A double-layer flexible light backboard with high pressure resistance and expandability and a preparation method thereof

Abstract

The application discloses a double-layer flexible optical backboard with high compression resistance and expandability and a preparation method thereof. The double-layer flexible optical backboard comprises two layers of upper and lower flexible optical backboards, each of which comprises two layers of flexible films, optical fibers and optical fiber ports. The number of the optical fiber ports of each layer of the flexible optical backboard is 2n, n of which are uplink ports, and the other n are downlink ports. The optical fibers at the uplink ports with the same number and the downlink ports with the same number are gathered together into a bundle of optical fibers and connected with an MPO optical fiber connector. The maximum number of overlapping layers of the optical fibers crossing each other on each layer of the flexible optical backboard is 2, the spacing of the optical fiber crossing points is 4-6 mm, and the optical fiber ports on the upper and lower optical backboards are staggered. The double-layer flexible optical backboard with high compression resistance and expandability and the preparation method thereof can effectively solve the problem of poor impact resistance and compression resistance of the flexible optical backboard in the prior art.

Description

Technical Field

[0001] This invention relates to the field of flexible backlight technology, and in particular to a double-layer flexible backlight with strong compressive strength and scalability, and its preparation method. Background Technology

[0002] In the field of data communication and transmission, early electronic backplanes used traditional wires and conductors for data transmission. However, this method had many problems, such as low transmission speed, limited bandwidth, and electromagnetic interference. With the development of fiber optic communication technology, the advantages of fiber optics, such as high speed, high bandwidth, low loss, and strong anti-interference capabilities, became apparent. Therefore, fiber optics were gradually applied to backplane technology to provide more efficient, reliable, and high-density data transmission. Optical interconnect backplanes are a type of backplane technology that uses fiber optics to replace traditional electrical interconnect backplanes, enabling high-speed, high-bandwidth, and low-latency data transmission and switching.

[0003] In recent years, fiber optic backplane technology has developed rapidly, with modern fiber optic backplanes demanding higher density, dimensionality, and adaptability. The overall structure of fiber optic backplanes has evolved from the initial box-type backplanes to today's flexible backplanes. Compared to traditional box-type backplanes, flexible backplanes offer advantages such as thinness, flexibility, energy efficiency, environmental friendliness, high-efficiency transmission, and smaller size. Figure 1 As shown, a typical flexible optical backplane has only a single-layer structure, consisting of two flexible thin films, an intermediate optical fiber layer located between the flexible thin films, and optical fiber ports evenly distributed at the four edges of the flexible optical backplane. The characteristic of this structure is that the optical fiber ports are fixed and densely arranged, but the optical fiber crossover points are far apart. Furthermore, due to the use of flexible materials, the optical backplane can be bent and folded, resulting in less than ideal compressive and impact resistance. Even under relatively small pressure, the loss of optical fiber signal transmission can increase sharply, which may even lead to damage to the optical fiber and affect the overall performance of the optical backplane.

[0004] To address the aforementioned issues, a novel flexible optical backplane is needed. By using a double-layer flexible optical backplane and multi-layer fiber optic optimized cabling within each flexible optical backplane, the compressive strength of the optical backplane can be improved, thereby enhancing the overall performance of optical transmission and switching. Summary of the Invention

[0005] The purpose of this invention is to provide a double-layer flexible backplane with strong compressive strength and scalability, and its preparation method, so as to solve the problem of poor impact and compressive strength of flexible backplanes in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A double-layer flexible optical backplane with strong pressure resistance and scalability, and its fabrication method, are disclosed. The backplane comprises two flexible backplanes—an upper backplane and a lower backplane—arranged vertically. Each flexible backplane includes two flexible thin films, optical fibers, and optical fiber ports fixedly disposed on four sides of the backplane. The two flexible backplanes share a single flexible thin film. Each flexible backplane has 2n optical fiber ports, of which n are uplink ports and the other n are downlink ports. When n is even, uplink ports numbered 1 to n / 2 and n / 2+1 to n are respectively located on the upper and lower parallel sides of the flexible backplane. The left and right parallel sides of the flexible backplane... The upper side of the flexible optical backplane has downlink ports numbered 1 to n / 2 and n / 2+1 to n respectively. When n is odd, the upper and lower parallel sides of the flexible optical backplane have uplink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n respectively. The left and right parallel sides of the flexible optical backplane have downlink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n respectively. The optical fibers at the uplink and downlink ports with the same number are converged into a bundle of optical fibers and connected to the MPO optical fiber connector. The optical fibers at the uplink ports are densely arranged optical fiber array bundles, while the optical fibers at the downlink ports are separate individual optical fibers.

