Fiber optic connector and optical communication system

Abstract

The embodiments of the present application relate to the technical field of optical transmission. Provided are a fiber optic connector and an optical communication system, aiming at improving the connection performance between a hollow-core optical fiber and a solid-core optical fiber. The fiber optic connector comprises a first optical fiber, a second optical fiber and a connecting portion. The first optical fiber is a hollow-core optical fiber, and the second optical fiber is a solid-core optical fiber. A fiber optic connection is established between a first end of the first optical fiber and a second end of the second optical fiber. The connecting portion is fixedly connected to a circumferential surface of the first optical fiber and is fixedly connected to a circumferential surface of the second optical fiber, such that the first optical fiber and the second optical fiber can be fixed relative to each other. The connecting portion is not fixedly connected to the first end, or is not fixedly connected to the second end, thereby avoiding damage to the fiber optic connection by the connection between the connecting portion and the first optical fiber or the second optical fiber, ensuring that the fiber optic connection has a low insertion loss and a high return loss, and improving the connection performance between the hollow-core optical fiber and the solid-core optical fiber.

Description

Optical fiber connector and optical communication system

[0001] The present application claims priority to the Chinese patent application No. 202411355180.5, filed on September 26, 2024, and entitled "Optical fiber connector and optical communication system", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] Embodiments of the present application relate to the field of optical transmission technology, and in particular to an optical fiber connector and an optical communication system. BACKGROUND

[0003] Compared with traditional solid core optical fibers, hollow core optical fibers have low latency, high laser damage threshold, weak nonlinearity, low dispersion, and ultra-low loss. Therefore, as optical cables, hollow core optical fibers are gradually applied to long-distance optical communication systems. Moreover, in the fields of light-gas or light-liquid interaction, optical fiber sensing, high-power laser transmission, pulse compression, and the like, hollow core optical fibers also have considerable application prospects.

[0004] If hollow core optical fibers and solid core optical fibers are applied in the same scenario, it is often necessary to splice the hollow core optical fibers and the solid core optical fibers. For example, long-distance transmission optical cables can use hollow core optical fibers, while the tail fibers connecting optical communication equipment to the outside world usually use traditional solid core optical fibers. In order to realize optical communication, it is necessary to connect the hollow core optical fibers and the solid core optical fibers. The structure of the hollow core optical fibers is different from that of the solid core optical fibers. For example, the mode field diameter of the hollow core optical fibers is different from that of the solid core optical fibers, and appropriate means need to be used to adapt the connection of the hollow core optical fibers and the solid core optical fibers. Moreover, various application scenarios also have special requirements for the connection performance between the hollow core optical fibers and the solid core optical fibers. For example, in the scenario of bidirectional transmission of optical fiber communication, the connection of the hollow core optical fibers and the solid core optical fibers needs to maintain low insertion loss and high return loss.

[0005] Therefore, how to improve the connection performance between the hollow core optical fibers and the solid core optical fibers is a problem to be solved by technicians. SUMMARY

[0006] Embodiments of the present application provide an optical fiber connector and an optical communication system, and the main purpose is to improve the connection performance between the hollow core optical fibers and the solid core optical fibers.

[0007] To achieve the above purpose, embodiments of the present application adopt the following technical solutions:

[0008] In a first aspect, an optical fiber connector is provided. The optical fiber connector includes a first optical fiber, a second optical fiber, and a connecting portion. The first optical fiber is a hollow-core optical fiber, and the second optical fiber is a solid-core optical fiber. An optical fiber connection is established between a first end of the first optical fiber and a second end of the second optical fiber. The connecting portion is fixedly connected to a circumferential surface of the first optical fiber and fixedly connected to a circumferential surface of the second optical fiber. The connecting portion is not fixedly connected to the first end or the second end.

[0009] The optical fiber connector provided by the above-mentioned embodiments of the first aspect has the connecting portion fixedly connecting the first optical fiber and the second optical fiber, thereby improving the structural stability of the optical fiber connector. The connecting portion is not fixedly connected to the first end or the second end for establishing the optical fiber connection, thereby avoiding damaging the structural characteristics of the first end or the second end, and helping to improve the connection performance between the hollow-core optical fiber and the solid-core optical fiber. For example, if the connecting portion and the first optical fiber are fixedly connected, and the connecting portion and the second optical fiber are fixedly connected by a fusion connection, and the connecting portion is not fixedly connected to the first end or the second end for establishing the optical fiber connection, the high temperature of the fusion connection can be avoided from damaging the first end or the second end, thereby enabling the optical fiber connection between the hollow-core optical fiber and the solid-core optical fiber to have low insertion loss and high return loss, and helping to improve the transmission capacity of the optical communication system.

