Optical fiber image transmitting bundle design and preparation method for reducing inter-core crosstalk

Abstract

The invention discloses a design and preparation method of an optical fiber image-transmitting bundle for reducing inter-core crosstalk. The method comprises the following steps: S1, carrying out correlation calculation on the optical fiber image-transmitting bundle; s2, preparing core glass and cladding glass; s3, obtaining a single-core fiber through spinning; s4, preprocessing the image fibers; s5, arranging and integrating the single-core fibers; and S6, manufacturing an image transmitting bundle preform. According to the invention, the refractive index of the cores, the refractive index change between the cores and the spacing change can be determined through the correlation calculation of the optical fiber image transmitting bundle, so that the installation position of the single-core fiber group in the glass sleeve can be conveniently distributed, and arrangement and integration are realized according to the classification of the fiber cores in the single-core fiber group and the distribution of multiple fiber cores; the prepared optical fiber image transmitting bundle has small sacrifice on the light transmitting efficiency, the leakage phenomenon of the optical waveguide can be effectively reduced, and the inter-core crosstalk of the optical fiber image transmitting bundle is reduced, so that the image transmission quality is improved.

Description

Technical Field

[0001] This invention relates to the field of optical fiber fabrication technology, specifically to a method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk. Background Technology

[0002] Optical fiber is short for optical waveguide fiber. It is a type of fiber made of glass or plastic that can be used as a light transmission tool. The transmission principle is "total internal reflection of light". Since the light transmission loss in optical waveguide fiber is much lower than the electrical transmission loss in wire, optical fiber is used for long-distance information transmission. In daily life, optical fiber is widely used in medical or industrial applications.

[0003] In the existing technology, crosstalk exists between cores during the use of fiber optic image bundles. To ensure the transmission effect of the image, the crosstalk problem is solved by sacrificing the area of ​​the effective light transmission unit and increasing the inter-core distance during fiber fabrication. However, the fiber treated in the above way sacrifices a high light transmission efficiency and suffers from waveguide leakage during fiber use, which affects the use effect of the fiber optic image bundle.

[0004] Therefore, we propose a method for designing and fabricating fiber optic image bundles to reduce inter-core crosstalk, in order to solve the problems mentioned above. Summary of the Invention

[0005] The purpose of this invention is to provide a design and fabrication method for fiber optic image bundles that reduces inter-core crosstalk, in order to solve the problem proposed in the background art that the fiber optics processed by sacrificing the area of ​​the effective light transmission unit to increase the inter-core distance have a high sacrifice in light transmission efficiency and suffer from optical waveguide leakage during fiber use, which affects the performance of the fiber optic image bundle.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk, comprising the following steps: S1. Calculation of fiber optic image bundle: Calculate the shared multi-refractive-index cladding between cores according to the fiber optic transmission wave equation. Set the core refractive index to n1 and the shared refractive indices between cores to n2, n3, and n4. S2. Core glass and cladding glass preparation: Before making core glass and cladding glass, the raw materials are purified to obtain high-purity raw materials. The two raw materials are mixed and placed in a swing furnace for processing. Then, degassing and annealing are performed to obtain core glass and cladding glass rods. The core glass and cladding glass are combined into optical fiber preforms using the sleeve method or combination method. S3. Obtaining single-core fibers through spinning: Preheat the optical fiber drawing furnace, put the optical fiber preform prepared by the sleeve method into the drawing furnace, and after drawing, prepare preliminary single-core fibers. Calculate the diameter, cladding thickness and core-to-skin ratio of the single-core fibers, and determine whether the single-core fibers match the calculation results. If they match, continuously spin from the drawing machine to produce single-core fibers. S4. Fiber pretreatment: Set the length of the single core fiber, cut the single core fiber prepared in S3 into a predetermined length, the cut single core fiber is arranged in a sheet, and then screen the defects in the single core fiber and remove them quickly. S5. Arrangement and integration of single-core fibers: Before arrangement, the single-core fibers are classified within groups and allocated to multiple groups according to the calculation results in S1. After allocation, multiple groups of single-core fibers are filled into the glass sleeve, and the filled glass sleeve is thermally fused to achieve integration. S6. Fabrication of image bundle preform: Slowly cool the preform at a predetermined temperature and a predetermined temperature gradient to obtain a glass rod-shaped preform. Grind and polish the outer ring surface of the preform. Fabricate the processed preform into an image bundle preform. Finally, place the preform into a drawing furnace to draw the fiber image bundle.

