Hollow microstructured optical fiber with additive markings, preform and drawing detection method

Abstract

The application discloses a hollow microstructure optical fiber with additive marks, a preform and a drawing detection method. The optical fiber comprises a cladding hollow sleeve and a plurality of anti-resonant microstructure units arranged and attached to the inner wall of the cladding hollow sleeve, and the anti-resonant microstructure units are used for forming an air core area with an inscribed circle size. The plurality of anti-resonant microstructure units are rotationally symmetrical. One or more additive mark units are arranged outside the core, so that the end face structure of the hollow microstructure optical fiber has asymmetry. The area of the additive mark unit accounts for 0.002% to 2% of the area of the cladding hollow sleeve. The hollow microstructure optical fiber with additive marks can mark and identify each anti-resonant microstructure unit in the drawing detection through the additive mark unit, judge the geometric uniformity of the hollow microstructure optical fiber, and provide reference and guidance for the production of the subsequent hollow microstructure optical fiber preform, and timely process adjustment and improvement.

Description

Technical Field

[0001] This invention belongs to the field of optical communication, and more specifically, relates to hollow microstructure optical fibers with additive manufacturing markings, preforms, and methods for detecting fiber drawing. Background Technology

[0002] Hollow-core microstructured optical fibers are characterized by their simple structure, single-mode optical guidance, and wide transmission spectrum, making them important for applications in fields such as light-filled material interaction, nonlinear optics, gas detection, gas laser generation, and optofluidics. Large-aperture fiber cores exhibit ultra-low Rayleigh scattering, low nonlinear coefficients, and tunable dispersion, providing a higher laser damage threshold and potential applications in high-power laser transmission, ultraviolet / mid-infrared light transmission, pulse compression, and optical soliton transmission. The ultra-low loss, low dispersion, low nonlinearity, and near-light-speed propagation of the air core enable the development of communication transmission and devices using hollow-core microstructured optical fibers, laying the foundation for the construction and development of next-generation ultra-high-capacity, low-latency, and high-speed optical communication systems.

[0003] Even though hollow-core microstructured optical fibers have significant advantages in design and application, their transmission loss has consistently been higher than that of traditional silica optical fibers. Recent discoveries have shown that hollow-core microstructured optical fibers based on the anti-resonance principle, with proper structural design, can effectively reduce transmission loss and possess the potential to serve as ultra-long-distance communication optical fibers. Further reducing attenuation is a crucial issue in the manufacturing of hollow-core microstructured optical fibers.

[0004] Although known hollow-core antiresonant fibers, especially those with nested structural elements, can significantly reduce fiber attenuation, their manufacturing process differs fundamentally from that of existing solid fibers. The microscopic three-dimensional structure of hollow-core microstructured fibers is the basis for their light guiding. Maintaining or forming a specific microstructure requires a continuous gas flow during the fiber drawing process. Due to factors such as the inhomogeneity of raw materials, deviations during the stacking of nested structural elements, and uneven thermal field distribution during drawing, the antiresonant structural elements in the drawn hollow-core antiresonant fibers may exhibit variations in size. Figure 1 As shown. This geometric inhomogeneity will greatly affect the transmission loss of hollow anti-resonant optical fibers. Because this manufacturing method is revolutionary compared to existing solid optical fibers, it is impossible to improve the geometric inhomogeneity using the methods typically employed in solid optical fibers, such as increasing the size of the fiber preform. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a hollow microstructure optical fiber with additive marking, a preform, and a fiber drawing inspection method. The additive marking unit can mark and identify each anti-resonant microstructure unit during fiber drawing inspection, providing guidance for the production and operation of hollow microstructure optical fibers.

[0006] According to one aspect of the invention, a hollow microstructured optical fiber with additive markings is provided, comprising a cladding hollow sleeve and a plurality of anti-resonant microstructure units arranged and attached to the inner wall of the cladding hollow sleeve, the anti-resonant microstructure units being used to form an air core region of the size of their inscribed circle; the plurality of anti-resonant microstructure units are rotationally symmetrical.

