Multi-core optical fiber and method for manufacturing same
By bundling and heating the multi-core optical fiber with relatively low core count, the core count is significantly increased and the doping characteristics are maintained, and the problem of manufacturing multi-core optical fibers with high core count and complex geometric shapes in the prior art is solved, and suitable for optical calculations and High-efficiency multi-core fiber for communication.
Patent Information
- Application Number
- CN202380040971.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-05-31
- Filing Date
- 2023-05-29
- Publication Date
- 2024-12-13
AI Technical Summary
The prior art is difficult to manufacture multi-core optical fibers with high core count and complex geometry, especially when maintaining a small fiber diameter, and the core doping process is complicated, making it difficult to achieve efficient core tight arrangements.
By using relatively low core number multi-core fibers as initial packages, bundled into a bundle structure and heated treatment, the core number is significantly increased and the doping characteristics of the core are maintained during the process, achieving complex geometry and high core number of multi-cores Core fiber manufacturing.
Multi-core optical fiber manufacturing with at least 3 times increased core number is achieved, maintaining small fiber diameter and core doping characteristics, suitable for complex optical computing and communication applications.
Smart Images
Figure CN119137515A_ABST
Abstract
Description
Technical Field and Background
[0001] The present disclosure relates to multi-core optical fibers and methods of making the same. The techniques of the present disclosure are particularly useful in optical computing devices, such as those used for artificial neural networks.
[0002] Multicore fibers (MCFs) are increasingly being used for various applications, including high-density coupling for photonic integrated circuits, space-division multiplexing (SDM) of optical communication channels, artificial neural networks, and other in-fiber computing operations / tasks.
[0003] Various neural network configurations have been developed that rely on light propagation and coupling between the cores of multi-core optical fibers. For example, the article by Eyal Cohen et al., "Neural networks within multi-core optic fibers," Scientific Reports, Vol. 6, July 7, 2016, pp. 1-14, describes the use of multi-core optical fibers for the hardware implementation of artificial neural networks, which facilitates real-time parallel processing of large-scale data sets. According to this technology, optical signals are transferred laterally between the cores of the optical fiber with the help of optical coupling.
[0004] Furthermore, patent publication WO 2021064727 assigned to the assignee of the present application teaches an artificial neural network and corresponding neuronal units based on the use of multi-core optical fibers. Overview
[0005] In recent years, the demand for various in-fiber operations has increased in the optical communications industry. To this end, complex fiber geometries are required. More specifically, multi-core fibers with high core counts and possible selective core doping are needed to enable computing operations in optical fibers.
[0006] Therefore, there is a need in the art for a novel technology that enables a multi-core optical fiber having as many cores as possible while being arranged with as small an optical fiber diameter (usually a cross-sectional dimension) as possible.
[0007] As is well known, a multi-core optical fiber comprises a plurality of cores within a common cladding.In the following description, the terms "size" or "lateral size" are sometimes used in relation to the cross-sectional dimensions of the multi-core optical fiber (ie the cladding).
[0008] The present disclosure provides a novel method for manufacturing multi-core optical fibers with complex geometry (ie, multi-core optical fibers with high core counts) that allows for complex pre-designed positioning of cores with different compositions.
[0009] The complex geometry multicore optical fibers of the present disclosure are manufactured from several optical packages, each of which includes several (relatively low count, e.g., 3-19) light-guiding elements (waveguides). Such packages can be simple low-core-count custom multicore optical fibers, or standard (commercially available) multicore optical fibers, or a bundle of polymer optical fibers or glass tubes, or a hybrid configuration formed by polymer optical fibers and glass tubes.
[0010] Complex geometry multi-core optical fibers fabricated by the disclosed techniques from several (typically at least two) such packages have significantly increased core counts (eg, at least a 3-fold increase in core count) compared to the number of light-guiding elements in the package.
[0011] More specifically, the technology of the present disclosure utilizes a relatively low core count multi-core optical fiber as an initial package of multiple light guide units, and is therefore described below with respect to the present application. However, the principles of the present disclosure are not limited to this particular example, and therefore the term "initial multi-core optical fiber" used herein should be broadly interpreted as "initial package of multiple light guide units", which covers low core count multi-core optical fibers (single mode optical fibers or multimode optical fibers), and also covers optical packages / bundles of light guide units such as polymer optical fibers and / or glass tubes.
