Optical fiber and method for preparing optical fiber

Abstract

The embodiment of the invention provides an optical fiber and a method for preparing the optical fiber. The refractive index difference value of at least two points in the cross section of the optical fiber is greater than or equal to 0.01, at least five groups of points in the cross section meet preset conditions, the kth group of points in the at least five groups of points comprises an xk point and a yk point, the xk point and the yk point are any point in the cross section, and the preset conditions comprise that nxk-nyk is greater than or equal to 0.001 and rxk-ryklt; nxk is the refractive index of the point xk, nyk is the refractive index of the point yk, rxk is the distance from the point xk to the center of the cross section, ryk is the distance from the point yk to the center of the cross section, and k is a positive integer larger than or equal to 1. The optical fiber comprises a plurality of groups of points with different refractive indexes, so that the cross section of the optical fiber has different refractive index distribution characteristics, light can be totally reflected at corresponding positions in the optical fiber transmission process, and the effect of improving the bandwidth of the optical fiber is further achieved.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of materials, and more specifically, to an optical fiber, a method for preparing an optical fiber, a communication medium, an optical module, and an optical transmission system. Background Art

[0002] Plastic optical fiber (POF) is an optical fiber made of highly transparent polymers. Compared with quartz optical fiber, plastic optical fiber has the advantages of light weight and strong flexibility, and has been widely used in vehicle-mounted, fiber-to-the-home, medical and other application scenarios. In order to increase the bandwidth of plastic optical fiber, the core part of the plastic optical fiber is usually adjusted so that the refractive index of the core layer material of the core part is different. When preparing plastic optical fiber in the prior art, it is necessary to prepare a variety of materials with different refractive indices in advance, and then compound the multiple materials into one optical fiber, and the preparation process is complicated. At the same time, due to the different viscosities of materials with different refractive indices, it is difficult to compound the multiple materials into an optical fiber with a more uniform structural distribution, which affects the performance of the optical fiber.

[0003] How to improve the performance of plastic optical fiber has become an urgent problem to be solved. Summary of the invention

[0004] The embodiments of the present application provide an optical fiber, a method for preparing an optical fiber, a communication medium, an optical module, and an optical transmission system. The optical fiber contains multiple groups of points with different refractive indices, so that the cross-section of the optical fiber has different refractive index distribution characteristics, so that light can be totally reflected at corresponding positions during optical fiber transmission, thereby achieving the effect of increasing the optical fiber bandwidth.

[0005] In a first aspect, an optical fiber is provided. The refractive index difference between at least two points in a cross section of the optical fiber is greater than or equal to 0.01, at least five groups of points in the cross section meet a preset condition, and the kth group of points in the at least five groups of points includes x k Point and y k point, the x k Point and y k The point is any point in the cross section, and the preset conditions include nx k -ny k ≥0.001 and rx k -ry k <0, where nx k For x k Refractive index of the point, ny k for y k Refractive index of a point, rx k For x k The distance from the point to the center of the cross section, ry k for y kThe distance from the point to the center of the cross section, k is a positive integer greater than or equal to 1.

[0006] In the embodiment of the present application, the optical fiber includes points with a refractive index difference greater than or equal to 0.01. By controlling the refractive index difference of each point, optical fibers with different numerical apertures can be prepared, thereby obtaining optical fibers that meet performance requirements. The optical fiber also includes at least five groups of points with a refractive index difference greater than 0.001, so that the cross section of the optical fiber has different refractive index distribution characteristics, so that light can be totally reflected at the corresponding position during optical fiber transmission, thereby achieving the effect of increasing the optical fiber bandwidth. In addition, each group of points satisfies rx k -ry k <0, so that the refractive index of the optical fiber is distributed in a gradient manner.

[0007] In combination with the first aspect, in certain implementations of the first aspect, at least seven groups of points in the cross section satisfy the preset condition.

[0008] In combination with the first aspect, in certain implementations of the first aspect, the difference in refractive index between at least two points in the cross section is greater than or equal to 0.013.

[0009] In the embodiment of the present application, the optical fiber includes a plurality of points whose refractive index difference is greater than or equal to 0.013, so that the numerical aperture of the optical fiber is larger, thereby improving the optical fiber performance.

[0010] In combination with the first aspect, in some implementations of the first aspect, the x of the i-th group of points in the at least one group of points in the cross section is i Point and y i The spacing between points is less than or equal to 50 microns, the x i Point and y i The refractive index difference of the points is greater than 0.002, and i is a positive integer greater than or equal to 1.

[0011] In combination with the first aspect, in certain implementations of the first aspect, the light transmittance of the material of the optical fiber is greater than 80%.

[0012] In combination with the first aspect, in certain implementations of the first aspect, the light transmittance of the material of the optical fiber is greater than 90%.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the test wavelength of the transmittance is 650 nanometers.

[0014] In the embodiment of the present application, the light transmittance of the material of the optical fiber is relatively high, so that the loss of light when transmitted in the optical fiber can be relatively small, thereby improving the performance of the optical fiber.

[0015] In combination with the first aspect, in certain implementations of the first aspect, a distance between every two points in the cross section is greater than or equal to 0.2 micrometers.

[0016] In combination with the first aspect, in certain implementations of the first aspect, the distribution of the refractive index of some points in the line from the center to the edge of the cross section is fitted as a curve, or the distribution of the refractive index difference between the some points and the center point of the cross section is fitted as a curve.

[0017] In the embodiment of the present application, the refractive index in the cross section of the optical fiber presents a relatively smooth gradient distribution.

[0018] In combination with the first aspect, in some implementations of the first aspect, the curve is an upward convex curve.

[0019] In combination with the first aspect, in some implementations of the first aspect, the curve is a partial curve in a quadratic equation curve or a partial curve in a cubic equation curve.

[0020] In the embodiment of the present application, the refractive index distribution in the cross section of the optical fiber is in a parabolic shape, that is, the refractive index distribution in the cross section of the optical fiber is a relatively smooth gradient curve.

