US-20260126581-A1 - OPTICAL FIBER AND METHOD FOR PREPARING OPTICAL FIBER

Abstract

An optical fiber and a method for preparing an optical fiber is described. A 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, a k th group of points in the at least five groups of points include a point x k and a point y k , the point x k and the point y k are any point in the cross section, the preset condition includes nx k −ny k ≥0.001 and rx k −ry k <0, nx k is a refractive index of the point x k , ny k is a refractive index of the point y k , rx k is a distance from the point x k to a center of the cross section, ry k is a distance from the point y k to the center of the cross section, and k is a positive integer greater than or equal to 1.

Inventors

• Zemeng Sun
• Hongyu Chen
• Botong QIU
• Daming Wu
• Xiaolong GAO

Assignees

• HUAWEI TECHNOLOGIES CO., LTD.
• BEIJING UNIVERSITY OF CHEMICAL TECHNOLOGY

Dates

Publication Date

20260507

Application Date

20251231

Priority Date

20230703

Claims (20)

1. 1 . An optical fiber, wherein a 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, a k th group of points in the at least five groups of points comprise a point x k and a point y k , the point x k and the point y k are any point in the cross section, the preset condition comprises nx k −ny k ≥0.001 and rx k −ry k <0, nx k is a refractive index of the point x k , ny k is a refractive index of the point y k , rx k is a distance from the point x k to a center of the cross section, ry k is a distance from the point y k to the center of the cross section, and k is a positive integer greater than or equal to 1.
2. 2 . The optical fiber according to claim 1 , wherein at least seven groups of points in the cross section meet the preset condition.
3. 3 . The optical fiber according to claim 1 , wherein a refractive index difference between at least two points in the cross section is greater than or equal to 0.013.
4. 4 . The optical fiber according to claim 1 , wherein a distance between a point x i and the point y i in an i th group of points in at least one group of points in the cross section is less than or equal to 50 micrometers, a refractive index difference between the point x i and the point y i is greater than 0.002, and i is a positive integer greater than or equal to 1.
5. 5 . The optical fiber according to claim 1 , wherein a transmittance of a material of the optical fiber is greater than 80%.
6. 6 . The optical fiber according to claim 1 , wherein the transmittance of the material of the optical fiber is greater than 90%.
7. 7 . The optical fiber according to claim 5 , wherein a test wavelength of the transmittance is 650 nanometers.
8. 8 . The optical fiber according to claim 1 , wherein a distance between any two points in the cross section is greater than or equal to 0.2 micrometers.
9. 9 . The optical fiber according to claim 1 , wherein one of distribution of refractive indexes of a plurality of points in a connection line from the center to an edge in the cross section is fitted as a curve, or distribution of refractive index differences between a plurality of points and the center point in the cross section is fitted as a curve.
10. 10 . The optical fiber according to claim 9 , wherein the curve is an upward convex curve.
11. 11 . The optical fiber according to claim 9 , wherein the curve is one of a partial curve in a curve of a quadratic equation with one unknown or a partial curve in a curve of a cubic equation with one unknown.
12. 12 . The optical fiber according to claim 1 , wherein the optical fiber is a plastic optical fiber.
13. 13 . A method for preparing an optical fiber, comprising: inputting M initial materials into an optical fiber preparer, and obtaining the optical fiber from an outlet of the optical fiber preparer, wherein refractive indexes of at least two of the M initial materials are different.
14. 14 . The method according to claim 13 , wherein the optical fiber preparer comprises a splitter and a combiner, the splitter comprises M first inlets and N first outlets, at least two of the M first inlets communicate with at least one of the N first outlets, the combiner comprises P second inlets and Q second outlets, the P second inlets communicate with the Q second outlets, the N first outlets communicate with 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.
15. 15 . The method according to claim 14 , wherein inputting the M initial materials into the optical fiber preparer, and obtaining the optical fiber from the outlet of the optical fiber preparer comprises: separately inputting the M initial materials into the M first inlets of the splitter, and obtaining N materials from the N first outlets of the splitter, wherein proportions of initial materials comprised in at least two of the N materials are different.
16. 16 . The method according to claim 15 , wherein the method further comprises: separately inputting the N materials into the P second inlets of the combiner, and obtaining the optical fiber from the Q second outlets of the combiner, wherein P is equal to N.
17. 17 . The method according to claim 15 , wherein one of a floating rate of a refractive index of each of the N materials in the first outlet of the splitter is less than 0.5% or the second inlet of the combiner is less than 0.5%.
18. 18 . The method according to claim 14 , wherein the splitter further comprises a porous plate structure, at least two of the M initial materials are sequentially input to the at least one first outlet through the at least two first inlets and the porous plate structure, and quantities of the at least two of the M initial materials that are input to the first outlet through the porous plate structure are different.
19. 19 . The method according to claim 14 , wherein a first split structure is disposed in at least one of the M first inlets, and quantities of the initial materials split through the first split structure are different.
20. 20 . The method according to claim 13 , wherein the method further comprises: obtaining the M initial materials through M extruders.