[0010] In combination with the first aspect, in a possible implementation, the first optical fiber includes a first section with the first end as an end portion. A circumferential surface of the first section has a first recess for accommodating the connecting portion. In this implementation, the diameter of the first optical fiber as a hollow-core optical fiber is generally larger than the diameter of the second optical fiber as a solid-core optical fiber. The first end of the first optical fiber is provided with the first recess, which is conducive to the structural connection between the first optical fiber and the second optical fiber through the connecting portion.

[0011] In combination with the first aspect, in a possible implementation, the connecting portion is fixedly connected to the circumferential surface of the second end and is an integral structure with the second optical fiber. The connecting portion is not fixedly connected to the first end. In this implementation, the connecting portion and the second optical fiber can be made as an integral structure in advance, and then the connecting portion and the first optical fiber are connected. The connecting portion is not fixedly connected to the first end, which can avoid affecting the part of the first end and the second end for establishing the optical fiber connection, for example, the high temperature of the fusion process can be avoided from damaging the optical fiber connection.

[0012] In combination with the first aspect, in a possible implementation, the second optical fiber includes a second section with the second end as an end portion. A circumferential surface of the second section has a second recess for accommodating the connecting portion. In this way, the connecting portion can be embedded in the second recess of the second optical fiber, thereby improving the fit between the connecting portion and the second optical fiber, and also improving the integration of the connecting portion and the second optical fiber when the connecting portion and the second optical fiber are an integral structure.

[0013] With reference to the first aspect, in a possible implementation manner, a mode field diameter of the second end of the second optical fiber is not equal to a mode field diameter of the third end of the second optical fiber. The second end and the third end are located at opposite ends of the second optical fiber. In this implementation manner, the mode field diameter of the second end of the second optical fiber can be matched with the mode field diameter of the first end of the first optical fiber, and the mode field diameter of the third end of the second optical fiber can be matched with the mode field diameter of the solid-core transmission optical fiber in the optical communication system, and the mode field diameter of the first end of the first optical fiber can be matched with the mode field diameter of the hollow-core transmission optical fiber in the optical communication system, so that the coupling efficiency in the optical communication system is improved, lower insertion loss is achieved, and the chain transmission requirement of the optical communication system is met.

[0014] With reference to the first aspect, in a possible implementation manner, the optical fiber connector further includes a third optical fiber. The third end of the second optical fiber is optically connected to a fourth end of the third optical fiber, and the second end and the third end are located at opposite ends of the second optical fiber. A mode field diameter of the fourth end of the third optical fiber is not equal to a mode field diameter of a fifth end of the third optical fiber, and the fourth end and the fifth end are located at opposite ends of the third optical fiber. In this implementation manner, the second optical fiber and the third optical fiber can be used as an optical fiber adapter between the hollow-core optical fiber and the solid-core optical fiber. For example, the second optical fiber is a solid-core optical fiber matched with the mode field diameter of the first optical fiber, and the third optical fiber is an optical fiber with different mode field diameters at two ends, for example, the third optical fiber is a tapered optical fiber or a heat-expanded core optical fiber. In this way, the mode field diameter of the fourth end of the third optical fiber can be matched with the mode field diameter of the second optical fiber, and the mode field diameter of the fifth end of the third optical fiber can be matched with the mode field diameter of the solid-core transmission optical fiber in the optical communication system, so that the coupling efficiency in the optical communication system is improved, and lower insertion loss is achieved.

[0015] With reference to the first aspect, in a possible implementation manner, the connecting portion surrounds the circumferential surface of the first end and surrounds the circumferential surface of the second end. The connecting portion is fixedly connected to the annular surface along the circumference of the first optical fiber or is fixedly connected to the annular surface along the circumference of the second optical fiber. In this way, for example, the connecting portion is a cylindrical structure, which can be connected to the annular surface along the circumference of the first optical fiber and the annular surface along the circumference of the second optical fiber, so that the structural stability of the connecting portion fixedly connected to the first optical fiber and the second optical fiber, respectively, is improved. Moreover, taking the cylindrical structure of the connecting portion as an example, the circumferential surface of the first end and the circumferential surface of the second end can be covered, so that the first end and the second end are sealed relative to the outside of the optical fiber connector, and the pollutants such as dust and water vapor are prevented from entering the optical fiber connection, so that the working stability of the optical communication system is improved.

