A hybrid optical cable of skeleton hollow optical fiber and solid optical fiber and a manufacturing method thereof

Abstract

This invention discloses a hybrid optical cable combining hollow-core and solid optical fibers in a skeleton configuration and its fabrication method. Belonging to the field of low-carbon, high-density optical cable technology, the cable includes a central skeleton with multiple spirally arranged grooves along its circumference. Multiple first optical units are housed within each groove, and each first optical unit includes multiple hollow-core optical fibers and a flexible sleeve. Multiple second optical units are stranded around the outer periphery of the central skeleton, with the stranding direction opposite to the spiral arrangement direction of the grooves. Each second optical unit includes multiple solid optical fibers, which can be G.652D, G.654E, G.655, G.657A, etc., forming a hybrid optical cable. This invention solves the problem of accommodating hollow-core optical fibers through the cooperation of the central skeleton and the flexible sleeve. By reverse-stranding the second optical units, the possibility of the second optical units embedding into the skeleton grooves is reduced, avoiding pressure on the flexible sleeve. Furthermore, the shared use of solid and hollow optical fibers effectively improves the overall fiber core density of the optical cable.

Description

Technical Field

[0001] This invention belongs to the field of low-carbon high-density optical cable technology, specifically relating to a hybrid optical cable of skeleton-type hollow optical fiber and solid optical fiber and its preparation method. Background Technology

[0002] Hollow-core optical fiber uses air (or an inert gas) as the transmission channel for optical signals, with light primarily propagating in the air within the fiber core. This fundamentally overcomes the material limitations of traditional solid-core optical fiber. Compared to solid-core optical fiber, hollow-core optical fiber possesses core advantages such as low latency, low loss, and high power, demonstrating irreplaceable potential in scenarios such as financial data center interconnection, intelligent computing center internals, and cluster interconnection.

[0003] Although hollow-core optical fiber boasts superior performance, its high production cost and complex, inefficient maintenance make it difficult to achieve a universal replacement for solid-core optical fiber under current circumstances. Therefore, hollow-core optical fiber is often used in a limited number of high-speed communication lines, while solid-core optical fiber is still used for communication lines with conventional performance requirements. Furthermore, due to space constraints imposed by existing urban communication pipelines, subway tunnels, and building shafts, existing pipeline resources are extremely limited. Constructing new pipelines is costly and subject to municipal planning restrictions, necessitating the deployment of a small number of hollow-core optical fibers within limited space. Traditional optical cables have a limited core count, often requiring the laying of multiple cables to meet capacity demands. This not only consumes a large amount of already scarce pipeline resources but also leads to a significant increase in the consumption of raw materials such as sheathing and reinforcement components, resulting in continuously rising construction energy consumption and maintenance costs, which is incompatible with the green development requirements under the current "dual-carbon" context. Using hybrid optical cables of hollow-core and solid-core optical fibers can fully utilize existing pipeline resources, enabling the normal operation of most communication lines while meeting the high-speed communication needs of some special lines.

[0004] In the fabrication process of hybrid optical cables containing hollow and solid optical fibers, hollow optical fibers have complex internal microstructures, poor bending performance, and are sensitive to temperature changes. They are prone to high losses under large temperature differences or pressure environments. Because solid and hollow optical fibers need to meet different structural design requirements, it is difficult to fabricate them together in the same optical cable. Summary of the Invention

[0005] In response to one or more of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a hybrid optical cable of skeleton hollow optical fiber and solid optical fiber, which solves the problem that it is difficult to jointly manufacture hollow optical fiber and solid optical fiber into the same optical cable.

[0006] To achieve the above objectives, the present invention provides a hybrid optical cable of skeletonized hollow fiber and solid fiber, comprising: A central skeleton, wherein the central skeleton is provided with multiple spirally arranged skeleton grooves in the circumferential direction; Multiple first optical units are respectively housed in each of the skeleton slots; each first optical unit includes multiple hollow optical fibers and a flexible sleeve sleeved around the periphery of the multiple hollow optical fibers. Multiple second optical units are stranded and arranged around the outer periphery of the central skeleton, and the stranding direction of the multiple second optical units is opposite to the spiral arrangement direction of the skeleton grooves; each second optical unit includes multiple solid optical fibers; An outer sheath covers the outer periphery of a plurality of second optical unit stranded structures.