[0007] The distance D between the additive marking unit and the center of the optical fiber structure is such that:

[0008] E D ≤0.5%

[0009]

[0010] Among them, E D Let f(r,θ) be the energy distribution percentage of the region on the cross-section of the optical fiber that is more than D away from the center of the optical fiber structure; for a point in the polar coordinate system with the center of the optical fiber structure as the pole within the cross-section of the optical fiber, its polar radius is r, its polar angle is θ, and f(r,θ) is the normalized optical field distribution function of the cross-section of the optical fiber; R is the radius of the optical fiber.

[0011] On the cross-section of the hollow microstructured optical fiber, the area enclosed by the outer contour of a single additive marking unit accounts for 0.002% to 2% of the cladding area.

[0012] Preferably, the outer contour of the cladding hollow sleeve is circular; the additive marking unit is a solid glass strip or a hollow glass tube, and the outer contour of the additive marking unit is circular, elliptical, rectangular and / or polygonal.

[0013] Preferably, the distance D between the additive marking unit and the center of the optical fiber structure is such that: E D ≤0.1%; The distance D between the additive marking unit and the center of the optical fiber structure satisfies: D≥d, where d is the core diameter of the hollow microstructure optical fiber.

[0014] Preferably, the additive marking unit is attached to the inner wall of the hollow sleeve, and preferably located outside the anti-resonance microstructure unit.

[0015] Preferably, the additive marking unit is attached between adjacent anti-resonant microstructure units, close to one of the anti-resonant microstructure units.

[0016] Preferably, on the inner wall of the hollow sleeve, the arc between the attachment point of the additive marking unit and the attachment point of the anti-resonant microstructure unit close to the additive marking unit is R1, and the arc between the attachment points of two adjacent anti-resonant microstructure units is R2, with R1 / R2 = 1 / 6 to 1 / 3.

[0017] Preferably, the inner wall of the cladding hollow sleeve has a plurality of additive marking units, and the plurality of additive marking units have different outer contour shapes, types and / or areas.

[0018] According to another aspect of the invention, a preform of a hollow microstructured optical fiber with additive markings is also provided, comprising a glass element for drawing the hollow microstructured optical fiber with additive markings.

[0019] According to another aspect of the present invention, a method for detecting the drawing of a preform of a hollow microstructure optical fiber is also provided, comprising the following steps:

[0020] (1) Cut the hollow microstructure optical fiber with additive marking at a preset position;

[0021] (2) Image the cut end face obtained in step (1) using transmitted light or reflected light to obtain an image of the end face of the hollow microstructure fiber at that location.

[0022] (3) For the end face image obtained in step (2), anti-resonance microstructure identification is performed based on its additive marking unit to obtain the image of each anti-resonance microstructure unit;

[0023] (4) Extract geometric parameters from the image of the anti-resonant microstructure unit obtained in step (3) to determine the geometric uniformity of the hollow microstructure fiber.

[0024] Preferably, step (2) involves using a microscope to image the end face.

[0025] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0026] 1) The hollow microstructure optical fiber with additive marking of the present invention can quickly identify the anti-resonant microstructure unit in the hollow microstructure optical fiber, which facilitates online control of the size uniformity of the anti-resonant microstructure unit and helps to reduce the transmission loss of the hollow microstructure optical fiber.

[0027] 2) The hollow microstructure optical fiber with additive marking of the present invention can mark and identify each anti-resonant microstructure unit in the fiber drawing inspection through the additive marking unit, judge and analyze the geometric uniformity of the hollow microstructure optical fiber, thereby providing reference and guidance for the subsequent production of hollow microstructure optical fiber preforms, and timely process adjustment and improvement to control geometric uniformity. It can ensure the geometric uniformity of hollow microstructure optical fiber in the subsequent manufacturing process of hollow microstructure optical fiber from preforms.

