Method for manufacturing a multi-core optical fiber and multi-core optical fiber

Abstract

The embodiment of the application provides a kind of manufacturing method of multicore optical fiber and multicore optical fiber, it is related to optical fiber technical field, wherein, the manufacturing method of multicore optical fiber includes: connecting core with multiple core rods, to form multicore module, wherein, multiple core rods are distributed around core with interval;Fan-shaped deposition area between two adjacent core rods is sequentially deposited, to form deposition layer in each fan-shaped deposition area, to obtain preform initial product, wherein, deposition layer fills the gap between two adjacent core rods and core.The manufacturing method of multicore optical fiber and multicore optical fiber provided by the embodiment of the application solve the problem that the distance and relative position between each core rod are difficult to accurately control in the related art, resulting in large inter-core crosstalk, affecting the use effect.

Description

Technical Field

[0001] This application relates to the field of optical fiber technology, and in particular to a method for manufacturing a multi-core optical fiber and the multi-core optical fiber itself. Background Technology

[0002] Multi-core fiber (MCF), as an important implementation scheme of space division multiplexing (SDM) technology, can significantly improve transmission capacity by integrating multiple independent fiber cores in a single cladding.

[0003] In related technologies, multi-core optical fibers are often manufactured using the hole-filling method. The steps of the hole-filling method include: drilling holes in a quartz rod and filling them with core rods, followed by heat treatment to form a preform, and finally melting and drawing the preform to obtain the finished multi-core optical fiber.

[0004] However, the above-mentioned method for fabricating multi-core optical fibers is easily affected by the assembly precision between the core rods and the holes, making it difficult to accurately control the distance and relative position between the core rods, resulting in large crosstalk between the cores and affecting the performance. Summary of the Invention

[0005] This application provides a method for manufacturing a multi-core optical fiber and a multi-core optical fiber, in order to solve the problem in related technologies that it is difficult to accurately control the distance and relative position between each core rod, resulting in large crosstalk between core rods and affecting the performance.

[0006] In a first aspect, an embodiment of this application provides a method for manufacturing a multi-core optical fiber, comprising:

[0007] The fiber core is connected to multiple core rods to form a multi-core module, wherein the multiple core rods are distributed around the fiber core at intervals;

[0008] Fan-shaped deposition zones are sequentially deposited between two adjacent core rods to form a deposition layer within each fan-shaped deposition zone, thereby obtaining a preformed rod. The deposition layer fills the voids between two adjacent core rods and the fiber core.

[0009] In one possible implementation, the sequential deposition of fan-shaped deposition zones between two adjacent mandrels to form a deposition layer within each fan-shaped deposition zone includes:

[0010] A deposition device is used to sequentially deposit each of the fan-shaped deposition areas along the circumference of the multi-core module to form a deposition layer within each of the fan-shaped deposition areas.

[0011] In one possible implementation, the deposition of each of the fan-shaped deposition zones includes:

[0012] The torch in the deposition apparatus scans along the axial direction of the fiber core to deposit each of the fan-shaped deposition areas, and the deposition direction of the torch is adjusted within the α angle range along the width direction of the fan-shaped deposition area.

[0013] In one possible implementation, prior to the sequential deposition of the fan-shaped deposition region between two adjacent mandrels, the method further includes:

[0014] The multi-core module is mounted on a rotating component that can reciprocate axially, so that the rotating component drives the multi-core module to rotate and reciprocate axially relative to the deposition equipment.

[0015] In one possible implementation, the sequential deposition of fan-shaped deposition regions between two adjacent mandrels to form a deposition layer within each fan-shaped deposition region further includes:

[0016] When the outer surface of the deposited layer is tangent to the end of the adjacent mandrel away from the fiber core, the deposition of the current sector deposition zone is stopped.

[0017] In one possible implementation, after obtaining the preform, the process further includes:

[0018] An outer cladding layer is deposited on the preform primary product to obtain a preform semi-finished product.

[0019] In one possible implementation, the deposition of an outer cladding layer on the preform primary product includes:

[0020] The preform is continuously and uniformly rotated, and the axial direction of the preform is scanned and deposited to deposit the outer cladding layer on the outside of the preform.

[0021] In one possible implementation, after obtaining the preform semi-finished product, the process further includes:

[0022] The preform semi-finished product is subjected to dehydration, sintering and vitrification treatment in sequence to obtain the preform finished product.

[0023] In one possible implementation, connecting the fiber core to multiple core rods to form a multi-core module includes: using fasteners to connect the fiber core to multiple core rods to form the multi-core module;

[0024] And / or, the fiber core is a pure silicon core, or the fiber core includes an inner core rod and an inner core rod cladding deposited on the inner core rod.

[0025] Secondly, the multi-core optical fiber provided in this application embodiment is manufactured using the manufacturing method of the multi-core optical fiber described in any of the above embodiments.

