Hollow-core antiresonant single-mode fiber

Abstract

The present invention provides a hollow-core antiresonant single-mode optical fiber. The hollow-core antiresonant single-mode optical fiber comprises: a cladding region and a core region; the cladding region comprises an outer cladding and an inner cladding region arranged sequentially from the outside to the inside; the inner cladding region comprises a cladding capillary and a teardrop-shaped inner tube disposed within the cladding capillary; the cladding capillary is tangent to the inner surface of the outer cladding and is uniformly distributed circumferentially at a first distance along the circumferential direction of the inner surface of the outer cladding, surrounding the core region; the teardrop-shaped inner tube comprises a teardrop tube structure composed of a semi-ellipse and a semi-circle, one end of the semi-ellipse is tangent to the inner surface of the cladding capillary; the cladding capillary forms a first internal tangent point with the outer cladding, and one end of the semi-ellipse forms a second internal tangent point with the cladding capillary, which coincides with the first internal tangent point. The method provided by the present invention suppresses light leakage through a nested structure, thereby enabling the optical fiber to have lower confinement loss and bending loss over a longer wavelength range while maintaining a larger gap between adjacent tubes.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber communications, and in particular to a hollow-core anti-resonant single-mode optical fiber. Background Art

[0002] In recent years, with the explosive growth of data capacity in the information age, the inherent defects of quartz as an optical fiber material (nonlinear effects, dispersion, photodamage, and high loss in the ultraviolet and mid-infrared bands, which makes light transmission difficult) have become increasingly constraining the development of optical communications. To overcome this development bottleneck, hollow-core optical fibers, which use air as a light-guiding medium, have attracted widespread attention and become a current research focus. Hollow-core optical fibers offer advantages such as low latency, low dispersion, low nonlinearity, and a high power damage threshold. They are potentially an ideal transmission fiber that can replace traditional solid-core optical fibers and break through the nonlinear capacity limits of optical fibers.

[0003] Based on the light-guiding principle, hollow-core fibers are primarily divided into hollow-core photonic bandgap fibers (PBGs) based on the photonic bandgap effect and hollow-core antiresonant single-mode fibers (HC-ARFs) based on a combination of antiresonant reflection and mode coupling suppression. Unlike PBGs, which have complex cladding structures, HC-ARFs have simple cladding structures and lower transmission losses. Furthermore, due to limitations in the fiber structure, PBG fiber losses are difficult to reduce below 1 dB / km. However, due to its antiresonant properties, HC-ARFs offer lower surface scattering losses and wider transmission bandwidths. Consequently, they have become a hot research topic in the hollow-core fiber field in recent years. With the in-depth study of hollow-core antiresonant single-mode fibers, fibers with simpler structures and better performance have become a key focus of current research. Therefore, it is of great significance to further reduce the confinement and bending losses of hollow-core fibers over longer wavelengths and obtain hollow-core antiresonant single-mode fibers with excellent single-mode characteristics. Summary of the Invention

[0004] The present invention provides a hollow-core anti-resonant single-mode optical fiber, which is used to solve the defects in the prior art that the confinement loss and bending loss of the hollow-core optical fiber in a longer wavelength range are still relatively high.

[0005] The present invention provides a hollow-core antiresonant single-mode optical fiber, comprising: a cladding region and a core region; the cladding region comprises an outer cladding and an inner cladding region arranged in sequence from the outside to the inside; the inner cladding region comprises a cladding capillary and a teardrop-shaped inner tube arranged inside the cladding capillary; the cladding capillary is tangent to the inner surface of the outer cladding, and is circumferentially distributed at a first distance uniformly spaced along the circumferential direction of the inner surface of the outer cladding, and surrounds the core region; the teardrop-shaped inner tube is an internally connected teardrop tube structure formed by combining a semi-ellipse and a semi-circle, one end of the semi-ellipse is tangent to the inner surface of the cladding capillary; wherein the cladding capillary is tangent to the inner surface of the outer cladding to form a first intangent point, and one end of the semi-ellipse is tangent to the inner surface of the cladding capillary to form a second intangent point, and the first intangent point and the second intangent point are coincident points.

