A multi-core fiber multiplexer / demultiplexer and a method for manufacturing the same

Abstract

The application belongs to the technical field of passive optical devices, and discloses a multi-core optical fiber multiplexer / demultiplexer and a preparation method thereof. In the application, a small outer diameter optical fiber is fused at one end of a single-mode optical fiber. The cladding diameter of the small outer diameter optical fiber is smaller than the cladding diameter of the single-mode optical fiber, and the cladding diameter of the small outer diameter optical fiber is equal to the core spacing of the multi-core optical fiber to be matched. The mode field diameter of the small outer diameter optical fiber is consistent with the mode field diameter of each core of the multi-core optical fiber. The small outer diameter optical fiber is used as a transition optical fiber between the single-mode optical fiber and the multi-core optical fiber, high-precision matching between the single-mode optical fiber and the multi-core optical fiber is achieved, the problems existing in the prior art preparation method can be avoided, and the application has the advantages of good scalability, simple preparation, high precision, and industrial mass production.

Description

Technical Field

[0001] This invention belongs to the field of passive optical device technology, and more specifically, relates to a multi-core optical fiber multiplexer / demultiplexer and its preparation method. Background Technology

[0002] In optical communication networks, spatial division multiplexing based on multi-core optical fibers is one of the most effective methods to solve the current bottleneck in optical communication transmission capacity. Multi-core optical fibers are a new type of optical fiber with multiple independent cores in a common cladding region. Based on the spatial division multiplexing concept, multi-core optical fibers can transmit multiple optical signals simultaneously in a single fiber, which can greatly improve communication capacity and break through the current transmission capacity limit of ordinary single-mode optical fibers. Multi-core optical fibers can increase the channel and transmission capacity of the system by several times or even tens of times. Especially in the era of 5G cabling with rapidly developing transmission capacity, they can greatly save cabling space in high-density cabling in data centers and short-to-medium distance transmission.

[0003] A major challenge in the commercial application of multi-core optical fibers is the fabrication of high-performance multiplexing / demultiplexing devices between multi-core and standard single-mode fibers. These devices enable each core of the multi-core fiber to connect with the single-mode fiber, achieving optical signal input and output. Therefore, multi-core fiber multiplexers / demultiplexers and their fabrication methods are extremely important, becoming a key technology for promoting the practical application of multi-core fibers and reducing costs.

[0004] Currently, there are several main methods for manufacturing multi-core optical fiber multiplexers and demultiplexers:

[0005] Bundling method: Etched single-mode and multi-core optical fibers are inserted into cylindrical sleeves that have been mechanically drilled or laser-drilled. Alignment is achieved using an alignment platform, and then adhesive is applied to fix the fibers, thus fabricating the multi-core coupler. This method for fabricating multi-core fiber multiplexers and demultiplexers uses hydrofluoric acid to etch the optical fibers; the etching precision of the single-mode fiber affects the device's performance.

[0006] Tapering method: A single-mode fiber with its coating removed is inserted into a pre-tapered glass sleeve. The waist region of the capillary is tapered so that the diameter of the tapered single-mode fiber matches the core diameter of the multi-core fiber. The single-mode fiber and glass sleeve are then cut from the waist region and fused with the multi-core fiber. This method for fabricating multi-core fiber multiplexers and demultiplexers is technically complex and requires high precision control of the tapering and fusion splicing equipment, making mass production impossible. Summary of the Invention

[0007] This invention provides a multi-core optical fiber multiplexer / demultiplexer and its fabrication method, solving the problems of existing multi-core optical fiber multiplexer / demultiplexer fabrication methods affecting device performance, complex processing techniques, or high equipment requirements.

[0008] This invention provides a method for fabricating a multi-core optical fiber multiplexer / demultiplexer, comprising the following steps:

[0009] Step 1: Strip the coating of n single-mode optical fibers to obtain n first intermediate components; fused a small-diameter optical fiber to one end of each first intermediate component to obtain a second intermediate component; the cladding diameter of the small-diameter optical fiber is equal to the core spacing of the multi-core optical fiber to be matched, and the mode field diameter of the small-diameter optical fiber is consistent with the mode field diameter of each core in the multi-core optical fiber.

