A high birefringence bend-resistant hollow-core antiresonant optical fiber for green light band

Abstract

The present invention discloses a high birefringence anti-bending hollow core anti-resonant optical fiber applied to the green light band, belonging to the field of optical fiber technology. The present invention comprises: an outer cladding, an inner cladding and an air core region arranged in sequence from the outside to the inside; the outer cladding region is a hollow cylinder with a certain thickness; the inner cladding is a nested cladding tube structure, including a circular cladding tube and a first circular nested tube arranged inside it, an ice cream-shaped cladding tube composed of two sides of an equilateral triangle and a semicircular arc, and a second circular nested tube arranged inside it; the first nested cladding tube structure composed of the first circular nested tube and the circular cladding tube and the second nested cladding tube structure composed of the second circular nested tube and the ice cream-shaped cladding tube adopt different dielectric materials, different tube wall thicknesses and different deviation angles, thereby introducing high birefringence. The present invention can be applied to the green light band, has high birefringence and low bending loss, and has good polarization maintenance characteristics and anti-bending performance.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber technology, and more specifically to a high birefringence bending-resistant hollow core anti-resonance optical fiber applied to a green light band. Background Art

[0002] Polarization, as a basic property of light, has important research significance and application value in any research field involving optics. When the surface of the optical fiber is uneven or the structure is incomplete, or it is disturbed by external factors such as stress and temperature, it will introduce uncontrollable birefringence or polarization mode dispersion, resulting in changes in the polarization state of the transmitted light and crosstalk between orthogonal polarization modes, thereby affecting the stability of the optical device function and restricting the application of optical fiber in areas such as fiber gyroscopes, laser systems, and laser transmission.

[0003] Hollow core fiber (HCF) is an important research direction in fiber optics. With its specific microstructure design, the light field can be confined to its air core for transmission, reducing the overlap between the light field and the quartz area. Compared with traditional solid core fiber, it overcomes the intrinsic losses such as material and scattering, and in principle can achieve ultra-low loss light transmission; in addition, it also has the advantages of low latency, low dispersion, low nonlinearity, high light-induced damage threshold, and high flexibility, and has broad application prospects in the fields of high-power pulsed laser transmission, ultrafast optics, and nonlinear optics. Hollow-core anti-resonant fiber (HC-ARF) is a special hollow core fiber with lower transmission loss, higher laser damage threshold, and higher mode purity; and its cladding structure is very simple, and the internal structure and specific size of HC-ARF can be flexibly designed according to a specific transmission wavelength and the needs of practical applications.

[0004] Although HC-ARF has been rapidly developed due to its excellent characteristics such as low loss, low dispersion and high damage threshold, it still has some imperfections. First, most of the current research on HC-ARF is concentrated in the communication band, and there is relatively little research on the visible light band, such as the green light band, which limits the application of HC-ARF in industries such as underwater laser imaging, underwater lidar and laser precision processing; secondly, compared with solid core optical fiber, it is difficult to achieve high birefringence in HC-ARF due to the lack of mechanical stress; in addition, since the core mode of hollow core optical fiber has a low overlap with glass, it is difficult to use deliberate geometric asymmetry to obtain substantial birefringence, and the problem of introducing polarization-maintaining characteristics in HC-ARF while maintaining its excellent comprehensive performance has not yet been solved.

[0005] Therefore, it is urgent to design a new type of hollow-core antiresonant optical fiber, which can have small restrictive loss and bending loss in the working band of green light, and at the same time have a high birefringence coefficient, so as to achieve low-loss signal transmission and good polarization maintenance characteristics, so that it can be fully used in underwater laser imaging, underwater laser radar, laser precision processing and other industries. This has very important practical significance. Summary of the invention

[0006] Purpose of the invention: In view of the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a high birefringence bending-resistant hollow-core antiresonant optical fiber for use in the green light band, so as to have lower limiting loss and bending loss, as well as higher birefringence coefficient within the green light band that can be used in fields such as underwater detection and laser precision processing, thereby achieving long-distance, high-energy stable transmission and obtaining good polarization maintenance characteristics.