[0021] In combination with the first aspect, in some implementations of the first aspect, the optical fiber is a plastic optical fiber.

[0022] Optionally, the plastic optical fiber in the embodiment of the present application may contain a polymer material. Alternatively, the plastic optical fiber in the embodiment of the present application may contain quartz and a polymer material.

[0023] In a second aspect, a method for preparing optical fiber is provided, which comprises: inputting M starting materials into an optical fiber preparation device, obtaining optical fiber from an outlet of the optical fiber preparation device, and at least two starting materials of the M starting materials have different refractive indices.

[0024] In the embodiment of the present application, an optical fiber can be prepared based on at least two initial materials with different refractive indices and an optical fiber preparation device, so that the method for preparing the optical fiber is relatively simple and efficient.

[0025] In combination with the second aspect, in certain implementations of the second aspect, the optical fiber preparation device includes a splitter and a recombiner. The splitter includes M first inlets and N first outlets, and at least two of the M first inlets are connected to at least one of the N first outlets. The recombiner includes P second inlets and Q second outlets, and the P second inlets are connected to the Q second outlets. The N first outlets are connected to the P second inlets, M, N, and P are positive integers greater than or equal to 2, Q is a positive integer greater than or equal to 1, and P is greater than or equal to Q.

[0026] In combination with the second aspect, in certain implementations of the second aspect, M kinds of initial materials are respectively input into M first inlets of the diverter, and N kinds of materials are obtained from N first outlets of the diverter, and at least two of the N kinds of materials contain different proportions of the initial materials.

[0027] In the embodiment of the present application, the M kinds of initial materials can be simultaneously divided and mixed by the splitter in the optical fiber preparation device, so as to simultaneously prepare N kinds of materials to be compounded into optical fibers. That is, according to the method in the embodiment of the present application, it is not necessary to prepare N kinds of materials required for compounding into optical fibers according to M kinds of initial materials before preparing the optical fibers, so that the process of preparing the optical fibers is relatively simple, thereby improving the efficiency of preparing the optical fibers.

[0028] In combination with the second aspect, in some implementations of the second aspect, N materials are respectively input into P second inlets of the compounder, and optical fibers are obtained from Q second outlets of the compounder, where P equals N.

[0029] In an embodiment of the present application, after M kinds of initial materials are put into the optical fiber preparation device, N kinds of materials can be obtained from the splitter, and the N kinds of materials are compounded in the compounder to obtain optical fiber, thereby reducing the difficulty of preparing optical fiber.

[0030] In combination with the second aspect, in some implementations of the second aspect, a floating rate of the refractive index of each of the N materials in the first outlet of the splitter or the second inlet of the recombiner is less than 0.5%.

[0031] In the embodiment of the present application, the refractive index fluctuation rate of the N materials obtained in the splitter is small, that is, the refractive index of the N materials is relatively stable, so that an optical fiber with a relatively stable structure can be prepared. By controlling the refractive index of the material of each flow channel, the refractive index in the cross section of the optical fiber is gradually distributed.

[0032] In conjunction with the second aspect, in some implementations of the second aspect, the flow divider further comprises a porous plate structure. At least two of the M kinds of initial materials are sequentially input to at least one first outlet through at least two first inlets and the porous plate structure, and at least two of the M kinds of initial materials are input to the first outlet in different amounts through the porous plate structure.

[0033] In the embodiment of the present application, the amount of initial material input to each first outlet can be controlled by the porous plate structure in the diverter, so that N kinds of materials can be prepared by the diverter, and at least two of the N kinds of materials contain different proportions of initial materials.

[0034] In combination with the second aspect, in certain implementations of the second aspect, at least one of the M first inlets is provided with a first diversion structure, and the amounts of the initial material diverted by the first diversion structure are different.

[0035] In the embodiment of the present application, the amount of the initial material to be diverted can be controlled by the first diversion structure, so as to prepare N kinds of materials, and at least two of the N kinds of materials contain different proportions of the initial materials.

[0036] In combination with the second aspect, in certain implementations of the second aspect, M types of initial materials are obtained through M extruders.

[0037] In combination with the second aspect, in certain implementations of the second aspect, the optical fiber is the optical fiber as described in the first aspect or any possible implementation of the first aspect.

[0038] In the embodiments of the present application, an optical fiber as described in the first aspect or any possible implementation of the first aspect can be prepared based on at least two initial materials with different refractive indices and an optical fiber preparation device, thereby reducing the difficulty of preparing optical fibers with higher performance.

[0039] In a third aspect, a communication medium is provided. The communication medium comprises an outer casing and an optical fiber as described in the first aspect or any possible implementation of the first aspect. Alternatively, the optical fiber in the communication medium is prepared by the method as described in the second aspect or any possible implementation of the second aspect.

[0040] In a fourth aspect, an optical module is provided. The optical module includes a photoelectric converter and an optical fiber as described in the first aspect or any possible implementation of the first aspect. Alternatively, the optical fiber in the optical module is prepared by the method as described in the second aspect or any possible implementation of the second aspect.

[0041] In a fifth aspect, an optical transmission system is provided. The optical transmission system includes an optical transmitter, an optical receiver, and the optical fiber as described in the first aspect or any possible implementation of the first aspect. Alternatively, the optical fiber in the optical transmission system is prepared by the method as described in the second aspect or any possible implementation of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic diagram of a cross section of an optical fiber according to an embodiment of the present application.

[0043] Figure 2 It is a schematic distribution curve diagram of the refractive index difference of some points in a cross section according to an embodiment of the present application.

[0044] Figure 3It is a schematic flow chart of a method for preparing an optical fiber according to one embodiment of the present application.

[0045] Figure 4 It is a schematic structural diagram of a device for preparing optical fiber according to an embodiment of the present application.

[0046] Figure 5 is a schematic structural diagram of a device for preparing optical fiber according to another embodiment of the present application.

[0047] Figure 6 It is a schematic cross-sectional view of a first inlet according to an embodiment of the present application.

