Hollow-core optical fiber with multi-layer opening structure anti-resonance layer

Abstract

The invention, which relates to the technical field of the hollow-core optical fiber, provides a hollow-core optical fiber with an anti-resonance layer having a multi-layer opening structure, comprising an outer cladding sleeve, an anti-resonance area and a hollow-core fiber core area enclosed by the anti-resonance area. The anti-resonance area comprises a plurality of anti-resonance units, each anti-resonance unit comprises at least one anti-resonance layer of an opening structure, and the edges of the two sides of an opening of each anti-resonance layer are connected with the inner wall of the outer cladding sleeve through two parallel thin walls. The optical fiber has the beneficial effects that multiple anti-resonance effects are generated through the opening anti-resonance layer, so that a light field is prevented from leaking to the cladding from the fiber core, and the light field is effectively limited in the hollow fiber core area for transmission; each anti-resonance layer is indirectly connected with the inner wall of the outer sleeve through a parallel thin wall, so that a connection node is far away from the fiber core, node coupling is reduced, and leakage of a light field to the cladding is weakened. The anti-resonance layer and the sleeve form a closed cavity, so that a high-refractive-index area is compared with a low-refractive-index medium in the cavity, a specific wavelength is reflected, a light field is prevented from being coupled with a cladding mode, and the light limiting capability is enhanced.

Description

Technical Field

[0001] This invention relates to the field of hollow optical fiber technology, and more particularly to a hollow optical fiber with a multi-layered open anti-resonant layer. Background Technology

[0002] Hollow-core optical fiber uses an air core as the light guiding medium. Because air has ultra-low Rayleigh scattering and nonlinear coefficient, hollow-core optical fiber can, in principle, break through the transmission limit of solid-core optical fiber and achieve low delay, low dispersion, low loss, and high-power laser transmission.

[0003] Based on the light guiding mechanism, hollow optical fibers are mainly divided into photonic bandgap hollow optical fibers and anti-resonant hollow optical fibers. Among them, photonic bandgap hollow optical fibers have a narrower transmission bandwidth. At the same time, the light field in the air core has a strong coupling with the surface mode of the cladding structure, which easily leads to the leakage of the core light field into the cladding structure, resulting in generally high transmission loss of the light field.

[0004] Antiresonant hollow-core fiber has been proven to be a fiber structure capable of achieving low transmission loss. Its light-guiding principle involves a well-designed structure that prevents the optical field modes propagating in the air core from coupling with those in the antiresonant cladding (quartz medium), thus effectively confining the optical field within the air core for low-loss transmission. Theoretically, the transmission loss of antiresonant hollow-core fiber is expected to surpass the Rayleigh scattering limit, thereby lowering the intrinsic transmission loss of solid-core fiber. Therefore, how to better prevent the coupling between the optical field modes in the air core and the antiresonant cladding material is a key technical challenge in the development and fabrication of low-loss antiresonant hollow-core fiber. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides a hollow optical fiber with a multi-layered open structure anti-resonance layer, including an outer cladding tube, an anti-resonance region connected to the inner wall of the outer cladding tube, and a hollow fiber core region surrounded by the anti-resonance region. The anti-resonance region includes multiple anti-resonance units, and each anti-resonance unit includes at least one anti-resonance layer with an open structure. The two sides of the opening of the anti-resonance layer are connected to the inner wall of the outer sheath through two parallel thin walls.

[0006] Preferably, each anti-resonance unit includes two anti-resonance layers, namely an inner anti-resonance layer and an outer anti-resonance layer; The opening edges of the inner and outer anti-resonance layers are connected to the inner wall of the outer cladding sleeve through their respective parallel thin walls.

[0007] Preferably, each anti-resonance unit further includes an open negative curvature anti-resonance layer surrounding the outer anti-resonance layer, with the two sides of the opening of the negative curvature anti-resonance layer directly connected to the inner wall of the outer sheath.

[0008] Preferably, a plurality of first circular solid structures are further filled between the parallel thin wall corresponding to the inner anti-resonance layer and the parallel thin wall corresponding to the outer anti-resonance layer; A second circular solid structure is also provided on the outer surface of the parallel thin wall corresponding to the outer anti-resonance layer near the outer cladding sleeve.

[0009] Preferably, the diameter of the anti-resonant layer is greater than the distance between its two corresponding parallel thin walls.