[0007] Technical solution: To achieve the above-mentioned purpose, the present invention provides a high birefringence bending-resistant hollow-core antiresonant optical fiber for use in the green light band, comprising an outer cladding, an inner cladding and an air core region arranged in sequence in the radial direction from the outside to the inside of the optical fiber;

[0008] The outer cladding is a hollow cylinder, covering the inner cladding and the air core region;

[0009] The inner cladding is a nested cladding tube structure, including a first circular nested tube, a circular cladding tube, a second circular nested tube, and an ice cream-shaped cladding tube composed of two sides of an equilateral triangle and a semicircular arc, wherein: the first circular nested tube and the circular cladding tube are inscribed to form a first nested cladding tube structure with a double-layer structure, and the inscribed point is in contact and connected with the inner wall surface of the outer cladding; the vertex of the ice cream-shaped cladding tube is in contact and connected with the outer cladding; the second circular nested tube is inscribed and fixedly connected with the two sides of the equilateral triangle constituting the ice cream-shaped cladding tube, and together with the ice cream-shaped cladding tube, forms a second nested cladding tube structure with a double-layer structure; the first nested cladding tube structure and the second nested cladding tube structure use different dielectric materials, different tube wall thicknesses and deviation angles;

[0010] The hollow core antiresonant optical fiber is axially symmetrically distributed about the x-axis and the y-axis, and each first nested cladding tube structure and its adjacent second nested cladding tube structure are located in the same quadrant;

[0011] The air core region is composed of the first circular nested tube, the circular cladding tube, the second circular nested tube and the ice cream-shaped cladding tube.

[0012] Preferably, the outer diameter of the outer cladding is 120-125 μm, and the wall thickness is 30-35 μm.

[0013] Preferably, the ratio of the outer diameter of the first circular nested tube to the outer diameter of the circular cladding tube is 0.4-0.6, and the ratio of the outer diameter of the second circular nested tube to the side length of the equilateral triangle or the outer diameter of the semicircular arc constituting the cladding tube in the shape of an ice cream is 0.4-0.8.

[0014] Preferably, the outer diameter of the first circular nested tube is 5.6-9.6 μm, and the outer diameter of the circular cladding tube is 14-16 μm.

[0015] Preferably, the side length of the equilateral triangle of the cladding tube forming the ice cream shape is consistent with the outer diameter of the semicircular arc, both of which are 14-16 μm; the outer diameter of the second circular nested tube is 5.6-12.8 μm.

[0016] Preferably, the wall thickness of the first circular nested tube and the circular cladding tube is the same, which is 0.122-0.19 μm.

[0017] Preferably, the wall thickness of the semicircular part in the ice cream-shaped cladding tube is 0.423~0.657μm, and the wall thickness of the two sides of the equal-side triangle in the second circular nested tube and the ice cream-shaped cladding tube is the same, which is smaller than the wall thickness of the semicircular part, which is 0.366~0.57μm.

[0018] Preferably, the first nested cladding tube structure deviates from the x-axis by an angle of 65° to 75°; and the second nested cladding tube structure deviates from the x-axis by an angle of 25° to 30°.

[0019] Preferably, there are four of each of the first nested cladding tube structures and the second nested cladding tube structures, and two adjacent nested cladding tube structures of different types form a group, which are respectively arranged in four quadrants and are symmetrical about the x-axis and the y-axis.

[0020] Preferably, the dielectric material of the outer cladding, the first circular nested tube and the circular cladding tube is consistent, and its refractive index is 1.4533~1.4613; the dielectric material of the second circular nested tube and the ice cream-shaped cladding tube is consistent, and its refractive index is 3.6649~4.1317.

[0021] Beneficial effects: The present invention provides a high birefringence, bend-resistant hollow-core antiresonant optical fiber for use in the green light band, which comprises, from the outside to the inside, an outer cladding, an inner cladding composed of two nested cladding tube structures, and an air core; wherein the two types of double-layer nested cladding tube structures are designed to meet the antiresonant reflection waveguide (ARROW) principle, are made of different materials and have a certain thickness, and have negative curvature relative to the air core; these double-layer nested cladding tube structures can produce double antiresonance, thereby reducing losses. In addition, since the two types of nested cladding tube structures use different materials, and there are differences in tube wall thickness and deviation angle, high birefringence is introduced. Compared with the prior art, the present invention has at least the following advantages and beneficial effects:

[0022] (1) The optical fiber structure proposed in the present invention is simple and easy to prepare. First, only a circular nested cladding tube structure and an ice cream-shaped nested cladding tube structure are used. Both structures are easy to draw and not prone to deformation during industrial preparation. Second, the two nested cladding tube structures used also have only two layers, which are less complex. Finally, the use of two double-layer tube structure designs is conducive to increasing geometric asymmetry to a certain extent, thereby further enhancing the birefringence characteristics.