[0007] Preferably, it is necessary to calculate the optical intensity of the fiber core. By increasing the core intensity, the leakage of the waveguide can be reduced. In step S1, the wave equation for fiber transmission is Maxwell's equations, and its expression is as follows: ; In the formula, H is the magnetic field strength, J is the conduction current density, D is the electric displacement, E is the electric field strength, and B is the magnetic flux density. The electric field strength E is obtained. According to the relationship that the light intensity is the square of the electric field modulus, the analysis process can be simplified and the electric field strength can be directly compared.

[0008] Preferably, the electric field distribution of the optical fiber is constructed using the Maxwell equations to obtain a comparison of the central electric field of the single-refractive-index cladding and the central electric field of the multi-refractive-index cladding, and the core-to-cladding ratio of the single-core fiber is obtained to calculate the influence of the core-to-core spacing variation on the central electric field.

[0009] Preferably, in step S2, during the fabrication of the optical fiber preform, the material of the sleeve is changed, and different materials correspond to different refractive indices to achieve different refractive indices between the cores. By changing the thickness of the tube, the spacing between the cores is changed.

[0010] Preferably, in step S3, when using an optical fiber drawing furnace for fiber drawing, the drawing speed is 1-8 m / min and the drawing temperature is 800-900℃.

[0011] Preferably, in step S3, if the difference between the core-sheath ratio of a single fiber and the calculated result exceeds the standard range, the drawing speed is adjusted until the difference between the core-sheath ratio and the calculated result is within the standard range.

[0012] Preferably, in step S4, when screening single-core fibers, a positioning plate is selected according to the radius of the single-core fiber. A limiting groove is opened on the top of the positioning plate to make the single-core fiber stably placed in the limiting groove. Multiple single-core fibers are laid flat on the positioning plate, and the single-core fibers are rotated one by one to detect defects on the surface of the single-core fiber.

[0013] Preferably, in step S5, when allocating the fiber cores within a group, the optimal multi-refractive index distribution scheme is obtained, the single-core fibers are bundled into groups, and then filled into the glass sleeve to achieve an orderly arrangement of the single-core fiber groups.

[0014] Compared with the prior art, the beneficial effects of the present invention are: In this invention, the core refractive index and the refractive index variation between cores can be determined through relevant calculations of the optical fiber image bundle. This facilitates the allocation of the installation position of the single-core fiber assembly inside the glass sleeve and aids in the combination of the single-core fiber assembly and the glass sleeve. The raw materials for single-core fiber preparation can be obtained through the preparation of the core glass and cladding glass. The core glass and cladding glass, after purification treatment, have high purity. Then, they can be quickly processed into single-core fibers through a drawing furnace. By uniformly processing the single-core fibers, the length of the single-core fibers can be standardized, and defects in the single-core fibers can be eliminated to ensure... After processing, the quality of single-core fibers is determined by arranging and integrating them according to the classification of cores within a group and the allocation of multiple cores, thereby forming a preform. After processing the preform, an optical fiber rod can be obtained. After drawing the optical fiber rod, the optical fiber image bundle can be prepared. The prepared optical fiber image bundle has a small sacrifice in light transmission efficiency and can effectively reduce the phenomenon of optical waveguide leakage. Under the premise of ensuring the normal use of the optical fiber image bundle, the inter-core crosstalk of the optical fiber image bundle is reduced, thereby improving the image transmission quality and ensuring the use effect of the optical fiber image bundle. Attached Figure Description