[0010] Preferably, a closed cavity is formed between the inner anti-resonance layer and the outer anti-resonance layer, and the closed cavity is filled with air or is in a vacuum state.

[0011] Preferably, the inner diameter of the outer sheath is larger than the diameter of the outer anti-resonant layer, and the diameter of the outer anti-resonant layer is larger than the diameter of the inner anti-resonant layer.

[0012] Preferably, the hollow fiber core region is filled with air or is in a vacuum state.

[0013] Preferably, the outer sheath and the anti-resonance layer are made of silicon dioxide, a plastic polymer, or doped glass.

[0014] Preferably, the length of the parallel thin wall is greater than 7 micrometers.

[0015] The above technical solution has the following advantages or beneficial effects: 1. Set at least one anti-resonant layer with an open structure. Through multiple anti-resonance effects, reflect light waves and prevent the light field from leaking from the fiber core to the cladding, thereby better confining the light field to the hollow fiber core region for transmission.

[0016] 2. Each anti-resonant layer is connected to the inner wall of the outer cladding tube via two parallel thin walls, rather than directly. The parallel thin walls have a certain length. This design allows the connection nodes to be located far from the fiber core region. The use of parallel thin walls to connect reduces node coupling, thereby weakening the coupling of the optical field in the fiber core to the cladding.

[0017] 3. The open structure of the anti-resonance layer connects with the inner wall of the outer cladding tube to form a closed cavity, which helps to generate anti-resonance conditions. As a high-refractive-index region, the anti-resonance layer contrasts with the low-refractive-index medium inside the cavity, reflecting light of a specific wavelength and preventing the optical field from coupling with the cladding mode. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the hollow optical fiber in a preferred embodiment of the present invention. Figure 2This is a schematic diagram of the hollow optical fiber in a preferred embodiment of the present invention, in Embodiment 2. Figure 3 This is a schematic diagram of the hollow optical fiber in a preferred embodiment of the present invention, specifically embodiment three. Figure 4 This is a schematic diagram of the hollow optical fiber in Embodiment 4, which is a preferred embodiment of the present invention. Figure 5 A schematic diagram of the structure of a single anti-resonant unit in Embodiment 4, which is a preferred embodiment of the present invention; Figure 6 The simulation test results of the hollow optical fiber in Embodiment 4 are shown in the preferred embodiment of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment; other embodiments that conform to the spirit of the present invention may also fall within the scope of the present invention.

[0020] In a preferred embodiment of the present invention, based on the above-mentioned problems existing in the prior art, a hollow fiber is provided, including an outer cladding tube, an anti-resonance region connected to the inner wall of the outer cladding tube, and a hollow fiber core region surrounded by the anti-resonance region. The anti-resonance region includes multiple anti-resonance units, each of which includes at least one anti-resonance layer with an open structure. The two sides of the opening of the anti-resonance layer are connected to the inner wall of the outer sheath through two parallel thin walls.

[0021] Specifically, this invention provides at least one anti-resonant layer with an open structure, offering a multi-layer anti-resonant structure (in specific embodiments, the anti-resonant unit typically includes two or more anti-resonant layers). This design, through multiple anti-resonant effects, reflects light waves, preventing the light field from leaking from the fiber core to the cladding, thereby better confining the light field within the hollow fiber core region.

[0022] Furthermore, this embodiment utilizes parallel thin-walled connections to reduce node coupling. Specifically, the anti-resonant layer is connected to the inner wall of the outer cladding sleeve via two parallel thin walls, rather than being directly connected. The parallel thin walls have a certain length, and this design allows the connection node to be located away from the fiber core region, thereby weakening the coupling of the optical field in the fiber core to the cladding.

[0023] Furthermore, the open structure of the anti-resonance layer connects with the inner wall of the outer cladding tube to form a closed cavity, which helps to generate anti-resonance conditions. As a high-refractive-index region, the anti-resonance layer contrasts with the low-refractive-index medium inside the cavity, reflecting light of a specific wavelength and preventing the optical field from coupling with the cladding mode.

[0024] The following four embodiments are provided for detailed description of the optical fiber structure in this invention.