[0023] (2) Compared with the existing common hollow-core antiresonant optical fiber, the present invention has good structural adjustability. Experiments have found that by adjusting the wall thickness of the outer cladding and the size of the two nested cladding tube structures, the limiting loss can be further improved to achieve long-distance low-loss transmission.

[0024] (3) The optical fiber proposed in the present invention has a high birefringence coefficient and good polarization maintaining properties, which can reduce the coupling of the transmission signal in the two polarization directions, thereby suppressing the influence of external disturbances on optical transmission.

[0025] (4) Experiments show that the present invention can achieve a loss of less than 10 within the green light band. -4 dB / m, even up to 1.05891×10 -6 dB / m @0.531μm ultra-low loss, achieving ultra-low loss transmission; in addition, the present invention also has 10 -5 The birefringence coefficient is of the order of magnitude, and when the bending radius is 6 cm, it reaches 10 -4 The bending loss of dB / m indicates that the present invention has good polarization maintaining characteristics and anti-bending performance, can reduce the coupling of transmission signals in two polarization directions and can perform long-distance signal transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0027] Figure 1 It is a schematic structural diagram of a high birefringence bend-resistant hollow-core antiresonant optical fiber applied to the green light band provided by an embodiment of the present invention.

[0028] Figure 2 yes Figure 1 Detailed structural diagram of the ice cream-shaped nested cladding tube structure.

[0029] Figure 3 1 is an electric field mode distribution diagram at a wavelength of 0.532 μm provided by an embodiment of the present invention, wherein (a) is an electric field mode distribution diagram of the fundamental mode x polarization state, and (b) is an electric field mode distribution diagram of the fundamental mode y polarization state.

[0030] Figure 4 It is a relationship diagram of the limiting loss of the fundamental mode x polarization state and the fundamental mode y polarization state as a function of wavelength provided by an embodiment of the present invention.

[0031] Figure 5 It is a relationship diagram of the effective refractive index of the fundamental mode x polarization state and the fundamental mode y polarization state as a function of wavelength provided by an embodiment of the present invention.

[0032] Figure 6 It is a relationship diagram of the birefringence coefficient of the fundamental mode x polarization state and the fundamental mode y polarization state as a function of wavelength provided by an embodiment of the present invention.

[0033] Figure 7 It is a relationship diagram of bending loss versus bending radius when an optical fiber is bent in the x-direction and the y-direction at a wavelength of 0.532 μm, provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described and illustrated in conjunction with the drawings in the embodiments of the present invention. It should be pointed out that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of protection claimed in the present invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0036] See also Figure 1 , a schematic diagram of the structure of a high birefringence, bend-resistant hollow-core antiresonant optical fiber for green light band proposed by the present invention, the hollow-core antiresonant optical fiber comprises: an outer cladding 1, an inner cladding and an air core region arranged in sequence from the outside to the inside. The outer cladding 1 is a hollow cylinder with a certain thickness, covering the inner cladding and the air core region, and serving as a protective layer on the outside of the high birefringence, bend-resistant hollow-core antiresonant optical fiber; the first circular nested tube 2 is inscribed in the circular cladding tube 3 to form a first nested cladding tube structure of a double-layer structure, and the inscribed point is in contact with and connected to the inner wall surface of the outer cladding 1, and deviates from the x-axis by a certain angle; the ice cream-shaped cladding tube 5 is composed of two sides of an equilateral triangle and a semicircular arc with the third side as the diameter, and is in contact with and connected to the outer cladding 1; the second circular nested tube 4 is inscribed in the two sides of the equilateral triangle constituting the ice cream-shaped cladding tube 5, and the two The second nested cladding tube structure formed by the first circular nested tube 2 and the circular cladding tube 3 deviates from the x-axis by a certain angle; each first nested cladding tube structure composed of the first circular nested tube 2 and the circular cladding tube 3 is located in the same quadrant together with its adjacent second nested cladding tube structure composed of the second circular nested tube 4 and the ice cream-shaped cladding tube 5, and the overall structural arrangement is axisymmetric about the x-axis and the y-axis; the first nested cladding tube structure and the second nested cladding tube structure use different dielectric materials and thicknesses; the air hole enclosed by the first circular nested tube 2, the circular cladding tube 3, the second circular nested tube 4 and the ice cream-shaped cladding tube 5 is the air fiber core 6.