[0007] As a further improvement of the present invention, the flexible sleeve has a modulus of 50~400MPa, a diameter of 0.6~2.0mm, and a wall thickness of 0.05~0.15mm.

[0008] As a further improvement of the present invention, the flexible sleeve is made of TPU or TPE.

[0009] As a further improvement of the present invention, the bottom wall of the skeleton groove on the side opposite to the groove opening is concave arc-shaped, and the depth of the skeleton groove is greater than the outer diameter of the first optical unit.

[0010] As a further improvement of the present invention, the second optical unit further includes a rigid sleeve disposed on the outer periphery of the plurality of solid optical fibers, the rigid sleeve having a modulus of 800~3000MPa, a diameter of 1.2~3.2mm, and the diameter of the rigid sleeve being larger than the width of the opening of the skeleton groove.

[0011] As a further improvement of the present invention, the second optical unit further includes a rigid sleeve disposed on the outer periphery of the plurality of solid optical fibers, the rigid sleeve having a modulus of 2000~3000MPa, a diameter of 1.2~3.2mm, and the diameter of the rigid sleeve being larger than the width of the opening of the skeleton groove.

[0012] As a further improvement of the present invention, the rigid sleeve is made of PP, PBT, PA or PC.

[0013] As a further improvement of the present invention, the outer periphery of the central skeleton is also longitudinally surrounded by a first water-blocking strip.

[0014] As a further improvement of the present invention, the duty cycle of the first optical unit is 40% to 70%.

[0015] As a further improvement of the present invention, the central skeleton includes a reinforcing member disposed at the center and a skeleton structure covering the outer periphery of the reinforcing member, the skeleton structure being made of high-density polyethylene.

[0016] This invention also includes a method for preparing a hybrid optical cable of skeleton-type hollow optical fiber and solid optical fiber, comprising the following steps: Extruded central skeleton; Multiple first optical units are respectively housed in the slots of the central skeleton, and a first water-blocking strip is wrapped around the outer periphery of the central skeleton. With the central skeleton as the center, multiple second optical units are twisted around the outer periphery of the central skeleton, and a second water-blocking strip is wrapped around the outer periphery of the twisted structure of the multiple second optical units. An outer sheath is extruded around the second water-blocking strip to form a hybrid optical cable of skeleton-type hollow optical fiber and solid optical fiber.

[0017] The aforementioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0018] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include: (1) The skeleton-type hybrid optical cable of hollow and solid optical fibers of the present invention solves the problem of hollow optical fiber placement by cooperating with the central skeleton and the flexible sleeve. By stranding the second optical unit on the outer periphery of the central skeleton and by reverse stranding the second optical unit, the possibility of the second optical unit being embedded in the skeleton slot is reduced, and the second optical unit is avoided from compressing the flexible sleeve. Moreover, the solid optical fiber is smaller in size than the hollow optical fiber and can be arranged at a higher density. By using hollow and solid optical fibers to jointly prepare the optical cable, the solid and hollow optical fibers can be shared, and the overall fiber core density of the optical cable can be effectively improved. Under the same transmission capacity requirements, a single optical cable can replace multiple traditional optical cables, which greatly reduces the consumption of raw materials such as sheath, materials, reinforcement, and fillers, and significantly reduces the resource occupation of the optical cable product throughout its entire life cycle, reflecting the green and environmentally friendly design concept.

[0019] (2) The skeleton-type hollow fiber and solid fiber hybrid optical cable of the present invention sets the bottom wall of the skeleton groove away from the groove opening as arc, so that the first optical unit fits against the bottom wall, avoids the flexible sleeve from contacting and deforming the flat bottom wall, and ensures that the hollow fiber is not squeezed in the flexible sleeve; secondly, the present invention adjusts the depth of the skeleton groove so that the first optical unit falls completely in the skeleton groove, and avoids the second optical unit located at the groove opening of the skeleton groove from squeezing the first optical unit.