[0048] Figure 7 is a schematic flow chart of a method for preparing an optical fiber according to another embodiment of the present application. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0050] Figure 1 It is a schematic diagram of the cross section of the optical fiber provided in the embodiment of the present application. Figure 1 The cross section of the optical fiber 100 in the embodiment may include at least two points. The refractive index difference of the at least two points is greater than or equal to 0.01. At least five groups of points in the cross section meet the preset conditions, and the kth group of points in the at least five groups of points includes x k Point and y k point, the x k Point and y k The point is any point in the cross section, and the preset conditions include nx k -ny k ≥0.001 and rx k -ry k <0, where nx k For x k Refractive index of the point, ny k for y k Refractive index of a point, rx k For x k The distance from the point to the center of the cross section, ry k for y k The distance from the point to the center of the cross section, k is a positive integer greater than or equal to 1.

[0051] In some embodiments, each point in the cross section is an intersection point between the light ray passing through the cross section and the cross section when testing the refractive index or refractive index difference. Figure 1 As shown, the cross section may include point a and point b. The embodiment of the present application does not limit the area or size of each point in the cross section.

[0052] In some embodiments, the refractive index difference between two points in the cross section can be determined based on the propagation speed of light at the two points.

[0053] In some embodiments, the center of the cross section may be the geometric center or the center of gravity of the cross section. For example, if the cross section is a regular shape with symmetry, the center of the cross section may be the geometric center of the cross section. A regular shape with symmetry may be, for example, a parallelogram, a square, an equilateral triangle, a circle, etc. For example, Figure 1 As shown, since the cross section is circular, the center of the cross section can be the center of the circle, that is, point Z. If the cross section is a non-symmetrical or irregular figure, the center of the cross section can be the centroid of the cross section.

[0054] In some embodiments, the optical fiber 100 may be a plastic optical fiber.

[0055] In some embodiments, the cross section may include at least five groups of points that satisfy the preset condition. The points included in each of the at least five groups of points may be different. Alternatively, one point included in any two of the at least five groups of points may be the same.

[0056] For example, assume that the cross section includes five groups of points, and the five groups of points are (x1, y1), (x2, y2), (x3, y3), (x4, y4), and (x5, y5). Among them, (x1, y1) is the first group of points, that is, the first group of points includes the x1 point and the y1 point. Similarly, (x5, y5) is the fifth group of points, that is, the fifth group of points includes the x5 point and the y5 point. The x1 point, y1 point, x2 point, y2 point, x3 point, y3 point, x4 point, y4 point, x5 point, and y5 point can be ten different points. Alternatively, for the first group of points (x1, y1) and the second group of points (x2, y2), the x1 point and the x2 point can be the same point, and the y1 point and the y2 point can be different points. Alternatively, the x1 point and the x2 point can be different points, and the y1 point and the y2 point can be the same point.

[0057] In some embodiments, each point in the at least five groups of points in the cross section is located in a sector-shaped area of ​​the cross section. The embodiment of the present application does not limit the area of ​​the sector-shaped area. Particularly preferably, each point in the at least five groups of points in the cross section is located on a line from the center to the edge of the cross section.

[0058] Preferably, the cross section includes at least seven groups of points that satisfy the preset condition.

[0059] Preferably, the refractive index difference between at least two points in the cross section is greater than or equal to 0.013.

[0060] In some embodiments, a distance between every two points in the cross section is greater than or equal to 0.2 micrometers (μm).

[0061] In some embodiments, the distance between two points included in each group of at least one group of points in the cross section is less than or equal to 50 microns, and the refractive index difference between the two points included in each group of points is greater than 0.002. i Point and y i The spacing between points is less than or equal to 50 microns, the x i Point and y i The refractive index difference of the points is greater than 0.002, and i is a positive integer greater than or equal to 1.

[0062] Preferably, a distance between two points included in each group of at least one group of points in the cross section is less than or equal to 50 micrometers, and a refractive index difference between the two points included in each group of points is greater than 0.004.

[0063] For example, when point x is the center of the cross section, the refractive index differences between some points y and x in the cross section are as shown in Table 1.

[0064] Table 1 Refractive index difference between some points y and x in the cross section

[0065] The distance between point y and point x The difference in refractive index between point y and point x nx-ny rx-ry 0 0.0000 0.0000 0 80 -0.0010 0.0010 -80 100 -0.0017 0.0017 -100 120 -0.0027 0.0027 -120 140 -0.0042 0.0042 -140 160 -0.0060 0.0060 -160 180 -0.0080 0.0080 -180 200 -0.0107 0.0107 -200 220 -0.0140 0.0140 -220 240 -0.0151 0.0151 -240

[0066] In Table 1, the unit of the distance between point y and point x is micrometer, and the unit of rx-ry is micrometer.

[0067] As shown in Table 1, when point x is the center of the cross section of the optical fiber 100, for point y which is 80 micrometers away from point x, the refractive index difference between point x and point y is 0.001.

[0068] In some embodiments, the distribution of the refractive index of some points in the line from the center to the edge of the cross section can be fitted into a curve. Alternatively, the distribution of the refractive index difference between the some points and the center point of the cross section can be fitted into a curve.

[0069] In some embodiments, the curve may be a downward convex curve or an upward convex curve. Preferably, the curve is an upward convex curve.

[0070] In some embodiments, the curve is a partial curve in a quadratic equation curve or a partial curve in a cubic equation curve.

[0071] In some embodiments, the curve may include 2 or 3 extreme values.

[0072] For example, when point x is the center of the cross section, the distribution of the refractive index difference between some points y and x in the cross section is as follows: Figure 2 shown.

[0073] Figure 2 It is a schematic distribution curve diagram of the refractive index difference at some points in the cross section of the optical fiber provided in the embodiment of the present application. Figure 2 The horizontal axis is the distance between the y point and the x point in the cross section, in micrometers. Figure 2 The ordinate is the difference in refractive index between the y-point and the x-point in the cross section. Figure 2 The graph includes curve 1 and curve 2. Curve 1 represents the refractive index difference between some points y and x in the cross section of the optical fiber 100, and the some points y are some points on the same line from the center to the edge of the cross section. Curve 2 is a curve obtained by fitting curve 1.