[0037] Figure 1 , Figure 2In the embodiment, the outer diameter of the outer cladding 1 is D1, the thickness of the outer cladding 1 is d1, the outer diameter of the first circular nested tube 2 is D2, the outer diameter of the circular cladding tube 3 is D3, the wall thickness of the first circular nested tube 2 and the circular cladding tube 3 is t1, the outer diameter of the second circular nested tube 4 is D4, the side length of the medium-side triangle and the outer diameter of the semicircular arc in the ice-cream-shaped cladding tube 5 are D5, the wall thickness of the two sides of the medium-side triangle in the second circular nested tube 4 and the ice-cream-shaped cladding tube 5 is t2, the wall thickness of the semicircular arc part in the ice-cream-shaped cladding tube 5 is t3, the angle of the first nested cladding tube structure deviating from the x-axis is α, and the angle of the second nested cladding tube structure deviating from the x-axis is β.

[0038] In some embodiments, the outer diameter D1 of the outer cladding 1 can be set to 120-125 μm, and the wall thickness d1 can be set to 30-35 μm.

[0039] In some embodiments, the ratio D2 / D3 of the outer diameters of the first circular nested tube 2 and the circular cladding tube 3 can be set to 0.4-0.6, and the ratio D4 / D5 of the outer diameter of the second circular nested tube 4 to the side length of the equilateral triangle or the outer diameter of the semicircular arc of the cladding tube 5 forming the shape of ice cream can be set to 0.4-0.8. Specifically, the outer diameter D2 of the first circular nested tube 2 can be optimized in the range of 5.6-9.6 μm, and the outer diameter D3 of the circular cladding tube 3 can be optimized in the range of 14-16 μm. The outer diameter D4 of the second circular nested tube 4 can be optimized in the range of 5.6-12.8 μm; the side length of the equilateral triangle and the outer diameter D5 of the semicircular arc of the cladding tube 5 forming the shape of ice cream can be optimized in the range of 14-16 μm.

[0040] In some embodiments, the wall thickness t1 of the first circular nested tube 2 and the circular cladding tube 3 is the same, which can be set to 0.122-0.19 μm.

[0041] In some embodiments, the wall thickness t2 of the two sides of the equilateral triangle of the second circular nested tube 4 and the ice cream-shaped cladding tube 5 is the same and can be set to 0.366~0.57μm, and the wall thickness t3 of the semicircular arc part of the ice cream-shaped cladding tube 5 can be set to 0.423~0.657μm.

[0042] In some embodiments, the angle α of the first nested cladding tube structure deviating from the x-axis may be set to 65°-75°; the angle β of the second nested cladding tube structure deviating from the x-axis may be set to 25°-30°.

[0043] In some embodiments, each of the first nested cladding tube structures and its adjacent second nested cladding tube structure are located in the same quadrant, and the overall structural arrangement is axially symmetrical about both the x-axis and the y-axis.

[0044] In some embodiments, the dielectric materials of the outer cladding 1, the first circular nested tube 2 and the circular cladding tube 3 are consistent, and their refractive index is 1.4533~1.4613; the dielectric materials of the second circular nested tube 4 and the ice cream-shaped cladding tube 5 are consistent, and their refractive index is 3.6649~4.1317.

[0045] The present invention is illustrated by the following examples to illustrate the design advantages.

[0046] Example: See Figure 1 and Figure 2 Detailed structural diagram of hollow core optical fiber shown; In this embodiment, the detailed structure of a high birefringence bending-resistant hollow core anti-resonant optical fiber applied to the green light band includes:

[0047] Outer cladding 1: outer diameter D1 is 125 μm; thickness d1 is 32.5 μm; material selected is silicon dioxide.

[0048] The nested cladding tube structure in the inner cladding region, wherein: the outer diameter D2 of the first circular nested tube 2 is 7.6 μm, the outer diameter D3 of the circular cladding tube 3 is 15.2 μm, the angle α of the first nested cladding tube structure composed of the first circular nested tube 2 and the circular cladding tube 3 deviates from the x-axis by 70°, the tube wall thickness t1 of the first circular nested tube 2 and the circular cladding tube 3 is 0.141 μm, and the dielectric material is silicon dioxide; the outer diameter D4 of the second circular nested tube 4 is 8.66 μm, the side length of the equilateral triangle in the ice cream-shaped cladding tube 5 and the outer diameter D5 of the semicircular arc are 15 μm, the angle β of the second nested cladding tube structure composed of the second circular nested tube 4 and the ice cream-shaped cladding tube 5 deviates from the x-axis by 27°, the tube wall thickness t2 of the two sides of the equilateral triangle in the second circular nested tube 4 and the ice cream-shaped cladding tube 5 is 0.424 μm, the tube wall thickness t3 of the semicircular arc part of the ice cream-shaped cladding tube 5 is 0.49 μm, and the dielectric material is silicon.