[0020] (3) The skeleton-type hollow fiber and solid fiber hybrid optical cable of the present invention uses a rigid sleeve with a modulus of 800~3000MPa. The rigid sleeve has better shape support capability than the flexible sleeve. This means that when the second optical unit is stranded on the outer periphery of the central skeleton, the contact part between the rigid sleeve and the skeleton groove will not undergo too much deformation, thereby preventing the second optical unit from being recessed and embedded in the skeleton groove. This makes the rigid sleeve form a seal at the groove opening of the skeleton groove, thereby preventing external pressure from being transmitted to the inside, and thus preventing the hollow fiber from being compressed. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the hybrid optical cable of skeleton hollow fiber and solid fiber in an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the fabrication process of the hybrid optical cable consisting of skeleton-type hollow optical fiber and solid optical fiber in an embodiment of the present invention.

[0022] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1. Hollow-core optical fiber; 2. Flexible sleeve; 3. Central skeleton; 4. Skeleton groove; 5. First water-blocking strip; 6. Solid-core optical fiber; 7. Rigid sleeve; 8. Second water-blocking strip; 9. Outer sheath; 10. Reinforcing member. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and 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.

[0024] In the description of this invention, it should be understood that, unless otherwise stated, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0025] Furthermore, unless otherwise stated, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0028] Please see Figure 1 The preferred embodiment of the present invention provides a hybrid optical cable of hollow and solid optical fibers, comprising a central skeleton 3, wherein the central skeleton 3 is provided with a plurality of spirally arranged skeleton grooves 4 in the circumferential direction; a plurality of first optical units, wherein the plurality of first optical units are respectively housed in each skeleton groove 4, and each first optical unit includes a plurality of hollow optical fibers 1 and a flexible sleeve 2 sleeved on the outer periphery of the plurality of hollow optical fibers 1; a plurality of second optical units, wherein the plurality of second optical units are stranded on the outer periphery of the central skeleton 3, and the stranding direction of the plurality of second optical units is opposite to the spiral arrangement direction of the skeleton grooves 4, and each second optical unit includes a plurality of solid optical fibers 6; and an outer sheath 9, which covers the outer periphery of the stranded structure of the plurality of second optical units.

[0029] The hybrid optical cable of hollow-core and solid optical fibers in this invention features a central skeleton 3 structure within the cable. Hollow-core optical fibers 1 are placed within the skeleton groove 4, while solid optical fibers 6 are stranded and wrapped around the outer periphery of the central skeleton 3. Placing the hollow-core optical fibers 1 within the skeleton groove 4 utilizes the central skeleton 3 to provide circumferential protection, preventing compression of the hollow-core optical fiber 1 sheath during conventional optical unit stranding and outer sheath forming. Furthermore, unlike conventional skeleton-type optical cables where the optical fiber or fiber ribbon is placed directly within the skeleton groove 4, this invention incorporates a flexible sheath 2 around the hollow-core optical fiber 1. This flexible sheath 2 wraps around the hollow-core optical fiber 1, preventing direct contact between the hollow-core optical fiber 1 and the rigid central skeleton 3, thus reducing micro-bending stress caused by friction between the hollow-core optical fiber 1 and the skeleton groove 4 surface. In this invention, the essential protective structure of the hollow optical fiber 1 is a combination of a central skeleton 3 and a flexible sleeve 2. The central skeleton 3 isolates external impacts and pressures, reducing the pressure transmitted to the hollow optical fiber 1 during cable use; while the flexible sleeve 2 isolates the rigid skeleton structure from friction with the hollow optical fiber 1, ensuring that the hollow optical fiber 1 has a flexible protective structure without the concern of external pressure squeezing the flexible sleeve 2. This combination of the central skeleton 3 and the flexible sleeve 2 allows multiple hollow optical fibers 1 to be placed inside the sleeve, similar to conventional solid optical fibers 6, without the difficulties in selecting the sheath, stranding process, and external pressure transmission caused by the bending sensitivity of the hollow optical fiber 1.