[0008] The maximum number of fiber overlap layers on each flexible optical backplane is 2, and the spacing between fiber crossover points is 4-6mm. The fiber ports on the upper and lower optical backplanes are staggered. Each uplink port on the upper parallel side of the upper optical backplane is connected to a downlink port on the left parallel side with a different number via fiber. Each uplink port on the lower parallel side of the upper optical backplane is connected to a downlink port on the right parallel side with a different number via fiber. Each uplink port on the upper parallel side of the lower optical backplane is connected to a downlink port on the right parallel side via fiber. Each uplink port on the lower parallel side of the lower optical backplane is connected to a downlink port on the left parallel side via fiber.

[0009] Preferably, the optical fiber is connected to the flexible film by an adhesive, and the flexible film is an FR4 flexible film with a thickness of 0.1 mm.

[0010] Preferably, the spacing between the fiber optic crossover points on each flexible backplane is 5 mm.

[0011] Preferably, the distance between fiber optic ports on the same side is 1 cm.

[0012] Preferably, the minimum bending angle of the optical fiber in each layer of flexible optical backplane is 60° and the bending radius of the optical fiber is 9.5mm.

[0013] A method for preparing a double-layer flexible optical backplane with high compressive strength and scalability includes the following steps:

[0014] Step 1: Prepare three flexible films, namely the first flexible film, the second flexible film and the third flexible film. Apply adhesive evenly to one side of the first flexible film and the third flexible film, and apply adhesive evenly to both sides of the second flexible film.

[0015] Step 2: Arrange and position the fiber optic ports on the upper and lower backplanes: The arrangement and positioning method for the fiber optic ports on the upper backplane is the same as that on the lower backplane, except that the fiber optic ports on the upper backplane are positioned on the four sides of the first flexible film, while the fiber optic ports on the lower backplane are positioned on the four sides of the third flexible film. The fiber optic ports on the upper and lower backplanes are staggered. The following is a detailed description using the arrangement and positioning method of the upper backplane fiber optic ports as an example: 2n fiber optic ports are evenly fixed at intervals on the four sides of the first flexible film, with a distance of 1cm between fiber optic ports on the same side. n of these fiber optic ports are uplink ports. The outer n fiber optic ports are downlink ports. When n is even, uplink ports numbered 1 to n / 2 and n / 2+1 to n are placed on the upper and lower parallel sides of the first flexible film, respectively, and downlink ports numbered 1 to n / 2 and n / 2+1 to n are placed on the left and right parallel sides of the first flexible film, respectively. When n is odd, uplink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n are placed on the upper and lower parallel sides of the first flexible film, respectively, and downlink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n are placed on the left and right parallel sides of the first flexible film, respectively.

[0016] Step 3: Employ a multi-layer fiber crossover and staggered stacking layout to achieve interconnection and switching between fiber ports: Lay the upper optical backplane fiber on the first flexible film and lay the lower optical backplane fiber on the third flexible film. When laying the fiber, ensure that the maximum number of overlapping layers of fiber crossover is 2 layers, and the spacing between fiber crossover points is 4-6mm. Each uplink port on the upper parallel side of the upper optical backplane is connected to a downlink port on the left parallel side with a different number via fiber. Each uplink port on the lower parallel side of the upper optical backplane is connected to a downlink port on the right parallel side with a different number via fiber. Each uplink port on the upper parallel side of the lower optical backplane is connected to a downlink port on the right parallel side via fiber. Each uplink port on the lower parallel side of the lower optical backplane is connected to a downlink port on the left parallel side via fiber.

[0017] Step 4: Using the second flexible film, the first flexible film and the optical fiber laid on it, and the third flexible film and the optical fiber laid on it are bonded together to form a double-layer flexible optical backplane with strong pressure resistance and scalability.