[0074] from Figure 2 It can be seen that curve 2 is an upward convex curve. In other words, curve 2 is a partial curve in a quadratic equation curve. In other words, curve 2 is a partial curve in a cubic equation curve. Moreover, curve 1 and curve 2 are basically coincident, that is, the refractive index difference between some points y and x in the cross section of the optical fiber 100 is in a relatively smooth gradient distribution.

[0075] from Figure 2 It can also be seen that the difference between the refractive index of the point y near the center of the cross section and the refractive index of the point x is small, and the difference between the refractive index of the point y far from the center of the cross section and the refractive index of the point x is large. In other words, the refractive index of the point y near the center of the cross section is large, and the refractive index of the point y far from the center of the cross section is small.

[0076] In some embodiments, the optical fiber 100 is prepared from M starting materials, where M is a positive integer greater than or equal to 2.

[0077] In some embodiments, the M initial materials include a first initial material. The light transmittance of the first initial material is greater than 80%, preferably greater than 85%, and more preferably greater than 90%.

[0078] In some embodiments, the M initial materials include a second initial material. The light transmittance of the second initial material is greater than 80%, preferably greater than 85%, and more preferably greater than 90%. The second initial material is an initial material different from the first initial material in the M initial materials.

[0079] In some embodiments, each of the M starting materials may be a fluorine-containing material, or may be a fluorine-free material.

[0080] When any of the M initial materials is a fluorine-containing material, the fluorine content of the initial material is not limited. Generally, fluorine-containing materials, especially non-crystalline fluorine-containing materials, have a low refractive index and good light transmittance. By reasonable selection, high-performance plastic optical fibers can be prepared.

[0081] In some embodiments, the refractive index of the material can be obtained by Abbe refractometer testing. The present application embodiment does not limit the test wavelength of the refractive index, for example, it can be 656 nanometers (nm).

[0082] In some embodiments, the starting material may be a single material, or may be a mixed material including materials of different refractive indices.

[0083] In some embodiments, the first initial material may be a high refractive index polymer, for example, a material comprising a high refractive index small molecule and polymethyl methacrylate (PMMA).

[0084] In some embodiments, the second initial material may be a low refractive index polymer, for example, a PMMA material.

[0085] The embodiments of the present application do not limit the specific value or value range of the refractive index of the first initial material or the second initial material.

[0086] In some embodiments, the difference in refractive index between the first initial material and the second initial material is greater than or equal to 0.01. Preferably, the difference in refractive index between the first initial material and the second initial material is greater than or equal to 0.013. For example, as shown in Tables 2 and 3 below, assuming that the refractive indices of the first initial material and the second initial material under the test condition of a wavelength of 656 nm are 1.507 and 1.488, respectively, the difference in refractive index between the first initial material and the second initial material can be 0.019.

[0087] In some embodiments, the optical fiber 100 may include N materials, and the N materials are prepared from M initial materials, where N is a positive integer greater than or equal to 2. At least two of the N materials have different refractive indexes.

[0088] The embodiment of the present application does not limit the size relationship between N and M. For example, N may be smaller than M, or N may be greater than or equal to M. Preferably, N is greater than M.

[0089] In some embodiments, the optical fiber 100 may include a first material, where the first material is a first initial material.

[0090] In some embodiments, the optical fiber 100 may include a second material, which is prepared from at least two initial materials. The light transmittance of the second material is greater than 80%, preferably greater than 85%, and more preferably greater than 90%.

[0091] In some embodiments, the optical fiber 100 may include a third material, which is prepared from at least two initial materials. The light transmittance of the third material is greater than 80%, preferably greater than 85%, and more preferably greater than 90%.

[0092] In some embodiments, the optical fiber 100 may include a fourth material, which is prepared from at least two initial materials. The fourth material has a light transmittance greater than 80%, preferably greater than 85%, and more preferably greater than 90%.

[0093] In some embodiments, the optical fiber 100 may include a fifth material, which is prepared from at least two initial materials. The light transmittance of the fifth material is greater than 80%, preferably greater than 85%, and more preferably greater than 90%.

[0094] In some embodiments, the optical fiber 100 may include a sixth material, which is prepared from at least two initial materials. The light transmittance of the sixth material is greater than 80%, preferably greater than 85%, and more preferably greater than 90%.

[0095] In some embodiments, the optical fiber 100 may include a seventh material, and the seventh material is the second initial material.

[0096] It should be understood that the first material, the second material, the third material, the fourth material, the fifth material, the sixth material, and the seventh material are different materials among the N materials, and the proportions of the initial materials contained in at least two materials of the N materials are different. The N materials may include any one or more of the first material, the second material, the third material, the fourth material, the fifth material, the sixth material, and the seventh material. For example, the first material, the second material, the third material, the fourth material, the fifth material, the sixth material, and the seventh material may be one material among the seven first outlets in Tables 2 and 3 below, respectively.

[0097] In some embodiments, the light transmittance of the material of the optical fiber is greater than 80%. Preferably, the light transmittance of the material of the optical fiber is greater than 85%. More preferably, the light transmittance of the material of the optical fiber is greater than 90%.

[0098] In some embodiments, the light transmittance of the optical fiber material is determined by testing after film formation using a finished optical fiber or a portion of a finished optical fiber. Similarly, the light transmittance of any of the M initial materials or any of the N materials can be determined by testing after film formation using the finished material. The embodiments of the present application do not limit the specific test wavelength of the light transmittance, and preferably use a wavelength near the light source, for example, the test wavelength can be 650nm.

[0099] In some embodiments, each of the N materials may be a fluorine-containing material, or may be a fluorine-free material.