[0016] With reference to the first aspect, in a possible implementation manner, the radial surface of the second end is provided with an anti-reflection film layer. In the implementation manner, the anti-reflection film layer helps to reduce the back reflection, thereby realizing high return loss of the optical fiber connection, and meanwhile, the connection part is not fused with the second end for establishing the optical fiber connection, so that damage of the anti-reflection film layer located at the second end caused by high temperature of the fusion can be avoided, and high return loss of the optical fiber connection is ensured.

[0017] With reference to the first aspect, in a possible implementation manner, an included angle between the radial surface of the first end and the radial surface of the second end is greater than zero. In the implementation manner, for example, the laying direction of the radial surface of the second end is not perpendicular to the extension direction of the second optical fiber at the second end, and the end face of the second optical fiber as a solid core optical fiber is inclined, so that the back reflection can be reduced, and thereby the high return loss of the optical fiber connection can be further increased.

[0018] With reference to the first aspect, in a possible implementation manner, the material of the connection part includes any one of phosphate, vanadate, bismuthate, and silicon dioxide. In this way, the connection part can be fused with the first optical fiber or the second optical fiber, and fixed connection is realized.

[0019] In the second aspect, the embodiments of the present application provide an optical communication system, which includes a first transmission optical fiber, a second transmission optical fiber, and the optical fiber connector in any one of the above embodiments. The first transmission optical fiber is a hollow core optical fiber, and the second transmission optical fiber is a solid core optical fiber. The first optical fiber is connected with the first transmission optical fiber, and the second optical fiber is connected with the second transmission optical fiber.

[0020] The technical effects brought by the design manners in the embodiments of the second aspect can be referred to the technical effects brought by the different design manners in the first aspect, and will not be described herein again. BRIEF DESCRIPTION OF DRAWINGS

[0021] FIG. 1 is an architecture diagram of an optical communication system provided by an embodiment of the present application;

[0022] FIG. 2 is a structural sectional view of an optical fiber connector along an optical fiber extension direction provided by an embodiment of the present application;

[0023] FIG. 3 is a structural sectional view of the optical fiber connector in the embodiment shown in FIG. 2 along A-A' direction;

[0024] FIG. 4 is a structural sectional view of the optical fiber connector in the embodiment shown in FIG. 2 along B-B' direction;

[0025] FIG. 5 is another structural sectional view of an optical fiber connector along an optical fiber extension direction provided by an embodiment of the present application;

[0026] FIG. 6 is still another structural sectional view of an optical fiber connector along an optical fiber extension direction provided by an embodiment of the present application;

[0027] FIG. 7 is another structural cross-sectional view of the optical fiber connector along the extending direction of the optical fiber according to an embodiment of the present application;

[0028] FIG. 8 is another structural cross-sectional view of the optical fiber connector along the extending direction of the optical fiber according to an embodiment of the present application;

[0029] FIG. 9 is another structural cross-sectional view of the optical fiber connector along the extending direction of the optical fiber according to an embodiment of the present application. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

[0031] In order to clearly describe the technical solutions in the embodiments of the present application, in the embodiments of the present application, the same items or similar items with basically the same functions and effects are distinguished by using "first", "second", and the like. Those skilled in the art can understand that "first", "second", and the like do not limit the quantity and execution order, and "first", "second", and the like do not necessarily mean different.

[0032] In describing some embodiments, "connection" and its derivatives are used. The term "connection" should be understood broadly, for example, "connection" can be fixed connection, can be detachable connection, or can be integrated. "Connection" can be direct connection, or can be indirect connection through an intermediate medium. In a specific scenario, "connection" has a corresponding meaning. For example, "connection" can refer to the connection between two optical fibers, specifically, a connection mode for transmitting signals through optical fibers.

[0033] In the embodiments of the present application, the positional relationship described by "inner", "outer", and the like can have a relative concept, and is not limited to the definition generated by the relative position of the component in the drawing. The specific meaning of these directional terms can change accordingly according to the change of the position of the component in the drawing. In the drawings, the thickness of the layers and regions is exaggerated for clarity, and the size ratio relationship between the parts in the drawing does not reflect the actual size ratio relationship.