[0026] This application provides a method for manufacturing a multi-core optical fiber and the multi-core optical fiber itself. The method includes: connecting a fiber core to multiple core rods to form a multi-core module, wherein the multiple core rods are spaced apart and distributed around the fiber core; sequentially depositing fan-shaped deposition areas between adjacent core rods to form a deposition layer within each fan-shaped deposition area, obtaining a preform, wherein the deposition layer fills the gaps between adjacent core rods and the fiber core. Thus, by positioning each core rod and the fiber core to form a multi-core module, the distance and relative position between each core rod can be precisely controlled; and by sequentially depositing each fan-shaped deposition area, it can be ensured that each core rod gap (i.e., the fan-shaped deposition area) is fully filled, obtaining a preform, which is then used in subsequent processes to produce the finished multi-core optical fiber. Compared to manufacturing methods in related technologies, this method can more precisely control the distance and relative position between each core rod, while controlling the consistency of the spacing between core rods, reducing inter-core crosstalk (such as mode coupling and signal interference), and improving the performance of the subsequently manufactured multi-core optical fiber. This solves the problem in related technologies where it is difficult to precisely control the distance and relative position between the mandrels, resulting in large crosstalk between the mandrels and affecting the performance. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0028] Figure 1 A flowchart illustrating a method for manufacturing a multi-core optical fiber, as provided in an embodiment of this application;

[0029] Figure 2 A schematic diagram of the structure of the preform obtained in a method for manufacturing a multi-core optical fiber according to an embodiment of this application. Figure 1 ;

[0030] Figure 3 A schematic diagram of the installation structure during the deposition of a multi-core module in a method for manufacturing a multi-core optical fiber provided in this application embodiment;

[0031] Figure 4 A schematic diagram illustrating the torch angle adjustment in a method for manufacturing a multi-core optical fiber, as provided in this application embodiment;

[0032] Figure 5 A schematic diagram of the structure of the preform obtained in a method for manufacturing a multi-core optical fiber according to an embodiment of this application. Figure 2 ;

[0033] Figure 6 A schematic diagram of the deposition process in Example 1 of a method for manufacturing a multi-core optical fiber provided in this application;

[0034] Figure 7A schematic diagram of the deposition process in Example 2 of a method for manufacturing a multi-core optical fiber provided in this application;

[0035] Figure 8 A schematic diagram of the preform obtained in Example 3 of a method for manufacturing a multi-core optical fiber according to an embodiment of this application;

[0036] Figure 9 A schematic diagram of the deposition process in Example 3 of a method for manufacturing a multi-core optical fiber provided in this application.

[0037] Explanation of reference numerals in the attached figures:

[0038] 100 - Core; 110 - Inner core rod; 120 - Inner core rod cladding;

[0039] 200-core rod;

[0040] 300-fan-shaped sedimentary zone;

[0041] 400 - Inner cladding; 410 - Depositional layer;

[0042] 500 - Outer cladding;

[0043] 600-Blowtorch;

[0044] 700-Chuck;

[0045] 800-Telescopic pole.

[0046] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0047] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0048] Among related technologies, multi-core fiber (MCF), as an important implementation scheme of space division multiplexing (SDM) technology, can significantly improve transmission capacity by integrating multiple independent fiber cores in a single cladding.

[0049] Multi-core optical fibers are often manufactured using the hole-filling method. The steps of the hole-filling method include: drilling holes in a quartz rod and filling them with core rods, followed by heat treatment to form a preform, and finally melting and drawing the preform to obtain the finished multi-core optical fiber.

[0050] However, the above-mentioned method for fabricating multi-core optical fibers is susceptible to the influence of the assembly precision between the core rod and the hole when assembling the core rod onto the quartz rod. This makes it difficult to accurately control the distance and relative position between the core rods, and also makes it difficult to control the consistency of the spacing between the core rods. Consequently, it is easy to cause large crosstalk between cores (such as mode coupling and signal interference), which affects the performance of multi-core optical fibers.

[0051] Based on this, embodiments of this application provide a method for manufacturing a multi-core optical fiber and the multi-core optical fiber itself. The method includes: connecting a fiber core to multiple core rods to form a multi-core module, wherein the multiple core rods are spaced apart and distributed around the fiber core; sequentially depositing fan-shaped deposition areas between adjacent core rods to form a deposition layer within each fan-shaped deposition area, obtaining a preform, wherein the deposition layer fills the gaps between adjacent core rods and the fiber core. Thus, by positioning each core rod and the fiber core to form a multi-core module, the distance and relative position between each core rod can be precisely controlled; and by sequentially depositing each fan-shaped deposition area, it can be ensured that each core rod gap (i.e., the fan-shaped deposition area) is fully filled, obtaining a preform, which is then used in subsequent processes to produce the finished multi-core optical fiber. Compared to manufacturing methods in related technologies, this method can more precisely control the distance and relative position between each core rod, while controlling the consistency of the spacing between core rods, reducing inter-core crosstalk (such as mode coupling and signal interference), and improving the performance of the subsequently manufactured multi-core optical fiber. This solves the problem in related technologies where it is difficult to precisely control the distance and relative position between the mandrels, resulting in large crosstalk between the mandrels and affecting the performance.

