Multi-core optical fiber and method for splicing thereof

Abstract

The application provides a multi-core optical fiber and a butt joint method thereof, relates to the technical field of optical fibers, and aims to solve the technical problem of crosstalk between an identification layer and its adjacent fiber cores during optical fiber communication. The multi-core optical fiber comprises a cladding, an identification structure and a plurality of fiber cores; the plurality of fiber cores are uniformly arranged in the cladding, and the cross section of the cladding is circular; the cladding is provided with an identification hole, the identification hole is arranged in parallel with the fiber cores, and the identification hole penetrates through the entire cladding along the extension direction of the cladding; the identification structure is arranged in the identification hole, and the identification structure is arranged in offset with the symmetry axes of any two fiber cores and the central axis of the cladding; the identification structure comprises an identification layer arranged on the inner wall of the identification hole, and the identification layer surrounds a hollow; the identification layer is configured to form a refractive index difference with the cladding, and can absorb light introduced therein. The multi-core optical fiber provided by the application is one of space division multiplexing technical means, and is suitable for optical communication.

Description

Technical Field

[0001] This application relates to the field of optical fiber technology, and in particular to a multi-core optical fiber and its splicing method. Background Technology

[0002] Multi-core optical fiber, as one of the means of realizing space division multiplexing technology, generally consists of a cladding and multiple fiber cores disposed within the cladding, thus increasing the information transmission capacity of the optical fiber. However, in long-distance optical communication, there are scenarios where multiple fiber segments are connected together, which in turn raises issues related to multi-core fiber splicing.

[0003] To avoid significant light loss during transmission after splicing two optical fibers, high precision is required for the splicing of corresponding fiber cores. Currently, for symmetrical optical fibers with multiple cores symmetrically arranged in the cladding, a marking layer is typically installed within the cladding. This marking layer is configured as a solid structure formed by doping the cladding with a high-refractive-index material. During the connection of two optical fibers, the marking layer is used to identify and locate each fiber core.

[0004] However, when using optical fiber communication with the aforementioned identification layer, there is a problem of crosstalk between the identification layer and its adjacent fiber cores. Summary of the Invention

[0005] In view of the above problems, this application provides a multi-core optical fiber and its splicing method, which can not only avoid the problem of crosstalk between the identification layer and its adjacent optical fibers, but also achieve rapid splicing of two optical fiber segments through the identification layer.

[0006] To achieve the above objectives, the embodiments of this application provide the following technical solutions:

[0007] A first aspect of this application provides a multi-core optical fiber, including a cladding, an identification structure, and multiple fiber cores; the multiple fiber cores are uniformly arranged within the cladding, and the cladding has a circular cross-section; the cladding is provided with an identification hole, which is arranged parallel to the fiber cores and extends through the entire cladding along its extension direction; the identification structure is disposed within the identification hole, and the identification structure is offset from the symmetry axis of any two fiber cores and the central axis of the cladding; the identification structure includes an identification layer disposed on the inner wall of the identification hole, and the identification layer is hollow; the identification layer is configured to form a refractive index difference with the cladding and is capable of absorbing light introduced therein.

[0008] In one optional embodiment, the marking layer is a germanium-doped layer; the refractive index difference between the germanium-doped layer and the cladding layer is set between 0.15% and 1.5%.

[0009] In one optional embodiment, the marking structure is a ring structure; the diameter of the marking structure is set to be between 5-8 μm, and the thickness of the marking layer is set to be between 1-3 μm.

[0010] In one alternative embodiment, the marking structure further includes a support layer formed on the inner wall of the marking layer; the side of the support layer away from the marking layer forms the hollow.

[0011] In one optional embodiment, the support layer is a boron-doped layer; the thickness of the boron-doped layer is set to be between 1 and 2 μm.

[0012] In one alternative embodiment, each of the fiber cores is circumferentially distributed around the central axis of the cladding.