[0049] Air core 6: The medium material is air, and the refractive index is set to 1.

[0050] The present invention uses finite element simulation software COMSOL Multiphysics to simulate and test the present embodiment, and uses the finite element method and combines the boundary absorption condition of the perfect matching layer to perform theoretical calculations. The electric mode field distribution diagram of the present invention, the relationship curve of the limiting loss, effective refractive index and birefringence coefficient with wavelength, the relationship curve of the bending loss with the bending radius and the mode field distribution diagram in different bending directions are obtained by calculation.

[0051] See also Figure 3 From the mode field distribution diagram of the fundamental mode of the embodiment of the present invention, it can be seen that the energy of the x-polarization state and the y-polarization state of the fundamental mode of the hollow-core antiresonant optical fiber constructed in this embodiment is concentrated in the core region, indicating that the light is confined in the core region.

[0052] See also Figure 4 From the relationship diagram of the restrictive loss versus wavelength of the embodiment of the present invention, it can be seen that the fundamental mode x polarization state and y polarization state of the hollow core antiresonant optical fiber constructed in this embodiment have relatively low restrictive losses, both reaching 10 - 4 dB / m level and below; the lowest loss of the fundamental mode x polarization state measured at a transmission wavelength of 0.531μm is 1.05891×10 -6 dB / m, the y polarization state is measured at a transmission wavelength of 0.529 μm to be 4.54767×10 -6 dB / m; within the entire working band of green light, the limit loss is 10 -6 dB / m~10 -4 dB / m, indicating that the embodiment of the present invention has a lower restrictive loss in the green light band, which is conducive to low-loss transmission of optical signals within this band.

[0053] See also Figure 5 From the graph showing the relationship between the effective refractive index and the wavelength of the embodiment of the present invention, it can be seen that the effective refractive index of the fundamental mode x polarization state and y polarization state of the hollow-core antiresonant optical fiber constructed in this embodiment decreases with the increase of wavelength, and the effective refractive index is close to 1, indicating that the transmission in the hollow core has a transmission refractive index close to 1.

[0054] See also Figure 6 From the relationship diagram of the birefringence index versus wavelength of the embodiment of the present invention, it can be seen that the hollow-core antiresonant optical fiber constructed in this embodiment has a relatively high birefringence index, reaching 10 -5 This can reduce the coupling of the transmission signal in the two polarization directions and suppress the influence of the uncontrollable birefringence introduced by external disturbances and the crosstalk between polarization modes on the optical transmission.

[0055] See also Figure 7 From the relationship between the bending loss and the bending radius of the embodiment of the present invention, it can be seen that the hollow-core antiresonant optical fiber constructed in this embodiment has low bending loss when bending in the x direction and in the y direction under the condition of a transmission wavelength of 0.532 μm. When the bending radius is 6 cm, the bending loss of the optical fiber when bending in the x direction and in the y direction reaches 10 -4 The dB / m level indicates that the present embodiment has good anti-bending performance, which is beneficial for long-distance signal transmission.

[0056] In summary, the high birefringence bending-resistant hollow core antiresonant optical fiber applied to the green light band of the present invention has low limiting loss and good bending resistance within the working wavelength range of green light, and can achieve low-loss long-distance transmission. Specifically, within the transmission wavelength range of green light, the minimum birefringence can reach 10 -6 The limiting loss is in the order of dB / m, and when the bending radius is only 6cm, the bending loss can be less than 10 -4 dB / m level, that is, the limiting loss and bending loss of the fundamental mode at the working wavelength of the present invention are both low, and the bending resistance is good; at the same time, the hollow core antiresonant optical fiber of the present invention also has 10 -5 The birefringence coefficient is of the order of magnitude, the birefringence coefficient is high, and the polarization maintaining property is good.

[0057] The basic principle, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed for protection.