[0006] According to a hollow-core antiresonant single-mode optical fiber provided by the present invention, the teardrop-shaped inner tube and the cladding capillary are radially separated, and the radial separation distance z between the semicircle of the teardrop-shaped inner tube and the cladding capillary ranges from 0.35*R to 0.5*R. The radius r of the semicircle of the teardrop-shaped inner tube is equal to the length of the inner semi-minor axis of the semi-ellipse of the teardrop-shaped inner tube, and the radius r of the semicircle of the teardrop-shaped inner tube ranges from 0.2*R to 0.5*R. The length of the inner semi-major axis of the semi-ellipse of the teardrop-shaped inner tube is determined to be (R+t)*2-z-(r+t)-t / 2; wherein R is the radius of the cladding capillary, and t is the thickness of the cladding capillary and the teardrop-shaped inner tube wall.

[0007] According to a hollow-core antiresonant single-mode optical fiber provided by the present invention, the thickness t of the cladding capillary and the teardrop-shaped inner tube wall is the same, and the thickness t satisfies the antiresonance condition and can achieve coherent cancellation of light waves, thereby suppressing light leakage and reducing optical fiber loss; the expression corresponding to the thickness t satisfying the antiresonance condition is specifically:

[0008]

[0009] Wherein, λ is the antiresonance center wavelength, m is the antiresonance order, m is a positive integer greater than or equal to 1, n1 is the refractive index of the refractive index material, and n0 is the refractive index of the low refractive index material.

[0010] According to a hollow-core antiresonant single-mode optical fiber provided by the present invention, the radius R of the cladding capillary is determined by the following formula:

[0011]

[0012] Wherein, N is the number of the cladding capillaries, g is the first distance between adjacent cladding capillaries, D is the core diameter of the core region, and t is the thickness of the cladding capillaries and the teardrop-shaped inner tube wall.

[0013] According to the hollow-core antiresonant single-mode optical fiber provided by the present invention, the first distance between adjacent cladding capillaries is 1 μm-5 μm.

[0014] According to a hollow-core antiresonant single-mode optical fiber provided by the present invention, the outer cladding, the cladding capillary and the teardrop-shaped inner tube are all refractive index materials made of high refractive index materials; the interior of the outer cladding, the interior of the cladding capillary and the interior of the teardrop-shaped inner tube are all filled with low refractive index materials.

[0015] According to the hollow-core antiresonant single-mode optical fiber provided by the present invention, the high-refractive index material is silica, PVC soft crystal plate or plastic; and the low-refractive index material is air.

[0016] According to the hollow-core antiresonant single-mode optical fiber provided by the present invention, the core diameter D of the core region is 20 μm-40 μm.

[0017] According to the hollow-core antiresonant single-mode optical fiber provided by the present invention, the number of the cladding capillaries is equal to the number of the teardrop-shaped inner tubes.

[0018] According to the hollow-core antiresonant single-mode optical fiber provided by the present invention, the thickness t of the cladding capillary and the teardrop-shaped inner tube are both 0.35 μm-0.70 μm.

[0019] The present invention provides a hollow-core anti-resonant single-mode optical fiber, which comprises: a cladding region and a core region; the cladding region comprises an outer cladding and an inner cladding region arranged sequentially from the outside to the inside; the inner cladding region comprises a cladding capillary and a teardrop-shaped inner tube arranged inside the cladding capillary; the cladding capillary is tangent to the inner surface of the outer cladding and is circumferentially distributed at a first distance along the circumferential direction of the inner surface of the outer cladding, surrounding the core region; the teardrop-shaped inner tube is an internally connected teardrop tube structure composed of a semi-ellipse and a semi-circle, one end of the semi-ellipse is tangent to the inner surface of the cladding capillary; a first intangent point formed by the cladding capillary and the outer cladding coincides with a second intangent point formed by one end of the semi-ellipse and the cladding capillary, thereby suppressing light leakage through a nested structure and enabling the optical fiber to have ultra-low confinement loss and bending loss within a longer wavelength range while maintaining a large gap between adjacent tubes. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0021] Figure 1 It is a schematic structural diagram of the hollow-core antiresonant single-mode optical fiber provided by the present invention.