[0052] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0053] like Figure 1 and Figure 2 As shown in the embodiment of this application, a method for manufacturing a multi-core optical fiber includes:

[0054] S100: Connect the fiber core 100 to a plurality of core rods 200 to form a multi-core module, wherein the plurality of core rods 200 are distributed around the fiber core 100 at intervals; preferably, the plurality of core rods 200 can be evenly distributed around the fiber core 100 at intervals.

[0055] S200, sequentially depositing fan-shaped deposition areas 300 between two adjacent core rods 200 to form a deposition layer 410 in each fan-shaped deposition area 300, thereby obtaining a preformed rod, wherein the deposition layer 410 fills the gap between two adjacent core rods 200 and the fiber core 100.

[0056] Therefore, by positioning each core rod 200 and fiber core 100 to form a multi-core module, it is convenient to accurately control the distance and relative position between each core rod 200; then, by sequentially depositing each fan-shaped deposition area 300, it can be ensured that the gap between each core rod 200 (i.e., the fan-shaped deposition area 300) is fully filled to obtain a preform, and then proceed to the subsequent process to produce a multi-core optical fiber (each deposition layer 410 can be combined to form the inner cladding 400, core rod 200 and fiber core 100 in the multi-core optical fiber to form the fiber core 100 in the multi-core optical fiber).

[0057] Compared to manufacturing methods in related technologies, this method is less affected by the assembly precision of the core rods 200 and the holes, thus allowing for more precise control over the distance and relative position of each core rod 200. It also ensures consistent spacing between core rods 200, reducing inter-core crosstalk (such as mode coupling and signal interference) and improving the performance of the resulting multi-core optical fiber. This method solves the problem in related technologies where it is difficult to precisely control the distance and relative position of each core rod 200, leading to significant inter-core crosstalk and affecting performance.

[0058] In some embodiments, connecting the fiber core 100 to a plurality of core rods 200 to form a multi-core module includes: connecting the fiber core 100 to a plurality of core rods 200 using fasteners to form a multi-core module.

[0059] The fasteners can be clamps or molds (such as high-purity, low-thermal-expansion-coefficient graphite clamps) used to fasten the fiber core 100 and the core rod 200. The number of fasteners is not limited and can be one, two, or other quantities. In this embodiment, a fastener can be provided at each end of the fiber core 100's extension direction to clamp and fix the fiber core 100 and the core rod 200 from both ends, and to make the multiple core rods 200 evenly spaced around the fiber core 100.

[0060] To address this, during installation, one end of the fiber core 100 extending in the direction of its extension can be fastened to one of the fixing components. Then, one end of each of the multiple core rods 200 extending in the direction of their extensions can also be fastened to the same fixing component, ensuring that the axial direction of the core rods 200 is parallel to the axial direction of the fiber core 100, and that the multiple core rods 200 are evenly spaced around the fiber core 100. Finally, another fixing component is used to clamp and secure the other ends of the fiber core 100 and the core rods 200 extending in the direction of their extensions, thus forming a multi-core module. This allows for precise control of the distance and relative position between each core rod 200, while also ensuring the consistency of the spacing between the core rods 200.

[0061] During implementation, there is no limit to the number of core rods 200 in the multi-core module; it can be four, six, seven, or other numbers.

[0062] In some embodiments, fan-shaped deposition regions 300 between two adjacent mandrels 200 are sequentially deposited to form a deposition layer 410 within each fan-shaped deposition region 300, including:

[0063] A deposition device is used to deposit each fan-shaped deposition zone 300 sequentially along the circumference of the multi-core module to form a deposition layer 410 within each fan-shaped deposition zone 300.

[0064] Therefore, by depositing each fan-shaped deposition zone 300 sequentially along the circumference of the multi-core module using a deposition device, the deposition process can be easily controlled, and the deposition can be more uniform.

[0065] The deposition equipment can be an existing product, such as... Figure 3 As shown, the device includes, for example, a deposition chamber and multiple torches 600 disposed within the deposition chamber; other types of deposition equipment are also possible. During deposition, deposition can be performed using the OVD deposition method through each torch 600 in the deposition equipment. In practice, either the torches 600 can be rotated relative to the multi-core module, or the multi-core module can be rotated relative to the torches 600. Other deposition methods are also possible.

[0066] like Figure 3 and Figure 4 As shown, in some embodiments, depositing each fan-shaped deposition region 300 includes: scanning and depositing each fan-shaped deposition region 300 with a torch 600 in the deposition equipment along the axial direction of the fiber core 100, and adjusting the deposition direction of the torch 600 within the range of α angle along the width direction of the fan-shaped deposition region 300.

[0067] In this embodiment, the torch 600 in the deposition equipment can scan and deposit each sector deposition area 300 along the axial direction of the fiber core 100, thus ensuring that the axis of the multi-core module is parallel to the scanning axis of the torch 600. In practice, the torch 600 can be moved axially relative to the multi-core module, or the multi-core module can be moved axially relative to the torch 600.