[0028] 3) During the coupling process of hollow microstructured optical fiber, it is easier to identify different anti-resonant microstructure units, thereby reducing the coupling loss of hollow microstructured optical fiber. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an unmarked hollow microstructure optical fiber;

[0030] Figure 2 This is a schematic diagram of the hollow microstructure optical fiber preform with additive manufacturing markings provided in Embodiment 1 of the present invention;

[0031] Figure 3 This is a schematic diagram of pressure control during the drawing process of a hollow microstructure optical fiber preform with additive markings provided in Embodiment 1 of the present invention;

[0032] Figure 4 This is a schematic diagram of pressure control during the drawing process of a hollow microstructure optical fiber preform with additive markings provided in Embodiment 2 of the present invention;

[0033] Figure 5 This is a schematic diagram of pressure control during the drawing process of a hollow microstructure optical fiber preform with additive markings provided in Embodiment 3 of the present invention.

[0034] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-anti-resonant microstructure unit, 2-additive marking unit, 3-clad hollow sleeve. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0036] According to one aspect of the invention, a hollow microstructure optical fiber with additive markings is provided, comprising a cladding hollow sleeve 3 and a plurality of anti-resonant microstructure units 1 arranged and attached to the inner wall of the cladding hollow sleeve 3, the anti-resonant microstructure units 1 having an air core region tangent to the inner wall of the cladding hollow sleeve 3; the plurality of anti-resonant microstructure units 1 are rotationally symmetrical.

[0037] In the region where the optical fiber energy distribution on the outer side of the fiber core is less than 0.5%, one or more additive marking units 2 are provided, so that the end face structure of the hollow microstructure optical fiber has asymmetry;

[0038] The hollow microstructure optical fiber with additive manufacturing markings includes a cladding hollow sleeve 3 and a plurality of anti-resonant microstructure units 1 arranged and attached to the inner wall of the cladding hollow sleeve 3. The anti-resonant microstructure units 1 have an air core region that is tangent to the inner wall of the cladding hollow sleeve 3. The plurality of anti-resonant microstructure units 1 are rotationally symmetrical.

[0039] In the region where the optical fiber energy distribution on the outer side of the fiber core is less than 0.5%, one or more additive marking units 2 are provided, so that the end face structure of the hollow microstructure optical fiber has asymmetry;

[0040] On the cross-section of the hollow microstructure optical fiber, the area of ​​a single additive marking unit 2 accounts for 0.002% to 2% of the cladding area; the cladding includes an outer cladding formed by a hollow sleeve and an anti-resonant cladding formed by anti-resonant microstructure units.

[0041] Preferably, the outer contour of the cladding hollow sleeve 3 is circular; the additive marking unit 2 is a solid glass strip or a hollow glass tube, and the outer contour of the additive marking unit 2 is circular, elliptical, rectangular and / or polygonal.

[0042] Preferably, the additive marking unit 2 is disposed in the region outside the fiber core where the optical fiber energy distribution is less than 0.1%; the additive marking unit 2 is disposed in the corresponding region of the optical fiber preform used to form a region where the distance from the fiber core to the center of the optical fiber structure exceeds the diameter of the fiber core.

[0043] Preferably, the additive marking unit 2 is attached to the inner wall of the hollow cladding sleeve 3, and is preferably located outside the anti-resonance microstructure unit 1.

[0044] Preferably, the additive marking unit 2 is attached between adjacent anti-resonant microstructure units 1, close to one of the anti-resonant microstructure units 1.

[0045] Preferably, on the inner wall of the hollow cladding sleeve 3, the arc between the attachment point of the additive marking unit 2 and the attachment point of the anti-resonant microstructure unit 1 close to the additive marking unit 2 is R1, and the arc between the attachment points of two adjacent anti-resonant microstructure units 1 is R2, with R1 / R2 = 1 / 6 to 1 / 3.