[0022] Figure 2 This is a simulation diagram of the mode field distribution of the hollow-core antiresonant single-mode optical fiber provided by the present invention.

[0023] Figure 3 This is a curve showing how the effective refractive index of the fundamental mode of the hollow-core anti-resonant single-mode optical fiber provided by the present invention changes with wavelength.

[0024] Figure 4 This is a curve showing how the fundamental mode limitation loss of the hollow-core antiresonant single-mode optical fiber provided by the present invention varies with wavelength.

[0025] Figure 5 This is a simulation diagram of the fundamental mode field distribution of the hollow-core antiresonant single-mode optical fiber provided by the present invention when the bending radius is 3 cm.

[0026] Figure 6 This is a curve showing how the bending loss of the hollow-core anti-resonant single-mode optical fiber provided by the present invention changes with the bending radius.

[0027] Figure 7 This is a curve showing how the high-order mode extinction ratio of the hollow-core antiresonant single-mode optical fiber provided by the present invention varies with wavelength.

[0028] Reference numerals: 1: core region; 2: cladding capillary; 3: teardrop-shaped inner tube; 4: outer cladding. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0030] The following combination Figure 1-Figure 7 The hollow-core anti-resonant single-mode optical fiber of the present invention is described, and embodiments thereof are described in detail.

[0031] Figure 1 Schematic diagram of the structure of the hollow core anti-resonant single-mode optical fiber provided by the present invention. Figure 1As shown, the hollow-core antiresonant single-mode optical fiber includes: a cladding region and a core region 1; the cladding region includes an outer cladding 4 and an inner cladding region arranged in sequence from the outside to the inside; the inner cladding region includes a cladding capillary 2 and a teardrop-shaped inner tube 3 arranged inside the cladding capillary 2; the cladding capillary 2 is tangent to the inner surface of the outer cladding 4, and is uniformly distributed circumferentially at a first distance along the circumferential direction of the inner surface of the outer cladding 4, and surrounds the core region 1; the teardrop-shaped inner tube 3 is an internally connected teardrop tube structure composed of a semi-ellipse and a semi-circle, one end of the semi-ellipse is tangent to the inner surface of the cladding capillary 2; wherein the cladding capillary 2 is tangent to the inner surface of the outer cladding 4 to form a first intangent point, and one end of the semi-ellipse is tangent to the inner surface of the cladding capillary 2 to form a second intangent point, and the first intangent point and the second intangent point are coincident points. Specifically, the first distance between adjacent cladding capillaries 2 is 1 μm-5 μm. The core diameter D of the core region 1 is 20 μm-40 μm. The outer cladding 4 is a circular outer cladding 4. The number of cladding capillaries 2 is 4-8. The multiple cladding capillaries 2 can be spaced from each other along the circumferential direction of the inner surface of the outer cladding 4 ring (inscribed in the circular outer cladding 4), uniformly distributed circumferentially, and surround the core region 1. The teardrop-shaped inner tube 3 is a teardrop tube structure, which is composed of a semi-ellipse and a semi-circle. The teardrop tube structure is inscribed in the cladding capillary 2; the inscription point between the cladding capillary 2 and the circular outer cladding 4 coincides with the inscription point between the teardrop tube structure and the cladding capillary 2.

[0032] The present invention arranges a cladding capillary in a circular outer cladding and nests a teardrop-shaped inner tube in the cladding capillary. In principle, an additional anti-resonance layer is provided. The nested structure can effectively suppress light leakage, thereby better confining light for transmission in the fiber core area. This allows the optical fiber to have lower confinement loss and bending loss in a longer wavelength range while maintaining a larger gap between adjacent tubes.