[0068] Furthermore, the deposition direction of the blowtorch 600 is adjusted within the α angle range along the width of the fan-shaped deposition zone 300 to ensure sufficient deposition within the fan-shaped deposition zone 300. For example, the α angle can be 3° to 15°, or other angle values.

[0069] This allows for more thorough deposition in each fan-shaped depositional zone 300, reducing the possibility of undeposited areas appearing in some gaps and ensuring the depositional effect of the depositional layer 410.

[0070] In some embodiments, fan-shaped deposition regions 300 between two adjacent mandrels 200 are sequentially deposited to form a deposition layer 410 within each fan-shaped deposition region 300, and the method further includes:

[0071] When the outer surface of the deposition layer 410 is tangent to the end of the adjacent core rod 200 away from the fiber core 100, the deposition of the current fan-shaped deposition zone 300 is stopped.

[0072] This ensures the deposition thickness of the deposition layer 410, ensures that the deposition layer 410 has filled the gaps between the two adjacent core rods 200 and the fiber core 100, and ensures the deposition effect of the fan-shaped deposition area 300.

[0073] In this embodiment, taking the rotation and axial movement of the multi-core module relative to the torch 600 as an example, in some embodiments, before depositing the fan-shaped deposition area 300 between two adjacent core rods 200, the following steps are also included:

[0074] The multi-core module is mounted on a rotating component that can reciprocate axially, so that the rotating component drives the multi-core module to rotate and reciprocate axially relative to the deposition equipment.

[0075] For example, such as Figure 3 As shown, the rotating component may include a chuck 700 and a telescopic rod 800 (which may be an existing product). The telescopic rod 800 is coaxially connected to the chuck 700, allowing the chuck 700 to rotate circumferentially. The telescopic rod 800 can control the axial reciprocating movement of the chuck 700. Of course, other forms of rotating components are also possible.

[0076] Therefore, during installation, the multi-core module can be mounted on the chuck 700. For example, the fasteners on the multi-core module can be connected to the chuck 700. This allows the chuck 700 to drive the multi-core module to rotate circumferentially relative to the deposition equipment. Subsequently, with the extension and retraction of the telescopic rod 800, the multi-core module can be driven to move axially back and forth relative to the deposition equipment, so as to achieve the purpose of deposition on the multi-core module.

[0077] In practice, rotating parts can be installed at both ends of the extension direction of the multi-core module, so that the fixing parts at both ends of the multi-core module are connected to the chucks 700 in the two rotating parts respectively.

[0078] Based on this, the deposition process can be refined as follows: The multi-core module is rotated to an initial angle (e.g., 0°), so that the torch 600 is directly facing the first fan-shaped deposition area 300. The torch 600 is activated; at this time, the multi-core module does not rotate continuously as a whole, but maintains this angle. By controlling the axial movement of the multi-core module, the torch 600 scans and deposits along the axial direction on the current fan-shaped deposition area 300. The deposited soot particles accumulate directly in the target gaps and on the outer sides of adjacent mandrels 200. When the thickness of the deposition layer 410 reaches a point where the outer sides of adjacent mandrels 200 begin to be tangent to or nearly tangent to the outer surface of the deposition layer 410, deposition in this fan-shaped deposition area is stopped.

[0079] The multi-core module is rotated by a certain angle (e.g., 90 degrees when there are four core rods 200) so that the next adjacent sector-shaped deposition area 300 is directly facing the torch 600, and the above scanning deposition process is repeated. Similarly, the remaining sector-shaped deposition areas 300 are deposited sequentially. After all sector-shaped deposition areas 300 have been deposited, in cross-section, the gap area between each core rod 200 and the fiber core 100 has been initially filled with a high-quality soot layer, and each core rod 200 and the fiber core 100 are initially bonded into a whole by the deposition layer 410, forming a pre-formed rod.

[0080] In some embodiments, after obtaining the preform, the method further includes:

[0081] An outer cladding layer 500 is deposited on the outer surface of the preform to obtain a preform semi-finished product. The deposition thickness of the outer cladding layer 500 is not limited, as long as the preform semi-finished product reaches the target outer diameter or the outer cladding layer 500 reaches the target thickness.

[0082] Therefore, the outer cladding layer 500 can effectively protect the internal structure and provide mechanical support for the whole, thereby improving the performance of the multi-core optical fiber produced later.

[0083] Specifically, an outer cladding layer of 500 is deposited on the outside of the preform, including:

[0084] The preform is continuously and uniformly rotated, and the deposition is scanned along the axial direction of the preform to deposit an outer cladding layer 500 on the outside of the preform. This results in a better deposition effect and more comprehensive coverage of the outer cladding layer 500.

[0085] It should be noted that the deposition of the outer cladding layer 500 can also be achieved using the aforementioned deposition equipment and rotating components. The rotating components control the preform to rotate continuously (i.e., rotate continuously at a constant speed) and move axially back and forth relative to the deposition equipment, thereby completing the deposition of the outer cladding layer 500 (which can be done using the OVD deposition method) through the torch 600 in the deposition equipment.