[0046] Preferably, the inner wall of the cladding hollow sleeve 3 has a plurality of additive marking units 2, and the plurality of additive marking units 2 have different outer contour shapes, types and / or areas; the type of additive marking unit is either solid or hollow additive marking unit.

[0047] According to another aspect of the invention, a preform of a hollow microstructured optical fiber with additive marking is provided, comprising a glass element for drawing into the hollow microstructured optical fiber with additive marking.

[0048] Currently, there is no mature and feasible technical solution for detecting the geometric uniformity of antiresonant microstructured optical fibers. This patent concept uses an image-based method for end-face detection to extract geometric features and solve the problem of geometric uniformity detection. The difficulty of image-based detection lies in the end faces of antiresonant microstructured optical fibers, which theoretically possess perfect symmetry and are difficult to distinguish from each other. Some antiresonant microstructured optical fibers already have asymmetrical end faces, such as CN115185034A, which uses a circular nested structure within one capillary and U-shaped nested structures within the remaining capillaries to form a single-mode, low-loss, structurally simple, single-polarization hollow-core antiresonant optical fiber suitable for long-distance applications and easy to fabricate. Patent CN113885120A proposes a hollow-core microstructured optical fiber with a two-layer cladding structure. The first cladding layer defines the outer surface of the inner unsealed cladding; the second cladding layer is unsealed and has a microchannel running through the optical fiber; the second cladding layer is tightly connected to the first cladding layer and defines the inner surface of the inner unsealed cladding; the capillary layer, as an anti-resonant layer, is attached to the inner surface of the second cladding layer and, together with the second cladding layer, defines the fiber core with an effective radius; the capillaries in the capillary layer are spaced apart, and there is a gap between adjacent capillaries; the first cladding layer can effectively ensure the mechanical reliability of the optical fiber, and the second cladding layer, with its unsealed structure, can greatly reduce the complexity of post-processing of the optical fiber and improve its performance, solving the problems of loss characteristics and processing complexity of existing anti-resonant hollow-core microstructure optical fibers.

[0049] While the aforementioned patents propose asymmetric hollow microfiber structures, they primarily address polarization issues and post-processing problems in fiber optic sensing. None of them offer solutions for controlling the geometric uniformity during the fiber drawing process. Therefore, they do not consider the difficulty of imaging the fiber end face or whether the asymmetry is sufficiently pronounced to distinguish anti-resonant microstructure units in the end face image. Additive marking units, compared to other types of markings, do not require precise machining, do not affect existing preform assembly processes, and have the advantage of simple setup. However, considering asymmetric marking, a crucial issue is whether it affects the performance and drawing difficulty of the hollow microfiber. Specifically, sufficiently prominent additive marking units require a large enough area, which makes them more likely to impact the transmission performance and drawing difficulty of the microfiber.

[0050] Through ingenious design, the additive marking unit is placed in a region outside the fiber core where the fiber energy distribution is less than 0.5%, preferably less than 0.1%, to minimize the impact on the transmission performance of the hollow-core microstructure fiber. That is:

[0051] The distance D between the additive marking unit and the center of the optical fiber structure is such that:

[0052] ED ≤0.5%

[0053]

[0054] Among them, E D Let f(r,θ) be the energy distribution percentage of the region on the cross-section of the optical fiber that is more than D away from the center of the optical fiber structure; for a point in the polar coordinate system with the center of the optical fiber structure as the pole within the cross-section of the optical fiber, its polar radius is r, its polar angle is θ, and f(r,θ) is the normalized optical field distribution function of the cross-section of the optical fiber; R is the radius of the optical fiber.

[0055] Preferred option, E D ≤0.1%.

[0056] Preferably, the distance D between the additive marking unit and the center of the optical fiber structure satisfies: D≥d, where d is the core diameter of the hollow microstructure optical fiber.