[0034] FIG. 1 is an architecture diagram of an optical communication system according to an embodiment of the present application.

[0035] As shown in FIG. 1, the present application provides an optical communication system, which includes a first transmission optical fiber 100, a second transmission optical fiber 200, and an optical fiber connector 300.

[0036] In some optional embodiments, the first transmission optical fiber 100 is a hollow core optical fiber, and the second transmission optical fiber 200 is a solid core optical fiber. The optical fiber connector 300 is used to connect the first transmission optical fiber 100 and the second transmission optical fiber 200. In some optional embodiments, the optical fiber connector 300 can be connected to the first transmission optical fiber 100 or to the second transmission optical fiber 200 in a cold-connection manner. For example, the cold-connection manner can include, but is not limited to, a mechanical cold-connection, a fiber-breaking cold-connection, an optical adhesion, and the like. For example, in the mechanical cold-connection, the two optical fibers can be precisely aligned by a mechanical device, and fixed by a mechanical clamp or a mechanical connector, so as to realize the optical fiber connection.

[0037] Optionally, the first transmission optical fiber 100 further includes a solid core optical fiber. In some examples, the second transmission optical fiber 200 is a combination of a hollow core optical fiber and a solid core optical fiber, so as to realize long-distance signal transmission.

[0038] In some optional embodiments, the first transmission optical fiber 100 can be an optical cable used for long-distance transmission in the optical communication system 1000, and the second transmission optical fiber 200 can be a pigtail used for connection with the outside in the optical communication device in the optical communication system 1000.

[0039] In the embodiments of the present application, the hollow core optical fiber is an optical fiber with a hollow cylindrical structure in the core or core layer, and the hollow structure is used for optical transmission. The solid core optical fiber is an optical fiber with a solid structure in the core or core layer, and the solid structure is used for optical transmission.

[0040] In the embodiments of the present application, the hollow core optical fiber is an optical fiber with a hollow cylindrical structure in the core or core layer, and the hollow structure is used for optical transmission. The solid core optical fiber is an optical fiber with a solid structure in the core or core layer, and the solid structure is used for optical transmission.

[0041] For example, the mode field diameter of the first optical fiber is equal to the mode field diameter of the first transmission optical fiber 100, and the mode field diameter of the second optical fiber is equal to the mode field diameter of the second transmission optical fiber 200.

[0042] In the embodiments of the present application, the "equal" includes absolute equality and approximate equality. For example, the approximate equality can be that the difference between the two equalities is less than or equal to 5% of any one of them.

[0043] In some optional examples, as shown in FIG. 1, the optical communication system 1000 can further include a transmitting end 400 and a receiving end 500. The transmitting end 400 is provided with an optical communication device for transmitting an optical signal, and the receiving end 500 is provided with an optical communication device for receiving an optical signal. Among them, the pigtail of the optical communication device of the transmitting end 400 and the pigtail of the optical communication device of the receiving end 500 are both the second transmission optical fiber 200, and the optical cable for long-distance transmission is the first transmission optical fiber 100. For example, the transmitting end 400 is connected with the optical fiber connector 300 through the first transmission optical fiber 100, the optical fiber connector 300 is connected with one end of the second transmission optical fiber 200, and the opposite end of the second transmission optical fiber 200 is connected with the first transmission optical fiber 100 as the pigtail of the optical communication device of the receiving end 500 through another optical fiber connector 300, so as to combine the solid core optical fiber and the hollow core optical fiber to form a complete optical transmission link in the optical communication system 1000.

[0044] Through the above examples, the first optical fiber as the hollow core optical fiber in the optical fiber connector 300 is matched and connected with the first transmission optical fiber 100 as the hollow core optical fiber in the optical communication system 1000, and the second optical fiber as the solid core optical fiber in the optical fiber connector 300 is matched and connected with the second transmission optical fiber 200 as the solid core optical fiber in the optical communication system 1000, so as to efficiently and quickly realize the optical communication connection between the optical cable and the optical communication device in the case that the optical cable in the optical communication system 1000 adopts the hollow core optical fiber and the pigtail of the optical communication device adopts the solid core optical fiber.