[0010] Step 2: Insert n second intermediate components into the first ferrule. The small outer diameter optical fiber passes through the first ferrule and extends a first distance. After curing, grind the end face of the small outer diameter optical fiber to obtain the third intermediate component. Connect the third intermediate component coaxially with the first sleeve.

[0011] Step 3: Obtain the fiber core position information of the third intermediate component;

[0012] Step 4: Connect the second ferrule and the second sleeve coaxially; strip the coating layer of the multi-core optical fiber, insert the stripped end of the multi-core optical fiber into the second ferrule, and let the multi-core optical fiber pass through the second ferrule and extend out a second distance;

[0013] Step 5: Based on the fiber core position information of the third intermediate component, rotate and adjust the multi-core optical fiber, and after curing, grind the end face of the multi-core optical fiber used to dock with the third intermediate component.

[0014] Step 6: Insert the first sleeve into the second sleeve, so that the end faces of the first ferrule and the second ferrule are aligned and fitted, thus completing the preparation of the multi-core optical fiber multiplexer / demultiplexer.

[0015] Preferably, the cladding diameter of the small-diameter optical fiber ranges from 40 to 80 micrometers, and the mode field diameter of the small-diameter optical fiber ranges from 8 to 10 micrometers; the cladding diameter of the multi-core optical fiber ranges from 125 to 250 micrometers.

[0016] Preferably, the fiber cores of the multi-core optical fiber are arranged in one of the following ways: rectangular arrangement, straight line arrangement, or circular ring arrangement.

[0017] Preferably, the first ferrule is an optical module ferrule, and the multi-core optical fiber contains 4 or 8 fiber cores.

[0018] Preferably, in step 3, before obtaining the fiber core position information of the third intermediate component, the method further includes: using a first component to limit the first sleeve; the first component is a planar structure, and a portion of the outer surface of the first sleeve is a planar structure, and the planar structure of the first sleeve can restrict the rotation of the first sleeve after being placed horizontally along the first component.

[0019] In step 5, before rotating and adjusting the multi-core optical fiber, the method further includes: using a second component to limit the second sleeve; the second component is a planar structure, and a portion of the inner surface of the second sleeve is a planar structure, and the planar structure of the second sleeve, when placed horizontally along the second component, can restrict the rotation of the second sleeve;

[0020] The first component and the second component have the same dimensions.

[0021] Preferably, in step 3, the fiber core position information of the third intermediate component is obtained by the following method: using an imaging system to observe the position of each fiber core in the third intermediate component, finding the two fiber cores that are farthest apart and closest to the horizontal axis, calculating the angle between the line connecting the two found fiber cores and the horizontal axis, and recording it as the first angle value;

[0022] In step 5, the multi-core optical fiber is rotated and adjusted in the following way: the position of each core in the multi-core optical fiber is observed using an imaging system, the two cores that are farthest apart and closest to the horizontal axis are found, and the multi-core optical fiber is rotated so that the angle between the line connecting the two found cores and the horizontal axis reaches the first angle value.

[0023] Preferably, in step 4, after inserting the end of the multi-core optical fiber with the coating removed into the second ferrule, the method further includes: cleaning and cutting the multi-core optical fiber that has exited the second ferrule to obtain a neat and flat end face.

[0024] Preferably, in step 6, the fiber end faces of the first ferrule and the second ferrule used for alignment and bonding are also coated.

[0025] Preferably, in step 6, the outer diameter of the first sleeve is the same as the inner diameter of the second sleeve, the first sleeve is made of metal, and the second sleeve is made of plastic.

[0026] On the other hand, the present invention provides a multi-core optical fiber multiplexer / demultiplexer, which is prepared by the above-described method for preparing a multi-core optical fiber multiplexer / demultiplexer.