[0057] In a preferred embodiment, the marking unit is positioned on the inner wall of the hollow sleeve, outside the anti-resonant microstructure unit, i.e., between adjacent anti-resonant microstructure sleeves. This not only minimizes the impact on transmission performance but also reduces the influence on airflow within the sleeve during the drawing process, thus reducing sleeve deformation or structural impact. More preferably, it is positioned closer to the adjacent microstructure unit. This effectively disrupts the symmetry of the fiber end face, improving the identifiability of the anti-resonant microstructure unit, while also reducing the impact on airflow within the sleeve during drawing. The drawing process requires the introduction of a large amount of gas, which is a key technical difference between anti-resonant microstructure fiber and other fibers such as solid fiber and photonic crystal fiber. Minimizing the impact on the airflow during drawing is one of the key considerations for the placement of the additive marking unit. Meanwhile, since gas needs to be introduced into the anti-resonant microstructure unit during fiber drawing, and the gas pressure even exceeds the gas pressure at the center of the sleeve, it is necessary to avoid unexpected changes in the thickness and shape of the anti-resonant microstructure unit due to the setting of the additive marking unit, such as adhesion to the additive marking unit, excessive thickness deviation, etc., which would ultimately lead to the deterioration of fiber performance. The preferred setting of the additive marking unit is such that the arc between the attachment points of the additive marking unit and the anti-resonant microstructure unit is R1, and the arc between the attachment points of two adjacent anti-resonant microstructure units is R2, with R1 / R2 = 1 / 6 to 1 / 3. This ensures that the additive marking unit with an easily observable area is set in a suitable position, forming obvious asymmetric markings, while having little impact on the fabrication of the anti-resonant microstructure unit, avoiding adhesion between the additive marking unit and the anti-resonant microstructure unit during fiber drawing, or changes in the shape of anti-resonant microstructure units that are close in position.

[0058] According to another aspect of the present invention, a method for detecting the drawing of a preform of a hollow microstructure optical fiber is also provided, comprising the following steps:

[0059] (1) Cut the hollow microstructure optical fiber with additive marking at a preset position;

[0060] (2) Image the cut end face obtained in step (1) using transmitted light or reflected light to obtain an image of the end face of the hollow microstructure fiber at that location.

[0061] (3) For the end face image obtained in step (2), anti-resonance microstructure identification is performed based on its additive marking unit 2 to obtain the image of each anti-resonance microstructure unit 1;

[0062] (4) Extract geometric parameters from the image of the anti-resonant microstructure unit obtained in step (3) to determine the geometric uniformity of the hollow microstructure fiber.

[0063] Preferably, step (2) involves using a microscope to image the end face.

[0064] A typical hollow microstructure optical fiber with additive marking includes an anti-resonant microstructure unit 1, an additive marking unit 2, and a cladding hollow core tube 3. The number of anti-resonant microstructure units 1 is n≥3, and m additive marking units 2 are inserted between the anti-resonant microstructure units 1, where m≥1.

[0065] Furthermore, the anti-resonant microstructure unit 1 is composed of components with single-layer or multi-layer negative curvature structures.

[0066] Furthermore, the additive marking unit 2 may be composed of a rod, tube, plate or a combination thereof, and may be circular, elliptical, rectangular, polygonal or the like.

[0067] The above-mentioned method for fabricating hollow microstructured optical fibers with additive markings includes the following steps:

[0068] Step 1: Preparation of anti-resonance microstructure unit 1: The required capillary tube is drawn into the mother tube in a high-temperature wire drawing furnace; the capillary tube can be further processed according to design requirements, such as cutting, grinding, welding, etc.

[0069] Step 2: Prepare additive marking unit 2: The required capillary tube or capillary rod is drawn in a high-temperature wire drawing furnace using a mother tube or mother rod; the capillary tube or capillary rod can be used directly as additive marking unit 2, or it can be processed in a secondary manner, such as cutting, grinding, or welding, before being used as additive marking unit 2.

