner wall of the outer cladding. The initial outer diameters of the 15 capillaries are consistent, and the ratio of the outer diameter of T3 to the inner diameter of C3 is 0.172, thereby ensuring that the 15 filling capillaries in the preform rod are tightly and evenly connected to the sleeve. The inner cladding is composed of nested structural units, and the nested structural unit E3 is a 3-layer nested structure, with a total of 5 nested structural (anti-resonance) units. The wall thickness of the nested structural unit is 1.2±0.1μm. The nested structural unit is located at the concave adjacent to the capillary of the filling layer capillary and tangent to the adjacent capillary. The five nested structural units are evenly spaced along the circumference of the inner wall of the filling layer to form an air core in the middle of the inner cavity. The outer cladding, the nested structural unit and the filling layer are pure silica glass and / or doped quartz glass (doped with one or more elements such as germanium, fluorine, chlorine, boron, aluminum, etc.). During the drawing process, the spacing of the nested structural units is measured in real time. The spacing of the nested structural units is adjusted by filling the filling capillary T3 with gases of different air pressures so that the maximum difference between the spacings g3-1, g3-2, g3-3, g3-4, and g3-5 is controlled within ±0.9μm. Thus, the deviations of the azimuth angles θ3-1, θ3-2, θ3-3, θ3-4, and θ3-5 of the final optical fiber are within 2°. The attenuation performance of the optical fiber is tested, and the loss at 1550nm is 0.14dB / km.

[0048] Example 2: Figure 4 As shown, the outer cladding C4 of the hollow-core optical fiber is made of quartz material, and its outer diameter after drawing is 325μm and its inner diameter is 160μm. The filling layer is composed of 5 capillaries T4 and 10 capillary (solid core) rods R4 arranged closely around the inner wall of the outer cladding. One capillary and two capillary rods are staggered along the circumference. The initial outer diameters of the 5 capillaries T4 and 10 solid core rods R4 are consistent, and the ratio of their outer diameter to the inner diameter of C4 is 0.172, thereby ensuring that the 15 filling units in the preform are tightly and evenly connected to the sleeve. The anti-resonance unit E4 is a 3-layer tube structure with a total of 5 nested structural units, and the wall thickness of the nested structural unit is 1.15±0.15μm. The nested structural unit is located at the concave junction of the capillary rods and the capillary rods in the filling layer, and is tangent to the adjacent capillary rods. During the drawing process, the spacing of the nested structural units is measured in real time. By filling the filling capillary T4 with different air pressures, the spacing of the nested structural units is adjusted so that the maximum difference between the spacings g4-1, g4-2, g4-3, g4-4, and g4-5 is controlled within ±1.0μm. As a result, the deviations of the azimuth angles θ4-1, θ4-2, θ4-3, θ4-4, and θ4-5 of the final optical fiber are within 1.7°. The attenuation performance of the optical fiber is tested, and the loss at 1550nm is 0.12dB / km.

[0049] Example 3: Figure 5 As shown, the hollow-core optical fiber cladding C5 is made of quartz, and its outer diameter after drawing is 220μm and its inner diameter is 114μm. The filling layer is composed of 10 capillaries T5 and 5 capillary rods R5. Two capillaries and one capillary rod are staggered along the circumference. The initial outer diameters of the 10 capillaries T5 and the 5 capillary rods R5 are consistent, and the ratio of their outer diameter to the inner diameter of C5 is 0.344, thereby ensuring that the 15 filling units in the preform are tightly and evenly connected to the sleeve. The nested structural unit E5 is a 3-layer tube structure with a total of 5 nested structural units, and the wall thickness of the nested structural unit is 0.4±0.11μm. The nested structural unit is located at the concave adjacent to the capillary of the filling layer, and is tangent to the adjacent capillaries. During the drawing process, the spacing of the nested structural units is measured in real time. By filling the filling capillary T5 with gas of different pressures, the spacing of the nested structural units is adjusted so that the maximum difference between the spacings g5-1, g5-2, g5-3, g5-4, and g5-5 is controlled within ±0.7μm. As a result, the deviation of the azimuth angles θ5-1, θ5-2, θ5-3, θ5-4, and θ5-5 of the final optical fiber is within 1.3°. The attenuation performance of the optical fiber is tested, and the loss at 1550nm is 0.08dB / km.