[0027] One or more technical solutions provided in this invention have at least the following technical effects or advantages:

[0028] (1) Typically, the cladding diameter of a single-mode fiber is larger than the intercore spacing of a multi-core fiber, making direct matching impossible. Existing technologies involve etching or tapering the single-mode fiber to achieve matching, which can affect device performance or lead to complex processing techniques and high equipment requirements. The multi-core fiber multiplexer / demultiplexer proposed in this invention adopts a different approach from existing solutions. This invention fuses a small-diameter fiber at one end of the single-mode fiber. The cladding diameter of the small-diameter fiber is smaller than that of the single-mode fiber, and the cladding diameter of the small-diameter fiber is equal to the intercore spacing of the multi-core fiber to be matched. The mode field diameter of the small-diameter fiber is consistent with the mode field diameter of each core in the multi-core fiber. In other words, this invention uses the small-diameter fiber as a transition fiber between the single-mode fiber and the multi-core fiber, achieving high-precision matching between the single-mode fiber and the multi-core fiber, thus avoiding the problems existing in existing preparation methods.

[0029] (2) This invention addresses the difficulty of connecting multi-core optical fibers and single-mode optical fibers by improving the connection method. This invention utilizes a first component and a second component, which not only serve as reference lines for fiber core alignment (facilitating observation of the position of each fiber core by the imaging system), but also restrict the rotation of the two sleeves and facilitate repeated insertion and removal of the two sleeves. Compared to the prior art which requires rotational alignment and adhesive application, this invention eliminates the need for adhesive application and can directly perform a locking fixation. In other words, this invention utilizes two planar structures to achieve rapid connection of the first and second sleeves, thereby achieving precise alignment of the first and second ferrules. This simplifies and speeds up the time-consuming and labor-intensive task of connecting multi-core optical fibers to single-mode optical fibers (since in this invention, single-mode optical fibers are connected to small-diameter optical fibers, and the small-diameter optical fibers serve as transition fibers between single-mode and multi-core optical fibers, it is actually a connection of a small-diameter fiber bundle to a multi-core optical fiber).

[0030] (3) In this invention, the fiber end faces of the first ferrule and the second ferrule used for alignment and bonding are also coated, which can effectively improve the return loss of the multi-core fiber multiplexer and demultiplexer and improve the device performance.

[0031] (4) The multi-core optical fiber multiplexer and demultiplexer and its preparation method provided by the present invention have the characteristics of good scalability, simple preparation, high precision, and industrial mass production. Attached Figure Description

[0032] Figure 1 A cross-sectional schematic diagram of a multi-core optical fiber multiplexer / demultiplexer provided by the present invention;

[0033] Figure 2 This is a structural schematic diagram of the first sleeve and the first component;

[0034] Figure 3 This is a structural schematic diagram of the second sleeve and the second component;

[0035] Figure 4 This is a schematic diagram illustrating the alignment and positioning of a rectangular four-core optical fiber multiplexer / demultiplexer provided in Embodiment 1 of the present invention.

[0036] Figure 5 This is a schematic diagram illustrating the alignment and positioning of a linear four-core optical fiber multiplexer / demultiplexer provided in Embodiment 2 of the present invention.

[0037] Figure 6 This is a schematic diagram illustrating the alignment and positioning of an eight-core optical fiber multiplexer / demultiplexer provided in Embodiment 3 of the present invention. Detailed Implementation

[0038] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0039] This invention provides a method for fabricating a multi-core optical fiber multiplexer / demultiplexer, see [link to documentation]. Figures 1 to 3 This includes the following steps:

[0040] Step 1: Strip the coating of n single-mode optical fibers to obtain n first intermediate components; fused a small-diameter optical fiber 7 to one end of each first intermediate component to obtain a second intermediate component; the cladding diameter of the small-diameter optical fiber 7 is equal to the core spacing of the multi-core optical fiber 8 to be matched, and the mode field diameter of the small-diameter optical fiber 7 is consistent with the mode field diameter of each core in the multi-core optical fiber 8.

[0041] The cladding diameter of the small-diameter optical fiber 7 ranges from 40 to 80 micrometers, and the mode field diameter of the small-diameter optical fiber 7 ranges from 8 to 10 micrometers; the cladding diameter of the multi-core optical fiber 8 ranges from 125 to 250 micrometers.

