Flexible optical fiber ribbon and optical cable

Abstract

A flexible optical fiber ribbon and an optical cable. The flexible optical fiber ribbon comprises several core ribbon groups (1), wherein the core ribbon groups (1) are configured in parallel, and eac

Description

Field of the Invention The present application relates to the technical field of optical fiber communication, in particular to a flexible optical fiber ribbon and an optical cable. Background of the Invention In recent years, with the vigorous advancement of the construction of "all-optical network", the construction of traditional underground access network is facing new challenges. On the basis of making full use of the original underground facilities, the demand for ultra-large-core and high-core-density optical cables is increasing. How to increase the core number of optical cables while maintaining the original outer diameter of optical cables has become the direction of exploration in the industry. The existing flat optical fiber ribbon has been paid special attention to because of its high density, high integration, light weight, and convenience for multi-fiber splicing, and is widely used in ultra-large core-number optical cables. However, limited by the size of the existing flat optical fiber ribbon cables, the size of the optical cables with the same number of cores is also relatively large, which has been unable to make more reasonable and effective use of existing pipelines and space. The flexible optical fiber ribbon is a new type of close-packed optical fiber ribbon. Compared with the traditional flat optical fiber ribbon, the new optical fiber cable with the flexible optical fiber ribbon can greatly increase the density of the optical fiber. In the existing situation of maintaining the same outer diameter of the optical cable, the optical cable with the flexible optical fiber ribbon can effectively solve the key problem of the expansion of optical fiber cores in the traditional optical fiber access network. The flexible optical fiber ribbon can be flexibly wound and arranged and quickly separated because of the non-continuous fixed state between each optical fiber, and more optical fiber cores can be received within the same outer diameter of the optical cable. However, there are still many deficiencies in the current mainstream flexible optical fiber ribbons. For example, when the optical fiber ribbon is bent along the width 13 06 25 direction, the resin used to connect the optical fiber to form the optical fiber ribbon is easily damaged, which results in the optical fiber ribbon having disadvantages such as poor flatness. Therefore, there is an urgent need to develop a new structure to meet the technical requirements. 5 Summary of the Invention The embodiment of the present application provides a flexible optical fiber ribbon and an optical cable so as to solve the problem in the related art of the poor flatness of an optical fiber ribbon caused by resin used to connect optical fibers to form the optical 10 fiber ribbon being prone to being damaged when the optical fiber ribbon is bent in a width direction. In a first aspect, a flexible optical fiber ribbon is provided, which comprises a plurality of core ribbon groups, wherein the core ribbon groups are configured in parallel, and each core ribbon group comprises three optical fiber units; 15 the three optical fiber units of each core ribbon group are configured in parallel, the optical fiber units located on two sides each comprise one optical fiber, and the optical fiber unit located in the middle comprises at least one optical fiber, which is configured to be in parallel and connected; two adjacent core ribbon groups and two adjacent optical fiber units in each core 20 ribbon group are respectively connected by means of a plurality of first connecting portions, which are arranged at intervals in a length direction of the optical fibers; and taking a plane passing through an axes of two adjacent optical fibers as a reference plane, each of the first connecting portions comprises two connecting units respectively located above and below the reference plane; and 25 a non-enclosed buffer cavity is formed between two adjacent optical fibers and between the two connecting units above and below the reference plane. In some embodiments, one ends of the two connecting units of the first connecting portion are connected to each other to form a closed end of the buffer cavity, and the other ends of the two connecting units of the first connecting portion are spaced apart 30 from each other to form an open end of the buffer cavity; or the middle portions of the two connecting units of the first connecting portion are connected to each other to form a closed end of the buffer cavity, and the ends of the two connecting units of the first connecting portion located on the same side of the closed end are spaced apart from each other to form an open end of the buffer cavity. In some embodiments, in the first connecting portion between every two adjacent core ribbon groups, or in the first connecting portion between every two adjacent optical fiber units in the core ribbon group, a distance Li between two adjacent first connecting portions is greater than a length L2 of the first connecting portion in the length direction of the optical fiber. In some embodiments, a distance Li between every two adjacent first connecting portions and a length L2 of the first connecting portion in the length direction of the optical fiber satisfy Li:L2>2:1. In some embodiments, along a width direction of the flexible optical fiber ribbon, every two adjacent first connecting portions are arranged in a staggered manner in the length direction of the optical fiber. In some embodiments, along the width direction of the flexible optical fiber ribbon, a distance L3 between every two adjacent first