[0086] It should be noted that, during implementation, the deposition equipment and rotating parts can also be achieved using an OVD lathe (which can be an existing product).

[0087] In some embodiments, after obtaining the preformed rod semi-finished product, the method further includes:

[0088] The preform semi-finished product is subjected to dehydration, sintering, and vitrification treatment in sequence to obtain the preform finished product. Among them, dehydration, sintering, and vitrification treatment can be existing conventional processing methods to obtain a dense, transparent, and integrated preform finished product, thereby optimizing the quality of the preform and subsequent multi-core optical fiber finished products.

[0089] Finally, the preform can be subjected to high-temperature drawing (such as sintering, stretching, and drawing in sequence) to obtain a multi-core optical fiber. This results in high positioning accuracy of each core layer (the core 100 and core rod 200 in the preform form the core layer) in the multi-core optical fiber, that is, precise control of the distance and relative position between each core rod 200, while controlling the consistency of the spacing between each core rod 200 to reduce inter-core crosstalk. The cladding (the inner cladding 400 and outer cladding 500 in the preform form the cladding) in the multi-core optical fiber has a uniform refractive index distribution and high production efficiency.

[0090] like Figure 2 and Figure 5 As shown, in some embodiments, the fiber core 100 may be a pure silicon core, or the fiber core 100 may include an inner core rod 110 and an inner core rod cladding 120 deposited on the inner core rod 110.

[0091] Therefore, the fiber core 100 can be selected according to actual needs to fabricate a multi-core optical fiber with the desired structure. For example, the fiber core 100 can be a pure silicon core, or it can be a structure in which an inner core rod 110 (which can be the same as the core rod 200 mentioned above) is combined with an inner core rod cladding 120. When the inner core rod cladding 120 is deposited on the inner core rod 110, the same deposition equipment and rotating components mentioned above can be used for deposition. Fluorine can also be doped to control the refractive index of the inner core rod cladding 120.

[0092] It should be noted that the mandrel 200 can be prepared according to the design requirements by methods such as MCVD (in-tube thermal oxidation deposition), VAD (vapor phase axial deposition), OVD (external vapor phase deposition), or PCVD (in-tube plasma deposition).

[0093] In summary, this manufacturing method is based on multi-core modules and leverages the advantages of OVD cladding to deposit OVD cladding and form large-size multi-core preforms. It enables large-scale mass production while maintaining excellent optical performance (e.g., low attenuation <0.2dB / km and low crosstalk <-40dB).

[0094] In summary, the manufacturing method of a multi-core optical fiber provided in this application provides a way to precisely control the distance and relative position between each core rod 200 by positioning each core rod 200 and fiber core 100 to form a multi-core module. Then, by sequentially depositing each fan-shaped deposition area 300, it can be ensured that the gap between each core rod 200 (i.e., the fan-shaped deposition area 300) is fully filled to obtain a preform, and then proceed to subsequent processes to produce a finished multi-core optical fiber (each deposition layer 410 can be combined to form the inner cladding 400, core rod 200 and fiber core 100 in the multi-core optical fiber to form the fiber core 100 in the multi-core optical fiber).

[0095] Compared to manufacturing methods in related technologies, this method is less affected by the assembly precision of the core rods 200 and the holes, thus allowing for more precise control over the distance and relative position of each core rod 200. It also ensures consistent spacing between core rods 200, reducing inter-core crosstalk (such as mode coupling and signal interference) and improving the performance of the resulting multi-core optical fiber. This method solves the problem in related technologies where it is difficult to precisely control the distance and relative position of each core rod 200, leading to significant inter-core crosstalk and affecting performance.

[0096] In addition, this method of manufacturing multi-core optical fibers has the following advantages:

[0097] Using multi-core modules as master rods for cladding deposition completely eliminates the need for machining high-precision porous quartz sleeves and the tedious and error-prone stacking and assembly of 200 core rods. This significantly reduces process steps and human intervention points, fundamentally improving process stability and batch-to-batch consistency of preforms, laying the technological foundation for high yield, shortening the process, and increasing production efficiency.

[0098] Direct cladding deposition can effectively avoid the physical interface in traditional methods, reduce or even eliminate the hidden dangers such as microbubbles and microcracks introduced by the interface, and is expected to achieve lower intrinsic loss, better mechanical fatigue performance and more stable long-term reliability.

[0099] Traditional methods for filling gaps often require extensive "ineffective" deposition (deposited on the already thick outer layer) in a 360° rotation mode, resulting in low efficiency. This multi-core fiber manufacturing method prioritizes filling the most needed areas, reducing material waste and shortening the deposition time required to achieve the desired gap-filling thickness, thereby improving overall deposition efficiency.

[0100] The manufacturing method for this multi-core optical fiber allows for fully automated closed-loop control of all key parameters, including deposition rate, temperature, and doping, ensuring batch stability. It possesses the capability to fabricate large-size, low-cost preforms, facilitating large-scale mass production of multi-core optical fibers.