[0042] The fiber cores of the multi-core optical fiber 8 are arranged in one of the following ways: rectangular, linear, or circular.

[0043] Step 2: Insert n second intermediate components into the first ferrule 1. The small outer diameter optical fiber 7 passes through the first ferrule 1 and extends a first distance. After curing, grind the end face of the small outer diameter optical fiber 7 to obtain the third intermediate component. Connect the third intermediate component coaxially with the first sleeve 3.

[0044] Specifically, n second intermediate parts are inserted into the first insert 1 that has been injected with adhesive to achieve curing.

[0045] The first ferrule 1 can be an optical module ferrule, and the corresponding multi-core optical fiber 8 contains 4 or 8 fiber cores.

[0046] Step 3: Obtain the fiber core position information of the third intermediate component.

[0047] For details, see Figure 1 , Figure 2 Before obtaining the fiber core position information of the third intermediate component, the method further includes: using the first component 5 to limit the first sleeve 3; the first component 5 is a planar structure, and a portion of the outer surface of the first sleeve 3 is a planar structure. When the planar structure of the first sleeve 3 is placed horizontally along the first component 5, it can restrict the rotation of the first sleeve 3.

[0048] For example, the fiber core position information of the third intermediate component can be obtained by observing the position of each fiber core in the third intermediate component using an imaging system (e.g., a microscope), finding the two fiber cores that are farthest apart and closest to the horizontal axis, calculating the angle between the line connecting the two found fiber cores and the horizontal axis, and recording it as the first angle value.

[0049] Alternatively, the two fiber cores that are furthest apart but closest to the vertical axis can be identified, and the angle between the line connecting these two cores and the vertical axis can be calculated and denoted as the first angle value. This method (vertical axis) is essentially the same as the method described above for obtaining the first angle value (horizontal axis). If step 3 uses the vertical axis method, then step 5 also achieves the first angle value based on the vertical axis method.

[0050] Step 4: Connect the second ferrule 2 and the second sleeve 4 coaxially; strip the coating layer of the multi-core optical fiber 8, insert the stripped end of the multi-core optical fiber 8 into the second ferrule 2, and the multi-core optical fiber 8 passes through the second ferrule 2 and extends out a second distance.

[0051] Specifically, the end of the multi-core optical fiber 8 with the coating removed is inserted into the second ferrule 2 that has been injected with adhesive to achieve curing.

[0052] In addition, after stripping the coating layer from one end of the multi-core optical fiber 8 and inserting it into the second ferrule 2, the process may further include cleaning and cutting the multi-core optical fiber 8 that has exited the second ferrule 2 to obtain a neat and flat end face.

[0053] Step 5: Based on the fiber core position information of the third intermediate component, rotate and adjust the multi-core optical fiber 8, and after curing, grind the end face of the multi-core optical fiber 8 used for docking with the third intermediate component.

[0054] For details, see Figure 1 , Figure 3 Before rotating and adjusting the multi-core optical fiber 8, the method further includes: using the second component 6 to limit the second sleeve 4; the second component 6 is a planar structure, and a portion of the inner surface of the second sleeve 4 is a planar structure. When the planar structure of the second sleeve 4 is placed horizontally along the second component 6, it can restrict the rotation of the second sleeve 4.

[0055] The first component 5 and the second component 6 have the same dimensions.

[0056] For example, the multi-core optical fiber 8 can be rotated and adjusted in the following way: observe the position of each core in the multi-core optical fiber 8 using an imaging system, find the two cores that are farthest apart and closest to the horizontal axis, and rotate the multi-core optical fiber 8 so that the angle between the line connecting the two found cores and the horizontal axis reaches the first angle value.

[0057] Step 6: Insert the first sleeve 3 into the second sleeve 4, so that the end faces of the first ferrule 1 and the second ferrule 2 are aligned and fitted, thus completing the preparation of the multi-core optical fiber multiplexer / demultiplexer.

[0058] In addition, the fiber end faces of the first ferrule 1 and the second ferrule 2 used for alignment and bonding are both coated.