[0045] In various application scenarios of the hollow core optical fiber, it is inevitable to be coupled and connected with the traditional solid core optical fiber. Taking the optical communication system 1000 as an example, the hollow core optical fiber used as the first transmission optical fiber 100 has the characteristic of low-loss anti-resonance, and the core diameter of this kind of hollow core optical fiber is generally about 30 μm, while the mode field diameter of the solid core optical fiber used as the second transmission optical fiber 200 is about 10 μm, and the mode field of the hollow core optical fiber with a larger core diameter and the mode field of the solid core optical fiber with a smaller core diameter are not matched. Therefore, the two ends of the optical fiber connector 300 are connected with the first transmission optical fiber 100 and the second transmission optical fiber 200, so as to realize the mode field matching of the hollow core optical fiber and the solid core optical fiber in the optical communication system 1000.

[0046] In the embodiments of the present application, the matching between the optical fibers, or the matching between the mode fields or mode field diameters of the optical fibers, can mean that the mode field diameters of the two optical fibers to be connected are equal or similar at the optical fiber connection.

[0047] At the fiber optic connection between hollow-core and solid-core optical fibers, the greater the return loss, the smaller the optical signal echo, thereby reducing the adverse effects of reflected light on the light source of the transmitter 400 and the entire optical communication system 1000. The return loss of the fiber optic connection can refer to the ratio of the back-reflected light to the input light in decibels. For example, the back-reflected light is the scattered light continuously transmitted to the transmitter 400 in the optical fiber.

[0048] In practical applications of fiber optic connectors 300, some optical communication systems 1000 have high requirements for the return loss of fiber optic connections. For example, single-fiber bidirectional transmission systems require return losses exceeding 40 dB. However, current fiber optic connectors 300 often struggle to simultaneously meet the demands of low insertion loss and high return loss. For instance, although transition fiber devices are used as fiber optic connectors to achieve mode field matching between hollow-core and solid-core fibers, the return loss of these connectors is generally in the 30-40 dB range, which does not meet the return loss requirements of single-fiber bidirectional transmission systems.

[0049] Therefore, the transmission capability of the aforementioned optical communication system 1000 needs to be improved.

[0050] Figure 2 is a structural cross-sectional view of the fiber optic connector 300 provided in an embodiment of this application along the fiber extension direction. Figures 3 and 4 are some structural cross-sectional views of the fiber optic connector 300 in the embodiment shown in Figure 2 along the radial direction of the fiber.

[0051] In view of this, this application proposes an optical fiber connector 300, as shown in FIG2. The optical fiber connector 300 includes a first optical fiber 1, a second optical fiber 2, and a connecting part 3. The first optical fiber 1 is a hollow-core optical fiber, and the second optical fiber 2 is a solid-core optical fiber.

[0052] An optical fiber connection is established between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2. In some examples, the optical signal coupling connection between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2 can be achieved through direct contact. In still other examples, the optical signal coupling connection between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2 can be achieved without direct contact. For example, the space between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2 is air, and there is a spacing of tens of micrometers between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2.

[0053] As shown in Figure 3, the connecting part 3 is fixedly connected to the circumferential surface of the first optical fiber 1. P1 is the location where the connecting part 3 is fixedly connected to the circumferential surface of the first optical fiber 1.

[0054] In the embodiments of the present application, the "circumferential direction" can be optionally a direction around the optical axis of the optical fiber, and the "circumferential direction" of the optical fiber intersects with the extension direction of the optical fiber. Exemplarily, the "circumferential direction" of the optical fiber is perpendicular to the extension direction of the optical fiber.

[0055] In some optional embodiments, along the extension direction of the optical fiber (including the first optical fiber 1 and the second optical fiber 2), the size of the region where the connecting part 3 is fixedly connected with the circumferential surface of the first optical fiber 1 is not less than 0.5 mm and not more than 10 mm. For example, along the extension direction of the optical fiber, the size of the region where the connecting part 3 is fixedly connected with the circumferential surface of the first optical fiber 1 can include but is not limited to one of the following: 0.5 mm, 1 mm, 3 mm, 5 mm, 10 mm.

[0056] As shown in FIG. 4, the connecting part 3 is fixedly connected with the circumferential surface of the second optical fiber 2. Wherein, P2 is the position where the connecting part 3 is fixedly connected with the circumferential surface of the second optical fiber 2.