[0025] Example 1: In this embodiment, as shown Figure 1 As shown, it includes an outer sheath 1, an anti-resonance region connected to the inner wall of the outer sheath, and a hollow fiber core region 6 surrounded by the anti-resonance region. The anti-resonance region includes five anti-resonance units evenly distributed along the inner wall of the outer cladding sleeve. In this embodiment, each anti-resonance unit includes a single-layer anti-resonance layer 2 and its corresponding parallel thin wall 3. The anti-resonance layer 2 is an open fan-shaped region with a negative curvature thin wall structure, which plays the main anti-resonance role and can effectively prevent the core mode from coupling to the high refractive index thin wall material, thereby reducing transmission loss.

[0026] In this embodiment, the opening of the anti-resonance layer 2 faces the outer cladding sleeve 1, and the edge of the opening is connected to the inner wall of the outer cladding sleeve 1 to form a closed cavity. The cavity is filled with air or a vacuum medium. The filling material in the hollow fiber core region 6 is air or a vacuum. The filling material of other high refractive index portions is silicon dioxide or polymer plastic. The thickness of all thin-walled structures in the high refractive index portions is similar to the wavelength of the transmitted light wave, on the order of micrometers.

[0027] Preferably, the diameter of the hollow fiber core region 6 in this embodiment is 30 micrometers.

[0028] In this embodiment, the wall thickness of the anti-resonant layer 2 and its corresponding parallel thin wall 3 ranges from 1 to 1.2 micrometers. Specifically, the outer diameter of the anti-resonant layer 2 is 42.4 micrometers, and its wall thickness is 1.2 micrometers.

[0029] In this embodiment, the distance between the two parallel thin walls 3 corresponding to the anti-resonance layer 2 is 20.65 micrometers, which is smaller than the outer diameter of the corresponding anti-resonance layer 2. Meanwhile, the anti-resonance layer 2 in this embodiment can be considered a fan-shaped thin-walled structure, with the central angle α formed by the edges of its opening being 200° < α < 30°. These parameter relationships ensure that the fan-shaped thin-walled structure of the anti-resonance unit 2 effectively blocks the connection node between the parallel thin-walled structure 3 and the outer cladding 1, reducing the coupling of the optical field from the air fiber core to the outer cladding.

[0030] Specifically, in this embodiment, the connection between each anti-resonant layer 2 and its corresponding parallel thin wall 3 is a smooth transition, avoiding the connection nodes between materials, which aims to effectively reduce the confinement loss of the light field.

[0031] Preferably, the length of the parallel thin wall 3 is greater than 7 micrometers. Specifically, in this embodiment, the length of the parallel thin wall 3 corresponding to the anti-resonant layer 2 is 7.54 micrometers. This ensures sufficient distance between the fiber core and the cladding, thereby reducing the coupling of the fiber core mode to the outer cladding sleeve and thus reducing transmission loss.

[0032] Example 2: Compared with Embodiment 1, each anti-resonance unit in this embodiment has an additional anti-resonance layer and a corresponding parallel thin wall, forming an anti-resonance unit with a multi-layer anti-resonance layer structure.

[0033] Specifically, in this embodiment, as follows: Figure 2 As shown, the hollow fiber in this embodiment includes an outer cladding tube 1, an anti-resonance region connected to the inner wall of the outer cladding tube, and a hollow fiber core region 6 surrounded by the anti-resonance region. Each anti-resonance unit includes two anti-resonance layers: an outer anti-resonance layer 2 and an inner anti-resonance layer 5. The opening edges of the inner anti-resonance layer 5 and the outer anti-resonance layer 2 are connected to the inner wall of the outer cladding sleeve through their respective parallel thin walls 3 and 4.

[0034] The outer anti-resonance layer 2 is an open, fan-shaped, thin-walled structure that plays a major role in anti-resonance. The parallel thin-walled structure 3 corresponding to the outer anti-resonance layer 2 connects the outer cladding sleeve 1 to the outer anti-resonance layer 2. The inner anti-resonance layer 5 is also an open, fan-shaped, thin-walled structure, but it is located inside the outer anti-resonance layer 2 and plays a major role in anti-resonance. The parallel thin-walled structure 4 corresponding to the inner anti-resonance layer 5 connects the outer cladding sleeve 1 to the inner anti-resonance layer 5. Both the inner and outer anti-resonance layers are open, with the openings facing the outer cladding sleeve. The edges of the openings connect to the inner wall of the outer cladding sleeve 1. A closed cavity is formed between the outer anti-resonance layer 2 and the inner anti-resonance layer 5, and the cavity is filled with air or a vacuum medium.

