A single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy

Abstract

The present invention discloses a single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectral analysis, which is sequentially arranged as an outer cladding region, an inner cladding region and an air core region from the outside to the inside. The outer cladding region is a kagome type, which is composed of a mesh periodic hole ring formed by alternating circles and triangles; the inner cladding is a three-nested anti-resonance type, which is composed of a circular and arc-shaped cladding tube, or an arc-shaped cladding tube; the core region is surrounded by the kagome mesh structure of the outer cladding region and the nested anti-resonance structure of the inner cladding region. The present invention utilizes the advantages of kagome-type and nested anti-resonance-type optical fibers, and realizes single-mode single-bias, near-zero dispersion and other characteristics while having low loss in the ultraviolet band, and can be used for spectral analysis at a wavelength of 210nm.

Description

Technical Field

[0001] The invention relates to the field of deep ultraviolet optical fibers, and in particular to a hybrid lattice cladding optical fiber composed of kagome and nested claddings with single-mode, single-polarization and low-loss characteristics. Background Art

[0002] Spectral analysis is mainly based on the absorption, reflection or scattering properties of light by substances. When the light emitted by the light source is irradiated on the sample to be tested, it will absorb, reflect or scatter part of the light energy, causing the spectrum of the transmitted light or reflected light to change. These spectral changes contain the type and concentration of the substance and other chemical information of the sample. The ultraviolet band is widely used in the detection of pesticides, DNA, food additives and other substances. Among them, the 210nm wavelength can be used to detect the antibiotic azithromycin or certain food additives. The detection and analysis technology using ultraviolet light requires a high-performance optical fiber to increase its application flexibility. The application of optical fiber provides a non-contact detection method to avoid damage and contamination to the sample, while improving the efficiency and accuracy of the detection.

[0003] In the ultraviolet band, quartz optical fiber has serious intrinsic defects. Under long-term irradiation, problems such as ultraviolet photo-darkening effect, low conductable power and multimode transmission will occur. Hollow-core optical fiber is an ideal carrier for ultraviolet light transmission. Hollow-core optical fiber based on the principle of photonic crystal light guidance can be divided into two types, one is the photonic bandgap guidance mechanism, and the other is the suppression of coupling light guidance mechanism. Among them, photonic bandgap optical fiber, through the design of microstructure, makes no cladding mode can couple with the core mode. On the contrary, in the suppressed coupling optical fiber, although there is no bandgap in the effective refractive index space of the cladding frequency, due to the small spatial overlap between the core and cladding mode field distributions and the strong mismatch between the transverse spatial phases of these modes, the coupling of the core mode with the cladding is strongly suppressed. The above-mentioned suppressed coupling light guidance theory introduces the concept of negative curvature into optical fiber and significantly enhances the optical fiber's ability to confine light. Representative examples are kagome hollow-core fiber and nested antiresonant hollow-core fiber.

[0004] However, there are relatively few hollow-core optical fibers designed for the deep ultraviolet region. Generally speaking, the short-wave band restricts the flexibility of hollow-core optical fiber design, which is mainly manifested in the restriction of short-wavelength on the core size. According to relevant theories, a larger air ratio in hollow-core optical fibers is a favorable way to solve the damage of ultraviolet radiation to optical fiber materials. However, hollow-core optical fibers optimized for the deep ultraviolet band are rarely able to balance the air ratio and beam-bearing capacity, thus failing to effectively solve the inherent optical damage and optical loss problems of ultraviolet optical fibers. On the other hand, although the loss data of suppressed coupled photonic crystal fibers is gradually decreasing, it is still impossible to design and manufacture a suppressed coupled guided optical fiber with ultra-low loss, single mode and polarization-maintaining characteristics at short wavelengths, making it difficult to meet the sensing and detection needs at specific deep ultraviolet wavelengths. Summary of the invention

[0005] Purpose of the invention: In view of the shortcomings of the prior art, the purpose of the present invention is to provide a hollow-core optical fiber for deep ultraviolet spectroscopy analysis, which has the characteristics of single mode, single polarization and low loss.