[0030] On the other hand, this invention solves the problem of accommodating hollow optical fiber 1 by cooperating the central skeleton 3 with the flexible sleeve 2. Furthermore, by stranding a second optical unit around the outer periphery of the central skeleton 3 and using reverse stranding, the possibility of the second optical unit being embedded in the skeleton slot 4 is reduced, thus avoiding pressure on the flexible sleeve 2. Moreover, the solid optical fiber 6 is smaller in size than the hollow optical fiber 1 and can be arranged at a higher density. By using both hollow optical fiber 1 and solid optical fiber 6 to fabricate the optical cable, the solid optical fiber 6 and hollow optical fiber 1 can be shared, effectively increasing the overall fiber core density of the optical cable. Under the same transmission capacity requirements, a single optical cable can replace multiple traditional optical cables, significantly reducing the consumption of raw materials such as sheathing, materials, reinforcements, and fillers. This significantly reduces the resource consumption throughout the entire life cycle of the optical cable product, reflecting a green and environmentally friendly design concept.

[0031] Optionally, in the hybrid optical cable of the skeleton-type hollow-core fiber and solid-core fiber of the present invention, the main target of action under large temperature difference or pressure environment is the bending sensitivity of the hollow-core fiber 1. When the temperature difference is large, the shrinkage deformation of the inner and outer sheaths 9, the sleeve, and the optical fiber of the optical cable is different, which leads to the bending of the optical fiber; when the optical cable is under pressure, the overall bending of the optical cable leads to the local bending of the sleeve, which in turn causes the optical fiber to bend. The present invention solves the bending sensitivity problem of the hollow-core fiber 1 through the central skeleton 3 and the flexible sleeve 2, thereby realizing the normal use of the hybrid optical cable of the skeleton-type hollow-core fiber 1 and solid-core fiber 6 in the environment of large temperature difference or pressure. Optionally, the solid-core fiber 6 in the present invention is single-mode fiber, multi-mode fiber, or other special fiber. The solid-core fiber 6 can be selected as G.652D, G.654E, G.655, or G.657A, thereby forming a hybrid optical cable of hollow-core fiber 1 and solid-core fiber 6 to meet the requirements of different transmission distances and costs.

[0032] Furthermore, as an optional embodiment of the present invention, the flexible sleeve 2 has a modulus of 50~400MPa, a diameter of 0.6~2.0mm, and a wall thickness of 0.05~0.15mm. In conventional hollow-core optical fiber cables, considering the bending sensitivity of the hollow-core optical fiber 1, the sleeve of the hollow-core optical fiber 1 is usually set as a double-layer co-extruded structure. The inner layer of the sleeve of the hollow-core optical fiber 1 is a flexible buffer material, and the outer layer is a tensile and compressive resistant material with a certain hardness and toughness, so that the sleeve remains round under the twisting pressure of the sleeve and the extrusion pressure of the outer sheath, avoiding the sleeve from squeezing the internal hollow-core optical fiber 1. In this application, the invention solves the problem of circumferential pressure on the hollow optical fiber 1 by using the central skeleton 3. Therefore, the flexible sleeve 2 in this invention only needs to play a flexible buffering role. It is mainly used to avoid hard contact between the hollow optical fiber 1 and the rigid central skeleton 3. It can be made of a flexible material with a lower modulus to wrap the hollow optical fiber 1. In addition, the wall thickness of the flexible sleeve 2 is controlled at 0.05~0.15mm, while the thickness of conventional sleeves is 0.25~0.5mm. This flexible thin-walled structure not only plays a buffering role on the internal hollow optical fiber 1, but also reduces the binding force of the flexible sleeve 2 on the internal optical fiber, so as to further reduce the squeezing force of the sleeve on the internal optical fiber when the optical cable is bent or under pressure. Furthermore, the skeleton groove 4 is a three-sided enclosed, one-sided slotted structure. In order to prevent the external second optical unit from squeezing and intruding into the space of the skeleton groove 4 and squeezing the first optical unit, the present invention uses a flexible sleeve 2 with a smaller diameter. This makes the overall size of the first optical unit smaller, and the flexible sleeve 2 occupies less space in the skeleton groove 4, reducing the possibility of the second optical unit squeezing the first optical unit, so as to ensure the stable placement of the hollow optical fiber 1 in the hybrid optical cable of skeleton-type hollow optical fiber 1 and solid optical fiber 6.