[0018] Preferably, in step 3, the spacing between the fiber optic crossover points is 5m, the minimum bending angle of the fiber optic in each layer of flexible backplane is 60°, and the bending radius of the fiber optic is 9.5mm.

[0019] This invention employs a double-layer flexible optical backplane with strong compressive strength and scalability, along with its fabrication method. By using a double-layer backplane and optimized cabling with multiple layers of optical fibers within each backplane, the optical backplane achieves a smaller size, better compressive strength, and more stable signal transmission performance for the same number of fiber ports. It facilitates interconnection and switching of uplink and downlink channels across various dimensions and branches, thereby improving the overall performance of optical transmission and switching. Furthermore, this solution can be extended to double-layer flexible n×n optical backplanes of any dimension, enabling all-optical cross-connection between any number of multi-dimensional uplink and downlink fiber ports. It exhibits excellent scalability and simplifies and facilitates fiber optic cabling. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an existing single-layer flexible backplane structure;

[0021] Figure 2 This is a schematic diagram of the structure of the double-layer flexible 8×8 backplane of the present invention;

[0022] Figure 3 This is a schematic diagram showing that the number of fiber overlap layers at the fiber crossover point of the present invention is 2;

[0023] Figure 4 This is a schematic diagram showing that the number of fiber overlap layers at the fiber crossover point is 3 in the control group;

[0024] Figure 5 This is an overall schematic diagram of the design structure of the optical fiber cabling scheme in the optical backplane of n×n when the number n is even.

[0025] Figure 6 This is an overall schematic diagram of the design structure of the optical fiber cabling scheme in the optical backplane under even number n and n×n.

[0026] Figure 7 This is a schematic diagram illustrating how the present invention connects the No. 1 uplink port of the n×n optical backplane to other downlink ports when the number n is even.

[0027] Figure 8 This is a schematic diagram illustrating how the present invention connects the uplink port 1 of the optical backplane to other downlink ports when the number n is even (n×n).

[0028] Figure 9This is a schematic diagram of the fiber optic cabling scheme design structure for an 8×8 optical backplane according to the present invention;

[0029] Figure 10 This is a schematic diagram of the fiber optic cabling scheme design structure for an 8×8 optical backplane according to the present invention;

[0030] Figure 11 This is a graph showing the average fiber loss of the 8×8 double-layer flexible optical backplane of this invention and the single-layer flexible optical backplane made according to the traditional cabling scheme.

[0031] Figure Labels

[0032] 1. Flexible film; 2. Optical fiber; 3. MPO optical fiber connector. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] A double-layer flexible optical backplane with high pressure resistance and scalability, and its fabrication method, are disclosed. The backplane comprises two layers of flexible optical backplanes—an upper backplane and a lower backplane—each consisting of two flexible thin films 1, an optical fiber 2, and optical fiber ports fixedly disposed on four sides of the flexible backplane. The two flexible backplanes share a single flexible thin film 1. The optical fibers 2 are connected to the flexible thin film 1 by an adhesive. The flexible thin film 1 is an FR4 flexible thin film with a thickness of 0.1 mm. The distance between the optical fiber ports on the same side is 1 cm. Each flexible optical backplane has 2n fiber optic ports, with n being uplink ports and the other n being downlink ports. When n is even, the top and bottom parallel edges of the flexible optical backplane have uplink ports numbered 1 to n / 2 and n / 2+1 to n, respectively, while the left and right parallel edges have downlink ports numbered 1 to n / 2 and n / 2+1 to n, respectively. When n is odd, the top and bottom parallel edges of the flexible optical backplane have... There are uplink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n on the left and right parallel sides of the flexible optical backplane, respectively. The optical fibers at the uplink and downlink ports with the same number are converged into a bundle of optical fibers and connected to the MPO optical fiber connector 3. The optical fibers at the uplink ports are densely arranged optical fiber array bundles, while the optical fibers at the downlink ports are separate individual optical fibers.