[0101] This method for manufacturing multi-core optical fibers is not only applicable to 4-core fibers, but can also be easily adapted to multi-core structures with different core numbers (e.g., 7-core, 19-core fibers) and different arrangements (hexagonal array, ring array) by adjusting the graduation angle (e.g., 60° graduation for 7-core fibers). Different torch parameters (e.g., doping gas flow rate) can be used in different partitions, providing more possibilities for the fabrication of multi-core optical fibers with heterogeneous core structures (e.g., different doping concentrations or profiles of the cores).

[0102] The manufacturing method of this multi-core optical fiber will be further described in detail below through specific embodiments.

[0103] Example 1:

[0104] 4-core optical fiber preform fabrication, such as Figure 2 and Figure 6 As shown, it includes the following steps:

[0105] Fiber design: 4 cores, square arrangement, core spacing of 40μm, single-mode core (i.e., the core layer formed by core rod 200) diameter of 8.6μm, cladding diameter of 125μm.

[0106] Mandrel 200 is prepared using standard MCVD process, with a diameter of 10mm and a length of 800mm. The target preform has an outer diameter of 80mm and a length of approximately 700mm (after sintering).

[0107] Assembly: Four core rods 200 and one fiber core 100 (pure silicon core in this embodiment) are fixed into a square bundle (i.e., forming a multi-core module) using a high-purity graphite fixture with a low coefficient of thermal expansion. The center distance of the core rods 200 is designed to be 3.2 mm. The fixture must ensure that the deformation is minimal at the high deposition temperature and that it is easy to disassemble.

[0108] Zoned deposition (gap filling): The multi-core module is mounted on an OVD lathe with high-precision indexing to ensure rotational concentricity. After each zone (i.e., fan-shaped deposition zone 300) is deposited, the multi-core module is rotated 90°. When the blowtorch 600 is aligned with the fan-shaped deposition zone 300, a "low-speed, multi-pass" scanning method is used to deposit the outer diameter of the multi-core module to a near-circular size, obtaining the preform.

[0109] Overall outer cladding 500 deposition: After each sector deposition zone 300 is filled, the OVD lathe is switched to continuous 360° rotation mode at a speed of 20~40 rpm. The blowtorch 600 performs conventional deposition to deposit the outer cladding 500 on the preform, forming a preform semi-finished product, until the diameter of the preform semi-finished product reaches 110 mm.

[0110] Dehydration and sintering: The preform semi-finished product is dehydrated at 1150~1250°C for 1~2 hours in a chlorine-containing (He / Cl2) atmosphere to fully remove hydroxyl groups. Then, it is sintered at 1450~1550°C in a helium or vacuum atmosphere to form a transparent and dense preform finished product.

[0111] Finally, the preform is drawn at high temperature to form a multi-core optical fiber, which can then be tested. The test results are as follows: the four cores are arranged in a regular square, and the intercores and the overall glass are clear, without visible bubbles, cracks, or unsintered white "white spots". The core spacing is 40.2±0.5μm, and the intercore crosstalk is -58km (meeting design requirements).

[0112] Example 2:

[0113] Preparation of fluorine-doped 4-core optical fiber preforms, such as Figure 5 and Figure 7 As shown, it includes the following steps:

[0114] Fiber design: 4 cores, square arrangement, core spacing of 40μm, single-mode core diameter of 8.6μm, cladding diameter of 125μm. Fabricated using standard MCVD process, core rod 200 has a diameter of 10mm and a length of 800mm. Target preform finished product has an outer diameter of 80mm and a length of approximately 700mm (after sintering).

[0115] OVD deposition of inner core cladding 120: One MCVD core 200 (i.e., the inner core 110 when the core 100 is a combination of inner core 110 and inner core cladding 120) is fixed with a graphite jig, and the core 200 is mounted on a high-precision OVD lathe to ensure rotational concentricity. Conventional OVD 360° rotational deposition is used to deposit the inner core cladding 120 on the outside of the core 200. During SiO2 fumigation, an F-containing gas is introduced to control the refractive index height of the inner core cladding 120. Conventional deposition ends when the fumigation thickness reaches the designed size.

[0116] Assembly: Install the four MCVD core rods 200 using graphite clamps to form a multi-core module, ensuring that they are axially parallel to the inner core rod 110 during installation.

[0117] Zoned deposition (gap filling): The multi-core module is mounted on an OVD lathe with high-precision indexing to ensure rotational concentricity. During deposition, SiO2 and fluorine-containing gas are introduced together to deeply dope the inner cladding 400 (i.e., each deposition layer 410). To prevent poor gap adhesion, a small amount of phosphorus-containing gas is introduced to increase the powder viscosity. After each zone (i.e., fan-shaped deposition zone 300) is deposited, the multi-core module is rotated 90°. The blowtorch 600 is used to scan the fan-shaped deposition zone 300 at low speed multiple times to deposit the outer diameter of the multi-core module to a near-circular size, obtaining the preform.

[0118] Overall outer cladding 500 deposition: After each sector deposition zone 300 is filled, the OVD lathe is switched to continuous 360° rotation mode at a speed of 20~40 rpm. The blowtorch 600 performs conventional deposition to deposit the outer cladding 500 on the preform, forming a preform semi-finished product, until the diameter of the preform semi-finished product reaches 110mm.