[0057] In some optional embodiments, along the extension direction of the optical fiber, the size of the region where the connecting part 3 is fixedly connected with the circumferential surface of the second optical fiber 2 is not less than 0.5 mm and not more than 10 mm. For example, along the extension direction of the optical fiber, the size of the region where the connecting part 3 is fixedly connected with the circumferential surface of the second optical fiber 2 can include but is not limited to one of the following: 0.5 mm, 1 mm, 3 mm, 5 mm, 10 mm.

[0058] In some optional embodiments, the connecting part 3 is fixedly connected with the circumferential surface of the first optical fiber 1 by means of fusion or adhesion, and the connecting part 3 is fixedly connected with the circumferential surface of the second optical fiber 2 by means of fusion or adhesion. Wherein, fusion is a technology of connecting two or more objects together by means of heating or pressurization.

[0059] In some examples, the material of the connecting part 3 can be a material whose melting point is not higher than the melting point of the material of the first optical fiber 1 or the second optical fiber 2. Wherein, the material of the connecting part 3 can be the same as the material of the first optical fiber 1, or the same as the material of the second optical fiber 2. Alternatively, the material of the connecting part 3 can be different from the material of the first optical fiber 1, or different from the material of the second optical fiber 2.

[0060] The optical fiber includes a core and a cladding wrapping the core, and the material of the cladding is a main material. Unless otherwise specified, the material of the optical fiber refers to the material of the cladding of the optical fiber, and the circumferential surface of the cladding of the optical fiber is fixedly connected with the connecting part 3. For example, the diameter of the core 1R of the first optical fiber is 30 μm, and the diameter of the cladding is 235 μm. For example, the diameter of the core 2R of the second optical fiber is 10 μm, and the diameter of the cladding is 235 μm.

[0061] In some optional embodiments, the material of the connecting portion 3 comprises any one of phosphate, vanadate, bismuthate, and silicon dioxide.

[0062] In some optional embodiments, the material of the first optical fiber 1 can include but is not limited to silicon dioxide, and the material of the second optical fiber 2 can include but is not limited to silicon dioxide.

[0063] Exemplarily, the main material of the first optical fiber 1, the second optical fiber 2, and the connecting portion 3 is silicon dioxide. By high-temperature heating on the specific part of the circumferential surface of the connecting portion 3 and the first optical fiber 1, the connecting portion 3 can be fixedly connected with the circumferential surface of the first optical fiber 1. By high-temperature heating on the specific part of the circumferential surface of the connecting portion 3 and the second optical fiber 2, the connecting portion 3 can be fixedly connected with the circumferential surface of the second optical fiber 2.

[0064] In some optional embodiments, the connecting portion 3 is in a cylindrical structure. Thus, the connecting portion 3 can be in the form of a sleeve, which is arranged at the position where the first optical fiber 1 and the second optical fiber 2 are connected. The connecting portion 3 can form a ring-shaped covering on the circumferential surface of the first optical fiber 1 and the circumferential surface of the second optical fiber 2, which helps to improve the structural stability of the connection and the sealing performance of the optical fiber connection.

[0065] In yet some optional embodiments, the cross-sectional shape of the connecting portion 3 along the radial direction of the optical fiber is C-shaped. The structural stability of the fixed connection of the connecting portion 3 to the first optical fiber 1 and the second optical fiber 2 can be improved by the matching of the shape of the circumferential surface of the connecting portion 3 and the first optical fiber 1 and the second optical fiber 2. Exemplarily, the connecting portion 3 is a three-quarter sleeve, and the cross-sectional shape of the connecting portion 3 along the radial direction of the optical fiber is a three-quarter circular shape.

[0066] In some optional embodiments, one end of the connecting portion 3 along the extending direction of the optical fiber is fixedly connected with the circumferential surface of the first optical fiber 1, and the other end of the connecting portion 3 along the extending direction of the optical fiber is fixedly connected with the circumferential surface of the second optical fiber 2.

[0067] In yet some optional embodiments, the distance between the part of the connecting portion 3 fixedly connected with the first optical fiber 1 and the two ends of the connecting portion 3 along the extending direction of the optical fiber is greater than zero. The distance between the part of the connecting portion 3 fixedly connected with the second optical fiber 2 and the two ends of the connecting portion 3 along the extending direction of the optical fiber is greater than zero.