[0059] The outer diameter of the first sleeve 3 is the same as the inner diameter of the second sleeve 4. The first sleeve 3 can be made of metal, and the second sleeve 4 can be made of plastic. The first sleeve 3 and the second sleeve 4 can be repeatedly inserted and removed.

[0060] Corresponding to the above preparation method, a schematic diagram of a multi-core optical fiber multiplexer / demultiplexer provided by the present invention is shown below. Figures 1 to 3 It includes a first ferrule 1, a second ferrule 2, a first sleeve 3, a second sleeve 4, a first component 5, a second component 6, a small outer diameter optical fiber 7, a multi-core optical fiber 8, and a single-mode optical fiber.

[0061] n single-mode optical fibers are fused with n small-diameter optical fibers 7, and the n small-diameter optical fibers 7 are inserted into the first ferrule 1 to form a small-diameter optical fiber bundle. The first ferrule 1 is coaxially connected to the first sleeve 3, and the end face of the first ferrule 1 is inside the first sleeve 3. The multi-core optical fiber 8 is inserted into the second ferrule 2, and the second ferrule 2 is coaxially connected to the second sleeve 4. The first sleeve 3 is inserted into the second sleeve 4, and the first sleeve 3 is coaxially connected to the second sleeve 4. The end faces of the first ferrule 1 and the second ferrule 2 are aligned and fitted, that is, the small-diameter optical fiber bundle and the multi-core optical fiber 8 are aligned and fitted to achieve a low insertion loss connection. The resulting multi-core optical fiber multiplexer / demultiplexer can realize the multiplexing and demultiplexing of signals in the multi-core optical fiber.

[0062] It can be understood that the first ferrule 1, the first sleeve 3 and the first component 5 constitute the first ferrule assembly, the second ferrule 2, the second sleeve 4 and the second component 6 constitute the second ferrule assembly, and the first component 5 and the second component 6 serve as auxiliary optimization devices, which can make the time-consuming, labor-intensive and difficult task of optical fiber connection simple and quick.

[0063] The present invention will be illustrated below with reference to specific embodiments.

[0064] Example 1:

[0065] Example 1: Fabrication of a rectangular four-core optical fiber multiplexer / demultiplexer.

[0066] See Figure 4 The rectangular four-core optical fiber has a core spacing of 42 micrometers, with an error within ±0.5 micrometers. The cladding diameter of the four-core optical fiber is 125 micrometers, with an error within ±0.5 micrometers. The cladding diameter of the small-diameter optical fiber is equal to the core spacing of the four-core optical fiber, and the mode field diameter of the small-diameter optical fiber is consistent with the mode field diameter of each core of the four-core optical fiber. The cladding diameter of the small-diameter optical fiber is 42 micrometers, with an error within ±0.5 micrometers.

[0067] See Figure 1 , Figure 4 The inner hole shape of the first ferrule is determined by the cladding diameter of the small-diameter optical fiber and the arrangement of the small-diameter optical fibers in the first ferrule. The inner hole of the first ferrule is a circular through hole, and the space of the inner hole can accommodate four small-diameter optical fibers simultaneously. The inner hole size of the second ferrule is determined by the cladding diameter of the four optical fibers. The inner hole diameter of the second ferrule is 125 micrometers, with an error within ±0.5 micrometers.

[0068] The coating layer of the single-mode fiber is stripped to obtain the first intermediate component. A section of small-diameter fiber is fused to the end face of the single-mode fiber to obtain the second intermediate component. Thermosetting adhesive is injected into the inner hole of the first ferrule. Four second intermediate components are inserted into the inner hole of the first ferrule. The small-diameter fiber passes through the end face of the first ferrule for a certain distance. The first ferrule is heated and cured. After curing, the end face of the fiber is polished. The end face is usually polished to a flat surface. The first ferrule is coaxially connected to the first sleeve.