[0015] Figure 1 This is a flowchart of a method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk according to the present invention. Figure 2 This is a schematic diagram of the adjacent image transmission unit structure of the fiber optic image transmission bundle design and fabrication method for reducing inter-core crosstalk according to the present invention. Figure 3 This is a bar chart comparing the center electric field intensity under different contrasts of inter-core refractive indices in the fiber optic image bundle design and fabrication method for reducing inter-core crosstalk according to the present invention. Figure 4This is a schematic diagram of the glass sleeve cross-section of a fiber optic image bundle design and fabrication method for reducing inter-core crosstalk according to the present invention. Figure 5 This is a schematic diagram of the fiber drawing equipment for a method of designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk according to the present invention. Figure 6 This is a simulated electric field intensity distribution diagram of a multi-refractive-index cladding optical fiber in Embodiment 2 of the present invention; Figure 7 This is a simulation diagram of the electric field intensity distribution of a single refractive index cladding fiber according to the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0017] Please refer to Figure 1-7 As shown, this embodiment provides a method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk, including the following steps: Step 1: Calculation of fiber optic image bundle: Calculate the shared multi-refractive-index cladding between cores according to the fiber optic transmission wave equation. Set the core refractive index to n1 and the shared refractive indices between cores to n2, n3, and n4. The wave equation for optical fiber transmission is Maxwell's equations, and its expression is as follows: ; In the formula, H is the magnetic field strength, J is the conduction current density, D is the electric displacement, E is the electric field strength, and B is the magnetic flux density. The electric field strength E is obtained. According to the relationship that the light intensity is the square of the electric field modulus, the analysis process can be simplified and the electric field strength can be directly compared. The electric field distribution of the optical fiber was constructed using Maxwell's equations. The central electric field of the single-refractive-index cladding and the central electric field of the multi-refractive-index cladding were compared. The core-to-cladding ratio of the single-core fiber was obtained, and the influence of the core-to-core spacing variation on the central electric field was calculated.

[0018] Step 2: Core Glass and Cladding Glass Preparation: Before preparing the core glass and cladding glass, the raw materials are purified to obtain high-purity raw materials. The two raw materials are mixed and processed in a swing furnace, followed by degassing and annealing to obtain core glass and cladding glass rods. The core glass and cladding glass are then combined into an optical fiber preform using a sleeve method or a combination method. During the preparation of the optical fiber preform, the material of the sleeve is changed. Different materials correspond to different refractive indices, thus achieving different refractive indices between the cores. By changing the thickness of the sleeve, the spacing between the cores can be changed.

[0019] Step 3, as follows Figure 5 As shown, single-core fibers are obtained through spinning: the fiber drawing furnace is preheated, and the fiber preform prepared by the sleeve method is placed into the drawing furnace. After drawing, preliminary single-core fibers are prepared. The diameter, cladding thickness, and core-to-skin ratio of the single-core fibers are calculated to determine whether the single-core fibers match the calculation results. If they match, the fibers are continuously spun from the drawing machine to produce single-core fibers. When drawing the fibers in the fiber drawing furnace, the drawing speed is 4 m / min and the drawing temperature is 800℃. If the difference between the core-to-skin ratio of the single-core fibers and the calculated results exceeds the standard range, the drawing speed is adjusted until the difference between the core-to-skin ratio and the calculated results is within the standard range.

[0020] Step 4, fiber pretreatment: Set the length of the single-core fiber, cut the single-core fiber prepared in step 3 into the predetermined length, and arrange the cut single-core fibers in sheet form. Then screen the single-core fibers for defects and remove them quickly. When screening the single-core fibers, select the positioning plate according to the radius of the single-core fiber. The top of the positioning plate has a limiting groove to make the single-core fiber stably placed in the limiting groove. Let multiple single-core fibers lay flat on the positioning plate, rotate the single-core fiber one by one, and detect the defects on the surface of the single-core fiber.

[0021] Step 5, Arrangement and Integration of Single-Core Fibers: Before arrangement, the single-core fibers are classified within groups and allocated to multiple groups based on the calculation results in Step 1. After allocation, multiple groups of single-core fibers are filled into the glass sleeve, and the filled glass sleeve is thermally fused to achieve integration. When allocating the single-core fibers within groups, the optimal multi-refractive index distribution scheme calculated at the current time is obtained. The single-core fibers are bundled into groups and then filled into the glass sleeve to achieve an orderly arrangement of the single-core fiber groups.