[0033] Furthermore, as an optional embodiment of the present invention, the flexible sleeve 2 is made of thermoplastic polyurethane (TPU) or thermoplastic elastomer (TPE). Besides having good heat resistance and oil resistance, both TPU and TPE have good flexibility. This allows the flexible sleeve 2 made of TPU and TPE to have good softness, forming a good buffer between the hollow optical fiber 1 and the rigid central skeleton 3, and absorbing the pressure generated when the optical cable is bent or subjected to compression, ensuring the stable use of the hollow optical fiber 1.

[0034] Furthermore, as an optional embodiment of the present invention, the bottom wall of the skeleton groove 4 on the side opposite to the groove opening is concave arc-shaped, and the depth of the skeleton groove 4 is greater than the outer diameter of the first optical unit, so that the outer periphery of the first optical unit does not protrude from the groove opening. In addition to limiting the flexibility and size of the flexible sleeve 2 to avoid pressure on the hollow optical fiber 1, the present invention also improves the pressure state of the hollow optical fiber 1 by adjusting the shape and size of the skeleton groove 4. The present invention sets the bottom wall of the skeleton groove 4 on the side opposite to the groove opening to be arc-shaped, so that the first optical unit fits against the bottom wall, avoiding deformation of the flexible sleeve 2 upon contact with the flat bottom wall, and ensuring that the hollow optical fiber 1 is not squeezed in the flexible sleeve 2; secondly, the present invention adjusts the depth of the skeleton groove 4 so that the first optical unit falls completely in the skeleton groove 4, avoiding the second optical unit located at the groove opening of the skeleton groove 4 from squeezing the first optical unit.

[0035] Optionally, the central skeleton 3 of the present invention includes a centrally located reinforcing member 10 and a skeleton structure covering the outer periphery of the reinforcing member 10. The reinforcing member 10 is located at the axis of the central skeleton 3, and a skeleton with a forward spiral, reverse spiral, or forward and reverse spiral shape is extruded around the reinforcing member 10, thereby forming the central skeleton 3. Further, the reinforcing member 10 can be KFRP, FRP, phosphated steel wire, or copper-plated steel wire; the skeleton is extruded from polyethylene, polypropylene, or other thermoplastic materials, and preferably made of high-density polyethylene. The skeleton structure made of high-density polyethylene gives the skeleton good shape retention capability, facilitating the setting of the concave arc shape of the bottom wall of the skeleton groove 4, and forming a predetermined spiral structure in the skeleton groove 4. This ensures that the first optical unit is arranged according to the predetermined stranding pitch after being placed in the skeleton groove 4, avoiding large-angle bending of the skeleton groove 4 which would increase the micro-bending loss of the hollow fiber 1.

[0036] Furthermore, as an optional embodiment of the present invention, the second optical unit further includes a rigid sleeve 7 disposed around the periphery of multiple solid optical fibers 6. The rigid sleeve 7 has a modulus of 800~2000MPa, a diameter of 1.2~3.2mm, and a diameter larger than the opening width of the skeleton groove 4. Compared to the flexible sleeve 2 that accommodates the hollow optical fiber 1, the second optical unit of the present invention uses a rigid sleeve 7 with a modulus of 800~2000MPa. The rigid sleeve 7 has better shape support capability than the flexible sleeve 2, which means that when the second optical unit is stranded around the periphery of the central skeleton 3, the contact portion between the rigid sleeve 7 and the skeleton groove 4 will not undergo significant deformation, thereby preventing the second optical unit from being recessed and embedded in the skeleton groove 4. By selecting the rigid sleeve 7 structure and controlling the diameter of the rigid sleeve 7, the deformation of the second optical unit is prevented from squeezing into the skeleton groove 4, thereby compressing the first optical unit. This invention utilizes a rigid sleeve 7, which forms a seal at the opening of the skeleton groove 4, thereby preventing external pressure from being transmitted to the interior and thus preventing the hollow optical fiber 1 from being compressed. Furthermore, unlike conventional stranded optical cable structures, this invention uses a central skeleton 3 to separate the internal first optical unit from the external second optical unit, thus preventing the problem of external optical units compressing internal optical units in stranded optical cables. Therefore, this invention can use a rigid sleeve 7 with higher rigidity to prevent the second optical unit from deforming, thus preventing the second optical unit from embedding into the skeleton groove 4 and compressing the first optical unit.