Claims

1. A high birefringence bend-resistant hollow core antiresonant optical fiber for use in the green light band, comprising an outer cladding, an inner cladding and an air core region arranged in sequence in the radial direction from the outside to the inside of the optical fiber, characterized in that: The outer cladding is a hollow cylinder, covering the inner cladding and the air core region; The inner cladding is a nested cladding tube structure, including a first circular nested tube, a circular cladding tube, a second circular nested tube, and an ice cream-shaped cladding tube composed of two sides of an equilateral triangle and a semicircular arc, wherein: the first circular nested tube and the circular cladding tube are inscribed to form a first nested cladding tube structure with a double-layer structure, and the inscribed point is in contact and connected with the inner wall surface of the outer cladding; the vertex of the ice cream-shaped cladding tube is in contact and connected with the outer cladding; the second circular nested tube is inscribed and fixedly connected with the two sides of the equilateral triangle constituting the ice cream-shaped cladding tube, and together with the ice cream-shaped cladding tube, forms a second nested cladding tube structure with a double-layer structure; the first nested cladding tube structure and the second nested cladding tube structure use different dielectric materials, different tube wall thicknesses and deviation angles; The hollow core antiresonant optical fiber is axially symmetrically distributed about the x-axis and the y-axis, and each first nested cladding tube structure and its adjacent second nested cladding tube structure are located in the same quadrant; The air core region is composed of the first circular nested tube, the circular cladding tube, the second circular nested tube and the ice cream-shaped cladding tube.

2. The high birefringence bend-resistant hollow core antiresonant optical fiber for use in the green light band according to claim 1, characterized in that: The outer diameter of the outer cladding is 120-125 μm, and the wall thickness is 30-35 μm.

3. The high birefringence bend-resistant hollow core antiresonant optical fiber for use in the green light band according to claim 1, characterized in that: The ratio of the outer diameter of the first circular nested tube to the circular cladding tube is 0.4-0.6, and the ratio of the outer diameter of the second circular nested tube to the side length of the equilateral triangle or the outer diameter of the semicircular arc of the cladding tube forming the ice cream shape is 0.4-0.

8.

4. A high birefringence bend-resistant hollow-core antiresonant optical fiber for use in the green light band according to claim 1 or 3, characterized in that: The outer diameter of the first circular nested tube is 5.6-9.6 μm, and the outer diameter of the circular cladding tube is 14-16 μm.

5. A high birefringence bend-resistant hollow core antiresonant optical fiber for use in the green light band according to claim 1 or 3, characterized in that: The side length of the equilateral triangle of the cladding tube forming the ice cream shape is consistent with the outer diameter of the semicircular arc, both of which are 14~16μm; the outer diameter of the second circular nested tube is 5.6~12.8μm.

6. The high birefringence bend-resistant hollow core antiresonant optical fiber for use in the green light band according to claim 1, characterized in that: The wall thickness of the first circular nested tube and the circular cladding tube is the same, which is 0.122-0.19 μm.

7. The high birefringence bend-resistant hollow core antiresonant optical fiber for use in the green light band according to claim 1, characterized in that: The wall thickness of the semicircular arc part in the ice cream-shaped cladding tube is 0.423-0.657 μm, and the wall thickness of the two sides of the medium-side triangle in the second circular nested tube and the ice cream-shaped cladding tube is the same, which is smaller than the wall thickness of the semicircular arc part, and is 0.366-0.57 μm.

8. The high birefringence bend-resistant hollow-core antiresonant optical fiber for use in the green light band according to claim 1, characterized in that: The first nested cladding tube structure deviates from the x-axis at an angle of 65° to 75°, and the second nested cladding tube structure deviates from the x-axis at an angle of 25° to 30°.

9. The high birefringence bend-resistant hollow core antiresonant optical fiber for use in the green light band according to claim 1, characterized in that: There are four of each of the first nested cladding tube structures and the second nested cladding tube structures, and two adjacent nested cladding tube structures of different types form a group, which are respectively arranged in four quadrants and are symmetrical about the x-axis and the y-axis.

10. The high birefringence bend-resistant hollow core antiresonant optical fiber for use in the green light band according to claim 1, characterized in that: The dielectric materials of the outer cladding, the first circular nested tube and the circular cladding tube are consistent, and their refractive index is 1.4533-1.4613; the dielectric materials of the second circular nested tube and the ice cream-shaped cladding tube are consistent, and their refractive index is 3.6649-4.1317.

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