[0022] Step 6: Fabrication of image bundle preform: Slowly cool the preform at a predetermined temperature and temperature gradient to obtain a glass rod-shaped preform. Grind and polish the outer ring surface of the preform. Fabricate the processed preform into an image bundle preform. Finally, place the preform into a drawing furnace to draw the fiber image bundle. Example 2

[0023] Please refer to Figure 1-7As shown, this embodiment provides a method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk, including the following steps: Step 1: Calculation of fiber optic image bundle: Calculate the shared multi-refractive-index cladding between cores according to the fiber optic transmission wave equation. Set the core refractive index to n1 and the shared refractive indices between cores to n2, n3, and n4. The wave equation for optical fiber transmission is Maxwell's equations, and its expression is as follows: ; In the formula, H is the magnetic field strength, J is the conduction current density, D is the electric displacement, E is the electric field strength, and B is the magnetic flux density. The electric field strength E is obtained. According to the relationship that the light intensity is the square of the electric field modulus, the analysis process can be simplified and the electric field strength can be directly compared. The electric field distribution of the optical fiber was constructed using Maxwell's equations. The central electric field of the single-refractive-index cladding and the central electric field of the multi-refractive-index cladding were compared. The core-to-cladding ratio of the single-core fiber was obtained, and the influence of the core-to-core spacing variation on the central electric field was calculated.

[0024] Step 2: Core Glass and Cladding Glass Preparation: Before preparing the core glass and cladding glass, the raw materials are purified to obtain high-purity raw materials. The two raw materials are mixed and processed in a swing furnace, followed by degassing and annealing to obtain core glass and cladding glass rods. The core glass and cladding glass are then combined into an optical fiber preform using a sleeve method or a combination method. During the preparation of the optical fiber preform, the material of the sleeve is changed. Different materials correspond to different refractive indices, thus achieving different refractive indices between the cores. By changing the thickness of the sleeve, the spacing between the cores can be changed.

[0025] Step 3: Obtaining single-core fibers through spinning: Preheat the optical fiber drawing furnace, place the optical fiber preform prepared using the cladding method into the drawing furnace, and prepare preliminary single-core fibers through drawing. Calculate the diameter, cladding thickness, and core-to-skin ratio of the single-core fibers to determine if they match the calculated results. If they match, continuously spin the fibers from the drawing machine to produce single-core fibers. During the drawing process in the optical fiber drawing furnace, the drawing speed is 6 m / min and the drawing temperature is 850℃. If the difference between the core-to-skin ratio of the single-core fiber and the calculated result exceeds the standard range, adjust the drawing speed until the difference is within the standard range.

[0026] Step 4, fiber pretreatment: Set the length of the single-core fiber, cut the single-core fiber prepared in step 3 into the predetermined length, and arrange the cut single-core fibers in sheet form. Then screen the single-core fibers for defects and remove them quickly. When screening the single-core fibers, select the positioning plate according to the radius of the single-core fiber. The top of the positioning plate has a limiting groove to make the single-core fiber stably placed in the limiting groove. Let multiple single-core fibers lay flat on the positioning plate, rotate the single-core fiber one by one, and detect the defects on the surface of the single-core fiber.

[0027] Step 5, Arrangement and Integration of Single-Core Fibers: Before arrangement, the single-core fibers are classified within groups and allocated to multiple groups based on the calculation results in Step 1. After allocation, multiple groups of single-core fibers are filled into the glass sleeve, and the filled glass sleeve is thermally fused to achieve integration. When allocating the single-core fibers within groups, the optimal multi-refractive index distribution scheme calculated at the current time is obtained. The single-core fibers are bundled into groups and then filled into the glass sleeve to achieve an orderly arrangement of the single-core fiber groups.

[0028] Step 6: Fabrication of image bundle preform: Slowly cool the preform at a predetermined temperature and temperature gradient to obtain a glass rod-shaped preform. Grind and polish the outer ring surface of the preform. Fabricate the processed preform into an image bundle preform. Finally, place the preform into a drawing furnace to draw the fiber image bundle. Example 3

[0029] Please refer to Figure 1-7 As shown, this embodiment provides a method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk, including the following steps: Step 1: Calculation of fiber optic image bundle: Calculate the shared multi-refractive-index cladding between cores according to the fiber optic transmission wave equation. Set the core refractive index to n1 and the shared refractive indices between cores to n2, n3, and n4. The wave equation for optical fiber transmission is Maxwell's equations, and its expression is as follows: ; In the formula, H is the magnetic field strength, J is the conduction current density, D is the electric displacement, E is the electric field strength, and B is the magnetic flux density. The electric field strength E is obtained. According to the relationship that the light intensity is the square of the electric field modulus, the analysis process can be simplified and the electric field strength can be directly compared. The electric field distribution of the optical fiber was constructed using Maxwell's equations. The central electric field of the single-refractive-index cladding and the central electric field of the multi-refractive-index cladding were compared. The core-to-cladding ratio of the single-core fiber was obtained, and the influence of the core-to-core spacing variation on the central electric field was calculated.

