阅读说明：本技术 一种带有隔离膜的多芯光纤结构 (Multi-core optical fiber structure with isolating film ) 是由 郑晶晶 裴丽 解宇恒 宁提纲 阮祖亮 李晶 于 2019-10-14 设计创作，主要内容包括：本发明提供了一种带有隔离膜的多芯光纤结构,属于特种光纤技术领域。包括共同包层,及均匀包裹在共同包层内的至少一根纤芯,相邻的两根纤芯通过在其中一根所述纤芯或两根所述纤芯外侧包覆隔离膜相互隔离,所述隔离膜与所述纤芯之间有保留包层。本发明将金属膜包覆在纤芯的周围,对金属膜外的纤芯模式有良好的隔离作用,同时膜内保留包层厚度较薄,各纤芯之间能够在保持低串扰特性的同时,距离更加相互靠近,满足多芯光纤高纤芯密度、低芯间串扰的要求；对各纤芯的具体参数没有要求,可以在同种纤芯的情况下提供高密度低串扰特性,不会增加器件和系统的复杂程度。(The invention provides a multi-core optical fiber structure with an isolation film, and belongs to the technical field of special optical fibers. The fiber core structure comprises a common cladding and at least one fiber core uniformly wrapped in the common cladding, wherein two adjacent fiber cores are mutually isolated by wrapping an isolating film on one of the fiber cores or the outer sides of the two fiber cores, and a reserved cladding is reserved between the isolating film and the fiber cores. The metal film is coated around the fiber core, so that the fiber core mode outside the metal film is well isolated, the thickness of the coating layer reserved in the film is thinner, the fiber cores can be closer to each other while the low crosstalk characteristic is kept, and the requirements of high fiber core density and low inter-core crosstalk of the multi-core optical fiber are met; the specific parameters of each fiber core are not required, the high-density low-crosstalk characteristic can be provided under the condition of the same fiber core, and the complexity of devices and systems is not increased.)

1. The utility model provides a multicore fiber structure with barrier film, includes common cladding (1), and at least one fibre core (2) of even parcel in common cladding (1), its characterized in that:

two adjacent fiber cores (2) are mutually isolated by coating an isolating film (3) on the outer side of one fiber core (2) or two fiber cores (2), and a reserved cladding (4) is reserved between the isolating film (3) and the fiber cores (2).

2. The multicore optical fiber structure with an isolation film of claim 1, wherein: the isolation film is made of a metal material.

3. The multicore optical fiber structure with an isolation film of claim 2, wherein: the isolation film is made of gold.

4. The multicore optical fiber structure with an isolation film of claim 3, wherein: the thickness of the remaining cladding is less than the radius of the core.

5. The multicore optical fiber structure with an isolation film of claim 4, wherein: the thickness of the isolation film is less than the thickness of the remaining cladding.

6. The multicore optical fiber structure with an isolation film of claim 5, wherein: the remaining cladding layer is made of the same material as the common cladding layer.

7. The multicore optical fiber structure with an isolation film of claim 6, wherein: the refractive index of the core is higher than that of the common cladding, and the difference between the refractive index of the core and that of the common cladding is 0.005.

8. The multicore optical fiber structure with an isolation film of claim 7, wherein: the diameter of the core was 8 μm.

9. The multicore optical fiber structure with an isolation film of claim 8, wherein: the remaining cladding layer had a thickness of 0.99 μm.

10. The multicore optical fiber structure with an isolation film of claim 8, wherein: the thickness of the isolation film was 0.01 μm.

Technical Field

The invention relates to the technical field of special optical fibers, in particular to a multi-core optical fiber structure with an isolation film, which realizes high-density low-crosstalk performance.

Background

The multi-core optical fiber is the basis of large-capacity optical fiber communication and optical fiber sensing. The multi-core optical fiber contains more than one fiber core in the same optical fiber, obviously improves the multiplexing density of a single optical fiber, and is an important development direction of special optical fibers. The cross talk between cores is a key index of the multi-core optical fiber, and the index shows the degree of mutual influence among the cores of the multi-core optical fiber. For the application of independent transmission of each fiber core, the crosstalk between the fiber cores can improve the signal error rate and reduce the transmission quality and the transmission distance of signals, so that special structural design is required to be carried out on the multi-core optical fiber to control and reduce the crosstalk between the cores.

Currently, there are three main types of common methods for controlling crosstalk between cores: increase the core distance, groove assistance, core differentiation. When the fiber cores are gradually close to each other, the mode field supported by one fiber core is overlapped with the areas where other fiber cores are located, and further the mode fields transmitted in other fiber cores are influenced. The closer the distance between the fiber cores and the higher the degree of mode field overlapping, the faster the power exchange between the fiber cores occurs, so that the fiber core distance is increased, and the mode field is limited by the aid of the grooves, which are effective means for controlling the crosstalk between the cores.