connecting portions in the length direction of the optical fiber is larger than or equal to 0. In some embodiments, when the optical fiber unit located in the middle comprises a plurality of optical fibers, the optical fibers are arranged in parallel, and every two adjacent optical fibers are connected by means of a second connecting portion, and along the length direction of the optical fiber, the second connecting portion extends from one end of the optical fiber to the other end. In some embodiments, the first connecting portion is made of photocurable resin. In some embodiments, a linear expansion coefficient of the photocurable resin at normal temperature is less than 8xlO'4 / °C, and an elongation at break is greater than 60%. In a second aspect, an optical cable is provided, which comprises: an outer sheath; and a plurality of flexible optical fiber ribbons as described in any one of the above, wherein the flexible optical fiber ribbons are received in the outer sheath. The beneficial effects of the technical solution provided in the present application are as follows: The embodiment of the present application provides a flexible optical fiber ribbon and an optical cable, which are connected by means of the first connecting portion. At the same time, the first connecting portion comprises two connecting units, so that the coating points on the optical fiber are in a state of double-sided coating, so that the optical fiber ribbon can be freely wound in both directions of the upper and lower surfaces, which effectively solves the uneven stress distribution of the surface coating in the bonding area of the two optical fibers caused by the single-sided coating of the resin, and can reduce the risk of potential stress concentration of the optical fiber ribbon, reduce the microbending attenuation, and improve the performance of communication transmission. Due to the double-sided coating structure, the traction force of the connecting units in the two directions of the upper and lower surfaces of the flexible optical fiber ribbon is consistent, which can ensure that the flatness of the cross section of the optical fiber ribbon after unfolding is good, and it is convenient for subsequent batch fusion splicing. Due to the double-sided coating structure, it can also ensure that after the connecting unit on one side is broken under tension, the optical fiber ribbon can still be in a connected state and not easy to scatter, so as to facilitate the recovery of a straight state for batch termination. Through the buffer cavity, the flexibility and cushioning performance of the first connecting portion can be improved, thereby preventing the first connecting portion from being damaged unintentionally, and avoiding poor flatness of the optical fiber ribbon due to the damage of the first connecting portion. The present application adopts a non-enclosed buffer cavity, so that the buffer cavity communicates with the outside atmosphere, and when the optical fiber ribbon is bent along the width direction, the air in the buffer cavity is squeezed out, which ensures the flexibility and cushioning of the first connecting portion, prevents the first connecting portion from being damaged, and makes the optical fiber ribbon have better flatness after recovery. In addition, the volume of the first connecting portion is compressed, which is beneficial to increase the packing density of the optical fiber. Moreover, the buffer cavity is deformed during the process of compression, which can effectively absorb the radial pressure, thereby reducing the risk of potential stress concentration of the optical fiber ribbon and reducing microbending attenuation, and improving communication transmission performance. Brief Description of the Drawings In order to better illustrate the technical solution in the embodiments of the present application, the following will briefly introduce the drawings needed in the description of the embodiments, and it is obvious that the drawings in the following description are part of embodiments of the present application, for those of ordinary skill in the art, other drawings may also be obtained based on these drawings without any inventive effort. Fig. 1 is a structural diagram of a flexible optical fiber ribbon in the embodiment of the present application; Fig. 2 is A-A direction view in Fig. 1; Fig. 3 is a schematic diagram of a buffer cavity formed by an optical fiber and a first connecting portion in the embodiment of the present application (single open end); Fig. 4 is a schematic diagram of a buffer cavity formed by an optical fiber and a first connecting portion in the embodiment of the present application (double open end); Fig. 5 is a schematic diagram of a direction of force transmission of an optical fiber ribbon in bending in the embodiment of the present application. In the figures: A-reference plane; 1-core ribbon group; 2-optical fiber unit; 3-optical fiber; 4-the first connecting portion; 40-connecting unit; 5-buffer cavity; 50-closed end; 51-open end; 6-the second connecting portion. Detailed Description of the Embodiments In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without inventive efforts shall fall within the protection scope of the present application. The embodiment of the present application provides a flexible optical fiber ribbon and an optical cable, which can solve the problem in the related art of the poor flatness of an optical fiber ribbon caused by resin used to connect optical fibers to form the optical fiber ribbon being prone to being damaged when the optical fiber ribbon is bent in a width direction. As shown in Fig. 1 and Fig. 2, the embodiment of the present application provides a flexible optical fiber ribbon, the flexible optical fiber ribbon comprises a plurality of core ribbon groups 1, the core ribbon groups 1 are configured in parallel, and each core