[0030] Step 2: Core Glass and Cladding Glass Preparation: Before preparing the core glass and cladding glass, the raw materials are purified to obtain high-purity raw materials. The two raw materials are mixed and processed in a swing furnace, followed by degassing and annealing to obtain core glass and cladding glass rods. The core glass and cladding glass are then combined into an optical fiber preform using a sleeve method or a combination method. During the preparation of the optical fiber preform, the material of the sleeve is changed. Different materials correspond to different refractive indices, thus achieving different refractive indices between the cores. By changing the thickness of the sleeve, the spacing between the cores can be changed.

[0031] Step 3: Obtaining single-core fibers through spinning: Preheat the optical fiber drawing furnace, place the optical fiber preform prepared using the cladding method into the drawing furnace, and prepare preliminary single-core fibers through drawing. Calculate the diameter, cladding thickness, and core-to-skin ratio of the single-core fibers to determine if they match the calculated results. If they match, continuously spin the fibers from the drawing machine to produce single-core fibers. During the drawing process in the optical fiber drawing furnace, the drawing speed is 8 m / min and the drawing temperature is 900℃. If the difference between the core-to-skin ratio of the single-core fiber and the calculated result exceeds the standard range, adjust the drawing speed until the difference is within the standard range.

[0032] Step 4, fiber pretreatment: Set the length of the single-core fiber, cut the single-core fiber prepared in step 3 into the predetermined length, and arrange the cut single-core fibers in sheet form. Then screen the single-core fibers for defects and remove them quickly. When screening the single-core fibers, select the positioning plate according to the radius of the single-core fiber. The top of the positioning plate has a limiting groove to make the single-core fiber stably placed in the limiting groove. Let multiple single-core fibers lay flat on the positioning plate, rotate the single-core fiber one by one, and detect the defects on the surface of the single-core fiber.

[0033] Step 5, Arrangement and Integration of Single-Core Fibers: Before arrangement, the single-core fibers are classified within groups and allocated to multiple groups based on the calculation results in Step 1. After allocation, multiple groups of single-core fibers are filled into the glass sleeve, and the filled glass sleeve is thermally fused to achieve integration. When allocating the single-core fibers within groups, the optimal multi-refractive index distribution scheme calculated at the current time is obtained. The single-core fibers are bundled into groups and then filled into the glass sleeve to achieve an orderly arrangement of the single-core fiber groups.

[0034] Step 6: Fabrication of image bundle preform: Slowly cool the preform at a predetermined temperature and temperature gradient to obtain a glass rod-shaped preform. Grind and polish the outer ring surface of the preform. Fabricate the processed preform into an image bundle preform. Finally, place the preform into a drawing furnace to draw the fiber image bundle.

[0035] Please refer to Figure 1 As shown, this embodiment provides a method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk. The method is roughly the same as that in Embodiment 1. The main difference is that in step three, the cladding thicknesses d1 and d2 correspond to the refractive index thicknesses n2 and n3, respectively, and the ratio of their thicknesses is 0.56.

[0036] Please refer to Figure 1 As shown, this embodiment provides a method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk. The method is roughly the same as that in Embodiment 1. The main difference is that in step three, the cladding thicknesses d1 and d2 correspond to the refractive index thicknesses n2 and n3, respectively, and the ratio of their thicknesses is 1.

[0037] Please refer to Figure 1 As shown, this embodiment provides a method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk. The method is roughly the same as that in Embodiment 1. The main difference is that in step three, the cladding thicknesses d1 and d2 correspond to the refractive index thicknesses n2 and n3, respectively, and the ratio of their thicknesses is 3.7.