[0035] The maximum number of overlapping layers of fiber 2 on each flexible backplane is 2, and the spacing between fiber crossing points is 4-6 mm, preferably 5 mm. The minimum bending angle of fiber 2 in each flexible backplane is 60°, and the bending radius of fiber 2 is 9.5 mm. The fiber ports on the upper and lower backplanes are staggered. Each uplink port on the upper parallel side of the upper backplane is connected to a downlink port on the left parallel side with a different number via fiber 2. Each uplink port on the lower parallel side of the upper backplane is connected to a downlink port on the right parallel side with a different number via fiber 2. Each uplink port on the upper parallel side of the lower backplane is connected to a downlink port on the right parallel side via fiber 2. Each uplink port on the lower parallel side of the lower backplane is connected to a downlink port on the left parallel side via fiber 2.

[0036] A method for preparing a double-layer flexible optical backplane with high compressive strength and scalability includes the following steps:

[0037] Step 1: Prepare three flexible films 1, namely the first flexible film, the second flexible film and the third flexible film. Apply adhesive evenly to one side of the first flexible film and the third flexible film, and apply adhesive evenly to both sides of the second flexible film.

[0038] Step 2: Arrange and position the fiber optic ports on the upper and lower backplanes: The arrangement and positioning method for the fiber optic ports on the upper backplane is the same as that on the lower backplane, except that the fiber optic ports on the upper backplane are positioned on the four sides of the first flexible film, while the fiber optic ports on the lower backplane are positioned on the four sides of the third flexible film. The fiber optic ports on the upper and lower backplanes are staggered. The following is a detailed description using the arrangement and positioning method of the upper backplane fiber optic ports as an example: 2n fiber optic ports are evenly fixed at intervals on the four sides of the first flexible film, with a distance of 1cm between fiber optic ports on the same side. n of these fiber optic ports are uplink ports. The outer n fiber optic ports are downlink ports. When n is even, uplink ports numbered 1 to n / 2 and n / 2+1 to n are placed on the upper and lower parallel sides of the first flexible film, respectively, and downlink ports numbered 1 to n / 2 and n / 2+1 to n are placed on the left and right parallel sides of the first flexible film, respectively. When n is odd, uplink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n are placed on the upper and lower parallel sides of the first flexible film, respectively, and downlink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n are placed on the left and right parallel sides of the first flexible film, respectively.

[0039] Step 3: A multi-layered fiber optic crossover and staggered stacking layout is used to achieve interconnection and switching between fiber optic ports: Fiber 2 for the upper optical backplane is laid on the first flexible film, and fiber 2 for the lower optical backplane is laid on the third flexible film. When laying fiber 2, the maximum number of overlapping layers for fiber crossover is 2 layers, and the spacing between fiber crossover points is 4-6 mm, preferably 5 m. The minimum bending angle of fiber 2 in each layer of the flexible optical backplane is 60°, and the bending radius of fiber 2 is 9.5 mm. Each uplink port on the upper parallel side of the upper optical backplane is connected to a downlink port on the left parallel side with a different number via fiber 2. Each uplink port on the lower parallel side of the upper optical backplane is connected to a downlink port on the right parallel side with a different number via fiber 2. Each uplink port on the upper parallel side of the lower optical backplane is connected to a downlink port on the right parallel side via fiber 2. Each uplink port on the lower parallel side of the lower optical backplane is connected to a downlink port on the left parallel side via fiber 2.

[0040] Step 4: Using the second flexible film, the first flexible film and the optical fiber laid on it, and the third flexible film and the optical fiber 2 laid on it are bonded together to form a double-layer flexible optical backplane with strong pressure resistance and scalability.

[0041] Based on the above ideas, this invention designs an n×n double-layer flexible backplane wiring scheme suitable for any dimension, such as... Figure 5 The diagram shows the overall design structure of the fiber optic cabling scheme in an n×n optical backplane when the number of n is even. Figure 6 The diagram shows the overall design structure of the fiber optic cabling scheme in the optical backplane for an even number of n×n. Figure 7 The diagram illustrates how to connect uplink port 1 of the optical backplane on an n×n array to other downlink ports when the number n is even. Figure 8 The diagram shows how to connect the uplink port 1 of the optical backplane to other downlink ports when the number n is even (n×n).