[0100] When any one of the N materials is a fluorine-containing material, there is no limit on the fluorine content of the material. Generally, fluorine-containing materials, especially non-crystalline fluorine-containing materials, have a low refractive index and good light transmittance. By reasonable selection, high-performance plastic optical fibers can be prepared.

[0101] Figure 3 is a schematic flow chart of a method for preparing an optical fiber provided in an embodiment of the present application, Figure 3 The process includes the following step S310.

[0102] S310, inputting M kinds of initial materials into an optical fiber preparation device, and obtaining optical fiber from an outlet of the optical fiber preparation device.

[0103] At least two of the M initial materials have different refractive indices, and M is a positive integer greater than or equal to 2. Preferably, M=2 or 3.

[0104] In some embodiments, the M initial materials include the first initial material and / or the second initial material mentioned above.

[0105] In some embodiments, the optical fiber obtained from the outlet of the optical fiber preparation device is Figure 1 The optical fiber 100 in FIG.

[0106] Optionally, the optical fiber preparation device can be as follows Figure 4 As shown in device 400.

[0107] Figure 4 It is a schematic structural diagram of a device for preparing optical fiber provided in an embodiment of the present application. Figure 4 The device 400 in the embodiment includes a cavity structure 410. The cavity structure 410 is provided with M inlets and Q outlets, where Q is a positive integer greater than or equal to 1. At least two of the M inlets are connected to the Q outlets. The M inlets are used to input M kinds of initial materials, and the Q outlets are used to obtain optical fibers.

[0108] Preferably, Q=1.

[0109] The embodiment of the present application does not specifically limit the specific shape or material of the cavity structure 410. For example, the cavity structure 410 may be a regular cuboid, cylinder, prism, etc., or the cavity structure 410 may have an irregular shape, or the cavity structure 410 may be composed of substructures with regular shapes and / or substructures with irregular shapes.

[0110] In some embodiments, the optical fiber can be directly obtained from the outlet of the optical fiber preparation device. Alternatively, an optical fiber preform, such as an optical fiber preform rod, can be obtained from the outlet of the optical fiber preparation device. The optical fiber preform can be formed into an optical fiber after operations such as stretching and winding.

[0111] Optionally, the optical fiber preparation device can be as follows Figure 5 It should be understood that the device 500 is one of the designs of the embodiment of the present application, and various functional parts can be added to the device according to the needs. The position of the added part is not limited, and it can be before the splitter 510, between the splitter 510 and the recombiner 520, or after the recombiner 520. Multiple functional parts can also be added.

[0112] Figure 5 It is a schematic structural diagram of a device 500 for preparing an optical fiber provided in an embodiment of the present application. Figure 5 The device 500 in the embodiment includes a splitter 510 and a recombiner 520. The splitter 510 includes M first inlets and N first outlets, and at least two of the M first inlets are connected to at least one of the N first outlets. The recombiner 520 includes P second inlets and Q second outlets, and the P second inlets are connected to the Q second outlets. The N first outlets of the splitter 510 are connected to the P second inlets of the recombiner 520. N and P are positive integers greater than or equal to 2, and P is greater than or equal to Q.

[0113] Optionally, the M first inlets of the splitter 510 may be the M inlets of the optical fiber preparation device 500, or each first inlet of the splitter 510 may be communicated with an inlet of the optical fiber preparation device 500. The Q second outlets of the compounder 520 may be the Q outlets of the optical fiber preparation device 500, or each second outlet of the compounder 520 may be communicated with an outlet of the optical fiber preparation device 500. The N first outlets of the splitter 510 are communicated with the P second inlets of the compounder 520.

[0114] Preferably, N is a positive integer greater than or equal to 5.

[0115] The embodiment of the present application does not limit the size relationship between P and N. For example, P may be smaller than N, or P may be greater than or equal to N. Preferably, P is equal to N.

[0116] In some embodiments, after M initial materials are respectively input into the M first inlets of the splitter 510, N materials can be obtained from the N first outlets of the splitter 510. At least two of the N materials contain different proportions of the initial materials.

[0117] The embodiment of the present application does not limit the size relationship between N and M. For example, N may be smaller than M, or N may be greater than or equal to M. Preferably, N is greater than M.

[0118] In some embodiments, after obtaining N materials from the N first outlets of the splitter 510 , the N materials may be respectively input into the P second inlets of the compounder 520 , and optical fibers may be obtained from the Q second outlets of the compounder 520 .

[0119] In some embodiments, the optical fiber can be directly obtained from the second outlet of the recombiner 520. Alternatively, an optical fiber preform, such as an optical fiber preform rod, can be obtained from the second outlet of the recombiner 520. The optical fiber preform can be formed into an optical fiber after operations such as stretching and winding.

[0120] Optionally, a porous plate structure may be included in the flow divider 510. At least two of the M kinds of initial materials are sequentially input to at least one first outlet of the flow divider 510 through at least two first inlets of the flow divider 510 and the porous plate structure. The amounts of at least two of the M kinds of initial materials input to the first outlet through the porous plate structure are different.

[0121] In some embodiments, the porous plate structure includes a substrate, and at least one through hole is provided on the substrate. When the porous plate structure includes a plurality of through holes, the plurality of through holes may be identical, or at least two through holes in the plurality of through holes may be different. The at least two through holes are different in shape and / or size.

[0122] For example, suppose that the porous plate structure includes two kinds of through holes, which are respectively the first through hole and the second through hole, and the first through hole and the second through hole are different. The first initial material can be input to the first outlet through the first through hole in the porous plate structure, and the second initial material can be input to the first outlet through the second through hole in the porous plate structure. Because the first through hole and the second through hole are different, the amount of the first initial material and the second initial material input to the first outlet is different. That is to say, by making different initial materials pass through the different through holes of the porous plate structure, the amount of the initial material through each through hole can be adjusted, thereby controlling the amount of the initial material through the porous plate structure, and then controlling the ratio of the initial material contained in the material output from the first outlet. For example, as shown in Table 2 and Table 3 below, after 2 kinds of initial materials are input to the splitter and shunted through the porous plate structure, 7 kinds of materials can be obtained from 7 first outlets of the splitter, and the ratio of the initial materials contained in at least two materials in the 7 kinds of materials is different, so the refractive index of at least two materials in the 7 kinds of materials is different.