[0038] The fiber optic image bundles obtained through the processing of Examples 1 to 3 are designated as Example Groups 1 to 3, and the fiber optic image bundles obtained through the processing of Comparative Examples 1 to 3 are designated as Comparison Groups 1 to 3. The core refractive index is n1, and the refractive index changes between cores are n2 and n3. The calculated core diameter n1 is designated as r1, the cladding thickness n2 is designated as d1, and the cladding thickness n3 is designated as d2. The ratio of inter-core refractive index and distance, as well as the maximum value of electric field strength, are calculated, and the relevant experimental data are recorded in Table 1.

[0039] Table 1: Experimental Data Recording Table Group n1 / n2 n2 / n3 d1 / d2 Emax Example 1 group 1.045 1.011 1 4e-6 Example 2 group 1.045 1.011 0.56 2e-6 Example 3 1.045 1.011 3.7 1.2e-6 Comparison Group 1 1.045 1.018 1 5e-6 Comparison of 2 groups 1.045 1.018 0.56 4.5e-6 Comparison of 3 groups 1.045 1.018 3.7 1.6e-6 As shown in Table 1, by adjusting the value ranges of n2 and n3 in Examples 1 to 3, the value of n2 / n3 changes accordingly. By adjusting the refractive index between cores, multiple refractive indices are shared between cores, and the maximum value of the electric field strength changes, thereby reducing fiber core crosstalk.

[0040] Figure 2 In an image-transmitting bundle, two adjacent image-transmitting units are represented by the fiber core in the middle. The distance between cores is the core diameter plus the cladding. The cladding between cores consists of different refractive indices, meaning multiple cores share claddings with different refractive indices. The distance between cores, i.e., the thickness of the multi-refractive-index cladding, reduces crosstalk by sharing different refractive indices among the cores, effectively reducing optical waveguide leakage and thus improving the effective optical transmission efficiency of the fiber image-transmitting bundle. The electric field distribution of the fiber is constructed using Maxwell's equations and the wave equation. In Examples 1 and 2 and Comparative Examples 1 and 2, with the same fiber diameter, a 0.6% increase in the cladding refractive index difference resulted in a 25% increase in the central electric field strength. While maintaining the same central light intensity, the effective core diameter can be appropriately increased to improve luminous flux. Calculations show that, while ensuring the same light intensity, the effective core diameter can be increased by 5%.

[0041] The central light intensity of a single-refractive-index cladding and the central light intensity of a multi-refractive-index cladding were compared through simulation calculations. Figure 6 The electric field intensity distribution of the optical fiber in the multi-clad refractive index design scheme of Example 2 is similar to... Figure 7Comparing the electric field distribution of fibers with single-refractive-index cladding, for the same fiber diameter, the maximum electric field at the center of a fiber with multi-refractive-index cladding is twice that of a fiber with single-refractive-index cladding. Therefore, for the same diameter, crosstalk issues with multi-refractive-index cladding are significantly reduced, and the greater the refractive index difference, the lower the crosstalk.

[0042] In this invention, the core refractive index and the refractive index variation between cores can be determined through relevant calculations of the optical fiber image bundle. This facilitates the allocation of the installation position of the single-core fiber assembly inside the glass sleeve and aids in the combination of the single-core fiber assembly and the glass sleeve. The raw materials for single-core fiber preparation can be obtained through the preparation of the core glass and cladding glass. The core glass and cladding glass, after purification treatment, have high purity. Then, they can be quickly processed into single-core fibers through a drawing furnace. By uniformly processing the single-core fibers, the length of the single-core fibers can be standardized, and defects in the single-core fibers can be eliminated to ensure... After processing, the quality of single-core fibers is determined by arranging and integrating them according to the classification of cores within a group and the allocation of multiple cores, thereby forming a preform. After processing the preform, an optical fiber rod can be obtained. After drawing the optical fiber rod, the optical fiber image bundle can be prepared. The prepared optical fiber image bundle has a small sacrifice in light transmission efficiency and can effectively reduce the phenomenon of optical waveguide leakage. Under the premise of ensuring the normal use of the optical fiber image bundle, the inter-core crosstalk of the optical fiber image bundle is reduced, thereby improving the image transmission quality and ensuring the use effect of the optical fiber image bundle.