[0013] In one alternative embodiment, of the plurality of fiber cores, at least one fiber core is located along the central axis of the cladding; the remaining fiber cores are circumferentially arranged around the central axis of the cladding.

[0014] In one optional embodiment, a plurality of the identification structures are provided within the cladding; in the cross-section of the cladding, any two of the identification structures are not aligned with the center of the cladding.

[0015] In one alternative embodiment, of the plurality of identification structures, at least two of the identification structures are arranged opposite each other on both sides of the center of the cladding.

[0016] The second aspect of this application provides a method for connecting multi-core optical fibers, comprising the following steps:

[0017] Provide two optical fibers, a first fiber and a second fiber, with identification structures to be connected;

[0018] The end face of the first optical fiber is aligned with the end face of the second optical fiber, and the central axes of the optical fibers are collinear.

[0019] Light is input into the first optical fiber, and part of the light enters the marking structure of the first optical fiber;

[0020] Based on the marking structure of the second optical fiber, rotate the second optical fiber so that the marking structures at the same positions of the second optical fiber and the first optical fiber are aligned.

[0021] Compared with related technologies, the multi-core optical fiber and its splicing method provided in this application have the following advantages:

[0022] The multi-core optical fiber provided in this application embodiment has an identification structure set in the cladding. The identification structure is offset from the axis of symmetry between any two fiber cores. Furthermore, the identification structure is also offset from the central axis of the cladding. Thus, the asymmetry of the identification structure can be identified and defined during the multi-core optical fiber splicing process. The identification structure is used to distinguish each fiber core so that each fiber core of the two multi-core optical fiber segments corresponds to the other. That is, the rapid splicing of two multi-core optical fiber segments is achieved through the hollow identification structure.

[0023] Furthermore, compared to the related technologies where the marking layer is configured as a solid structure formed by doping the cladding with a high-refractive-index material, the marking structure in this embodiment has an internal marking layer that is hollow. This hollow interior prevents light from propagating through the marking layer via total internal reflection. Additionally, by placing the marking layer within the marking hole, a refractive index difference exists between the marking layer and the cladding, effectively absorbing any light that might enter the marking layer and thus resolving the crosstalk problem between the marking layer and its adjacent fiber cores.

[0024] In addition to the technical problems solved by the embodiments of this application, the technical features constituting the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions described above, other technical problems that can be solved by the multi-core optical fiber and its splicing method provided by the embodiments of this application, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further explained in detail in the specific implementation. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the multi-core optical fiber provided in Embodiment 1 of this application. Figure 1 ;

[0027] Figure 2 This is a schematic diagram of the structure of the multi-core optical fiber provided in Embodiment 1 of this application. Figure 2 ;

[0028] Figure 3 This is a schematic diagram of the structure of the multi-core optical fiber provided in Embodiment 1 of this application. Figure 3 ;

[0029] Figure 4 This is a flowchart illustrating the steps of the multi-core optical fiber splicing method provided in Embodiment 2 of this application.

[0030] Explanation of reference numerals in the attached figures:

[0031] 10-Cladon;

[0032] 20-core fiber;

[0033] 30 - Identification Structure;

[0034] 31 - Identification layer; 32 - Support layer; 33 - Hollow;

[0035] 100-multi-core optical fiber. Detailed Implementation

[0036] As described in the background section, when symmetrical multi-core optical fibers with an identification layer are used in optical fiber communication, there is a problem of crosstalk between the identification layer and its adjacent cores. The inventors discovered that this problem arises because, typically, a identification layer is placed within the cladding of a symmetrical multi-core optical fiber. This identification layer is configured as a solid structure formed by doping the cladding with a high-refractive-index material. When two optical fiber segments are connected, the identification layer is used to identify and locate each core. However, when transmitting optical signals through the multi-core optical fiber, some light is guided into and transmitted within the identification layer, thus causing crosstalk to the light transmission of its adjacent cores.