[0123] It should be understood that the embodiment of the present application does not limit the number of porous plate structures included in the flow splitter 510. That is, the flow splitter 510 may include one or more porous plate structures.

[0124] In some embodiments, the porous plate structure may be disposed in the communication cavity, that is, the flow divider 510 may include a communication cavity. The communication cavity may be in communication with at least two of the M first inlets, and the communication cavity may also be in communication with at least one of the N first outlets. The initial material input into the communication cavity passes through the porous plate structure and is output to the first outlet in communication with the communication cavity.

[0125] In some embodiments, a non-planar structure may be further provided in the communication cavity. The non-planar structure is provided between the porous plate structure and an inlet of the communication cavity, and each inlet of the communication cavity is connected to at least one first inlet. In other words, the non-planar structure is provided near an inlet of the communication cavity. The flow rate of the initial material is different before and after passing through the non-planar structure.

[0126] Optionally, at least one of the M first inlets is provided with a first shunt structure. The amount of the initial material shunted by the first shunt structure is different. That is to say, by allowing the initial material to pass through the first shunt structure and then be input into the first outlet, the amount of the initial material input into the first outlet can be adjusted, thereby controlling the proportion of the initial material contained in the material output from the first outlet. For example, as shown in Tables 2 and 3 below, after two initial materials are input into the diverter and shunted through the first shunt structure, seven materials can be obtained from the seven first outlets of the diverter, and at least two of the seven materials contain different proportions of the initial materials, so that at least two of the seven materials have different refractive indices.

[0127] In some embodiments, the first diverter structure may include at least two different through holes, and a first inlet provided with the first diverter structure is connected to at least one first outlet through the at least two different through holes. The different through holes may be different sizes of the cross-sections of the through holes, and the sizes of the cross-sections of the through holes include information such as the length, width, radius, diameter, and area of ​​the cross-sections of the through holes. Alternatively, the first diverter structure may include at least two different flow channels, and a first inlet provided with the first diverter structure is connected to at least one first outlet through the at least two different flow channels. The different flow channels may be different lengths and / or cross-sectional sizes of the flow channels, and the same flow channels may be the same lengths and cross-sectional sizes of the flow channels.

[0128] In some embodiments, the first inlet may be connected to the at least one first outlet through at least one through hole, and the inner surface of the first inlet where the at least one through hole is located is the first inner surface. The first flow diversion structure may be in contact with the first inner surface.

[0129] Exemplarily, when the first inlet is a flow channel structure or a cavity structure, the distance between the first surface of the first flow diverter structure and the first through hole is different from the distance between the first through hole and the bottom surface of the first inlet. The first surface of the first flow diverter structure is the surface of the first flow diverter structure close to the first through hole, and the first through hole is any one of the at least one through hole of the first inlet. The first flow diverter structure is used to control the amount of initial material passing through each through hole of the first inlet.

[0130] The embodiment of the present application does not limit the specific shape of the first diversion structure. For example, the first diversion structure can have a regular shape, or can have an irregular shape. For example, the first diversion structure can be as follows: Figure 6 As shown in the first shunt structure 620 in FIG. It should be understood that Figure 6 It is a possible form of the first diversion structure. According to actual needs, the first diversion structure can also be expressed in various other forms such as a stepped structure and a curved surface structure.

[0131] Figure 6It is a cross-sectional schematic diagram of the first entrance provided in an embodiment of the present application. Figure 6 The first inlet 600 in the embodiment includes a through hole 610, a first shunt structure 620, a through hole 601, a through hole 602, a through hole 603, a through hole 604 and a through hole 605. Among them, the through hole 610 is used to input the initial material. The through holes 601 to the through holes 605 can be connected to at least one first outlet respectively. The amount of the initial material input through the through hole 610 after passing through the first shunt structure 620 is different. The embodiment of the present application does not limit the size of the cross section of the through holes 601 to the through holes 605. For example, the through holes 601 to the through holes 605 can be the same through holes, or at least two through holes in the through holes 601 to the through holes 605 can be different through holes.

[0132] Optionally, the apertures at both ends of each of the N first outlets may be the same, and the apertures of the first outlets with the same apertures at both ends close to the first inlet are the same as the apertures at the ends far from the first inlet. Alternatively, the N first outlets include at least one first outlet with different apertures at both ends, and the apertures of the first outlet with different apertures at both ends close to the first inlet are different from the apertures at the ends far from the first inlet. The flow rate of the material is different before and after passing through the first outlet with different apertures at both ends.

[0133] Optionally, the recombiner 520 may include a first flow channel. The first flow channel connects P second inlets and Q second outlets. N materials input from the P second inlets may be recombined in the first flow channel, and Q optical fibers or Q optical fiber preforms may be obtained from the Q second outlets.

[0134] Optionally, the recombiner 520 may include a mandrel. The mandrel is disposed between the P second inlets and the Q second outlets. The N materials input from the P second inlets may be recombined on the surface of the mandrel, and Q optical fibers or Q optical fiber preforms may be obtained from the Q second outlets.

[0135] In some embodiments, the mandrel may be disposed in the first flow channel, or a portion of the mandrel may be located in the first flow channel.

[0136] Optionally, at least one of the P second inlets of the recombiner 520 may include a first opening, a second flow channel, and a second opening that are connected in sequence. After the material is input from the first opening, it is input into the second outlet through the second flow channel and the second opening. The embodiment of the present application does not limit the specific form of the second flow channel. For example, the second flow channel is a flow channel with a linear structure, a flow channel with a non-linear structure, a groove with a linear structure, or a groove with a non-linear structure. When the second flow channel is a flow channel or a groove with a non-linear structure, the material input from the first opening will not flow directly into the first flow channel, or will not directly cover the core shaft. At the same time, the flow distance of the material in the second inlet can be better controlled, and the melt flow rate can be controlled, so that the structural distribution of each layer of material in the prepared optical fiber is more uniform. In some embodiments, the second flow channel can be a closed structure or a non-closed structure.