[0119] Dehydration and sintering: The preform semi-finished product is dehydrated at 1150~1250°C for 1~2 hours in a chlorine-containing (He / Cl2) atmosphere to fully remove hydroxyl groups. Then, it is sintered at 1450~1550°C in a helium or vacuum atmosphere to form a transparent and dense preform finished product.

[0120] Finally, the preform is drawn at high temperature to form a multi-core optical fiber, which can then be tested. The test results are as follows: the four cores are arranged in a regular square; the intercores and the overall glass matrix are clear, without visible bubbles, cracks, or unsintered white spots. The core spacing is 40.2±0.5μm, and the intercore crosstalk is -63dB (meets design requirements).

[0121] Example 3:

[0122] Fabrication of 7-core optical fiber preforms (hexagonal arrangement), such as Figure 8 and Figure 9 As shown, it includes the following steps:

[0123] Assembly: Use a custom graphite mold with a central positioning post to fix 7 core rods 200, so that 6 of the core rods 200 (the outer cores) are evenly spaced around 1 core rod 200 (the central core).

[0124] Zoned deposition (interstitial filling): Zones are created using a 60° rotation. After each 60° rotation, the blowtorch 600 is aimed at one of the six outermost interstitials (i.e., six fan-shaped deposition zones 300) for directional deposition. Note that the outermost interstitials are Y-shaped; see [reference needed]. Figure 4 During deposition, the torch angle needs to be optimized to 600 degrees or a small-amplitude oscillation scanning method (angle α is 3~15°) to ensure that the soot can effectively fill the triangular area between the central core and the outer core, thus obtaining the initial product of the preform.

[0125] Overall outer coating 500 deposition: After each sector deposition zone 300 is filled, switch to continuous 360° rotation mode at a speed of 20~40 rpm. Use a blowtorch 600 for conventional deposition to deposit an outer coating 500 on the preform, forming a preform semi-finished product, until the diameter of the preform semi-finished product reaches 140 mm.

[0126] Dehydration and sintering: The preform semi-finished product is dehydrated at 1150~1250°C for 1~2 hours in a chlorine-containing (He / Cl2) atmosphere to fully remove hydroxyl groups. Then, it is sintered at 1450~1550°C in a helium or vacuum atmosphere to form a transparent and dense preform finished product.

[0127] Finally, the preform is drawn at high temperature to form a multi-core optical fiber, which can then be tested. The test results show that the 7 cores are arranged in a regular hexagonal pattern, with obvious bubbles, cracks, or incompletely sintered areas between the cores and in the overall glass matrix. The core spacing is 42±0.5μm, and the inter-core crosstalk is -50dB (meets design requirements).

[0128] Comparative Example 1:

[0129] OVD deposition method involves continuous 360° rotational deposition without zoning (i.e., no separate fan-shaped depositional zone 300).

[0130] The same 4-core multi-core module and initial arrangement as in Example 1 were used. The conventional OVD process was employed directly from the beginning: the multi-core module rotated continuously 360° (20-40 rpm) throughout the process, and a 600° scan of the blowtorch was used for deposition until the soot diameter reached the predetermined coating value, resulting in a preform semi-finished product. The dehydration and sintering process parameters remained consistent with Example 1, yielding the finished preform.

[0131] Linear or clustered bubbles, as well as localized haze (incomplete sintering and densification), were observed on the end face of the preform in the intercore region. The root cause is that during continuous rotation, the effective deposition rate of soot at the gaps is much lower than that on the outer side, resulting in low soot packing density and high porosity in this area. During sintering, the pores close, trapping gas and forming bubbles, or the low density leads to incomplete sintering. During fiber drawing, internal fractures occur even under normal tension, with the breakpoint located at bubbles or defects in the intercore region of the preform. Multi-core fiber testing results show uneven core spacing and intercore crosstalk greater than -36dB.

[0132] Comparative Example 2:

[0133] Four-core optical fiber preforms were prepared by drilling.

[0134] Preparation of mandrel 200: Four homogeneous mandrels 200 were produced using MCVD.

[0135] Sleeve drilling: Using a 60mm diameter pure silicon base material, a precision drilling machine is used to drill holes according to the designed core spacing. After drilling, the inner wall of the hole is polished.

[0136] Sleeve cleaning and drying: Soak the sleeve in industrial cleaning alkali for cleaning, and after cleaning, put the sleeve in a clean cabinet to dry.

[0137] Assembly: Before assembly, wipe the surface of the mandrel 200 with alcohol. With the mandrel 200 parallel to the sleeve hole, insert 4 mandrels 200 in sequence.

[0138] Component welding: The front end of the sleeve is sealed with a cone, and an extension tube is welded to the tail end of the sleeve. When matching and welding, it is necessary to prevent the extension tube from blocking the multi-core drilled hole.