[0006] Technical solution: To achieve the above-mentioned invention object, the present invention adopts the following technical solution:

[0007] A single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis, wherein the optical fiber is sequentially arranged from outside to inside as an outer cladding region, an inner cladding region and an air core region;

[0008] The outer envelope region is of kagome type, and the kagome network structure is composed of mesh hole rings formed by alternating circles and triangles; the outer contour of the kagome network structure is a regular polygon, and is inscribed in the circular base of the outer envelope; the inner contour of the kagome network structure is a quasi-rectangular shape, and the long side direction is the y direction of the plane coordinate system;

[0009] The inner cladding region is a three-nested anti-resonance type, which is composed of a circular and two arc-shaped cladding tubes, or three arc-shaped cladding tubes to form a three-nested anti-resonance structure; the outermost cladding tube of the three-nested anti-resonance structure is a minor arc structure, and both ends are fused with the kagome mesh structure;

[0010] The kagome mesh structure is fused with the three-nested anti-resonance structure to enclose an air core region; the air core region is a quasi-rectangular region, and the long side direction is the x direction of the plane coordinate system.

[0011] Preferably, the outer diameter of the circular hole rings of the kagome mesh structure in the outer cladding area is 12μm~15μm, wherein every three circular hole rings are mutually intersected to form a triangular hole ring, the mutually intersecting parts of the circular hole rings share a cladding tube, and the enclosed triangular hole rings share the cladding tube of the circular hole rings, and a cladding tube is not separately set to enclose the triangular hole rings.

[0012] Preferably, the outer contour of the kagome mesh structure in the outer cladding area is a regular hexagon, the regular hexagon has three layers of circular hole rings along the y direction, and two layers of circular hole rings on the other sides; the three-layer circular hole ring structure along the y direction is two groups and is symmetrically distributed along the y axis.

[0013] Preferably, the three-nested antiresonance structure of the inner cladding region is composed of a circular and two arc-shaped cladding tubes, and is fused with the kagome mesh structure, including an arc cladding tube, an arc nested tube and a circular nested tube; the arc cladding tube is a minor arc with an outer diameter of 34μm~36μm and an arc of 110°~150°; the arc nested tube is a major arc with an outer diameter of 17μm~19μm and an arc of 270°~300°, forming a double-layer structure with the arc cladding tube; the circular nested tube has an outer diameter of 12μm~15μm, is nested in the double-layer structure, is tangent to the circular hole ring of the kagome mesh structure and shares the cladding tube at the tangent point.

[0014] Preferably, in the triple-nested anti-resonance structure, the gap between the outermost cladding tube and the middle cladding tube is 1 μm to 3 μm, and the gap between the middle cladding tube and the innermost cladding tube is 9 μm to 11 μm.

[0015] Preferably, the three-nested anti-resonance structures are in two sets and are symmetrically distributed along the x-axis.

[0016] Preferably, the thickness of the cladding tubes of the circular hole rings and the triangular hole rings of the kagome mesh structure, and the thickness of various cladding tubes of the triple-nested anti-resonance structure are the same, and are 710nm~730nm.

[0017] Preferably, the annular base, the kagome mesh hole ring, and the cladding tube of the three-nested anti-resonance structure are made of the same material, which is silicon dioxide or high-hydroxyl pure silicon, and the refractive index is 1.4878-1.5853.

[0018] Preferably, the inside of the circular hole ring of the kagome mesh structure, the inside of the triangular hole ring, the internal space of the triple-nested anti-resonance structure, and the air core region are all filled with air, and the refractive index is 1.

[0019] Preferably, the operating wavelength of the optical fiber is at 210 nm.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0021] 1. Compared with the existing common hollow-core optical fiber, the present invention combines the advantages of kagome optical fiber and antiresonance optical fiber, and provides more possibilities for adjusting the optical fiber structure. By adjusting the outer diameter and the number of layers of the circular hole ring of the kagome mesh, and adjusting the size and gap of various cladding tubes in the antiresonance area, the structure of the optical fiber is optimized to achieve lower restrictive loss while also having single-mode single polarization, near-zero flat dispersion and extremely low nonlinearity and other characteristics.

[0022] 2. The present invention adopts a three-nested anti-resonance structure in its design, which improves the light beaming capability of the optical fiber while effectively adjusting the single-mode single-polarization characteristics of the optical fiber. The three-nested anti-resonance structure is composed of simple arcs and circles, and the process is simple.