[0012] As described above, various applications require the use of doped cores and, moreover, the use of multi-core fibers in which only some of the cores are doped (e.g., a specific pattern of doped cores and passive cores is to be used). In fibers in which the cores are closely arranged, the doping process of the selected cores (i.e., individually addressing each core or selected cores) will be more complicated. The disclosed multi-core fiber manufacturing method is also particularly useful / advantageous for manufacturing such fibers in which at least some of the cores will be appropriately doped and may also have different doping levels (i.e., when a desired pattern of doped cores is to be used), because the controlled doping of the cores is only performed in the initial stage (i.e., applied to an initial low core count multi-core fiber) and is maintained during the process of manufacturing the resulting high core count multi-core fiber.
[0013] According to a broad aspect of the present disclosure, there is provided a method of manufacturing a multi-core optical fiber having a complex geometry, the method comprising: (i) providing a number N of initial optical packages, each optical package having an initial cross-sectional dimension a and comprising a number M of light guide units; (ii) bundling the plurality of optical packages, numbered N, into a bundle structure; and (iii) applying a heating-based treatment to the bundle structure to obtain a new multi-core optical fiber having a cross-sectional dimension c and comprising N×M cores, c being equal to or smaller than the initial cross-sectional dimension a.
[0014] In some embodiments, the initial optical package is a bundle of polymer optical fibers and / or glass tubes, which includes an array of M polymer optical fibers and / or glass tubes (which constitute light-guiding units). In some other embodiments, the initial optical package is an initial multi-core optical fiber including an array of M cores (which constitute light-guiding units). This initial multi-core optical fiber can be a single-mode optical fiber or a multi-mode optical fiber. The bundle structure of N multi-core bundles can include single-mode multi-core optical fibers, multi-mode multi-core optical fibers, or a mixture of single-mode optical fibers and multi-mode optical fibers.
[0015] In some embodiments, the method further comprises performing at least one repetition of the consecutive execution of the processes of (ii) bundling and (iii) heating-based treatment on a new number K of multiple new multi-core optical fibers, thereby obtaining a subsequent new multi-core optical fiber comprising N×M×K cores.
[0016] In some embodiments, the plurality N of initial multi-core optical fibers includes one or more multi-core optical fibers having doped cores (eg, a pattern of passive cores and doped cores).
[0017] It should also be noted that multicore fibers can be fused into the multimode region by more aggressive tapering, where the interaction occurs similar to that of a photonic lantern, i.e., several single-mode cores are adiabatically fused into one multimode core, thereby providing a low-loss interface between single-mode and multimode systems. More specifically, this enables a low-loss transformation of a multimode system into a discrete number of single-mode systems, and vice versa.
[0018] In another broad aspect, the present disclosure provides a multi-core optical fiber manufactured by the above method. Such a multi-core optical fiber may include at least 15 cores and a cladding size of at least 50 microns. In some embodiments, the multi-core optical fiber (manufactured by the above method) contains at least 30 or at least 40 cores.
[0019] The multi-core optical fiber of the present disclosure proposes an optical unit that can be used in various applications, ie as a part / functional block of an optical device or an electro-optical device, such as an artificial neuron unit. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] For a better understanding of the subject matter disclosed herein and in order to illustrate how it may be implemented in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which: Figure 1 Schematically illustrates a method for manufacturing a multi-core optical fiber having a complex geometry according to the technology of the present disclosure; and Figure 2A and Figure 2BTwo examples of the disclosed technique for manufacturing a multi-core optical fiber having a complex geometry, the multi-core optical fiber being formed of a passive core ( Figure 2A ) and formed by a pattern including a passive core and a doped core ( Figure 2B ). DETAILED DESCRIPTION
[0021] refer to Figure 1 , a flow chart 10 of a method of the present disclosure for manufacturing a multi-core optical fiber having a complex geometry is shown. The method achieves at least a 3-fold increase in the number of cores in the multi-core optical fiber compared to the number of light-guiding units (e.g., cores) in an initial optical package of light-guiding units (e.g., an initial multi-core optical fiber). The cladding size (diameter) of the manufactured relatively high core-count optical fiber can be equal to or less than the cladding size (diameter) of a given initial optical package of light-guiding units (e.g., an initial multi-core optical fiber).
[0022] As shown, the method starts with providing a number N (N ≥ 2) of multiple optical packages (e.g., low core count multi-core optical fibers) (step 12). These can be commercially available or custom multi-core optical fibers, each having a relatively low number of cores (e.g., 3-19 cores).