[0070] Step 3, Preform Stacking: The anti-resonant microstructure unit 1 obtained in Step 1 and the additive marking unit 2 obtained in Step 2 are stacked and assembled in the cladding hollow sleeve 3 to form a hollow microstructure optical fiber preform with additive marking.

[0071] Step 4: Directly draw the hollow microstructure fiber preform with additive markings from Step 3 into a hollow microstructure fiber, or first draw it into an intermediate preform and then insert it into an intermediate sleeve to draw it into a hollow microstructure fiber. During the drawing process, the additive marking unit 2 can quickly distinguish the correspondence between the anti-resonant microstructure unit 1 in the fiber and the anti-resonant microstructure unit 1 in the preform. Therefore, by controlling the air pressure within the anti-resonant microstructure unit 1 in the preform, the size of the anti-resonant microstructure unit 1 in the fiber can be adjusted.

[0072] Furthermore, the anti-resonance microstructure unit 1, the additive marking unit 2, and the cladding hollow sleeve 3 can be made of high-purity silicon dioxide, doped quartz (doped with one or more elements such as germanium, fluorine, chlorine, boron, and aluminum), multi-component glass, plastic, etc.

[0073] Furthermore, the hollow microstructure optical fiber has a cladding diameter of 100 μm or greater.

[0074] Furthermore, the hollow microstructure optical fiber prepared by the method of the present invention has low transmission loss, with the lowest transmission loss being ≤30dB / km and even better being ≤1dB / km.

[0075] Furthermore, the hollow microstructure optical fiber prepared by the method of the present invention has a low fusion splicing loss, with a self-fusion splicing loss of ≤0.5dB.

[0076] The following is an example:

[0077] Example 1

[0078] like Figure 2 As shown, a capillary tube is first fabricated from a mother tube to serve as the anti-resonance microstructure unit 1. The outer diameter of the anti-resonance microstructure unit 1 is 6.7 mm, and the wall thickness is 0.4 mm. Then, another capillary tube is drawn from other tubes to serve as the additive marking unit 2. The additive marking unit 2 is a hollow capillary tube with an outer diameter of 1.5 mm and a wall thickness of 0.35 mm. Five anti-resonance microstructure units 1 and one additive marking unit 2 are stacked in a cladding hollow sleeve 3 to form... Figure 2 The image shows a hollow microstructured fiber preform with additive manufacturing markings. These preforms can be directly drawn into hollow microstructured fibers in a drawing furnace. However, during the drawing process, temperature fluctuations, without applied pressure, can cause inconsistencies in the dimensions of the anti-resonant microstructure units, such as… Figure 1 The maximum deviation of the outer diameter of the anti-resonant microstructure unit 1 shown is 13%. Therefore, it is necessary to introduce gases at different pressures into the anti-resonant microstructure unit to ensure uniformity of its dimensions. Figure 3As shown, the required air pressure in the anti-resonant microstructure unit 1 is identified by the additive marking unit 2. P1, P2, P3, P4, and P5 represent the air pressure values ​​in the anti-resonant microstructure unit 1, which are 24.2 mbar, 26.6 mbar, 22.5 mbar, 26.7 mbar, and 24.5 mbar, respectively. The maximum deviation of the outer diameter of the anti-resonant microstructure unit 1 is 3.5%, and its attenuation at 1550 nm is 4.2 dB / km. During the fusion splicing of this hollow microstructure fiber, the orientation of the anti-resonant microstructure unit 1 can be identified by the additive marking unit 2, thereby achieving more precise splicing, with a minimum splicing loss of 0.44 dB.