[0037] To address the aforementioned technical problems, this application provides a multi-core optical fiber, which includes an identification structure disposed within the identification hole of the cladding. The identification structure includes an identification layer formed on the inner wall of the identification hole, and a refractive index difference is formed between the identification layer and the cladding. The side of the identification layer away from the inner wall of the identification hole is hollow.

[0038] With this configuration, the marking structure not only has a marking layer but is also hollow, preventing the light entering it from propagating through total internal reflection within the marking layer; and, the difference in refractive index between the marking layer and the cladding layer can absorb any light that may enter it, thus solving the problem of crosstalk between the marking layer and its adjacent fiber cores.

[0039] To make the above-mentioned objectives, features, and advantages of the embodiments of this application more apparent and understandable, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0040] like Figure 1As shown, this application embodiment provides a multi-core optical fiber 100 including a cladding 10, an identification structure 30, and multiple fiber cores 20. The cladding 10 can be made of pure silicon dioxide, and the cross-section of the cladding 10 is circular. That is, the multi-core optical fiber 100 has a cylindrical structure as a whole, and the cross-sectional shape along the extension direction perpendicular to the optical fiber is circular.

[0041] Furthermore, multiple fiber cores 20 are evenly arranged within the cladding 10, and the extending direction of the fiber cores 20 is consistent with the extending direction of the cladding 10. The fiber cores 20 can be arranged parallel to the central axis of the cladding 10. A marking hole is provided within the cladding 10, and the marking hole is arranged through the cladding 10 along its extending direction, that is, both ends of the marking hole extend to the end face of the cladding 10.

[0042] The label structure 30 is disposed inside the label hole. The label structure 30 includes a label layer 31. The shape of the label layer 31 is consistent with the shape of the label hole. The first side of the label layer 31 close to the label hole is attached to the inner wall of the label hole, and the second side of the label layer 31 away from the inner wall of the label hole forms a hollow 33.

[0043] Specifically, in this embodiment, the marking hole can be a circular hole or a hole of other shapes. For example, the marking hole can be a square hole, a triangular hole, etc. This embodiment does not limit this; this embodiment uses a circular hole as an example for illustration.

[0044] Doping is performed inside the marking hole to form a marking layer 31, or a pre-fabricated tubular structure with a marking layer 31 is embedded inside the marking hole. The marking layer 31 can be configured as a germanium-doped layer, and there is a refractive index difference between the germanium-doped layer and the cladding layer 10. The refractive index difference between the two is set as needed. In this embodiment, the refractive index difference between the germanium-doped layer and the cladding layer 10 is preferably set in the range of 0.15-1.5%.

[0045] Furthermore, the marking structure 30 is offset from the axis of symmetry of any two fiber cores 20, meaning the marking structure 30 is not located on the axis of symmetry of any two fiber cores 20, and the distance between the marking structure 30 and any two fiber cores 20 is unequal. Also, the marking structure 30 is offset from the central axis of the cladding 10, meaning the marking structure 30 is not located on the central axis of the cladding 10.

[0046] With this configuration, the asymmetry of the identification structure 30 can be identified during the splicing of the multi-core optical fiber 100, thereby distinguishing each fiber core 20 by means of the identification structure 30, so that each fiber core 20 of the two multi-core optical fiber segments 100 corresponds to the other, that is, the rapid splicing of the two multi-core optical fiber segments 100 is achieved through the identification structure 30.

[0047] Compared to the existing technology where the marking layer is configured as a solid structure formed by doping the cladding with a high refractive index material, the marking structure 30 in this embodiment has an internal marking layer 31, which forms a hollow 33. This configuration, with the hollow 33 inside the marking structure 30, prevents the light entering it from propagating through total internal reflection within the marking layer 31. Furthermore, by placing the marking layer 31 within the marking hole, a refractive index difference exists between the marking layer 31 and the cladding 10, which can absorb any light that may enter it, thereby solving the problem of crosstalk between the marking layer 31 and its adjacent fiber core 20.