[0033] The number of the cladding capillaries 2 is equal to the number of the teardrop-shaped inner tubes 3. The teardrop-shaped inner tubes 3 are radially separated from the cladding capillaries 2. The radial separation distance z between the semicircle of the teardrop-shaped inner tube 3 and the cladding capillary 2 is in the range of 0.35*R-0.5*R. The radius r of the semicircle of the teardrop-shaped inner tube 3 is equal to the length of the inner semi-minor axis of the semi-ellipse of the teardrop-shaped inner tube 3, and is in the range of 0.2*R-0.5*R. The length of the inner semi-major axis of the semi-ellipse of the teardrop-shaped inner tube 3 is determined to be (R+t)*2-z-(r+t)-t / 2. In determining the length of the inner semi-major axis of the semi-ellipse of the teardrop-shaped inner tube 3 as (R+t)*2-z-(r+t)-t / 2, the inner radius of the cladding capillary can be determined from the geometric structure as R. The outer radius of the cladding capillary is then (R+t), and the outer diameter is (R+t)*2. Subtracting z and (r+t) yields the length of the semi-major axis of the ellipse. However, it should be noted that a small gap of 0.5t is typically used during simulation to embed the outer tube and nested tube within the outer tube, in order to approximate realistic simulation results. Therefore, the small gap (0.5t) needs to be subtracted, resulting in (R+t)*2-z-(r+t)-t / 2).

[0034] Where R is the inner radius of the cladding capillary 2, and t is the wall thickness of the cladding capillary 2 and the teardrop-shaped inner tube 3. The thickness t of the cladding capillary 2 and the teardrop-shaped inner tube 3 is 0.35 μm to 0.7 μm. It should be noted that the range of the distance z is a low-loss scanning range determined by verification and comparative analysis after selecting a large-scale scan. The radius r of the semicircle is also a low-loss scanning range determined by verification and comparative analysis after selecting a large-scale scan.

[0035] In addition, the wall thickness t of the cladding capillary 2 and the teardrop-shaped inner tube 3 is the same, and the thickness t satisfies the antiresonance condition and can achieve coherent cancellation of light waves, thereby suppressing light leakage and reducing optical fiber loss. The expression corresponding to the thickness t satisfying the antiresonance condition is specifically:

[0036]

[0037] Wherein, λ is the antiresonance center wavelength, m is the antiresonance order, m is a positive integer greater than or equal to 1, n1 is the refractive index of the refractive index material, and n0 is the refractive index of the low refractive index material.

[0038] Specifically, the radius R of the cladding capillary 2 is determined by the following formula:

[0039]

[0040] Wherein, N is the number of the cladding capillaries 2, g is the first distance between adjacent cladding capillaries 2, D is the core diameter of the core region 1, and t is the thickness of the walls of the cladding capillaries 2 and the teardrop-shaped inner tube 3.

[0041] In addition, it should be noted that the outer cladding 4, the capillary cladding tube 2, and the teardrop-shaped inner tube 3 are all made of a high-refractive-index material; the interior of the outer cladding 4, the capillary cladding tube 2, and the teardrop-shaped inner tube 3 are all filled with a low-refractive-index material. For example, the high-refractive-index material can be silicon dioxide, PVC soft crystal plate, or plastic; the low-refractive-index material can be air, for example.

[0042] like Figure 1 As shown, D is the diameter of the core region 1, R is the radius of the cladding capillary 2, g is the gap between any two adjacent cladding capillaries 2 (i.e., the first distance between them), t is the wall thickness of the cladding capillary 2, r is the radius of the arc-shaped end of the teardrop-shaped inner tube 3 (i.e., the semicircular radius), and z is the radial separation distance between the arc-shaped end of the teardrop-shaped inner tube 3 and the cladding capillary 2.