[0137] Optionally, M kinds of starting materials can be obtained by M extruders. Each of the M extruders can be connected to an inlet of the optical fiber preparation device.

[0138] Optionally, a floating rate of the refractive index of each of the N materials in the first outlet of the splitter or the second inlet of the recombiner is less than 0.5%.

[0139] For example, suppose that the refractive indexes of the two initial materials input into the splitter under the test condition of 656nm wavelength are 1.507 and 1.488 respectively. In the case of N=7, the floating rate data of the refractive index of the materials at the same position in the splitter under the test condition of 656nm wavelength at different time points within 50 minutes are shown in Tables 2 and 3. Among them, floating rate=(sampling refractive index-average refractive index)*100 / average refractive index. The average refractive index is the average of the refractive indexes of 10 batches of sampled materials.

[0140] Table 2 Floating rate data table of refractive index of materials

[0141]

[0142] Table 3 Refractive index floating data table of materials

[0143]

[0144]

[0145] As shown in Tables 2 and 3, the average refractive index of the material at the first position within 50 minutes is about 1.507, and the floating rate of the refractive index of the material at the first position at the 15th minute = (1.505-1.507)*100 / 1.507≈-0.1. The first position, the second position, the third position, the fourth position, the fifth position, the sixth position, and the seventh position are respectively located in different first outlets of the diverter. It can be seen from Tables 2 and 3 that the floating rate of the refractive index of the material in different first outlets within 50 minutes is less than or equal to 0.1%.

[0146] When each first outlet is connected to a second inlet, the floating rate of the refractive index of the material in the connected first outlet and second inlet is substantially the same. That is, according to Table 2 and Table 3, the floating rate of the refractive index of the material in different second inlets within 50 minutes can be less than or equal to 0.1%.

[0147] It can be seen from Table 2 and Table 3 that according to the method in the embodiment of the present application, within a certain period of time, the floating rate of the refractive index of the material in each first outlet of the splitter or each second inlet of the recombiner is relatively small. That is, according to the method in the embodiment of the present application, the refractive index of the material in each first outlet of the splitter or each second inlet of the recombiner can be made relatively stable, thereby preparing an optical fiber with a relatively stable structure. At the same time, according to the method in the embodiment of the present application, a plastic optical fiber with a gradient refractive index can be prepared by using only two materials with different refractive indices, thereby reducing the difficulty of preparing the plastic optical fiber.

[0148] Figure 7 It is a schematic flow chart of a method for preparing optical fiber provided in an embodiment of the present application. Figure 7 The method comprises the following steps.

[0149] S710, two starting materials are fed into two extruders.

[0150] After drying two initial materials with different refractive indices, they are respectively put into two extruders. The specific extrusion temperature of the extruder is not limited in the embodiment of the present application, and can be determined according to the thermal properties of different initial materials. Preferably, the maximum extrusion temperature corresponding to each initial material can be in the range of Tg+50 degrees Celsius (℃) to Tg+150℃. Wherein, Tg is the glass transition temperature of the initial material.

[0151] Optionally, the two initial materials may include the first initial material and / or the second initial material mentioned above.

[0152] In some embodiments, the maximum extrusion temperature corresponding to the first initial material may be 210° C. The maximum extrusion temperature corresponding to the second initial material may be 220° C.

[0153] Alternatively, the two starting materials may be fed into the extruder after being dried at 80° C. for more than 4 hours.

[0154] S720, the two starting materials are input into the optical fiber preparation device from the extruder, and an optical fiber preform is obtained from the outlet of the optical fiber preparation device.

[0155] The fiber preparation device can be used with Figure 4 Fiber preparation device 400, Figure 5 The optical fiber preparation device 500 is similar to that in the embodiment of the present invention and will not be described in detail here.

[0156] In some embodiments, the optical fiber preparation device comprises two inlets. The two extruders are respectively connected to the two inlets of the optical fiber preparation device, so as to input two initial materials into the optical fiber preparation device.

[0157] In the fiber preparation device Figure 5 When the device 500 in FIG. 1 is similar, the embodiment of the present application does not limit the number of diversions of each initial material in the diverter. For example, each initial material can be diverted into greater than or equal to 5 portions after entering the diverter.

[0158] In the embodiment of the present application, there is no limitation on the composite temperature when multiple materials are composited into an optical fiber preform in the composite device. The composite temperature can be determined according to the thermal properties of each initial material. For example, when the two initial materials are the first initial material and the second initial material, the composite temperature can be between 215°C and 220°C.

[0159] In some embodiments, the optical fiber can be directly obtained from the outlet of the optical fiber preparation device. When the optical fiber can be directly obtained from the outlet of the optical fiber preparation device, the method 700 ends, that is, steps S730 and S740 may no longer be performed.

[0160] In some embodiments, the optical fiber preform may be obtained from the outlet of the optical fiber preparation device. When the optical fiber preform is obtained at the outlet of the optical fiber preparation device, the method 700 may further include steps S730 and S740.

[0161] S730, cooling the optical fiber preform.

[0162] Optionally, the optical fiber preform may be cooled by natural cooling or air cooling, etc. The natural cooling method is cooling at room temperature.

[0163] S740, stretching and winding the cooled optical fiber preform to obtain an optical fiber.

[0164] After the optical fiber preform is sufficiently cooled, it can be stretched and rolled up to obtain an optical fiber.

[0165] Optionally, the optical fiber can have different core diameters according to different winding speeds. The winding speed is not limited in the present application embodiment, and can be determined according to the core diameter of the optical fiber to be obtained. The core diameter of the optical fiber prepared in the present application embodiment is not limited, and can be determined according to actual use requirements. For example, the core diameter of the optical fiber can be 0.5 mm, that is, the radius can be 0.25 mm.