[0023] Thus, typically, each such initial optical package (eg, a multi-core optical fiber) has a number M (M ≥ 3) of multiple light-guiding units (cores) within a common cladding of cross-sectional size / diameter a.
[0024] In some embodiments, all M cores in the multi-core optical fiber are so-called "passive cores", and in some other embodiments, at least some (one or more) of the M cores in one or more of the N multi-core optical fibers are doped, i.e., P cores are doped (P≤M) - optional step 14. If the multi-core optical fiber includes passive cores and doped cores, they are arranged in a certain pattern. In general, the N multi-core optical fibers can have similar or different numbers / patterns of passive cores and doped cores.
[0025] Then, the N multi-core optical fibers are bundled (step 16) into a bundle with a transverse dimension of b, where b>>a. The bundling of the N multi-core optical fibers can be performed by any known suitable technique, for example, using a capillary or a holder (e.g., a ring holder) or any other technique for firmly holding a plurality of multi-core optical fibers together.
[0026] The multi-core optical fiber bundle of size b thus obtained then undergoes a processing technique (step 18) aimed at compressing the bundle into a multi-core optical fiber of size c, which is significantly smaller than size b and may be closer to the original size a of the initial multi-core optical fiber. Such processing may include heating the bundle and / or tapering the bundle. Such processing produces a new multi-core optical fiber (MCF) having a smaller size c (compared to the size b of the bundle), which comprises N×M cores (step 20).
[0027] It should be noted that the above process may include arc heating for tapering the optical fiber. The controlled process parameters include arc power and pull rate (e.g., about 0.05 mm / sec). Another suitable method is a burner method, in which the optical fiber bundle is heated to about 1600°C-1800°C.
[0028] In case the initial multi-core optical fiber has a pattern formed by passive cores and doped cores, the resulting multi-core optical fiber comprises a multiplication of said pattern.
[0029] When necessary, the above process (steps 12-18) can be repeated by applying these steps to several optical fibers of size c having N×M cores (which constitute a new initial package). More specifically, a plurality of such multi-core optical fibers of size c are bundled and then processed (heated and stretched) again. With regard to the size (cladding diameter) of the final new multi-core optical fiber, it should be understood that each stage involves a tapering of a ratio of about 3-10, resulting in a relatively small size of the final high-core-count multi-core optical fiber.
[0030] It should be understood that the principles of the disclosed technology are not limited to the number of optical fibers (packages) bundled, nor to the number of cores (light-guiding units) in each optical fiber. Furthermore, the disclosed technology is not limited to the number of repetitions of the bundling and processing stages. Typically, the number of repetitions depends on the size of the initial multi-core optical fiber used.
[0031] The overall process parameters are selected to provide a desired final core size (diameter), for example, about 3 microns to 10 microns, and to provide a desired final cladding size (diameter), for example, at least 50 microns.
[0032] Considering commercially available multi-core optical fibers, typical dimensions may be as follows: for a multi-core optical fiber with a passive core: the core diameter is 10 microns, the core spacing is 50 microns, and the cladding diameter is 125 microns; for a multi-core optical fiber with a doped core (Er / Yb doped): the core diameter is 6 microns, the core spacing is 35 microns, and the cladding diameter is 187.5 microns.
[0033] As mentioned above, another option is to start the process with an initial package / bundle of glass tubes (light guide units) held together by capillaries or specially constructed holders.
[0034] refer to Figure 2A and Figure 2B , schematically illustrating a specific but non-limiting example of the above-mentioned technology of the present disclosure.
[0035] Figure 2A A method 100 for manufacturing a multi-core optical fiber having a complex geometry is illustrated. Figure 2A As shown in , a number N (N=7) of multiple initial multi-core optical fibers MCF (package of light-guiding units) - each having M (M=7) cores and having a transverse dimension (cladding diameter) a - are bundled (step 101) (with or without a capillary) into a fiber bundle structure FBS with a transverse dimension b (b>>a). The bundled MCF structure FBS is then processed (e.g., heated and / or tapered) to compress the structure FBS, thereby producing another (new) multi-core optical fiber MCF' (step 102), which has a transverse dimension c that is significantly smaller than the size b and has 7×7 (N×M) cores.