[0035] Specifically, in this embodiment, the outer anti-resonance layer 2 has an outer radius of 21.2 micrometers and an outer diameter of 42.4 micrometers; an inner radius of 20 micrometers, an inner diameter of 40 micrometers, and a wall thickness of 1.2 micrometers.

[0036] Specifically, the diameter of the inner anti-resonant layer 5 ranges from 28 to 32 micrometers. In this embodiment, the outer radius of the inner anti-resonant layer 5 is 16 micrometers, the outer diameter is 32 micrometers, the inner radius is 14.8 micrometers, the inner diameter is 29.6 micrometers, and the wall thickness is 1.2 micrometers.

[0037] Specifically, in this embodiment, the length of the parallel thin wall 4 corresponding to the inner anti-resonance layer 5 is 11.23 micrometers, and the length of the parallel thin wall 3 corresponding to the outer anti-resonance layer 2 is 7.54 micrometers.

[0038] Specifically, in this embodiment, the spacing between the two parallel thin walls 4 corresponding to the inner anti-resonance unit 5 is 7.42 micrometers, and the spacing between the two parallel thin walls 3 corresponding to the outer anti-resonance layer 2 is 20.65 micrometers. Both are smaller than the outer diameters of the corresponding outer anti-resonance layer 2 and inner anti-resonance unit 5. Simultaneously, the central angle α of the thin-walled portions of the outer anti-resonance layer 2 and inner anti-resonance unit 5 is greater than 200°. These parameter relationships ensure that the fan-shaped thin-walled structure of the outer anti-resonance layer 2 and inner anti-resonance unit 5 effectively blocks the connection nodes between the parallel thin walls 3 and 4 and the outer cladding 1, reducing the coupling of the optical field from the air fiber core to the outer cladding.

[0039] Example 3: like Figure 3 As shown, the hollow fiber in this embodiment includes an outer cladding tube 1, an anti-resonance region connected to the inner wall of the outer cladding tube 1, and a hollow fiber core region 6 surrounded by the anti-resonance region. The anti-resonance region includes five anti-resonance units evenly distributed along the inner wall of the outer cladding tube. Each anti-resonance unit includes an outer anti-resonance layer 2 and its corresponding parallel thin wall 3, an inner anti-resonance layer 5 and its corresponding parallel thin wall 4, and a low-refractive-index air core structure 6. The parameters of the inner anti-resonance layer 5 and its corresponding parallel thin wall 4, and the outer anti-resonance layer 2 and its corresponding parallel thin wall 3 in this embodiment are the same as those in Embodiment 2.

[0040] The difference between this embodiment and Embodiment 2 is that each anti-resonance unit in this embodiment further includes an open negative curvature anti-resonance layer 7, which surrounds the outer anti-resonance layer 2. The two sides of the opening of the negative curvature anti-resonance layer 7 are directly connected to the inner wall of the outer cladding sleeve 1. This also constitutes a low-loss anti-resonance optical fiber structure.

[0041] In this embodiment, the circumferential angle β of the negative curvature anti-resonant layer 7 is 314°, the radius is 32 micrometers, the diameter is 64 micrometers, and the wall thickness is 1.2 micrometers. It can be understood that the negative curvature anti-resonant layer 7 is responsible for providing the negative curvature anti-resonant layer, so the radius and circumferential angle of the negative curvature anti-resonant layer 7 can be flexibly adjusted while satisfying the requirement of surrounding the two inner anti-resonant layers.

[0042] In this embodiment, the outer negative curvature anti-resonant layer 7 is a high refractive index structure with the same wall thickness as other thin-walled structures.

[0043] Example 4: like Figure 4As shown, in this embodiment, the optical fiber structure, from the outside in along the radial direction, includes a high-refractive-index outer cladding tube 1, an inner anti-resonant layer 5 and its corresponding parallel thin wall 4, an outer anti-resonant layer 2 and its corresponding parallel thin wall 3, and a low-refractive-index air core structure 6. The parameters of the inner anti-resonant layer 5 and its corresponding parallel thin wall 4, and the outer anti-resonant layer 2 and its corresponding parallel thin wall 3 in this embodiment are the same as those in Embodiment 2.