[0042] To verify the effectiveness of this invention, the following comparative and verification experiments were conducted:

[0043] Experiment 1: Comparison of Single-Layer and Double-Layer Structures

[0044] like Figure 1 As shown, a typical flexible optical backplane has only a single-layer structure, consisting of two thin films and an intermediate optical fiber layer. This structure is characterized by fixed and densely arranged fiber ports, but the fiber crossover points are spaced far apart, resulting in less than ideal compressive and impact resistance. Figure 2As shown, this invention replaces a single-layer flexible optical backplane with a two-layer stacked flexible optical backplane. The fiber ports of both layers are fixed and numbered. The fiber bundles from the same numbered fiber ports in the upper and lower layers are converged together and then connected to a multi-layer MPO optical connector. This improvement is equivalent to placing a portion of the fiber from the original flexible optical backplane into another flexible optical backplane, reducing the wiring area of ​​a single flexible optical backplane and the spacing between fiber ports. Furthermore, through the optimized layout of multi-layer fiber crossing and staggered stacking, the pressure resistance of the flexible optical backplane is improved, reducing the impact of pressure on its optical transmission performance.

[0045] Experiment 2: Comparison of 2-layer and 3-layer fiber overlap at fiber optic crossover points

[0046] The fiber optic cabling method is the most significant factor affecting the performance of flexible optical backplanes. Because the fibers in a flexible backplane need to be cross-connected between various optical ports, fiber crossover points are unavoidable. Analyzing the impact of pressure on the fiber transmission loss of a flexible optical backplane, the main issue is that pressure applied to the backplane causes significant fiber deformation at the crossover points, resulting in substantial microbending loss. Under high pressure, this can lead to fiber breakage. To address this problem, this solution proposes improving the pressure distribution of the optical backplane by optimizing the fiber cabling method. By improving the crossover method, fiber deformation at the crossover points can be reduced, thereby reducing microbending loss. Under high pressure, this improvement can reduce the risk of fiber breakage.

[0047] Firstly, a fabrication was made using bare optical fiber and FR4 flexible thin film, as shown in the example. Figure 3 and Figure 4 The fiber optic crossover method, its Figure 3 The fiber optic crossover point has two overlapping layers, serving as a control group. Figure 4 The fiber optic crossover point has three overlapping layers. In actual stress testing, the three-layer overlapping fiber optic crossover, serving as a control group, was highly susceptible to damage; under relatively low pressure, fiber loss increased dramatically, leading to fiber failure. In contrast, the two-layer overlapping fiber optic crossover showed no significant change or damage under higher pressure. Similarly, as the number of fibers per layer at the crossover point increased, fiber loss decreased under the same pressure. Based on these test results, the fiber optic cabling design should employ a tightly packed fiber optic layer layout, with a maximum overlap of two layers at the crossover point.

[0048] Experiment 3: Density Comparison of Fiber Optic Crossover Points

[0049] In actual testing, the number and spacing of fiber optic crossovers have a significant impact on fiber transmission loss. Experiments have shown that within the same area, as the number of fiber crossovers increases and the spacing decreases (i.e., the crossover density increases), the fiber loss in the optical backplane under the same pressure decreases.

[0050] When laying fiber optic cables, crossing fibers of the same layer results in closely spaced crossover points, while crossing fibers of different layers requires maintaining a certain spacing between these crossover points. Actual testing revealed that fiber loss is optimal when the spacing between crossover points of fibers of different layers is between 4-6 mm. However, when the spacing is less than 4 mm, fiber loss increases under the same stress.

[0051] To achieve ideal fiber optic cabling, we adopted a double-layer flexible optical backplane structure and rationally staggered the optical fibers in the cabling. Fibers at the same layer are tightly arranged, with a maximum overlap of 2 layers at fiber crossings. The spacing between fiber crossing points is maintained at approximately 5mm, ideally within the range of 4-6mm. Simultaneously, to balance the fiber port positions, we separated the uplink and downlink fiber ports on the backplane and evenly distributed them along the four edges of the backplane. The uplink ports consist of densely packed fiber array bundles, while the downlink output ports are separate individual fibers, with a distance of 1cm between fiber ports on the same side.

[0052] If the fiber optic cables cross in a perpendicular cross shape, the maximum bending radius can only be 5mm to avoid creating new crossing points, but this leads to significant bending loss. To reduce bending loss, we control the crossing angle between the fibers, reducing the minimum bending angle from 90° to 60°. This increases the bending radius to 9.5mm, thereby reducing bending loss.

[0053] Experiment 4: Comparison of average fiber loss between the 8×8 double-layer flexible optical backplane of this invention and the single-layer flexible optical backplane made according to the traditional cabling scheme.