[0043] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk, characterized in that: Includes the following steps: S1. Calculation of fiber optic image bundle: Calculate the shared multi-refractive-index cladding between cores according to the fiber optic transmission wave equation. Set the core refractive index to n1 and the shared refractive indices between cores to n2, n3, and n4. S2. Core glass and cladding glass preparation: Before making core glass and cladding glass, the raw materials are purified to obtain high-purity raw materials. The two raw materials are mixed and placed in a swing furnace for processing. Then, degassing and annealing are performed to obtain core glass and cladding glass rods. The core glass and cladding glass are combined into optical fiber preforms using the sleeve method or combination method. S3. Obtaining single-core fibers through spinning: Preheat the optical fiber drawing furnace, put the optical fiber preform prepared by the sleeve method into the drawing furnace, and after drawing, prepare preliminary single-core fibers. Calculate the diameter, cladding thickness and core-to-skin ratio of the single-core fibers, and determine whether the single-core fibers match the calculation results. If they match, continuously spin from the drawing machine to produce single-core fibers. S4. Fiber pretreatment: Set the length of the single core fiber, cut the single core fiber prepared in S3 into a predetermined length, the cut single core fiber is arranged in a sheet, and then screen the defects in the single core fiber and remove them quickly. S5. Arrangement and integration of single-core fibers: Before arrangement, multi-refractive-index cladding is distributed to the single-core fibers according to the calculation results in S1. After distribution, the multi-refractive-index single-core fibers are filled into the glass sleeve, and the filled glass sleeve is thermally fused to achieve integration. S6. Fabrication of image bundle preform: Slowly cool the preform at a predetermined temperature and a predetermined temperature gradient to obtain a glass rod-shaped preform. Grind and polish the outer ring surface of the preform. Fabricate the processed preform into an image bundle preform. Finally, place the preform into a drawing furnace to draw the fiber image bundle.

2. The method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk according to claim 1, characterized in that: The optical intensity of the fiber core needs to be calculated. By increasing the core intensity, the leakage of the waveguide can be reduced. In step S1, the wave equation for optical fiber transmission is Maxwell's equations, and its expression is as follows: ； In the formula, H is the magnetic field strength, J is the conduction current density, D is the electric displacement, E is the electric field strength, and B is the magnetic flux density. The electric field strength E is obtained. According to the relationship that the light intensity is the square of the electric field modulus, the analysis process can be simplified and the electric field strength can be compared.

3. The method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk according to claim 2, characterized in that: The electric field distribution of the optical fiber is constructed using Maxwell's equations. The central electric field of the single-refractive-index cladding and the central electric field of the multi-refractive-index cladding are compared. The core-to-cladding ratio of the single-core fiber is obtained, and the influence of the core-to-core spacing variation on the central electric field is calculated.

4. The method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk according to claim 1, characterized in that: In step S2, during the fabrication of the optical fiber preform, the material of the sleeve is changed. Different materials correspond to different refractive indices, thus achieving different refractive indices between the cores. By changing the thickness of the tube, the spacing between the cores is changed.

5. The method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk according to claim 1, characterized in that: In step S3, when using an optical fiber drawing furnace for fiber drawing, the drawing speed is 1-8 m / min and the drawing temperature is 800-900℃.

6. The method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk according to claim 1, characterized in that: In step S3, if the difference between the core-sheath ratio of a single fiber and the calculated result exceeds the standard range, the drawing speed is adjusted until the difference between the core-sheath ratio and the calculated result is within the standard range.

7. The method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk according to claim 1, characterized in that: In step S4, when screening single-core fibers, a positioning plate is selected according to the radius of the single-core fiber. A limiting groove is opened on the top of the positioning plate to make the single-core fiber stably placed in the limiting groove. Multiple single-core fibers are laid flat on the positioning plate, and the single-core fibers are rotated one by one to detect defects on the surface of the single-core fiber.

8. The method for designing and fabricating an optical fiber image bundle to reduce inter-core crosstalk according to claim 1, characterized in that: In step S5, when allocating the fiber cores within the group, the optimal multi-refractive index distribution scheme is obtained, the single-core fibers are bundled into groups, and then filled into the glass sleeve to achieve an orderly arrangement of the single-core fiber groups.

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