[0166] The present application embodiment may provide a communication medium, which may include an outer casing and an optical fiber as described in the above application embodiment. Alternatively, the optical fiber in the communication medium may include: Figure 3 or Figure 7 Prepared by the method described.

[0167] Optionally, the communication medium may be, for example, a plastic optical fiber, an optical cable, a patch cord, etc.

[0168] The present application embodiment may provide an optical module, which may include a photoelectric converter and an optical fiber as described in the above application embodiment. Alternatively, the optical fiber in the optical module is composed of Figure 3 or Figure 7 Prepared by the method described.

[0169] The present application embodiment may provide an optical transmission system, which may include an optical transmitter, an optical receiver, and an optical fiber as described in the above application embodiment. Alternatively, the optical fiber in the optical transmission system may include: Figure 3 or Figure 7 Prepared by the method described.

[0170] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An optical fiber, characterized in that: The refractive index difference between at least two points in the cross section of the optical fiber is greater than or equal to 0.01, at least five groups of points in the cross section meet the preset conditions, and the kth group of points in the at least five groups of points includes x k Point and y k point, the x k Point with the y k point is any point in the cross section, and the preset conditions include nx k -ny k ≥0.001 and rx k -ry k <0, where nx k For the x k Refractive index of the point, ny k For the y k Refractive index of a point, rx k For the x k The distance from the point to the center of the cross section, ry k For the y k The distance from the point to the center of the cross section, k is a positive integer greater than or equal to 1.

2. The optical fiber according to claim 1, characterized in that At least seven groups of points in the cross section meet the preset condition.

3. The optical fiber according to claim 1 or 2, characterized in that: The difference in refractive index between at least two points in the cross section is greater than or equal to 0.

013.

4. The optical fiber according to any one of claims 1 to 3, characterized in that The x of the i-th group of points in at least one group of points in the cross section i Point with the y i The spacing between points is less than or equal to 50 microns, the x i Point with the y i The refractive index difference of the points is greater than 0.002, and i is a positive integer greater than or equal to 1.

5. The optical fiber according to any one of claims 1 to 4, characterized in that The light transmittance of the material of the optical fiber is greater than 80%.

6. The optical fiber according to any one of claims 1 to 5, characterized in that The light transmittance of the material of the optical fiber is greater than 90%.

7. The optical fiber according to claim 5 or 6, characterized in that: The test wavelength of the light transmittance is 650 nanometers.

8. The optical fiber according to any one of claims 1 to 7, characterized in that The distance between every two points in the cross section is greater than or equal to 0.2 micrometers.

9. The optical fiber according to any one of claims 1 to 8, characterized in that The distribution of the refractive index of some points in the line from the center to the edge of the cross section is fitted into a curve, or the distribution of the refractive index difference between the some points and the central point of the cross section is fitted into a curve.

10. The optical fiber according to claim 9, characterized in that The curve is an upward convex curve.

11. The optical fiber according to claim 9 or 10, characterized in that: The curve is a partial curve in a quadratic equation curve or a partial curve in a cubic equation curve.

12. The optical fiber according to any one of claims 1 to 11, characterized in that The optical fiber is a plastic optical fiber.

13. A method for preparing an optical fiber, characterized in that: include: M kinds of initial materials are input into an optical fiber preparation device, and an optical fiber is obtained from an outlet of the optical fiber preparation device, wherein at least two of the M kinds of initial materials have different refractive indices.

14. The method according to claim 13, characterized in that The optical fiber preparation device includes a splitter and a composite device, the splitter includes M first inlets and N first outlets, at least two of the M first inlets are connected to at least one of the N first outlets, the composite device includes P second inlets and Q second outlets, the P second inlets are connected to the Q second outlets, the N first outlets are connected to the P second inlets, M, N, P are positive integers greater than or equal to 2, Q is a positive integer greater than or equal to 1, and P is greater than or equal to Q.

15. The method according to claim 14, characterized in that The step of inputting M kinds of initial materials into an optical fiber preparation device and obtaining an optical fiber from an outlet of the optical fiber preparation device comprises: The M kinds of initial materials are respectively input into the M first inlets of the splitter, and N kinds of materials are obtained from the N first outlets of the splitter, wherein at least two of the N kinds of materials contain different proportions of the initial materials.

16. The method according to claim 15, characterized in that The method further comprises: The N materials are respectively input into P second inlets of the compounder, and the optical fiber is obtained from Q second outlets of the compounder, where P is equal to N.

17. The method according to claim 15 or 16, characterized in that The floating rate of the refractive index of each of the N materials in the first outlet of the splitter or the second inlet of the recombiner is less than 0.5%.

18. The method according to any one of claims 14 to 17, characterized in that The diverter also includes a porous plate structure, and at least two of the M initial materials are sequentially input into the at least one first outlet through the at least two first inlets and the porous plate structure, and the amounts of at least two of the M initial materials input into the first outlet through the porous plate structure are different.

19. The method according to any one of claims 14 to 18, characterized in that At least one of the M first inlets is provided with a first flow-dividing structure, and the initial material is diverted in different amounts by the first flow-dividing structure.

20. The method according to any one of claims 13 to 19, characterized in that The method further comprises: The M starting materials are obtained by M extruders.

21. The method according to any one of claims 13 to 20, characterized in that The optical fiber is the optical fiber according to any one of claims 1 to 12.

22. A communication medium, characterized in that: The optical fiber comprises an outer sleeve and the optical fiber according to any one of claims 1 to 12, or the optical fiber in the communication medium is prepared by the method according to any one of claims 13 to 21.

23. An optical module, characterized in that: The optical module comprises a photoelectric converter and the optical fiber according to any one of claims 1 to 12, or the optical fiber in the optical module is prepared by the method according to any one of claims 13 to 21.

24. An optical transmission system, characterized in that: The optical transmission system comprises an optical transmitter, an optical receiver and the optical fiber according to any one of claims 1 to 12, or the optical fiber in the optical transmission system is prepared by the method according to any one of claims 13 to 21.

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