[0079] Example 2

[0080] like Figure 4 As shown, two sizes of capillaries are first prepared using a mother tube: a large capillary with an outer diameter of 8.2 mm and a wall thickness of 0.33 mm, and a small capillary with an outer diameter of 3.9 mm and a wall thickness of 0.36 mm. Then, an additive marking unit 2 is drawn using a mother rod. The additive marking unit 2 is a solid round rod with a diameter of 1.36 mm. The large and small capillaries are assembled by welding to form an anti-resonance microstructure unit 1. Five anti-resonance microstructure units 1 and one additive marking unit 2 are stacked in a cladding hollow sleeve 3 as shown. Figure 4 The image shows a hollow microstructure optical fiber preform with additive manufacturing markings. This preform can be drawn into an intermediate preform with an outer diameter of 8 mm in a drawing furnace, and then inserted into an intermediate sleeve with an outer diameter of 17 mm and an inner diameter of 8.5 mm for fiber drawing. Similar to the previous embodiment, different gas pressures are introduced into the anti-resonant microstructure unit 1 to ensure uniform dimensions. P1, P2, P3, P4, and P5 represent the gas pressures within the large capillary tube of the anti-resonant microstructure unit, with values ​​of 18.4 mbar, 19.6 mbar, 20.6 mbar, 20.8 mbar, and 19.5 mbar, respectively. P6, P7, P8, P9, and P10 represent the air pressure within the small capillaries of the anti-resonant microstructure unit, with values ​​of 82.4 mbar, 84.8 mbar, 85.2 mbar, 85.8 mbar, and 84.5 mbar, respectively. The drawn hollow-core microstructure fiber exhibits a maximum outer diameter deviation of 4.5% for the large capillary within its anti-resonant microstructure unit and 2.7% for the small capillary within its anti-resonant microstructure unit. Its attenuation at 1550 nm is 0.5 dB / km. During fusion splicing of this hollow-core microstructure fiber, the capillary orientation can be identified using marking units, and more precise splicing can be achieved through the rotation function of the fusion splicer, with a minimum splice loss of 0.32 dB.

[0081] Example 3

[0082] like Figure 5 As shown, two sizes of capillaries are first prepared using a mother tube: a large capillary with an outer diameter of 6.4 mm and a wall thickness of 0.25 mm, and a small capillary with an outer diameter of 3.2 mm and a wall thickness of 0.28 mm. Then, additive marking units 2 are drawn from a square mother rod. The additive marking units 2 are solid square rods with a side length of 0.95 mm. The large and small capillaries are assembled by welding to form an anti-resonance microstructure unit 1. Five anti-resonance microstructure units 1 and two additive marking units 2 are stacked in a cladding hollow sleeve 3 as shown. Figure 5 The image shows a hollow microstructure optical fiber preform with additive manufacturing markings. This preform can be drawn into an intermediate preform with an outer diameter of 6.2 mm in a drawing furnace, and then inserted into an intermediate sleeve with an outer diameter of 13 mm and an inner diameter of 6.8 mm for fiber drawing. Similar to the previous embodiment, different gas pressures are introduced into the anti-resonant microstructure unit to ensure uniform dimensions of the anti-resonant microstructure unit 1. P1, P2, P3, P4, and P5 represent the gas pressures within the large capillary tube of the anti-resonant microstructure unit 1, with values ​​of 33.6 mbar, 33.9 mbar, 34.5 mbar, 34.8 mbar, and 34.5 mbar, respectively. P6, P7, P8, P9, and P10 represent the air pressure within the small capillaries of the anti-resonant microstructure unit 1, with values ​​of 112.2 mbar, 112.8 mbar, 113.2 mbar, 113.8 mbar, and 112.4 mbar, respectively. The drawn hollow-core microstructure fiber exhibits a maximum outer diameter deviation of 2.9% for the large capillary within its anti-resonant microstructure unit and 2.5% for the small capillary within its anti-resonant microstructure unit. Its attenuation at 1550 nm is 0.4 dB / km. During fusion splicing of this hollow-core microstructure fiber, the capillary orientation can be identified using marking units, and more precise splicing can be achieved through the rotation function of the fusion splicer, with a minimum splice loss of 0.28 dB.