[0048] Based on the above embodiments, the marking structure 30 is generally annular, with a diameter ranging from 5 to 8 μm, and the thickness of the marking layer 31 ranging from 1 to 3 μm. It should be understood that regardless of the thickness of the marking layer 31, the second side assembly of the marking layer 31 can form a hollow 33, and the diameter of the marking structure 30 is consistent with the diameter of the marking hole.

[0049] By increasing the size of the marking structure 30, this embodiment of the application solves the problem of difficulty in processing and identifying solid high-refractive-index marking layers when they are too small, as seen in the prior art. Furthermore, when the size of a large-size solid high-refractive-index marking layer is too large, some light will be drawn into its interior, thus affecting the light transmission of adjacent fiber cores.

[0050] Furthermore, based on the above embodiments, such as Figure 2 As shown, the identification structure 30 in this embodiment further includes a support layer 32 formed on the inner wall of the identification layer 31; the first side of the support layer 32 near the identification layer 31 is attached and connected to the second side of the identification layer 31, and the second side of the support layer 32 away from the identification layer 31 forms a hollow 33. With this configuration, the support layer 32 can support the entire identification structure 30, thereby improving the structural strength of the entire identification structure 30 and making the identification layer 31 less susceptible to damage due to fiber bending.

[0051] Specifically, the support layer 32 can be a boron-doped layer, and the boron-doped layer has a certain thickness so that it can reinforce the marking layer 31. Preferably, with the diameter of the marking structure 30 set between 5-8 μm and the thickness of the marking layer 31 set between 1-3 μm, the thickness of the boron-doped layer is set between 1-2 μm, and regardless of the thickness of the boron-doped layer, the second side assembly of the boron-doped layer can form a hollow 33.

[0052] Continue reading Figure 1In the multi-core optical fiber 100 provided in this application embodiment, each fiber core 20 can be evenly distributed circumferentially around the central axis of the cladding 10, that is, no fiber core 20 is provided at the central axis of the cladding 10. For example, the optical fiber includes four fiber cores 20, which are evenly arranged circumferentially along the central axis of the cladding 10 and form a circle.

[0053] In this type of multi-core optical fiber 100, the marking structure 30 can be located on the upper left side of the cross-section of the entire cladding 10, and the marking structure 30 is offset from the axis of symmetry of the two fiber cores 20 closest to it, and the distance between the marking structure 30 and the two fiber cores 20 closest to it is different. With this configuration, the marking structure 30 can identify the specific position of each fiber core 20 in the cross-section, and when splicing two optical fibers, the fiber cores 20 of the two optical fibers can be quickly aligned.

[0054] Similarly, such as Figure 3 As shown, the optical fiber includes eight cores 20, which are evenly arranged circumferentially around the central axis of the cladding 10 and form a circle. In this type of multi-core optical fiber 100, the identification structure 30 can be set with reference to the identification structure 30 in the optical fiber with four cores 20, and will not be described again here.

[0055] like Figure 2 As shown, in the multi-core optical fiber 100 provided in this embodiment, at least one fiber core 20 is arranged at the central axis of the cladding 10, and the remaining fiber cores 20 are evenly arranged around the central axis of the cladding 10. For example, the optical fiber includes seven fiber cores 20, one of which is arranged at the central axis of the cladding 10, and the other six fiber cores 20 are evenly arranged circumferentially around the central axis of the cladding 10, forming a circle. In this type of multi-core optical fiber 100, the identification structure 30 can be set with reference to the identification structure 30 in the optical fiber including four fiber cores 20 described above, and will not be repeated here.

[0056] It should be noted that, regardless of the number of fiber cores 20 included in the multi-core optical fiber 100 and the layout method adopted, the identification structure 30 in the embodiments of this application is not limited to the above position, and the identification structure 30 may have an identification layer 31, or the identification structure 30 may have an identification layer 31 and a support layer 32. Different identification structures 30 and different numbers of fiber cores 20 can be combined as needed, and the embodiments of this application do not limit this.