[0050] Example 4: Figure 6 As shown, the hollow-core optical fiber cladding C6 is made of quartz material, and its outer diameter after drawing is 280μm and the inner diameter is 148μm. The filling layer is composed of 20 capillaries T6, and the initial outer diameters of the 20 capillaries T6 are consistent. The ratio of their outer diameter to the inner diameter of C6 is 0.135, thereby ensuring that the 20 filling units in the preform rod are tightly and evenly connected to the sleeve. The nested structural unit E6 is a 3-layer tube structure with a total of 5 nested structural units, and the wall thickness of the nested structural unit is 0.44±0.08μm. The nested structural unit is located at the concave junction between the filling layer capillaries and the capillaries, and is tangent to the adjacent capillaries. During the drawing process, the spacing of the nested structural units is measured in real time. By filling the filling capillary T6 with gas of different pressures, the spacing of the nested structural units is adjusted so that the maximum difference between the spacings g6-1, g6-2, g6-3, g6-4, and g6-5 is controlled within ±0.9μm. As a result, the deviation of the azimuth angles θ6-1, θ6-2, θ6-3, θ6-4, and θ6-5 of the final optical fiber is within 0.9°. The attenuation performance of the optical fiber is tested, and the loss at 1550nm is 0.07dB / km.

[0051] Example 5: Figure 7 As shown, the hollow-core optical fiber cladding C7 is made of quartz material, and its outer diameter after drawing is 266μm and the inner diameter is 135μm. The filling layer is composed of 8 smaller outer diameter capillaries T7-1 and 4 larger outer diameter capillaries T7-2. The 8 smaller outer diameter capillaries T7-1 are closely connected to the 4 larger outer diameter capillaries T7-2, and are all tangent to the inner wall of the outer cladding C7. The nested structural unit E7 is a 3-layer tube structure with a total of 4 nested structural units, and the wall thickness of the nested structural unit is 1.17±0.09μm. The nested structural unit is located at the concave junction of the smaller outer diameter capillary and the capillary in the filling layer, and is tangent to the adjacent smaller outer diameter capillary and capillary. During the drawing process, the spacing of the nested structural units is measured in real time. By filling the capillaries T7-1 and T7-2 with gases of different pressures, the spacing of the nested structural units is adjusted so that the maximum difference between the spacings g7-1, g7-2, g7-3, and g7-4 is controlled within ±0.6μm. As a result, the deviation of the azimuth angles θ7-1, θ7-2, θ7-3, and θ7-4 of the final optical fiber is within 1.0°. The attenuation performance of the optical fiber is tested, and the loss at 1550nm is 0.11dB / km.

[0052] Example 6: Figure 8As shown, the hollow-core optical fiber cladding C8 is made of quartz, with an outer diameter of 245 μm and an inner diameter of 136 μm after drawing. The filling layer is composed of 8 capillaries T8-1 with smaller outer diameters and 4 capillaries T8-2 with larger outer diameters. The 8 capillaries T8-1 with smaller outer diameters are closely connected to the 4 capillaries T8-2 with larger outer diameters, and are all tangent to the inner wall of the outer cladding C8. The nested structural unit E8 is a 3-layer tube structure with a total of 4 nested structural units, and the wall thickness of the nested structural unit is 1.17±0.09 μm. The nested structural unit is located at the concave adjoining place between the capillary with smaller outer diameter in the filling layer and the capillary, and the nested structural unit includes 3 layers of nested glass tubes with different radii, including outer nested glass tubes, first inner nested glass tubes and second inner nested glass tubes from outside to inside, and the first inner nested glass tube is deflected to one side relative to the outer nested glass tube, that is, the line connecting the center of the circle of the first inner nested glass tube and the center of the circle of the outer nested glass tube forms a deflection angle with the extension line of the line connecting the center of the circle of the outer nested glass tube and the geometric center of the fiber core, and the deflection angle β is 33°, and the second inner nested glass tube deflects with the first inner nested glass tube, and this deflection angle can further optimize the single-mode characteristics of the hollow-core optical fiber. During the drawing process, the spacing of the nested structural unit is measured in real time. The spacing of the nested structural unit is adjusted by filling the filling capillaries T8-1 and T8-2 with gases of different air pressures, so that the maximum difference between the spacings g8-1, g8-2, g8-3, and g8-4 is controlled within ±0.4μm. Thus, the deviation of the azimuth angles θ8-1, θ8-2, θ8-3, and θ8-4 of the final nested structure unit of the optical fiber is within 0.9°. The attenuation performance of the optical fiber is tested, and the loss at 1550nm is 0.06dB / km.