ribbon group 1 comprises three optical fiber units 2. The three optical fiber units 2 of each core ribbon group 1 are configured in parallel, the optical fiber units 2 located on two sides each comprise one optical fiber 3, and the optical fiber unit 2 located in the middle comprises at least one optical fiber 3, which is configured to be in parallel and connected. Two adjacent core ribbon groups 1 are connected by a plurality of first connecting portions 4, which are arranged at intervals in a length direction of the optical fibers 3, and two adjacent optical fiber units 2 in each core ribbon group 1 are also connected by means of a plurality of first connecting portions 4, which are arranged at intervals in the length direction of the optical fibers 3. Taking a plane passing through an axes of two adjacent optical fibers 3 as a reference plane A, each of the first connecting portions 4 comprises two connecting units 40 respectively located above and below the reference plane A and are connected by means of the first connecting portion 4. At the same time, the first connecting portion 4 comprises two connecting units 40, so that the coating points on the optical fiber 3 are in a state of double-sided coating, so that the optical fiber ribbon can be freely wound in both directions of the upper and lower surfaces, which effectively solves the uneven stress distribution of the surface coating in the bonding area of the two optical fibers 3 caused by the single-sided coating of the resin, and can reduce the risk of potential stress concentration of the optical fiber ribbon, reduce the microbending attenuation, and improve the performance of communication transmission. Due to the double-sided coating structure, the traction force of the connecting units 40 in the two directions of the upper and lower surfaces of the flexible optical fiber ribbon is consistent, which can ensure that the flatness of the cross section of the optical fiber ribbon after unfolding is good, and is convenient for subsequent batch fusion splicing. Due to the double-sided coating structure, after the connecting unit 40 on one side is broken under tension, the optical fiber ribbon can still be guaranteed to be in a connected state and not easy to scatter, so as to facilitate the recovery of a straight state for batch termination. As shown in Fig. 2, a buffer cavity 5 is formed between two adjacent optical fibers 3 and between the two connecting units 40 above and below the reference plane A, and through the buffer cavity 5, the flexibility (bendability) and cushioning (relaxation) of the first connecting portion 4 can be improved, thereby preventing the first connecting portion 4 from being damaged unintentionally, and avoiding poor flatness of the optical fiber ribbon due to the damage of the first connecting portion. After long-term and extensive research, the applicant found that when manufacturing the first connecting portion 4, if some closed air bubbles are generated in the first connecting portion 4 to form the buffer cavity 5, the flexibility and cushioning of the first connecting portion 4 can be improved to a certain extent, but new problems will be brought: on the one hand, there is still gas in the air bubbles, and when the optical fiber ribbon is bent along the width direction, the air bubbles will be compressed, and the greater the degree of bending, the greater the pressure of the gas in the air bubbles, and the greater the force required, which is not conducive to the bending operation; and on the other hand, this pressure resists bending in the radial direction, creating a risk of potential stress concentration for the optical fiber ribbon. Therefore, in order to solve the above-mentioned defects, the present application adopts a non-enclosed buffer cavity, so that the buffer cavity communicates with the outside atmosphere, and when the optical fiber ribbon is bent along the width direction, the air in the buffer cavity is squeezed out, which ensures the flexibility and cushioning of the first connecting portion, prevents the first connecting portion 4 from being damaged, and makes the optical fiber ribbon have better flatness after recovery. In addition, the volume of the first connecting portion 4 is compressed, which is beneficial to increase the packing density of the optical fiber, moreover, the buffer cavity 5 is deformed during the process of compression, which can effectively absorb the radial pressure, thereby reducing the risk of potential stress concentration of the optical fiber ribbon and reducing microbending attenuation, and improving communication transmission performance. When the optical fiber ribbon returns to a straight state, the buffer cavity 5 is filled with air. The buffer cavity 5 is recovered to form an effective support, thereby further ensuring the flatness of the optical fiber after the flexible optical fiber ribbon returns to the straight state, so as to facilitate batch fusion splicing. The non-closed buffer cavity has various forms, such as a single open end form and a double open end form. As shown in Fig. 3, in a preferred embodiment, the single open end form is adopted, specifically: one ends of the two connecting units 40 of the first connecting portion 4 are connected to each other to form a closed end 50 of the buffer cavity 5, and the other ends of the two connecting units 40 of the first connecting portion 4 are spaced apart from each other to form an open end 51 of the buffer cavity 5. As shown in Fig. 3, in a preferred embodiment, the double open end form is adopted, specifically: the middle portions of the two connecting units 40 of the first connecting portion 4 are connected to each other to form a closed end 50 of the buffer cavity 5, and the ends of the two connecting units 40 of the first connecting portion 4 located on the same side of the closed end 50 are spaced apart