[0023] 3. In the design of the present invention, a relatively simple optical fiber structure is designed to combine and weld the kagome mesh structure and the three-nested anti-resonance structure to reduce the possibility of surface scattering.

[0024] 4. In the preferred solution, the kagome mesh structure has fewer air holes, which is conducive to reducing the difficulty of the kagome mesh structure drawing process, and the outline of the kagome mesh structure is a regular hexagon, which increases the stability of the optical fiber.

[0025] 5. Compared with common glass core ultraviolet optical fibers, the present invention greatly reduces light loss and light damage caused by intrinsic material defects because it uses air as the main propagation medium.

[0026] 6. The present invention can use common silica glass without adding other dielectric materials, and the preparation cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the single-mode single-polarization hollow-core optical fiber of the present invention.

[0028] Figure 2 It is a local detail enlarged view of the kagome-type outer cladding region of the present invention.

[0029] Figure 3 It is a local detail enlarged view of the triple-nested anti-resonant inner cladding region of the present invention.

[0030] Figure 4 The mode field distribution and height expression diagram of the fundamental mode at a wavelength of 210nm provided in an embodiment of the present invention.

[0031] Figure 5 FIG. 4 is a graph showing the relationship between the limiting loss of the fundamental mode and the wavelength according to an embodiment of the present invention.

[0032] Figure 6FIG. 4 is a graph showing the relationship between the polarization extinction ratio and the wavelength according to an embodiment of the present invention.

[0033] Figure 7 FIG. 4 is a graph showing the relationship between the high-order mode extinction ratio and wavelength according to an embodiment of the present invention.

[0034] Figure 8 FIG. 4 is a graph showing the relationship between the dispersion of the fundamental mode and the wavelength according to an embodiment of the present invention.

[0035] Fig. 9 FIG. 4 is a graph showing the relationship between the nonlinear coefficient of the fundamental mode and the wavelength according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The technical scheme in the embodiment of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiment of the present invention. The described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] like Figure 1 As shown, a single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis has the characteristics of low loss, near-zero dispersion and low nonlinearity.

[0038] The optical fiber is sequentially arranged from outside to inside as a kagome-type outer cladding region, a three-nested antiresonance-type inner cladding region and an air core region; and sequentially arranged from inside to outside as an optical fiber air core 1, a three-nested antiresonance structure, a circular hole ring 3 of a kagome mesh structure, a triangular hole ring 4 of a kagome mesh structure, a closely adjacent portion 2 of each hole ring in the kagome structure, a gap 5 between the outer contour of the kagome mesh structure and the outer cladding circular ring base, and an outer cladding circular ring base 9.

[0039] The outer cladding region is composed of a mesh kagome structure in which circular hole rings 3 and triangular hole rings 4 are arranged alternately. The outer contour of the kagome mesh structure is a regular polygon and is inscribed in the circular ring base 9 of the outer cladding. The inner contour of the kagome mesh structure is asymmetric in the x and y directions and is a quasi-rectangular shape, with the long side direction being the y direction of the plane coordinate system.

[0040] The inner cladding region is composed of a three-nested anti-resonance structure consisting of a circular arc cladding tube 6, a circular arc nested tube 7 and a circular nested tube 8, and is welded and overlapped with the kagome mesh structure of the outer cladding; in addition to the three-nested anti-resonance structure shown in the figure, in the specific design, the three-nested anti-resonance structure can also be composed of three circular arc cladding tubes, or two circular arc cladding tubes and one circular cladding tube. Generally, the outermost cladding tube is a inferior arc structure, and both ends are welded to the kagome mesh structure.

[0041] The air core 1 is an air region, which is composed of the kagome mesh structure of the outer cladding region and the three-nested antiresonance structure of the inner cladding, and is the main light-guiding region of the hollow-core optical fiber. The air core region is rectangular, and the long side direction is the x direction of the plane coordinate system.

[0042] The parameters such as the wall thickness of the hole ring in the kagome structure and the cladding tube in the three-nested anti-resonance structure need to meet the anti-resonance condition. When the anti-resonance condition is met, the glass wall has the maximum reflection and the minimum transmission, and most of the light can be reflected back to the fiber core, thus forming an optical waveguide. The thickness t of each type of cladding tube is the same and meets: ; where t represents the thickness of the cladding tube, represents the operating wavelength, n1 and n0 are the refractive index of the cladding tube material and the refractive index of air respectively, and m is a positive integer. In some embodiments, m can be selected as 9.