[0036] As shown in this non-limiting example, the above process is repeated: a new number K of multiple multi-core optical fibers MCF' (K may be equal to or different from N, 7 such new multi-core optical fibers MCF' in this embodiment) are bundled into a new bundle structure FBS' (step 103), and then processed / compressed, for example, via heating and tapering (step 104), to produce a new multi-core optical fiber MCF'' of size d with (N×M×K) cores.
[0037] Figure 2B The example of FIG. 2 schematically illustrates a method 200 for manufacturing a multi-core optical fiber having a complex geometry, the multi-core optical fiber having a pattern of doped cores. The method 200 is generally similar to Figure 2A However, in Figure 2BIn the example of , the method starts with providing a number N (e.g., N=7) of multiple initial multi-core optical fibers MCF, which use heterogeneous composition cores, i.e., the multi-core optical fibers include a pattern of passive cores PC (e.g., silica cores) and doped cores DC (e.g., Er / Yb doping). The initial multi-core optical fibers MCF (each of size a) are bundled (step 101) into a fiber bundle structure FBS of size b (b>>a); the structure FBS is processed (e.g., heated and / or tapered) to produce a new multi-core optical fiber MCF' (step 102), which has a smaller size c and an increased number of 7×7 (N×M) cores. Optionally, a new number K of multiple multi-core optical fibers MCF' are bundled into a new bundle structure FBS' (step 103) and processed (step 104) to produce a new multi-core optical fiber MCF'', which has a size d and (N×M×K) cores. The disclosed technique enables controlled doping of selected cores only at an initial stage and maintaining the doping during the process of manufacturing the resulting multi-core optical fiber MCF' (or MCF'').
Claims
1. A method for manufacturing a multi-core optical fiber having a complex geometry, the method comprising: providing a plurality of initial optical packages, N in number, each optical package having an initial cross-sectional dimension a and comprising a predetermined number M of light guide units; Bundling the plurality of optical packages, which is N in number, into a bundle structure; A heating-based treatment is applied to the bundle structure to obtain a new multi-core optical fiber having a cross-sectional dimension c, which is equal to or smaller than the initial cross-sectional dimension a, and comprising N×M cores.
2. The method according to claim 1, wherein: The initial optical package is a bundle comprising a predetermined number M of glass tubes.
3. The method according to claim 1, wherein: The initial optical package is a bundle comprising a predetermined number M of polymer optical fibers.
4. The method according to claim 1, wherein: The initial optical package is a bundle comprising a predetermined number M of polymer optical fibers and glass tubes.
5. The method according to claim 1, wherein: The initial optical package is an initial multi-core optical fiber comprising a predetermined number M of cores.
6. The method according to claim 5, wherein: The multi-core optical fiber is a single-mode multi-core optical fiber or a multi-mode multi-core optical fiber.
7. The method according to claim 1, further comprising: At least one repetition of the continuous execution of the bundling and the heating-based treatment of a new number K of the new multi-core optical fibers is performed, thereby obtaining a subsequent new multi-core optical fiber including N×M×K cores.
8. The method according to claim 1, wherein: The initial optical package has one of the following configurations: a glass tube bundle including a predetermined number M of glass tubes; a polymer optical fiber bundle including a predetermined number M of polymer optical fibers; a bundle of a predetermined number M of polymer optical fibers and glass tubes; and is an initial multi-core optical fiber including a predetermined number M of cores.
9. The method according to claim 8, further comprising: At least one repetition of the continuous execution of the bundling and the heating-based treatment of a new number K of the new multi-core optical fibers is performed, thereby obtaining a subsequent new multi-core optical fiber including N×M×K cores.
10. The method according to claim 5, wherein: The plurality of initial multi-core optical fibers, numbered N, includes one or more multi-core optical fibers including a doped core.
11. The method according to claim 5, wherein: The plurality of initial multi-core optical fibers, numbered N, includes one or more multi-core optical fibers, the one or more multi-core optical fibers comprising a pattern of passive cores and doped cores.
12. The method according to claim 5, wherein: The multi-core optical fiber is fused into a multi-mode region.
13. A multi-core optical fiber manufactured by the method according to claim 1.
14. A multi-core optical fiber manufactured by the method according to claim 9.
15. A multi-core optical fiber comprising at least 15 cores within a common cladding having a cross-sectional dimension of at least 50 microns.
16. The multi-core optical fiber according to claim 15, wherein: The core comprises a doped core. The multi-core optical fiber according to claim 15 , wherein the core comprises a passive core and a doped core.
18. An optical device comprising at least one multi-core optical fiber configured according to claim 15.