[0057] Based on the above embodiments, the multi-core optical fiber 100 provided in this application embodiment includes multiple identification structures 30, which are respectively disposed within the cladding 10 and within the cross-section of the cladding 10. No two identification structures 30 are aligned with the center of the cladding 10 on the same straight line. In other words, the line connecting the center of each identification structure 30 to the center of the cladding 10 lies on different straight lines. With this arrangement, each identification structure 30 is located at a different position in the cross-section of the cladding 10 in this application embodiment, facilitating the differentiation and identification of each identification structure 30. Furthermore, when splicing two optical fibers, the cores 20 of the two optical fibers can be quickly aligned.

[0058] Continue reading Figure 3 In the aforementioned plurality of identification structures 30, at least two identification structures 30 are arranged opposite each other on both sides of the center of the cladding 10. For example, the multi-core optical fiber 100 includes a first identification structure 30 and a second identification structure 30, wherein the first identification structure 30 may be disposed on the left side of the center of the cladding 10, and the second identification structure 30 may be disposed on the right side of the center of the cladding 10. The line connecting the center of the first identification structure 30 and the center of the cladding 10 is the first connecting line, and the line connecting the center of the second identification structure 30 and the center of the cladding 10 is the second connecting line. The first connecting line and the second connecting line are located on different straight lines.

[0059] This configuration allows for the differentiation of the left and right sides of the cladding 10 using the first and second identification structures 30, enabling the quick alignment of the fiber cores 20 of the two optical fibers during splicing.

[0060] Example 2

[0061] like Figure 4 As shown in the embodiment of this application, a method for connecting multi-core optical fibers 100 is also provided, including the following steps:

[0062] Step S100: Provide two segments of a first optical fiber and a second optical fiber, each having an identification structure 30, to be connected. Specifically, both the first and second optical fibers are multi-core optical fibers 100, and each has the identification structure 30 as described in Embodiment 1, with the identification structures 30 positioned identically in the first and second optical fibers. The identification structure 30 is used to identify the fiber cores 20 of each fiber during the splicing of the two optical fibers.

[0063] Step S200: Align the end face of the first optical fiber with the end face of the second optical fiber, ensuring that the central axes of all optical fibers are collinear. Specifically, when the first and second optical fibers are connected, align the end face of the second end of the first optical fiber with the end face of the first end of the second optical fiber. When the two end faces are aligned, they can be fitted together or maintain a certain gap; however, this gap must ensure that light can be transmitted from the first optical fiber to the second optical fiber. Further, the central axis of the first optical fiber is collinear with the central axis of the second optical fiber; this arrangement facilitates subsequent rotation of the first or second optical fiber to align the marking structure 30 and each fiber core 20 of the first and second optical fibers.

[0064] Step S300: Input light into the first optical fiber, and part of the light enters the identification structure 30 of the first optical fiber.

[0065] Specifically, when the first optical fiber and the second optical fiber are connected, light is input to the first optical fiber from the first end, and part of the light is guided to the identification structure 30 of the first optical fiber. The identification layer 31 of the identification structure 30 absorbs the light, and the identification structure 30 of the first optical fiber is lit up to facilitate identification and differentiation.

[0066] Step S400: Based on the identification structure 30 of the second optical fiber, rotate the second optical fiber or the first optical fiber so that the identification structures 30 at the same position of the second optical fiber and the first optical fiber are aligned.

[0067] Specifically, as light propagates within the second optical fiber, some light is directed into its identification structure 30, where the identification layer 31 absorbs the light and is illuminated. The location of the identification structure 30 can then be identified by observing the end face of the second end of the second optical fiber. Furthermore, using this identification structure 30, the first and / or second optical fibers can be rotated to align the identification structures 30 in each fiber, thereby completing the connection of the two optical fibers.

[0068] It is important to understand that after the two optical fibers are spliced, the process also includes fusion splicing the first end face of the first optical fiber and the second end face of the second optical fiber. This can be done using methods such as an oxy-hydrogen burner or arc welding.