[0069] Place the first sleeve horizontally along the first component, see Figure 2 Using a high-precision microscopic imaging system, observe the core positions of the small-diameter optical fibers on the end face of the third intermediate component. Identify the cores of the two small-diameter optical fibers that are furthest apart relative to each other and closest to the horizontal axis. Measure the angle θ between the line connecting the two cores and the horizontal or vertical axis of the first sleeve. (See [reference needed]). Figure 4 .

[0070] The second ferrule is coaxially fixed to the second sleeve. Thermosetting adhesive is injected into the inner hole of the second ferrule. The coating of the four-core optical fiber is peeled off, and the fiber is inserted into the inner hole of the second ferrule, extending a distance beyond the end face of the second ferrule. The glass cladding of the four-core optical fiber on the end face of the second ferrule is cleaned and cut to obtain a neat and flat end face. The second sleeve is then placed horizontally along the second component. (See...) Figure 3Under the imaging system, observe the position of each fiber core of the four-core optical fiber, find the two fibers that are furthest apart from each other and are furthest from the horizontal axis, and measure the angle between the line connecting the two fibers and the horizontal or vertical axis of the second sleeve.

[0071] The diameter of the four-core optical fiber is smaller than the inner diameter of the second ferrule. The four-core optical fiber can rotate freely within the second ferrule. Rotating the four-core optical fiber ensures that the angle between the line connecting the two cores furthest apart from the horizontal axis and the horizontal or vertical axis of the second sleeve reaches θ, with an error within ±0.5 degrees. Due to the choice of observation direction, the core distribution of the four-core optical fiber under the microscopic imaging system is symmetrical to the core distribution of the four small-diameter optical fibers. See [reference needed]. Figure 4 The four-core optical fiber and the second ferrule are thermosetting to fix the position of the four-core optical fiber. After curing, the end face of the optical fiber is polished, and the end face is usually polished flat.

[0072] The first and second sleeves are coaxially connected so that the end faces of the first and second ferrules are aligned and fitted together, thus completing the fabrication of the four-core fiber optic multiplexer.

[0073] In addition, during the fabrication process, coating the end face of the small outer diameter fiber bundle and the end face of the four-core fiber can increase the transmission or reflection efficiency of optical signals and improve the insertion and return loss performance of the four-core fiber multiplexer and demultiplexer.

[0074] Example 2:

[0075] Example 2: Fabrication of a linear four-core optical fiber multiplexer / demultiplexer.

[0076] Example 2 differs from Example 1 in that the cores of the four-core optical fiber are arranged in a straight line, and the core arrangement of the small-diameter optical fiber in the first ferrule corresponds accordingly. The core spacing of the straight-line four-core optical fiber is 40 micrometers, with an error within ±0.5 micrometers, and the cladding diameter is 180 micrometers, with an error within ±0.5 micrometers. The cladding diameter of the small-diameter optical fiber is 40 micrometers, with an error within ±0.5 micrometers. The inner hole of the first ferrule is a square through-hole, and the space of the inner hole can accommodate four small-diameter optical fibers inserted simultaneously. A schematic diagram of the alignment and positioning of the straight-line four-core optical fiber multiplexer / demultiplexer is shown below. Figure 5 As shown.

[0077] Example 3:

[0078] Example 3: Preparation of an eight-core optical fiber multiplexer / demultiplexer.

[0079] Example 3 differs from Example 1 in that the cores of the eight-core optical fiber are arranged in a circular ring, and the core spatial arrangement of the small-diameter optical fiber in the first ferrule corresponds accordingly. A schematic diagram of the alignment and positioning of the eight-core optical fiber multiplexer / demultiplexer is shown below. Figure 6 As shown.