[0043] The core diameter D is selected based on actual conditions. Generally, a larger core diameter D results in lower confinement loss. However, an excessively large core diameter D can affect the bending performance of the optical fiber and even cause breakage during use. Therefore, the core diameter D of the present invention is in the range of 20-40 μm. The wall thicknesses t of the cladding capillary 2 and the teardrop-shaped inner tube 3 are equal, both satisfying the antiresonance condition and achieving coherent cancellation of light waves. When m = 1, the energy is maximized, which also has the greatest impact on optical fiber performance parameters. The wall thickness t of the present invention is in the range of 0.35-0.7 μm. The wall thickness of the outer cladding 4 is 5-10 μm. The gap between any two adjacent cladding capillaries 2 cannot be too large to prevent light leakage through the gap. The upper limit of the gap is 10 μm and cannot be 0 (because it must meet the no-node condition). Furthermore, a smaller gap not only complicates optical fiber preparation but also increases the likelihood of coupling between the core mode and the cladding mode when bent, thereby increasing loss. Therefore, a larger gap should be maintained to achieve lower confinement loss and bending loss.

[0044] After D, g, and t are determined, the radius of the cladding capillary 2 is determined by the following geometric relationship:

[0045]

[0046] Wherein, N is the number of cladding capillaries 2, which is generally 4 to 8; g is the gap between any two adjacent cladding capillaries 2, g>0; and D is the diameter of the core region 1.

[0047] The radial separation distance z between the teardrop-shaped inner tube 3 and the cladding capillary 2, as well as the radius r of the curved end of the teardrop-shaped inner tube 3, significantly influence the optical fiber's loss and single-mode characteristics. To ensure single-mode transmission while further reducing limiting loss, the radial separation distance z between the curved end of the teardrop-shaped inner tube 3 and the cladding capillary 2 is set to range from 0.35*R to 0.5*R, and the radius r of the curved end of the teardrop-shaped structure, or the semicircle, is set to range from 0.2*R to 0.5*R, where R is the radius of the cladding capillary 2.

[0048] The present invention further adjusts the structural parameters of the teardrop-shaped inner tube 3 so that the high-order mode in the fiber core is coupled with the cladding tube mode, thereby improving the high-order mode loss in the fiber core and increasing the high-order mode extinction ratio, thereby obtaining good single-mode characteristics.

[0049] Using 1550nm as the operating wavelength, finite element simulation is performed as follows Figure 1 The relevant parameters of the hollow-core antiresonant single-mode optical fiber with the structure shown are as follows: the diameter of the core region 1 D = 40 μm, the number of cladding capillaries 2 N = 5, and the gap g between any two adjacent capillaries = 3.3 μm.

[0050] The wall thickness t of the cladding capillary 2 and the teardrop-shaped inner tube 3 is 0.5 μm. The radius R of the cladding capillary 2 can be calculated by formula (1) as 24 μm. Then, the distance z between the arc-shaped end of the teardrop-shaped inner tube 3 and the radial separation of the capillary can be 8 μm, the radius r of the arc-shaped end of the teardrop-shaped inner tube 3 can be 10.32 μm, and the wall thickness of the outer cladding 4 can be 30 μm, which is not specifically limited here.

[0051] The effective refractive index of the fundamental mode of the hollow-core antiresonant single-mode optical fiber provided by the present invention is close to 1, indicating that the energy is mainly concentrated in the core region 1 and the light is well confined in the core region 1. For specific data, see Figure 3 In addition, if Figure 2 As shown, the different color distributions in the core region 1 represent the field intensity distribution diagram, which is Gaussian. The closer to the center of the core, the greater the field intensity, and gradually decreases towards the cladding side. That is, the darker the color, the greater the light intensity, and the lighter the color, the smaller the light intensity. For example, as the color changes from light to dark, the corresponding light intensity gradually increases from 0 to 1.