[0069] The multi-core optical fiber 100 splicing method provided in this application embodiment can be identified during the splicing process of the multi-core optical fiber 100 based on the asymmetry of the identification structure 30. Thus, the identification structure 30 is used to distinguish each fiber core 20, so that each fiber core 20 of the two multi-core optical fiber segments 100 corresponds to each other. That is, the identification structure 30 is used to achieve rapid splicing of the two multi-core optical fiber segments 100.

[0070] The various embodiments or implementation methods described in this specification are presented in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0071] It should be noted that the terms "one embodiment," "embodiment," "exemplary embodiment," "some embodiments," etc., mentioned in the specification indicate that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge scope of those skilled in the art.

[0072] Generally speaking, terms should be understood at least in part by their use in context. For example, at least in part by context, the term "one or more" as used in the text can be used to describe any feature, structure, or characteristic of the singular meaning, or a combination of features, structures, or characteristics of the plural meaning. Similarly, at least in part by context, terms such as "a" or "the" can also be understood to convey either singular or plural usage.

[0073] It should be readily understood that the terms “on,” “above,” and “on top of” in this application should be interpreted in the broadest possible sense, such that “on” means not only “directly on something” but also “on something” with an intermediate feature or layer therebetween, and that “above” or “on top of” means not only “on top of something” but also “on top of something” without an intermediate feature or layer therebetween (i.e., directly on something).

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A multi-core optical fiber, characterized in that, This includes the cladding, marking structure, and multiple fiber cores; Multiple fiber cores are evenly arranged within the cladding, and the cross-section of the cladding is circular; The cladding is provided with an identification hole, which is arranged parallel to the fiber core and extends through the entire cladding along its extension direction; The marking structure is disposed within the marking hole, and the marking structure is offset from the symmetry axes of any two of the fiber cores and the central axis of the cladding. The marking structure includes a marking layer disposed on the inner wall of the marking hole and a support layer formed on the inner wall of the marking layer, wherein the side of the support layer away from the marking layer is hollow; the marking layer is configured to form a refractive index difference with the cladding layer and is capable of absorbing light introduced therein; The marking structure is a ring structure, the diameter of the marking structure is set between 5-8 μm, and the thickness of the marking layer is set between 1-3 μm.

2. The multi-core optical fiber according to claim 1, characterized in that, The marking layer is a germanium-doped layer; the refractive index difference between the germanium-doped layer and the cladding layer is set between 0.15% and 1.5%.

3. The multi-core optical fiber according to claim 2, characterized in that, The support layer is a boron-doped layer; the thickness of the boron-doped layer is set to be between 1 and 2 μm.

4. The multi-core optical fiber according to claim 1, characterized in that, Each of the fiber cores is evenly distributed circumferentially around the central axis of the cladding.

5. The multi-core optical fiber according to claim 1, characterized in that, Of the plurality of said fiber cores, at least one said fiber core is located along the central axis of the cladding; The remaining fiber cores are evenly arranged circumferentially around the central axis of the cladding.

6. The multi-core optical fiber according to claim 1, characterized in that, The cladding layer contains a plurality of the aforementioned identification structures; Within the cross-section of the cladding, no two of the marking structures are aligned with the center of the cladding.

7. The multi-core optical fiber according to claim 6, characterized in that, In the plurality of said identification structures, at least two of said identification structures are arranged opposite each other on both sides of the center of the cladding.

8. A method for splicing multi-core optical fibers, characterized in that, Includes the following steps: Two optical fibers to be connected are provided, one first and one second, having an identification structure, wherein the first and second optical fibers are multi-core optical fibers as described in any one of claims 1-7; The end face of the first optical fiber is aligned with the end face of the second optical fiber, and the central axes of the optical fibers are collinear. Light is input into the first optical fiber, and part of the light enters the marking structure of the first optical fiber; Based on the marking structure of the second optical fiber, rotate the second optical fiber so that the marking structures at the same positions of the second optical fiber and the first optical fiber are aligned.

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