from each other to form an open end 51 of the buffer cavity 5. In some preferred embodiments, as shown in Fig. 1, in the first connecting portion 4 between every two adjacent core ribbon groups 1, or in the first connecting portion 4 between every two adjacent optical fiber units 2 in the core ribbon group 1, a distance Li between two adjacent first connecting portions 4 is greater than a length L2 of the first connecting portion 4 in the length direction of the optical fiber 3. The purpose of the distance Li of the first connecting portion 4 being greater than the length L2 of the first connecting portion 4 is twofold: 1) On the premise of using high-modulus curable resin to ensure the strength of connection, increasing the overall proportion of the non-connecting portion is conducive to realizing high flexibility of the optical fiber ribbon and facilitating winding. Generally, under the premise of ensuring the strength, the smaller the L2, the better, and L2 can be as close to 0 as possible. 2) The amount of resin used can also be reduced to reduce costs. In some preferred embodiments, the distance Li between every two adjacent first connecting portions 4 and the length L2 of the first connecting portion 4 in the length direction of the optical fiber 3 meet Li:L2>2:1. In some preferred embodiments, as shown in Fig. 1, along the width direction of the flexible optical fiber ribbon, every two adjacent first connecting portions 4 are arranged in a staggered manner in the length direction of the optical fiber 3, mainly to increase the overall proportion of non-connecting portions on the same optical fiber ribbon section, so as to improve the overall windability of the optical fiber ribbon. In some preferred embodiments, as shown in Fig. 1, along the width direction of the flexible optical fiber ribbon, a distance L3 between every two adjacent first connecting portions 4 in the length direction of the optical fiber 3 is greater than or equal to 0, preferably, L3=(Li-L2) / 2. In some preferred embodiments, as shown in Fig. 1 and Fig. 2, when the optical fiber unit 2 located in the middle comprises a plurality of optical fibers 3, the optical fibers 3 are arranged in parallel, and every two adjacent optical fibers 3 are connected by means of a second connecting portion 6, and along the length direction of the optical fiber 3, the second connecting portion 6 extends from one end of the optical fiber 3 to the other end. The plurality of the optical fibers 3 comprised in the optical fiber unit 2 in the middle are in a fully connected structure, and combined with the interval connection of the first connecting portion 4, the optical fiber ribbon is in a partially connected + fully connected structure, which can better ensure the flatness of the optical fiber after the flexible optical fiber ribbon returns to a straight state. When the flexible optical fiber ribbon is bent, compared with the fully connected structure, the partially connected part (namely the first connecting portion 4) can use the buffer cavity 5 and the closed end 50 to migrate the radial pressure generated by the bending of the bundle to the axial direction to play a role of force component, thereby effectively reducing the risk of stress concentration that may be caused by winding and reducing the microbending attenuation, as shown in Fig. 5, in the figure, the direction of the arrow is the direction of force transmission. In some preferred embodiments, the first connecting portion 4 is made of photocurable resin. In some preferred embodiments, a linear expansion coefficient of the photocurable resin at normal temperature is less than 8><10'4 / oC, and an elongation at break is greater than 60%. The embodiment of the present application further provides an optical cable, the optical cable comprises an outer sheath; and a plurality of flexible optical fiber ribbons provided in the above-mentioned embodiments, the flexible optical fiber ribbons are received in the outer sheath. In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", etc. are based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, instead of indicating or implying that the pointed device or element must have a specific orientation, be configured and operated in a specific orientation, therefore it cannot be understood as a limitation of the present application. Unless otherwise clearly specified and limited, the terms "installation", "connected" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; further can be a mechanical connection, or an electrical connection; further can be directly connected, or indirectly connected through an intermediate medium, or can be the internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above-mentioned terms in the present application can be understood according to specific circumstances. It should be noted that relational terms such as "first" and "second" are only for distinguishing one entity or operation from another entity or operation in the present application, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only comprises those elements, but also comprises those that are not explicitly listed, or further comprises 5 elements inherent to the process, method, article, or device. If there are no more restrictions, the elements defined by the sentence "comprising a..." does not exclude the existence of other same elements in the process, method, article, or device comprising the elements. The above-mentioned are only the embodiments of the present application, so that those 10 skilled in the art can understand or implement the present application. For those skilled in the art, various modifications to these embodiments will be obvious, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in this document, but will be subject to 15 the widest scope consistent with the principles and novel features applied herein. 13 06 25