[0037] It is worth noting that the flexible sleeve 2 and the rigid sleeve 7 in this invention are relative concepts. That is, the sleeve used to accommodate the solid optical fiber 6 has better rigidity and toughness than the sleeve used to accommodate the solid optical fiber 6. In this invention, the flexible sleeve 2 represents a sleeve with better flexibility, while the rigid sleeve 7 represents a sleeve with a certain degree of rigidity and toughness.

[0038] Furthermore, as an optional embodiment of the present invention, the rigid sleeve 7 is made of polypropylene (PP), polybutylene terephthalate (PBT), polyamide (PA), or polycarbonate (PC). PP, PBT, PA, and PC are commonly used materials for manufacturing optical cable sleeves, and the sleeve modulus prepared from these materials can reach 800~2500 MPa, thus preventing the rigid sleeve 7 from being deformed by extrusion and falling into the skeleton groove 4. It is worth noting that PP, PBT, PA, or PC can all meet the above modulus requirements. In optical cable design, different materials can be selected to prepare the sleeve according to the different application scenarios of the optical cable.

[0039] Furthermore, as an optional embodiment of the present invention, the second optical unit further includes a rigid sleeve 7 disposed around the periphery of multiple solid optical fibers 6. The rigid sleeve 7 has a modulus of 2000~3000MPa, a diameter of 1.2~3.2mm, and a diameter larger than the opening width of the skeleton groove 4. In addition to the conventional rigid sleeve with a modulus of 800~2000, the present invention can further be selected as a rigid sleeve with a modulus of 2000~3000MPa. By further strengthening the modulus of the rigid sleeve 7, the rigidity of the rigid sleeve 7 is increased, so that the outer wall of the rigid sleeve 7 is completely supported on the outside of the central skeleton 3, thereby avoiding the rigid sleeve 7 from sinking inward and avoiding the possibility of the rigid sleeve 7 squeezing the first optical unit. Optionally, the rigid sleeve 7 in this invention is made of polyetherketone (PEK), nylon, or glass fiber modified polybutylene terephthalate (PBT). Glass fiber modified PBT refers to the doping of glass fiber into PBT material to enhance the tensile, bending, and impact resistance of PBT.

[0040] Furthermore, as an optional embodiment of the present invention, the central frame 3 is further longitudinally surrounded by a first water-blocking strip 5. The first water-blocking strip 5 covers the outer periphery of the central frame 3, forming a protective structure around it. The second optical unit, when pressed against the surface of the first water-blocking strip 5, will not directly intrude into the frame groove 4. Through the isolating effect of the first water-blocking strip 5, even if the second optical unit presses against the frame groove 4, it will only cause a slight concave deformation of the first water-blocking strip 5, preventing the second optical unit from undergoing significant deformation and falling into the frame groove 4. In addition, the first water-blocking strip 5 itself has a water-blocking function, preventing water from spreading axially inside the optical cable when it is damaged.

[0041] Optionally, the longitudinal joint of the first water-blocking strip 5 is located in the skeleton area of ​​the central skeleton 3, that is, the longitudinal joint of the first water-blocking strip 5 is offset from the skeleton groove 4. In this way, the longitudinal joint of the first water-blocking strip 5 is prevented from becoming a weak area. Optionally, the longitudinal joint of the first water-blocking strip 5 is glued together so that the first water-blocking strip 5 forms a tubular structure.

[0042] Of course, alternatively, in addition to the longitudinal wrapping form, the first water-blocking strip 5 in this invention can also be wrapped around the outer periphery of the central frame 3.

[0043] Furthermore, as an optional embodiment of the present invention, the second optical unit is further covered with a second water-blocking strip 8. The second water-blocking strip 8 can be in the form of longitudinal wrapping or wrapping to form a water-blocking structure on the outer periphery of the second optical unit.