[0043] In some embodiments, the outer diameter of the circular hole ring 3 of the kagome mesh structure in the outer cladding area is 12μm~15μm, and three circular hole rings 3 are intersected and enclosed to form a triangular hole ring 4, wherein the intersecting parts of the circular hole rings 3 share the cladding tube, and the enclosed triangular hole rings 4 share the cladding tube of the circular hole rings 3, and a cladding tube is not separately set to enclose the triangular hole ring 4.

[0044] In some embodiments, Figure 2 As shown, each circular hole ring 3 in the kagome mesh structure is surrounded by 6 circular hole rings 3.

[0045] In some embodiments, the outer contour of the kagome mesh structure in the outer cladding region is a regular hexagon, inscribed in the annular base 9, and the thickness d2 of the annular base 9 is 8 μm to 10 μm. The use of a regular hexagonal contour increases the stability of the optical fiber. In some embodiments, an annular ring can be added to the outer ring to design other regular polygonal contours.

[0046] In some embodiments, the kagome mesh structure of the outer cladding region is a regular hexagon, wherein there are three layers of circular hole rings 3 along the y direction, and two layers of circular hole rings 3 on the other sides of the regular hexagon. The three-layer circular hole ring 3 structure along the y direction is divided into two groups, symmetrically distributed about the y axis.

[0047] Figure 1 In the three-nested anti-resonance structure composed of the arc cladding tube 6, the arc nested tube 7, and the circular nested tube 8, as shown in FIG. Figure 3As shown, in some embodiments, the circular arc cladding tube 6 of the three-nested anti-resonance structure belongs to the inferior arc of a circle with an outer diameter d3 of 34μm~36μm, an arc of 110°~150°, and is welded and overlapped with the kagome mesh structure. The circular arc nested tube 7 of the three-nested anti-resonance structure belongs to the superior arc of a circle with an outer diameter d4 of 17μm~19μm, an arc of 270°~300°, forms a double-layer structure with the circular arc cladding tube 6, and is welded with the kagome mesh structure. The outer diameter d5 of the circular nested tube 8 of the three-nested anti-resonance structure is 12μm~15μm, nested in the double-layer structure, tangent to the circular hole ring 3 of the kagome mesh structure and share the cladding tube at the tangent point. Preferably, the circular nested tube 8 and the circular hole ring 3 use the same structural parameters. The gap d7 between the circular arc cladding tube 6 and the circular arc nested tube 7 in the three-nested anti-resonance structure is 1 μm to 3 μm, and the gap d6 between the circular arc nested tube 7 and the circular nested tube 8 is 9 μm to 11 μm.

[0048] In other triple-nested anti-resonance structures, size tuning can also be achieved by adjusting the gap between the outermost cladding tube and the middle cladding tube to 1μm~3μm, and the gap between the middle cladding tube and the innermost cladding tube to 9μm~11μm.

[0049] In some embodiments, the three-nested anti-resonance structures are two sets, which are symmetrically distributed about the x-axis.

[0050] In some embodiments, the thickness of the cladding tube of the circular hole ring 3 and the triangular hole ring 4 of the kagome mesh structure, and the thickness of the cladding tube of the inner cladding triple nested anti-resonance structure are the same and are 710nm~730nm.

[0051] In some embodiments, the air core 1 is essentially an air hole surrounded by various cladding tubes, and the side length a of the rectangular air core is 26 μm to 28 μm, and b is 9 μm to 12 μm.

[0052] In some embodiments, the annular base 9 of the outer cladding, the kagome mesh hole ring of the outer cladding, and the cladding tube of the triple nested antiresonance structure of the inner cladding are made of the same material, namely silicon dioxide or high-hydroxyl pure silicon, with a refractive index of 1.4878-1.5853.

[0053] In some embodiments, the circular hole ring 3 of the kagome mesh structure, the triangular hole ring 4, the internal space of the three-nested anti-resonance structure, and the air core region are all filled with air with a refractive index of 1.

[0054] The present invention illustrates the design advantages through the following preferred embodiments.