[0052] like Figure 4 As shown, the fiber fundamental mode (LP 01 The loss spectrum of the optical fiber mode shows that the loss is less than 0.002dB / km in the wavelength range of 1400~1900nm, especially at the wavelength of 1550nm, the loss of the optical fiber is as low as 0.00065dB / km; Figure 5 and Figure 6 They are the mode field distribution and loss of the optical fiber structure in the bending state when the wavelength is 1.55μm. Figure 5 and Figure 6 It can be seen from the figure that when the optical fiber is bent toward the positive y-axis, the mode field will shift upward as the optical fiber bends, and when the bending radius is greater than 20 cm, the bending loss is less than 0.0018 dB / km.

[0053] In addition, its single-mode characteristics are as follows Figure 7 As shown in the figure, within the wavelength range of 1200 to 2000 nm, the loss ratio of the high-order mode to the fundamental mode is greater than 100, which has good single-mode characteristics.

[0054] In summary, this embodiment discloses a low-loss hollow-core antiresonant single-mode optical fiber. The minimum loss of this optical fiber at 1550nm is 0.00065dB / km, and the loss covering a bandwidth of approximately 500nm (wavelength range of 1400-1900nm) is less than 0.002dB / km. When the bending radius is greater than 20cm, the bending loss is less than 0.0018dB / km. In addition, good single-mode characteristics (loss ratio exceeds 100) are also achieved within this bandwidth range. Compared with existing optical fiber structure designs, the hollow-core antiresonant optical fiber disclosed in this embodiment has excellent comprehensive performance in terms of loss, bandwidth, and single-mode characteristics.

[0055] It should be noted that the hollow-core anti-resonant single-mode optical fiber existing in the prior art usually adds a cross arm to its teardrop-shaped inner tube. This design of adding a cross arm is equivalent to adding another anti-resonant layer. Although the loss will be lower, the cross arm is used to separate the cladding space of the teardrop-shaped inner tube, which suppresses the coupling of the cladding mode with the high-order mode of the core, making the single-mode characteristics of the hollow-core anti-resonant single-mode optical fiber worse. In addition, the prior art also needs to add support arms and outer cladding rings to reduce losses, but this design increases the structural complexity and design cost of the optical fiber. The confinement loss and bending loss of the hollow-core anti-resonant single-mode optical fiber proposed in the present invention are lower than those of the hollow-core anti-resonant single-mode optical fiber existing in the prior art.

[0056] The present invention combines the anti-resonant reflection waveguide model with the suppressed coupling model. By changing the structure of the nested inner tube (teardrop-shaped inner tube) on the basis of the nodeless nested optical fiber structure, the confinement loss and bending loss are further reduced. The teardrop-shaped nested node is far away from the core area, which can effectively avoid Fano resonance, so that the optical fiber has a stable loss spectrum characteristic and obtains a larger transmission bandwidth. By adjusting the size of the nested inner tube, the high-order mode in the core is coupled with the cladding tube mode, thereby obtaining good single-mode characteristics. The structural design of this patent invention is simpler and can achieve lower confinement loss and better single-mode characteristics than adding cross arms, support arms and outer cladding rings.