The crosstalk is reduced by increasing the core pitch, which is generally required to ensure that the core pitch is 4 to 5 times larger than the radius of the core, and is about 20 to 25 μm for a conventional single-mode core, and if the core is a few-mode or multimode fiber, the mode field expansion is more serious, and the core pitch is further increased. The groove is assisted by utilizing the characteristic that the refractive index of fluorine-doped quartz is slightly lower than that of pure quartz, and the optical field is better bound within the range of the groove through the transmission characteristic of light in a multi-layer medium, so that the influence on the areas where other fiber cores are positioned is reduced. The trench width of fluorine-doped silica is 2-5 μm, and a pure silica ring is usually present between the trench and the core, which increases the actual area of the core region while reducing crosstalk, and still results in a larger core pitch of about 18 μm at the same crosstalk level.

The heterogeneous cores can cause mismatch between the overlapping mode fields, inhibiting the degree to which power exchange occurs, thereby reducing the degree to which crosstalk occurs. When the core difference is sufficiently large, the power ratio of the exchange can be as low as 1% or less even if the cores are close to each other, and this is a good means for reducing the core pitch and increasing the core density while controlling crosstalk.

The distance between fiber cores can be increased to different degrees while the crosstalk of the conventional low-crosstalk multi-core fiber is reduced, and the density of the fiber cores is limited; the heterogeneous fiber core scheme can well meet the requirement of high density, but the mode fields supported by the fiber cores are different due to the dissimilarity of the fiber cores, so that the difficulty in forming a functional device and a system is increased.

Disclosure of Invention

The invention aims to provide a multi-core optical fiber structure with an isolating film, which has good isolating function on a fiber core mode outside a metal isolating film, meets the requirements of high fiber core density and low inter-core crosstalk of the multi-core optical fiber and has high density and low crosstalk, and solves at least one technical problem in the background art.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a multi-core optical fiber structure with an isolating film, which comprises a common cladding and at least one fiber core uniformly wrapped in the common cladding,

two adjacent fiber cores are mutually isolated by wrapping an isolating film at the outer side of one fiber core or two fiber cores, and a reserved cladding is reserved between the isolating film and the fiber cores.

Preferably, the isolation film is made of a metal material.

Preferably, the isolation film is made of gold.

Preferably, the thickness of the remaining cladding is less than the radius of the core.

Preferably, the thickness of the isolation film is smaller than the thickness of the remaining cladding.

Preferably, the remaining cladding is made of the same material as the common cladding.

Preferably, the refractive index of the core is higher than that of the common cladding, and the difference between the refractive index of the core and that of the common cladding is 0.005.

Preferably, the core has a diameter of 8 μm.

Preferably, the remaining cladding layer has a thickness of 0.99 μm.

Preferably, the thickness of the separation film is 0.01 μm.

The invention has the beneficial effects that: the metal isolation film is coated around the fiber core, so that a good isolation effect is achieved on the fiber core mode outside the metal film, the thickness of the coating layer reserved in the film is thin, the fiber cores can be closer to each other while the low crosstalk characteristic is kept, and the requirements of high fiber core density and low inter-core crosstalk of the multi-core optical fiber are met; the specific parameters of each fiber core are not required, the high-density low-crosstalk characteristic can be provided under the condition of the same fiber core, and the complexity of devices and systems is not increased.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic cross-sectional view of a multi-core optical fiber structure with an isolation film according to embodiment 1 of the present invention.

Fig. 2 is a schematic cross-sectional view of a multi-core optical fiber structure with an isolation film according to embodiment 2 of the present invention.

Fig. 3 is a schematic cross-sectional view of a multi-core optical fiber structure with an isolation film according to embodiment 3 of the present invention.

Wherein: 1-common cladding; 2-a fiber core; 3-an isolating membrane; 4-keep the cladding.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below by way of the drawings are illustrative only and are not to be construed as limiting the invention.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

In the description of this patent, it is to be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings for the convenience of describing the patent and for the simplicity of description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the patent.

In the description of this patent, it is noted that unless otherwise specifically stated or limited, the terms "mounted," "connected," and "disposed" are to be construed broadly and can include, for example, fixedly connected, disposed, detachably connected, disposed, or integrally connected and disposed. The specific meaning of the above terms in this patent may be understood by those of ordinary skill in the art as appropriate.

For the purpose of facilitating an understanding of the present invention, the present invention will be further explained by way of specific embodiments with reference to the accompanying drawings, which are not intended to limit the present invention.

It should be understood by those skilled in the art that the drawings are merely schematic representations of embodiments and that the elements shown in the drawings are not necessarily required to practice the invention.