Claims

1. An azimuthally controllable antiresonant hollow-core optical fiber, comprising an outer cladding and an inner cladding, wherein the inner cladding is composed of nested structural units, and the nested structural units are arranged at intervals along the circumference of the inner wall of the outer cladding to form an air core in the middle of the inner cavity, characterized in that A filling layer is arranged between the inner wall of the outer cladding and the nested structural units. The filling layer is composed of capillaries arranged closely around the inner wall of the outer cladding, or of capillaries and capillary rods arranged closely around the inner wall of the outer cladding. The nested structural units are located at the adjacent parts of the capillaries in the filling layer, or between the capillaries and the capillary rods, or between the capillary rods.

2. The azimuthally controllable antiresonant hollow-core optical fiber according to claim 1, characterized in that The nested structural unit comprises two or more layers of nested glass tubes with different radii, including outer nested glass tubes and inner nested glass tubes.

3. The azimuthally controllable antiresonant hollow-core optical fiber according to claim 1 or 2, characterized in that The number of the nested structural units is 3 to 10.

4. The azimuthally controllable antiresonant hollow-core optical fiber according to claim 2, characterized in that The cross sections of the capillary tube, the capillary rod and the inner and outer nested glass tubes are all circular.

5. The azimuthally controllable antiresonant hollow-core optical fiber according to claim 2, characterized in that The outer nested glass tubes of the nested structural units located adjacent to the filling layers are tangent to the adjacent capillaries, or capillaries and capillary rods, or capillary rods and capillary rods.

6. The azimuthally controllable antiresonant hollow core optical fiber according to claim 3, characterized in that The number of the capillary rods in the filling layer is twice or more than twice the number of the anti-resonance units.

7. The azimuthally controllable antiresonant hollow-core optical fiber according to claim 1 or 2, characterized in that The capillary rods in the filling layer are all tangent to the inner wall of the outer cladding layer, and the nested structural units are arranged at intervals along the circumferential direction of the inner surface of the filling layer.

8. The azimuthally controllable antiresonant hollow-core optical fiber according to claim 1 or 2, characterized in that The inner cladding has a diameter greater than or equal to 80 μm.

9. The azimuthally controllable antiresonant hollow-core optical fiber according to claim 1 or 2, characterized in that The azimuth angle deviation of the nested structural unit in the inner cladding is ≤10°.

10. The azimuthally controllable antiresonant hollow-core optical fiber according to claim 1 or 2, characterized in that The transmission loss of the hollow core optical fiber is ≤0.5dB / km.

11. The azimuthally controllable antiresonant hollow-core optical fiber according to claim 1 or 2, characterized in that In the nested structural unit, at least one inner nested glass tube of at least one layer of inner nested glass tubes is deflected to one side relative to its adjacent outer nested glass tube, and the deflection angle is 5-55 degrees.

12. The azimuthally controllable antiresonant hollow core optical fiber according to claim 11, characterized in that The nested structural unit includes 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. The first inner nested glass tube is deflected to one side relative to the outer nested glass tube and / or the second inner nested glass tube is deflected to one side relative to the first inner nested glass tube.