[0083] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hollow microstructure optical fiber with additive manufacturing markings, characterized in that, It includes a clad hollow sleeve and a plurality of anti-resonance microstructure units arranged and attached to the inner wall of the clad hollow sleeve, wherein the anti-resonance microstructure units are used to form an air core region with an inscribed circle size; the plurality of anti-resonance microstructure units are rotationally symmetrical. One or more additive marking units are provided on the outer side of the fiber core, which makes the end face structure of the hollow microstructure fiber asymmetrical; The distance between the additive marking unit and the center of the optical fiber structure , so that: ； ； in, The distance between the cross-section of the optical fiber and the center of the optical fiber structure is greater than The energy distribution percentage in the region; for a point in the polar coordinate system with the center of the fiber structure as the pole within the cross-section of the fiber, its polar radius is The polar angle is , is the normalized optical field distribution function of the optical fiber cross section; The radius of the optical fiber; On the cross-section of the hollow microstructured optical fiber, the area enclosed by the outer contour of a single additive marking unit accounts for 0.002% to 2% of the cladding area.

2. The hollow microstructure optical fiber with additive manufacturing markings as described in claim 1, characterized in that, The outer contour of the cladding hollow sleeve is circular; the additive marking unit is a solid glass strip or a hollow glass tube, and the outer contour of the additive marking unit is circular, elliptical, rectangular and / or polygonal.

3. The hollow microstructure optical fiber with additive marking as described in claim 1 or 2, characterized in that, The distance between the additive marking unit and the center of the optical fiber structure , so that: The distance between the additive marking unit and the center of the optical fiber structure satisfy: ,in The core diameter is the diameter of the hollow-core microstructure optical fiber.

4. The hollow microstructure optical fiber with additive manufacturing markings as described in claim 3, characterized in that, The additive marking unit is attached to the inner wall of the hollow sleeve.

5. The hollow microstructure optical fiber with additive marking as described in claim 4, characterized in that, It is located on the outside of the anti-resonant microstructure unit.

6. The hollow microstructure optical fiber with additive marking as described in claim 5, characterized in that, The additive marking unit is attached between adjacent anti-resonant microstructure units, close to one of the anti-resonant microstructure units.

7. The hollow microstructure optical fiber with additive marking as described in claim 6, characterized in that, On the inner wall of the hollow sleeve, the arc between the attachment point of the additive marking unit and the attachment point of the anti-resonant microstructure unit close to the additive marking unit is R1, and the arc between the attachment points of two adjacent anti-resonant microstructure units is R2, with R1 / R2 = 1 / 6 to 1 / 3.

8. The hollow microstructure optical fiber with additive marking as described in claim 1, characterized in that, The inner wall of the cladding hollow sleeve has multiple additive marking units, and the multiple additive marking units have different outer contour shapes, types and / or areas.

9. A preform of a hollow microstructured optical fiber with additive manufacturing markings, characterized in that, Includes hollow microstructured optical fiber glass with additive markings as described in any one of claims 1 to 8, used for drawing the fiber.

10. A method for detecting the drawing of preforms of hollow microstructured optical fibers, characterized in that, Includes the following steps: (1) Cut the hollow microstructure optical fiber with additive marking as described in any one of claims 1 to 8 at a predetermined position; (2) Image the cut end face obtained in step (1) using transmitted or reflected light to obtain an image of the end face of the hollow microstructure fiber at that location. (3) For the end face image obtained in step (2), anti-resonance microstructure identification is performed based on its additive marking unit to obtain the image of each anti-resonance microstructure unit; (4) Extract geometric parameters from the image of the anti-resonant microstructure unit obtained in step (3) and determine the geometric uniformity of the hollow microstructure fiber.

11. The method for detecting the drawing of hollow microstructure optical fiber preforms as described in claim 10, characterized in that, Step (2) Use a microscope to image the end face.

Images