Claims

1. A flexible optical fiber ribbon, wherein the flexible optical fiber ribbon comprises a plurality of core ribbon groups (1), wherein the core ribbon groups (1) are configured in parallel, and each core ribbon group (1) comprises three optical fiber units (2);the three optical fiber units (2) of each core ribbon group (1) are configured in parallel, the optical fiber units (2) located on two sides each comprise one optical fiber (3), and the optical fiber unit (2) located in the middle comprises at least one optical fiber (3), which is configured to be in parallel and connected;two adjacent core ribbon groups (1) and two adjacent optical fiber units (2) in each core ribbon group (1) are respectively connected by means of a plurality of first connecting portions (4), which are arranged at intervals in a length direction of the optical fibers (3);taking a plane passing through an axes of two adjacent optical fibers (3) as a reference plane (A), each of the first connecting portions (4) comprises two connecting units (40) respectively located above and below the reference plane (A); anda non-enclosed buffer cavity (5) is formed between two adjacent optical fibers (3) and between the two connecting units (40) above and below the reference plane (A).

2. The flexible optical fiber ribbon according to claim 1, whereinone ends of the two connecting units (40) of the first connecting portion (4) are connected to each other to form a closed end (50) of the buffer cavity (5), and the other ends of the two connecting units (40) of the first connecting portion (4) are spaced apart from each other to form an open end (51) of the buffer cavity (5); orthe middle portions of the two connecting units (40) of the first connecting portion (4) are connected to each other to form a closed end (50) of the buffer cavity (5), and the ends of the two connecting units (40) of the first connecting portion (4) located on the same side of the closed end (50) are spaced apart from each other to form an open end (51) of the buffer cavity (5).

3. The flexible optical fiber ribbon according to claim 1, wherein13 06 25in the first connecting portion (4) between every two adjacent core ribbon groups (1), or in the first connecting portion (4) between every two adjacent optical fiber units (2) in the core ribbon group (1), a distance Li between two adjacent first connecting portions (4) is greater than a length Lj of the first connecting portion (4) in the length direction of the optical fiber (3).

4. The flexible optical fiber ribbon according to claim 1, whereina distance Li between every two adjacent first connecting portions (4) and a length L2 of the first connecting portion (4) in the length direction of the optical fiber (3) meet Li:L2>2: 1.

5. The flexible optical fiber ribbon according to claim 1, whereinalong a width direction of the flexible optical fiber ribbon, every two adjacent first connecting portions (4) are arranged in a staggered manner in the length direction of the optical fiber.

6. The flexible optical fiber ribbon according to claim 5, whereinalong the width direction of the flexible optical fiber ribbon, a distance L3 between every two adjacent first connecting portions (4) in the length direction of the optical fiber (3) is larger than or equal to 0.

7. The flexible optical fiber ribbon according to claim 1, whereinwhen the optical fiber unit (2) located in the middle comprises a plurality of optical fibers (3), the optical fibers (3) are arranged in parallel, and every two adjacent optical fibers (3) are connected by means of a second connecting portion (6), and along the length direction of the optical fiber (3), the second connecting portion (6) extends from one end of the optical fiber (3) to the other end.

8. The flexible optical fiber ribbon according to claim 1, wherein the first connecting portion (4) is made of photocurable resin.

9. The flexible optical fiber ribbon according to claim 8, wherein a linear expansion coefficient of the photocurable resin at normal temperature is less than 8xlO'4 / °C, and an elongation at break is greater than 60%.

10. An optical cable, wherein the optical cable comprises:an outer sheath; anda plurality of flexible optical fiber ribbons according to any one of claims 1 to 9, wherein the flexible optical fiber ribbons are received in the outer sheath.LDCM

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