[0054] The fiber optic cabling structure of the upper and lower optical backplanes in the 8×8 double-layer flexible optical backplane designed in this invention is as follows: Figure 9 and Figure 10As shown, the entire double-layer flexible optical backplane consists of two layers of flexible optical backplanes stacked together. Each layer has a total of 16 fiber optic ports, including 8 uplink ports (numbered 1-8) and 8 downlink ports (numbered 1-8). These fiber optic ports are evenly distributed along the four edges of the backplane. The fiber optic cabling maintains a 60-degree bend angle, with approximately 5mm spacing between crossover points between different layers, and a bend radius of 9.5mm. The fiber optic ports on the backplane are interconnected via optical fibers. Uplink fibers from ports 1-4 connect to downlink fibers from ports 1-4, and uplink fibers from ports 5-8 connect to downlink fibers from ports 5-8. Uplink and downlink ports with the same number are not interconnected. The fiber optic interconnection between the fiber optic ports on the backplane is as follows: the uplink fibers from ports 1-4 are connected to the downlink fibers from ports 5-8, and the uplink fibers from ports 5-8 are connected to the downlink fibers from ports 1-4. The fibers are densely arranged in an array at the uplink ports, but are separate individual fibers at the downlink output. This design enables uplink and downlink optical interconnection between any two ports.

[0055] The 8×8 double-layer flexible optical backplane developed in this invention, compared to a conventional flexible optical backplane fabricated using traditional cabling methods, exhibits the following results when the average fiber loss is measured under continuous and uniform pressure, relative to the unpressurized state: Figure 11 As shown, the optimized layout of this scheme results in a more balanced pressure distribution on the optical backplane, can accommodate more layers of fiber stacking, reduces the backplane volume, and has excellent pressure resistance.

[0056] In summary, the advantages of this scheme are: by optimizing pressure distribution, it can achieve a multi-layer fiber stacking layout, reducing transmission loss; it can achieve a smaller size, better pressure resistance, and more stable signal transmission performance with the same number of fiber ports; at the same time, the manufacturing process is simpler and more convenient, and it can be expanded to realize more-dimensional uplink and downlink optical cross-connection.

[0057] Therefore, this invention employs the aforementioned highly pressure-resistant and scalable double-layer flexible optical backplane and its fabrication method. By using the double-layer backplane and multi-layer optical fiber optimization cabling within each backplane, a multi-layer optical fiber cabling stacking layout is achieved. With the same number of optical fiber ports, the optical backplane has a smaller volume, better pressure resistance, and more stable signal transmission performance, facilitating interconnection and switching of uplink and downlink channels in various dimensions and branches. Simultaneously, this solution also achieves all-optical cross-connection between any number of multi-dimensional uplink and downlink optical fiber ports, exhibiting good scalability and simplifying and facilitating optical fiber cabling operations.

[0058] The above are specific embodiments of the present invention, but the scope of protection of the present invention should not be limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A double-layer flexible backplane with strong pressure resistance and expandability, characterized in that: The system comprises two flexible backplanes—an upper backplane and a lower backplane—each consisting of two flexible thin films, optical fibers, and fiber optic ports fixed on four sides. The two backplanes share a single flexible thin film. Each backplane has 2n fiber optic ports, where n ≥ 8. n of these ports are uplink ports, and the other n are downlink ports. When n is even, the upper and lower parallel sides of the backplane have uplink ports numbered 1 to n / 2 and n / 2+1 to n, respectively. The left and right parallel sides of the backplane have ports numbered 1 to n. Downlink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n are provided on the upper and lower parallel sides of the flexible optical backplane, respectively. Downlink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n are provided on the left and right parallel sides of the flexible optical backplane, respectively. The optical fibers at the uplink ports and downlink ports with the same number are converged into a bundle of optical fibers and connected to the MPO optical fiber connector. The optical fibers at the uplink ports are densely arranged optical fiber array bundles, while the optical fibers at the downlink ports are separate individual optical fibers. The maximum number of fiber overlap layers on each flexible optical backplane is 2, and the spacing between fiber crossover points is 4-6mm. The fiber ports on the upper and lower optical backplanes are staggered. Each uplink port on the upper parallel side of the upper optical backplane is connected to a downlink port on the left parallel side with a different number via fiber. Each uplink port on the lower parallel side of the upper optical backplane is connected to a downlink port on the right parallel side with a different number via fiber. Each uplink port on the upper parallel side of the lower optical backplane is connected to a downlink port on the right parallel side via fiber. Each uplink port on the lower parallel side of the lower optical backplane is connected to a downlink port on the left parallel side via fiber.