[0044] The difference from that in Example 2 is that, as Figure 4 and Figure 5 As shown, in this embodiment, a plurality of first circular solid structures 1 are also filled between the parallel thin wall 4 corresponding to the inner anti-resonance layer 5 and the parallel thin wall 3 corresponding to the outer anti-resonance layer 2. Furthermore, a second circular solid structure 8 is provided on the outer surface of the parallel thin wall 3 corresponding to the outer anti-resonance layer 2 near the outer cladding sleeve 1.

[0045] The diameter of the first circular solid structure 8 is 5.23 micrometers. The diameter of the second circular solid structure 7 is 9.08 micrometers.

[0046] The function of the first circular solid core structure 8 and the second circular solid core structure 7 is to position the inner and outer anti-resonant layers during the optical fiber fabrication process. With the parallel thin-walled structures within the inner and outer anti-resonant layers positioned, air pressure is applied to the resonant layers. At this time, the unfixed areas within the resonant layers expand freely, forming a fan-shaped region structure, thus creating the anti-resonant layer geometry shown in the diagram. The aforementioned first circular solid core structure 8 and second circular solid core structure 7 can ensure, to the greatest extent possible, that the parallel thin walls remain undeformed, while simultaneously fixing the spacing and position between the inner and outer anti-resonant layers.

[0047] Numerical simulation of the fiber optic structure in this embodiment yielded transmission loss data within the wavelength range of 1.0 to 1.4 micrometers. The calculation results are as follows: Figure 6 As shown. The optical fiber of this invention has the lowest loss at a wavelength of 1.1 micrometers, with a transmission loss of 0.02 dB / km.

[0048] In all the above embodiments, the outer sheath and the anti-resonance layer are made of silicon dioxide, or plastic polymer, or doped glass.

[0049] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present invention.

Claims

1. A hollow core optical fiber having a multi-layered open-structured anti-resonant layer, characterized by, It includes an outer sheath, an anti-resonance region connecting the inner wall of the outer sheath, and a hollow fiber core region surrounded by the anti-resonance region. The anti-resonance region includes multiple anti-resonance units, and each anti-resonance unit includes at least one anti-resonance layer with an open structure. The two sides of the opening of the anti-resonance layer are connected to the inner wall of the outer sheath through two parallel thin walls.

2. The hollow core optical fiber according to claim 1, characterized in that, Each anti-resonance unit includes two anti-resonance layers, namely an inner anti-resonance layer and an outer anti-resonance layer; The opening edges of the inner and outer anti-resonance layers are connected to the inner wall of the outer cladding sleeve through their respective parallel thin walls.

3. The hollow-core optical fiber according to claim 2, characterized in that, Each anti-resonance unit also includes an open negative curvature anti-resonance layer surrounding the outer anti-resonance layer, with the two sides of the opening of the negative curvature anti-resonance layer directly connected to the inner wall of the outer sheath.

4. The hollow-core optical fiber according to claim 2, characterized in that, Multiple first circular solid structures are also filled between the parallel thin wall corresponding to the inner anti-resonance layer and the parallel thin wall corresponding to the outer anti-resonance layer. A second circular solid structure is also provided on the outer surface of the parallel thin wall corresponding to the outer anti-resonance layer near the outer cladding sleeve.

5. The hollow-core optical fiber according to claim 1, characterized in that, The diameter of the anti-resonant layer is greater than the distance between its two corresponding parallel thin walls.

6. The hollow-core optical fiber according to claim 2, characterized in that, A closed cavity is formed between the inner anti-resonance layer and the outer anti-resonance layer. The closed cavity is filled with air or is in a vacuum state.

7. The hollow-core optical fiber according to claim 4, characterized in that, The inner diameter of the outer sheath is larger than the diameter of the outer anti-resonant layer, and the diameter of the outer anti-resonant layer is larger than the diameter of the inner anti-resonant layer.

8. The hollow-core optical fiber according to claim 1, characterized in that, The hollow fiber core region is filled with air or is in a vacuum state.

9. The hollow-core optical fiber according to claim 1, characterized in that, The outer sheath and the anti-resonance layer are made of silicon dioxide, plastic polymer, or doped glass.

10. The hollow-core optical fiber according to claim 1, characterized in that, The length of the parallel thin wall is greater than 7 micrometers.

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