[0139] This method involves numerous steps, from preparing the master rod, drilling, preparing the mandrel 200, assembly, melting and shrinking to wire drawing. Errors at each step accumulate and are amplified, resulting in low yield of the final product, making it unsuitable for large-scale, standardized production. The long process and high-precision machining increase production costs by 30% to 50% compared to conventional OVD and other processes.

[0140] The gap between the mandrel 200 and the multi-core sleeve is prone to leaving tiny air gaps or generating stress, significantly increasing random crosstalk sensitive to temperature and bending, resulting in extreme instability. Machining drilling cannot achieve absolute positional and dimensional accuracy, and ellipticization is easily generated during wire drawing, leading to an actual crosstalk increase of 5-10 dB compared to theoretical simulations.

[0141] Drilling, assembly, and fusion processes are all carried out in open or semi-open environments, making it easy to introduce OH groups and other contaminants at the interface, which are difficult to remove. Therefore, the attenuation of optical fiber at the 1380nm hydroxyl peak is typically 0.05~0.15dB / km higher than that of optical fiber drawn from an integrated preform.

[0142] The multi-core optical fiber provided in this application embodiment is manufactured using the manufacturing method of the multi-core optical fiber in any of the above embodiments.

[0143] This results in high positioning accuracy of each core layer (the core 100 and core rod 200 in the preform) after high-temperature drawing of multi-core optical fiber. That is, the distance and relative position between each core rod 200 are precisely controlled, and the consistency of the spacing between each core rod 200 is controlled, which can effectively reduce inter-core crosstalk. The cladding (the inner cladding 400 and outer cladding 500 in the preform) in the multi-core optical fiber has a uniform refractive index distribution and high production efficiency.

[0144] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for manufacturing a multi-core optical fiber, characterized in that, include: The fiber core (100) is connected to a plurality of core rods (200) to form a multi-core module, wherein the plurality of core rods (200) are distributed around the fiber core (100) at intervals; Fan-shaped deposition areas (300) are deposited sequentially between two adjacent core rods (200) to form a deposition layer (410) in each fan-shaped deposition area (300) to obtain a preform rod, wherein the deposition layer (410) fills the gap between two adjacent core rods (200) and the fiber core (100).

2. The method for manufacturing a multi-core optical fiber according to claim 1, characterized in that, The sequential deposition of fan-shaped deposition regions (300) between two adjacent core rods (200) to form a deposition layer (410) within each fan-shaped deposition region (300) includes: A deposition device is used to deposit each of the fan-shaped deposition areas (300) sequentially along the circumference of the multi-core module to form a deposition layer (410) within each of the fan-shaped deposition areas (300).

3. The method for manufacturing a multi-core optical fiber according to claim 2, characterized in that, Each of the aforementioned fan-shaped depositional zones (300) includes: The torch (600) in the deposition apparatus is used to scan and deposit each of the fan-shaped deposition areas (300) along the axial direction of the fiber core (100), and the deposition direction of the torch (600) is adjusted within the α angle range along the width direction of the fan-shaped deposition area (300).

4. The method for manufacturing a multi-core optical fiber according to claim 3, characterized in that, Before the sequential deposition of the fan-shaped deposition zone (300) between two adjacent core rods (200), the method further includes: The multi-core module is mounted on a rotating component that can reciprocate axially, so that the rotating component drives the multi-core module to rotate and reciprocate axially relative to the deposition equipment.

5. The method for manufacturing a multi-core optical fiber according to claim 1, characterized in that, The sequential deposition of fan-shaped deposition regions (300) between two adjacent core rods (200) to form a deposition layer (410) within each fan-shaped deposition region (300) further includes: When the outer surface of the deposition layer (410) is tangent to the end of the adjacent core rod (200) away from the fiber core (100), the deposition of the current sector deposition area (300) is stopped.

6. The method for manufacturing a multi-core optical fiber according to any one of claims 1-5, characterized in that, After obtaining the preformed rod, the process further includes: An outer cladding layer (500) is deposited on the outer surface of the preform to obtain a preform semi-finished product.

7. The method for manufacturing a multi-core optical fiber according to claim 6, characterized in that, The deposition of an outer cladding layer (500) on the preform primary product includes: The preform is continuously and uniformly rotated, and the axial direction of the preform is scanned and deposited to deposit the outer cladding layer (500) on the outside of the preform.

8. The method for manufacturing a multi-core optical fiber according to claim 6, characterized in that, After obtaining the preformed semi-finished product, the process further includes: The preform semi-finished product is subjected to dehydration, sintering and vitrification treatment in sequence to obtain the preform finished product.

9. The method for manufacturing a multi-core optical fiber according to any one of claims 1-5, characterized in that, The method of connecting the fiber core (100) to multiple core rods (200) to form a multi-core module includes: using fasteners to connect the fiber core (100) to multiple core rods (200) to form the multi-core module; And / or, the core (100) is a pure silicon core, or the core (100) includes an inner core rod (110) and an inner core rod cladding (120) deposited on the inner core rod (110).

10. A multi-core optical fiber, characterized in that, It is manufactured using the manufacturing method of any one of claims 1-9 for multi-core optical fibers.

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