2. The double-layer flexible backplane with strong compressive strength and expandability according to claim 1, characterized in that: The optical fiber is connected to the flexible film by an adhesive. The flexible film is an FR4 flexible film with a thickness of 0.1 mm.

3. The double-layer flexible backplane with strong compressive strength and expandability according to claim 2, characterized in that: The spacing between the fiber optic crossover points on each layer of flexible backplane is 5mm.

4. The double-layer flexible backplane with strong compressive strength and expandability according to claim 3, characterized in that: The distance between fiber optic ports on the same side is 1 cm.

5. A double-layer flexible backplane with high compressive strength and expandability according to claim 4, characterized in that: The minimum bending angle of the optical fiber in each layer of flexible backplane is 60°, and the bending radius of the optical fiber is 9.5mm.

6. The method for preparing a double-layer flexible backplane with high compressive strength and scalability as described in any one of claims 1-5, characterized in that: Includes the following steps: Step 1: Prepare three flexible films, namely the first flexible film, the second flexible film and the third flexible film. Apply adhesive evenly to one side of the first flexible film and the third flexible film, and apply adhesive evenly to both sides of the second flexible film. Step 2: Arrange and position the fiber optic ports on the upper and lower backplanes: The arrangement and positioning method for the fiber optic ports on the upper backplane is the same as that on the lower backplane, except that the fiber optic ports on the upper backplane are positioned on the four sides of the first flexible film, while the fiber optic ports on the lower backplane are positioned on the four sides of the third flexible film. The fiber optic ports on the upper and lower backplanes are staggered. Specifically, the arrangement and positioning method for the fiber optic ports on the upper backplane is as follows: 2n fiber optic ports are evenly fixed at intervals on the four sides of the first flexible film, where n ≥ 8. The distance between fiber optic ports on the same side is 1 cm. n of these are uplink ports, and the remaining n are downlink ports. Each fiber optic port is a downlink port. When n is even, uplink ports numbered 1 to n / 2 and n / 2+1 to n are placed on the upper and lower parallel sides of the first flexible film, respectively, and downlink ports numbered 1 to n / 2 and n / 2+1 to n are placed on the left and right parallel sides of the first flexible film, respectively. When n is odd, uplink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n are placed on the upper and lower parallel sides of the first flexible film, respectively, and downlink ports numbered 1 to (n+1) / 2 and (n+1) / 2+1 to n are placed on the left and right parallel sides of the first flexible film, respectively. Step 3: Employ a multi-layer fiber crossover and staggered stacking layout to achieve interconnection and switching between fiber ports: Lay the upper optical backplane fiber on the first flexible film, and lay the lower optical backplane fiber on the third flexible film. When laying the fiber, ensure that the maximum number of overlapping layers of fiber crossover is 2 layers, and the spacing between fiber crossover points is 4-6mm. Each uplink port on the upper parallel side of the upper optical backplane is connected to a downlink port on the left parallel side with a different number via fiber. Each uplink port on the lower parallel side of the upper optical backplane is connected to a downlink port on the right parallel side with a different number via fiber. Each uplink port on the upper parallel side of the lower optical backplane is connected to a downlink port on the right parallel side via fiber. Each uplink port on the lower parallel side of the lower optical backplane is connected to a downlink port on the left parallel side via fiber. Step 4: Using the second flexible film, the first flexible film and the optical fiber laid on it, and the third flexible film and the optical fiber laid on it are bonded together to form a double-layer flexible optical backplane with strong pressure resistance and scalability.

7. The method for preparing a double-layer flexible backplane with strong compressive strength and scalability as described in claim 6, characterized in that: In step 3, the spacing between the fiber optic crossover points is 5mm, the minimum bending angle of the fiber optic in each layer of flexible backplane is 60°, and the bending radius of the fiber optic is 9.5mm.

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