[0044] Further, as an optional embodiment of the present invention, the duty cycle inside the first optical unit is 40%~70%. The duty cycle inside the first optical unit refers to the ratio of the total cross-sectional area of ​​all hollow optical fibers 1 inside the first optical unit to the cross-sectional area of ​​the inner cavity of the flexible sleeve 2 of the first optical unit. The hybrid optical cable of skeleton-type hollow optical fiber 1 and solid optical fiber 6 in the present invention is suitable for hollow optical fiber 1 optical cables with high fiber core density. Even if the duty cycle inside the first optical unit is controlled to 40~70%, the normal use of hollow optical fiber 1 can still be guaranteed. Of course, optionally, in actual optical cable design, the number of hollow optical fibers 1 inside the first optical unit can be adjusted according to customer needs to control the duty cycle inside the first optical unit to 5%~40%.

[0045] Furthermore, such as Figure 2 As shown, as an optional embodiment of the present invention, the present invention also includes a method for preparing a hybrid optical cable of skeleton-type hollow optical fiber and solid optical fiber, used to prepare the above-mentioned hybrid optical cable of skeleton-type hollow optical fiber 1 and solid optical fiber 6, which includes the following steps: Extrusion center frame 3; Multiple first optical units are respectively housed in each skeleton slot 4 of the central skeleton 3, and a first water-blocking strip 5 is wrapped around the outer periphery of the central skeleton 3. With the central frame 3 as the center, multiple second optical units are twisted around the outer periphery of the central frame 3, and a second water-blocking strip 8 is wrapped around the outer periphery of the twisted structure of the multiple second optical units. An outer sheath 9 is extruded around the second water-blocking strip 8 to form a hybrid optical cable of skeleton-type hollow optical fiber 1 and solid optical fiber 6. Specific implementation examples: A hybrid optical cable consisting of a skeleton-type hollow fiber 1 and a solid fiber 6 was prepared using the fabrication method of the present invention. In Examples 1-5, Example 1 removed the first water-blocking strip 5 from the original hybrid optical cable structure; Example 2 increased the opening size of the skeleton slot 4 in the original hybrid optical cable structure; Example 3 used a sleeve with a modulus below 800 MPa for the second optical unit; Example 4 was a hybrid optical cable with a rigid sleeve 7 prepared using PBT as described in the present invention; Example 5 was a hybrid optical cable with a rigid sleeve 7 prepared using PEK as described in the present invention; and Comparative Example 1 had a double-layer stranded arrangement of the first and second optical units, with other structural designs being the same. The specific parameters of Examples 1-5 and Comparative Example 1 are shown in Table 1 below. The additional losses of the solid fiber and hollow fiber in the examples and comparative examples were tested respectively.

[0047] Table 1

[0048] According to the test results in the table, in Example 1 compared to Example 4, Example 1 lacks the first water-blocking strip 5, causing the second optical unit to partially intrude into the skeleton groove 4. The flexible sleeve 2 undergoes partial deformation, and the hollow fiber 1 inside the first optical unit experiences less compression. The additional loss of the hollow fiber 1 increases slightly, but during subsequent use, when the optical cable is bent or compressed, the loss of the hollow fiber 1 will increase. In Example 2 compared to Example 4, the groove width of the skeleton groove 4 is too large, causing the second optical unit to intrude into the skeleton groove 4. The deformation of the flexible sleeve 2 is more severe, and the hollow fiber 1 inside the first optical unit experiences less compression. Due to the significant compression, the hollow fiber 1 experiences substantial additional loss. In Example 3, compared to Example 4, a lower modulus sleeve is used as the sleeve for the solid fiber 6, resulting in deformation of the second optical unit and thus, greater additional loss for the solid fiber 6. However, due to the obstruction of the first water-blocking band 5, the deformation of the second optical unit has less impact on the hollow fiber 1 inside the first optical unit. In Comparative Example 1, compared to Example 4, the first and second optical units are in direct contact, and the stranding pressure of the second optical unit and the forming pressure of the outer sheath 9 are transmitted to the first optical unit, resulting in greater additional loss for the hollow fiber 1 inside the first optical unit. It is worth noting that the difference between Example 4 and Example 5 lies in the different moduli of the rigid sleeve 7 used. During actual testing, the additional losses of both the hollow fiber 1 and the solid fiber 6 are at a low level. However, based on the modulus of the rigid sleeve 7 in Example 5, when the optical cable is subjected to bending and external impact, the rigid sleeve 7 in Example 5 can seal the skeleton groove 4, preventing external impact from being transmitted to the hollow fiber 1, thus keeping the bending loss of the hollow fiber 1 at a low level.