[0057] The hollow-core antiresonant single-mode optical fiber described in an embodiment of the present invention includes: a cladding region and a core region; the cladding region includes an outer cladding and an inner cladding region arranged sequentially from the outside to the inside; the inner cladding region includes a cladding capillary and a teardrop-shaped inner tube disposed within the cladding capillary; the cladding capillaries are tangent to the inner surface of the outer cladding and are circumferentially distributed at a first distance uniformly spaced along the circumference of the inner surface of the outer cladding, thereby surrounding the core region; the teardrop-shaped inner tube is an internally connected teardrop tube structure formed by combining a semi-ellipse and a semi-circle, one end of the semi-ellipse is tangent to the inner surface of the cladding capillary; a first intangent point formed by the cladding capillary and the outer cladding coincides with a second intangent point formed by one end of the semi-ellipse and the cladding capillary, thereby suppressing light leakage through a nested structure. While maintaining a large gap between adjacent tubes, the optical fiber can have ultra-low confinement loss and bending loss over a longer wavelength range.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A hollow-core antiresonant single-mode optical fiber, characterized in that: include: The cladding region and the core region; the cladding region includes an outer cladding and an inner cladding region arranged sequentially from the outside to the inside; The inner cladding region includes a cladding capillary and a teardrop-shaped inner tube arranged inside the cladding capillary; the cladding capillary is tangent to the inner surface of the outer cladding and is uniformly spaced at a first distance along the circumferential direction of the inner surface of the outer cladding, and surrounds the core region; The teardrop-shaped inner tube is an internally connected teardrop tube structure formed by combining a semi-ellipse and a semi-circle, and one end of the semi-ellipse is tangent to the inner surface of the cladding capillary tube; The cladding capillary is tangent to the inner surface of the outer cladding to form a first intangent point, one end of the semi-ellipse is tangent to the inner surface of the cladding capillary to form a second intangent point, and the first intangent point and the second intangent point are coincident points; The thickness t of the cladding capillary and the teardrop-shaped inner tube are both 0.35 μm to 0.70 μm.

2. The hollow-core antiresonant single-mode optical fiber according to claim 1, wherein: The radial separation between the teardrop-shaped inner tube and the cladding capillary is in the range of 0.

35. R-0.5 R, the radius r of the water drop-shaped inner tube semicircle is equal to the length of the inner semi-minor axis of the water drop-shaped inner tube semi-ellipse, and the radius r of the water drop-shaped inner tube semicircle ranges from 0.2 R-0.5 R; determine the length of the inner semi-major axis of the teardrop-shaped inner tube semi-ellipse to be (R+t) 2-z-(r+t)-t / 2; wherein R is the radius of the cladding capillary, and t is the thickness of the cladding capillary and the teardrop-shaped inner tube wall.

3. The hollow-core antiresonant single-mode optical fiber according to claim 1, wherein: The cladding capillary and the teardrop-shaped inner tube have the same thickness t, which satisfies the antiresonance condition and can achieve coherent cancellation of light waves, thereby suppressing light leakage and reducing optical fiber loss. The expression corresponding to the thickness t satisfying the antiresonance condition is specifically: ； Where λ is the antiresonance center wavelength, m is the antiresonance order, and m is a positive integer greater than or equal to 1. is the refractive index of the high refractive index material, is the refractive index of the low-refractive-index material.

4. The hollow-core antiresonant single-mode optical fiber according to claim 2, wherein: The radius R of the cladding capillary is determined by the following formula: ； Wherein, N is the number of the cladding capillaries, g is the first distance between adjacent cladding capillaries, D is the core diameter of the core region, and t is the thickness of the cladding capillaries and the teardrop-shaped inner tube wall.

5. The hollow-core antiresonant single-mode optical fiber according to claim 4, wherein: The first distance between adjacent cladding capillaries is 1 μm-5 μm.

6. The hollow-core antiresonant single-mode optical fiber according to claim 1, wherein: The outer cladding, the cladding capillary and the teardrop-shaped inner tube are all made of refractive index materials with high refractive index; the interior of the outer cladding, the interior of the cladding capillary and the interior of the teardrop-shaped inner tube are all filled with low refractive index materials.

7. The hollow-core antiresonant single-mode optical fiber according to claim 6, wherein: The high refractive index material is silicon dioxide or plastic; the low refractive index substance is air.

8. The hollow-core antiresonant single-mode optical fiber according to claim 1, wherein: The core diameter D of the core region is 20 μm-40 μm.

9. The hollow-core antiresonant single-mode optical fiber according to claim 1, wherein: The number of the cladding capillaries is equal to the number of the teardrop-shaped inner tubes.

10. The hollow-core antiresonant single-mode optical fiber according to claim 6, wherein: The high refractive index material is a PVC soft crystal plate.

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