[0080] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for fabricating a multi-core optical fiber multiplexer / demultiplexer, characterized in that, Includes the following steps: Step 1: Strip the coating of n single-mode optical fibers to obtain n first intermediate components; fused a small-diameter optical fiber to one end of each first intermediate component to obtain a second intermediate component; the cladding diameter of the small-diameter optical fiber is equal to the core spacing of the multi-core optical fiber to be matched, and the mode field diameter of the small-diameter optical fiber is consistent with the mode field diameter of each core in the multi-core optical fiber. Step 2: Insert n second intermediate components into the first ferrule. The small outer diameter optical fiber passes through the first ferrule and extends a first distance. After curing, grind the end face of the small outer diameter optical fiber to obtain the third intermediate component. Connect the third intermediate component coaxially with the first sleeve. Step 3: Use the first component to limit the first sleeve; the first component is a planar structure, and a portion of the outer surface of the first sleeve is a planar structure. When the planar structure of the first sleeve is placed horizontally along the first component, it can restrict the rotation of the first sleeve; obtain the fiber core position information of the third intermediate component; Step 4: Connect the second ferrule and the second sleeve coaxially; strip the coating layer of the multi-core optical fiber, insert the stripped end of the multi-core optical fiber into the second ferrule, and let the multi-core optical fiber pass through the second ferrule and extend out a second distance; Step 5: Use the second component to limit the second sleeve; the second component is a planar structure, and a portion of the inner surface of the second sleeve is a planar structure. When the planar structure of the second sleeve is placed horizontally along the second component, it can restrict the rotation of the second sleeve. Based on the fiber core position information of the third intermediate component, the multi-core optical fiber is rotated and adjusted, and after curing, the end face of the multi-core optical fiber used to dock with the third intermediate component is polished. Step 6: The first component and the second component are the same size. With the assistance of the first component and the second component, the first sleeve is inserted into the second sleeve so that the end faces of the first ferrule and the second ferrule are aligned and fitted, thus completing the preparation of the multi-core optical fiber multiplexer / demultiplexer.

2. The method for fabricating a multi-core optical fiber multiplexer / demultiplexer according to claim 1, characterized in that, The cladding diameter of the small-diameter optical fiber ranges from 40 to 80 micrometers, and the mode field diameter ranges from 8 to 10 micrometers; the cladding diameter of the multi-core optical fiber ranges from 125 to 250 micrometers.

3. The method for fabricating a multi-core optical fiber multiplexer / demultiplexer according to claim 1, characterized in that, The fiber cores of the multi-core optical fiber are arranged in one of the following ways: rectangular, linear, or circular.

4. The method for fabricating a multi-core optical fiber multiplexer / demultiplexer according to claim 1, characterized in that, The first ferrule is an optical module ferrule, and the multi-core optical fiber contains 4 or 8 fiber cores.

5. The method for fabricating a multi-core optical fiber multiplexer / demultiplexer according to claim 1, characterized in that, In step 3, the fiber core position information of the third intermediate component is obtained by the following method: using an imaging system to observe the position of each fiber core in the third intermediate component, finding the two fiber cores that are farthest apart and closest to the horizontal axis, calculating the angle between the line connecting the two found fiber cores and the horizontal axis, and recording it as the first angle value. In step 5, the multi-core optical fiber is rotated and adjusted in the following way: the position of each core in the multi-core optical fiber is observed using an imaging system, the two cores that are farthest apart and closest to the horizontal axis are found, and the multi-core optical fiber is rotated so that the angle between the line connecting the two found cores and the horizontal axis reaches the first angle value.

6. The method for fabricating a multi-core optical fiber multiplexer / demultiplexer according to claim 1, characterized in that, In step 4, after inserting the end of the multi-core optical fiber with the coating removed into the second ferrule, the process further includes cleaning and cutting the multi-core optical fiber that has exited the second ferrule to obtain a neat and flat end face.

7. The method for fabricating a multi-core optical fiber multiplexer / demultiplexer according to claim 1, characterized in that, In step 6, the fiber end faces of the first ferrule and the second ferrule used for alignment and bonding are also coated.

8. The method for fabricating a multi-core optical fiber multiplexer / demultiplexer according to claim 1, characterized in that, In step 6, the outer diameter of the first sleeve is the same as the inner diameter of the second sleeve. The first sleeve is made of metal, and the second sleeve is made of plastic.

9. A multi-core optical fiber multiplexer / demultiplexer, characterized in that, It is prepared by the method of preparing a multi-core optical fiber multiplexer / demultiplexer as described in any one of claims 1-8.

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