[0049] The skeleton-type hollow fiber and solid fiber hybrid optical cable in this application can also be used with a splice box. The fiber unit in the optical cable is spliced ​​in the splice box, and the spliced ​​connector is fixed on the fiber storage tray in the splice box. After the splicing is completed, the splicing of the optical cable can be completed by installing and fixing the splice box accordingly.

[0050] 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 hybrid optical cable combining hollow-core and solid-core optical fibers, characterized in that, include: A central skeleton, wherein the central skeleton is provided with multiple spirally arranged skeleton grooves in the circumferential direction; Multiple first optical units are respectively housed in each of the skeleton slots; each first optical unit includes multiple hollow optical fibers and a flexible sleeve sleeved around the periphery of the multiple hollow optical fibers. Multiple second optical units are stranded and arranged around the outer periphery of the central skeleton, and the stranding direction of the multiple second optical units is opposite to the spiral arrangement direction of the skeleton grooves; each second optical unit includes multiple solid optical fibers; An outer sheath covers the outer periphery of a plurality of second optical unit stranded structures.

2. The hybrid optical cable of skeletonized hollow fiber and solid fiber according to claim 1, characterized in that, The flexible sleeve has a modulus of 50~400MPa, a diameter of 0.6~2.0mm, and a wall thickness of 0.05~0.15mm.

3. The hybrid optical cable of skeleton-type hollow optical fiber and solid optical fiber according to claim 2, characterized in that, The flexible sleeve is made of thermoplastic polyurethane or thermoplastic elastomer.

4. The hybrid optical cable of skeletonized hollow fiber and solid fiber according to claim 2, characterized in that, The bottom wall of the skeleton groove on the side opposite to the groove opening is concave arc-shaped, and the depth of the skeleton groove is greater than the outer diameter of the first optical unit.

5. The hybrid optical cable of skeletonized hollow fiber and solid fiber according to claim 4, characterized in that, The second optical unit further includes a rigid sleeve disposed on the outer periphery of the plurality of solid optical fibers. The rigid sleeve has a modulus of 800~3000MPa, a diameter of 1.2~3.2mm, and the diameter of the rigid sleeve is greater than the width of the opening of the skeleton groove.

6. The hybrid optical cable of skeletonized hollow fiber and solid fiber according to claim 5, characterized in that, The rigid sleeve is made of polypropylene, polybutylene terephthalate, polyamide or polycarbonate.

7. The hybrid optical cable of skeletonized hollow fiber and solid fiber according to claim 1, characterized in that, The central frame is also longitudinally surrounded by a first water-blocking strip.

8. The hybrid optical cable of skeletonized hollow fiber and solid fiber according to claim 1, characterized in that, The duty cycle of the first optical unit is 40% to 70%.

9. The hybrid optical cable of skeletonized hollow fiber and solid fiber according to claim 1, characterized in that, The central skeleton includes a centrally located reinforcing member and a skeleton structure covering the outer periphery of the reinforcing member, the skeleton structure being made of high-density polyethylene.

10. A method for preparing a hybrid optical cable of skeleton-type hollow-core optical fiber and solid-core optical fiber, used to prepare a hybrid optical cable of skeleton-type hollow-core optical fiber and solid-core optical fiber as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Extruded central skeleton; Multiple first optical units are respectively housed in the slots of the central skeleton, and a first water-blocking strip is wrapped around the outer periphery of the central skeleton. With the central skeleton as the center, multiple second optical units are twisted around the outer periphery of the central skeleton, and a second water-blocking strip is wrapped around the outer periphery of the twisted structure of the multiple second optical units. An outer sheath is extruded around the second water-blocking strip to form a hybrid optical cable of skeleton-type hollow optical fiber and solid optical fiber.

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