[0055] exist Figure 1In the figure, the outer diameter D1 of the hollow-core optical fiber is 120 μm, the thickness d2 of the circular base in the outer cladding region is 8.84 μm, the outer diameter d1 of the circular hole ring in the kagome mesh structure in the outer cladding region is 12 μm, the long side a of the quasi-rectangular air core is 27.096 μm, the short side b is 10.992 μm, and the cladding tube thickness t of the kagome mesh structure is 720 nm.

[0056] exist Figure 3 In the figure, the outer diameter d3 of the circle to which the inferior arc cladding tube of the three-nested anti-resonance structure of the inner cladding belongs is 35.04μm, the outer diameter d4 of the circle to which the nested superior arc cladding tube belongs is 18.6μm, the outer diameter d5 of the nested circular cladding tube is 12μm, the gap d7 between the circular arc cladding tube and the circular arc nested tube is 1.76μm, and the gap d6 between the circular arc nested tube and the circular nested tube is 10.02μm.

[0057] The present invention uses finite element simulation software COMSOL Multiphysics to simulate and test the present embodiment, and adopts finite element method and combines the boundary absorption condition of perfect matching layer to perform theoretical calculation. The mode field distribution diagram, limiting loss, extinction ratio, dispersion and nonlinear coefficient of the present invention are obtained by calculation.

[0058] Figure 4 2 is a diagram showing the mode field distribution and height expression of the fundamental mode at a wavelength of 210 nm. Figure 4 As shown, the hollow core optical fiber of the embodiment can concentrate the energy of the light wave in the core region when transmitting light, indicating that the present invention can well confine the light in the air core region.

[0059] Figure 5 1 is a graph showing the relationship between the limiting loss of the fundamental mode in the x-direction and the y-direction and the wavelength of the embodiment. Figure 5 As shown in FIG. 1 , the limiting loss of the embodiment is at a low level when the incident wavelength is 180 nm to 300 nm, and is approximately stable at 8×10 -8 ~1.2×10 -6 It can be seen that the present invention has a lower limiting loss at deep ultraviolet wavelengths.

[0060] Figure 6 The figure is a graph showing the relationship between the polarization extinction ratio (PER) and the wavelength of the embodiment. According to relevant theories, the shape change of the optical fiber structure can introduce birefringence, where PER can be used as an important indicator to judge the birefringence performance, and PER is the ratio of the polarization fundamental mode loss in the y direction to the polarization fundamental mode loss in the x direction. Figure 6As shown, the polarization extinction ratio at a wavelength of 210 nm is greater than 100, indicating that this embodiment has a good single polarization characteristic at 210 nm.

[0061] Figure 7 1 is a graph showing the relationship between the ratio of the minimum high-order mode extinction ratio (HOMER) and the wavelength of the embodiment. According to relevant theories, among all the properties of antiresonant optical fiber, the single-mode property is the most important property. The standard for judging the single-mode property is the HOMER value, such as Figure 7 As shown, the HOMER value at a wavelength of 210 nm is greater than 100, indicating that this embodiment has good single-mode characteristics at 210 nm.

[0062] Figure 8 is the dispersion of the fundamental mode of the embodiment at the corresponding wavelength. Figure 8 As shown in FIG. 1 , the hollow-core optical fiber constructed in this embodiment exhibits near-zero dispersion characteristics in the ultraviolet band of 180 nm to 300 nm, and the value of its group velocity dispersion is stable at -2×10 -5 ~1×10 -5 ps·nm -1 km -1 According to the fiber dispersion theory, dispersion will cause the optical signal to generate pulse broadening problems during fiber transmission due to different propagation speeds, which will affect the quality of fiber communication. Therefore, the closer the dispersion is to zero, the higher the transmission quality of the fiber.

[0063] Fig. 9 : is a graph showing the relationship between the nonlinear coefficient of the base film of the embodiment and the wavelength, such as Fig. 9 As shown in the figure, the nonlinear coefficient of the hybrid hollow-core optical fiber constructed in this embodiment is extremely low in the deep ultraviolet band of 180nm~300nm, and the corresponding value is stable at 0.00355~0.00587W -1 km -1 According to relevant theories, in a high-intensity electromagnetic field, the effect of any medium on light will become nonlinear. Since the core of the optical fiber is small, the field strength inside the core is very high. When the transmission distance is long, the nonlinear effect in the optical fiber will accumulate to a certain intensity and seriously interfere with the signal, while limiting the transmission performance of the system. Therefore, an extremely low nonlinear coefficient means that the optical fiber is less affected by nonlinear effects such as the four-wave mixing effect during the transmission of light.