13. The azimuthally controllable antiresonant hollow core optical fiber according to claim 12, characterized in that The first inner nested glass tube is deflected to one side relative to the outer nested glass tube, that is, a line L2 connecting the curvature center O1 of the first inner nested glass tube and the curvature center O2 of the outer nested glass tube forms a deflection angle with an extended line L1 connecting the curvature center O1 of the outer nested glass tube and the core geometric center O.

14. The azimuthally controllable antiresonant hollow core optical fiber according to claim 12, characterized in that The second inner nested glass tube is deflected to one side relative to the first inner nested glass tube, that is, a line L3 connecting the curvature center O3 of the second inner nested glass tube and the curvature center O2 of the first inner nested glass tube forms a deflection angle with an extension line L2 connecting the curvature center O2 of the first inner nested glass tube and the curvature center O1 of the outer nested glass tube.

15. The azimuthally controllable antiresonant hollow core optical fiber according to claim 11, characterized in that All the inner nested glass tubes of one layer in the inner nested glass tubes are deflected to the same side relative to their adjacent outer nested glass tubes, and the deflection angles are the same or substantially the same.

16. The azimuthally controllable antiresonant hollow core optical fiber according to claim 11, characterized in that The ratio of the outer diameters of the outer nested glass tube to the first inner nested glass tube is 1:0.5-0.65, and the ratio of the outer diameters of the first inner nested glass tube to the second inner nested glass tube is 1:0.3-0.

5.

17. A method for preparing an antiresonant hollow core optical fiber with controllable azimuth angle according to any one of claims 1 to 16, characterized in that Preparation of nested structural unit prefabricated parts: using tubes, sheets, rods through cutting, grinding, welding to make nested structural unit prefabricated parts with 2 or more layers. Preparation of filling layer preforms: Drawing a mother tube or mother rod into a capillary tube or capillary rod of the required diameter in a high-temperature wire drawing furnace. The capillary tube and capillary rod are cut, polished and welded to form a filling layer preform. Preparation of optical fiber preform: stacking and assembling the obtained filling layer preform and the nested structural unit preform in a glass sleeve, wherein the filling layer is composed of capillary tubes arranged closely around the inner wall of the outer cladding, or is composed of capillary tubes and capillary rods arranged closely around the inner wall of the outer cladding, and the nested structural unit preform is located at the adjacent position between the filling layer capillary tube and the capillary tube, or the capillary tube and the capillary rod, or the capillary rod and the capillary rod, and the hollow core optical fiber preform with the filling layer is made by welding and bonding. Drawing hollow-core optical fiber: Place the hollow-core optical fiber preform in an optical fiber drawing furnace and directly draw it into a hollow-core optical fiber, or first draw it into an intermediate preform, and then put it into a glass sleeve to draw it into a hollow-core optical fiber. During the drawing process, the size of the filling layer capillary is adjusted by adjusting the pressure of the filling layer capillary piece, thereby adjusting the azimuth angle of the nested structural unit.

18. The method for preparing an azimuthally controllable antiresonant hollow-core optical fiber according to claim 17, characterized in that The nested structural unit preforms, filling layer preforms and glass sleeves are made of pure silica glass and / or doped quartz glass, or plastic.

19. The method for preparing an azimuthally controllable antiresonant hollow-core optical fiber according to claim 17, characterized in that The number of the nested structural unit prefabricated parts is 3 to 10.

20. The method for preparing an azimuthally controllable antiresonant hollow-core optical fiber according to claim 17, characterized in that The outer nested glass tubes of the nested structural unit preforms located adjacent to the filling layers are tangent to adjacent capillary tube members and capillary tube members, or capillary tube members and capillary rod members, or capillary rod members and capillary rod members.

21. The method for preparing an azimuthally controllable antiresonant hollow-core optical fiber according to claim 17, characterized in that The number of capillary rods in the filling layer is twice or more than twice the number of the nested structural unit preforms.

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