Description

CROSS-REFERENCE TO RELATED DISCLOSURES This application is a continuation of International Application No. PCT/CN2024/093911, filed on May 17, 2024, which claims priority to Chinese Patent Application No. 202310806279.1, filed on Jul. 3, 2023. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. TECHNICAL FIELD Embodiments of this disclosure 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 A plastic optical fiber (POF) is an optical fiber made of high-transparent polymer. Compared with a quartz optical fiber, the plastic optical fiber has advantages such as light weight and strong flexibility, and has been widely used in vehicle-mounted, fiber to the home, medical, and other disclosure scenarios. To improve a bandwidth of the plastic optical fiber, a fiber core part of the plastic optical fiber is usually adjusted, so that refractive indexes of core layer materials of the fiber core part are different. In the conventional technology, when a plastic optical fiber is prepared, a plurality of materials with different refractive indexes need to be prepared in advance, and then the plurality of materials are combined into one optical fiber. This preparation process is complex. In addition, because the materials with different refractive indexes have different viscosities, it is difficult to combine the plurality of materials into an optical fiber with uniform structure distribution, affecting performance of the optical fiber. Therefore, there is a need for improved methods of preparing plastic optical fibers and improved performance of plastic optical fibers. SUMMARY Embodiments of this disclosure 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 includes a plurality of groups of points with different refractive indexes, so that a cross section of the optical fiber has different refractive index distribution characteristics. In this way, light can be totally reflected at a corresponding position in a transmission process in the optical fiber, and an effect of improving optical fiber bandwidth is achieved. According to a first aspect, an optical fiber is provided. A 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, a kth group of points in the at least five groups of points include a point xk and a point yk, the point xk and the point yk are any point in the cross section, the preset condition includes nxk−nyk≥0.001 and rxk−ryk<0, nxk is a refractive index of the point xk, nyk is a refractive index of the point yk, rxk is a distance from the point xk to a center of the cross section, ryk is a distance from the point yk to the center of the cross section, and k is a positive integer greater than or equal to 1. In this embodiment of this disclosure, the optical fiber includes points whose refractive index difference is greater than or equal to 0.01. Optical fibers with different numerical apertures can be prepared by controlling the refractive index difference between the points, to obtain an optical fiber that meets a performance requirement. The optical fiber further includes at least five groups of points whose refractive index difference is greater than 0.001, so that the cross section of the optical fiber has different refractive index distribution characteristics. In this way, light can be totally reflected at a corresponding position in a transmission process in the optical fiber, and an effect of improving optical fiber bandwidth is achieved. In addition, each group of points meet the preset condition rxk−ryk<0, so that the refractive index of the optical fiber is in gradient distribution. With reference to the first aspect, in some implementations of the first aspect, at least seven groups of points in the cross section meet the preset condition. With reference to the first aspect, in some implementations of the first aspect, a refractive index difference between at least two points in the cross section is greater than or equal to 0.013. In this embodiment of this disclosure, the optical fiber includes a plurality of points whose refractive index difference is greater than or equal to 0.013, so that a numerical aperture of the optical fiber is large, and performance of the optical fiber is improved. With reference to the first aspect, in some implementations of the first aspect, a distance between a point xi and a point yi in an ith group of points in at least one group of points in the cross section is less than or equal to 50 micrometers, a refractive index difference between the point xi and the point yi is greater than 0.002