[0064] In summary, the basic principles, 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 single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis, characterized in that: The optical fiber is sequentially arranged from outside to inside as an outer cladding region, an inner cladding region and an air core region; The outer cladding region is of kagome type, and the kagome mesh structure is composed of mesh hole rings formed by alternating circles and triangles; the outer contour of the kagome mesh structure is a regular polygon, and is inscribed in the circular ring base of the outer cladding; the inner contour of the kagome mesh structure is a quasi-rectangular shape, and the long side direction is the y direction of the plane coordinate system; every three circular hole rings are mutually cut and enclosed to form a triangular hole ring, and the mutually cut parts of the circular hole rings share the cladding tube, and the triangular hole rings enclosed share the cladding tube of the circular hole rings, and the cladding tube is not separately provided to enclose the triangular hole ring; The inner cladding region is a three-nested anti-resonance type, and is composed of a circular and two arc-shaped cladding tubes, or three arc-shaped cladding tubes to form a three-nested anti-resonance structure; the outermost cladding tube of the three-nested anti-resonance structure is a minor arc structure, and both ends are fused with the kagome mesh structure; when the three-nested anti-resonance structure is composed of a circular and two arc-shaped cladding tubes, it includes an arc cladding tube, an arc nested tube and a circular nested tube, the arc cladding tube belongs to the minor arc of the circle, the arc nested tube belongs to the major arc of the circle, and forms a double-layer structure with the arc cladding tube; the circular nested tube is nested in the double-layer structure, tangent to the circular hole ring of the kagome mesh structure and shares the cladding tube at the tangent point; The kagome mesh structure is fused with the three-nested anti-resonance structure to enclose an air core region; the air core region is a quasi-rectangular region, and the long side direction is the x direction of the plane coordinate system.

2. The single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis according to claim 1, characterized in that: The outer diameter of the circular hole ring of the kagome mesh structure in the outer cladding region is 12 μm to 15 μm.

3. The single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis according to claim 1, characterized in that: The outer contour of the kagome mesh structure in the outer cladding area is a regular hexagon, and the regular hexagon has three layers of circular hole rings along the y direction and two layers of circular hole rings on the other sides; the three-layer circular hole ring structure along the y direction is divided into two groups and is symmetrically distributed along the y axis.

4. The single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis according to claim 1, characterized in that: The arc cladding tube is a minor arc with an outer diameter of 34μm~36μm and an arc of 110°~150°; the arc nested tube is a major arc with an outer diameter of 17μm~19μm and an arc of 270°~300°; the outer diameter of the circular nested tube is 12μm~15μm.

5. The single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis according to claim 1, characterized in that: In the three-nested anti-resonance structure, the gap between the outermost cladding tube and the middle cladding tube is 1 μm to 3 μm, and the gap between the middle cladding tube and the innermost cladding tube is 9 μm to 11 μm.

6. The single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis according to claim 1, characterized in that: The three-nested anti-resonance structures are in two sets and are symmetrically distributed along the x-axis.

7. The single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis according to claim 1, characterized in that: The thickness of the cladding tubes of the circular hole rings and the triangular hole rings of the kagome mesh structure and the thickness of various cladding tubes of the three-nested anti-resonance structure are the same, and are 710nm~730nm.

8. The single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis according to claim 1, characterized in that: The annular base, the kagome mesh hole ring, and the cladding tube of the three-nested anti-resonance structure are made of the same material, which is silicon dioxide or high-hydroxyl pure silicon with a refractive index of 1.4878-1.5853.

9. The single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis according to claim 1, characterized in that: The circular hole rings, the triangular hole rings, the internal space of the three-nested anti-resonance structure, and the air core area of ​​the kagome mesh structure are all filled with air, and the refractive index is 1.

10. The single-mode single-polarization hollow-core optical fiber for deep ultraviolet spectroscopy analysis according to claim 1, characterized in that: The working wavelength of the optical fiber is at 210 nm.

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