[0068] The conventional optical fiber cold connection method usually uses mechanical clamping or mechanical connectors to fix the solid core optical fiber and the hollow core optical fiber. Compared with the conventional optical fiber cold connection scheme, the optical fiber connector 300 in the above embodiments uses the connecting portion 3 to fixedly connect the first optical fiber 1 and the second optical fiber 2, which can improve the structural stability and reliability of the optical fiber connector 300.

[0069] In some optional embodiments, the connecting portion 3 is not fixedly connected with the first end 11. Specifically, the first distance between the part where the first optical fiber 1 is fixedly connected with the connecting portion 3 and the first end 11 is greater than zero.

[0070] In yet some optional embodiments, the connecting portion 3 is not fixedly connected with the second end 22. Specifically, the second distance between the part where the second optical fiber 2 is fixedly connected with the connecting portion 3 and the second end 22 is greater than zero.

[0071] For example, the connecting portion 3 is not fixedly connected with the first end 11 and is not fixedly connected with the second end 22.

[0072] Through the above embodiments, the first end 11 and the second end 22 are used to establish the optical fiber connection, and the connecting portion 3 is not fixedly connected with the first end 11 or the second end 22 used to establish the optical fiber connection, so that the damage to the structural characteristics of the first end 11 or the structural characteristics of the second end 22 can be reduced, and the connection performance between the hollow optical fiber and the solid optical fiber can be improved.

[0073] For example, if the connecting portion 3 and the first optical fiber 1 and the connecting portion 3 and the second optical fiber 2 are fixedly connected through the fusion splicing connection, and the connecting portion 3 is not fixedly connected with the first end 11 or the second end 22 used to establish the optical fiber connection, the high temperature of the fusion splicing can be avoided to damage the first end 11 or the second end 22, so that the optical fiber connection between the hollow optical fiber and the solid optical fiber can be considered with low insertion loss and high return loss, and the transmission capacity of the optical communication system 1000 can be improved.

[0074] In some optional embodiments, as shown in FIG. 3, the connecting portion 3 surrounds the circumferential surface of the first end 11. As shown in FIG. 4, the connecting portion 3 surrounds the circumferential surface of the second end 22.

[0075] In the embodiments of the present application, the connecting portion 3 is fixedly connected with the annular surface along the circumference of the first optical fiber 1 or the annular surface along the circumference of the second optical fiber 2.

[0076] For example, the connecting portion 3 is a cylindrical structure, which can be connected with the annular surface along the circumference of the first optical fiber 1 and the annular surface along the circumference of the second optical fiber 2, and the structural stability of the connecting portion 3 fixedly connected with the first optical fiber 1 and the second optical fiber 2 respectively can be improved.

[0077] Taking the connecting portion 3 as a cylindrical structure as an example, in the embodiments of the present application, the connecting portion 3 can cover the circumferential surface of the first end 11 and the circumferential surface of the second end 22, so that the first end 11 and the second end 22 are sealed relative to the outside of the optical fiber connector 300, the pollutants such as dust and water vapor are prevented from entering the optical fiber connection, and the working stability of the optical communication system 1000 can be improved.

[0078] As shown in FIG. 2, in the first example provided by the above embodiment, the first optical fiber 1 is a hollow core optical fiber, the cladding diameter of the first optical fiber 1 is 235 μm, and the mode field diameter of the first optical fiber 1 is 24 μm. The connecting part 3 is fixedly connected with the circumferential surface of the first optical fiber 1 by means of fusion, wherein the position P1 at which the connecting part 3 is fixedly connected with the first optical fiber 1 is a fusion zone.

[0079] In the first example, the connecting part 3 is a glass sleeve, and the size of the connecting part 3 along the direction of the optical fiber is 100 mm. The inner diameter of the connecting part 3 is 235 μm, and the outer diameter of the connecting part 3 is 300 μm.

[0080] In the first example, the mode field diameters of the two ends of the second optical fiber 2 are different. The second optical fiber 2 is a hot-drawn core optical fiber, the cladding diameter of the second optical fiber 2 is 235 μm, the mode field diameter of the second end 22 of the second optical fiber 2 is 24 μm, and the mode field diameter of the third end 23 of the second optical fiber 2 is 9 μm.

[0081] In the first example, the single-mode solid core optical fiber used for connecting with the third end 23 of the second optical fiber 2 in the communication system can be selected, the cladding diameter of the solid core optical fiber is 125 μm, and the mode field diameter of the solid core optical fiber is 9 μm.

[0082] In some optional embodiments, the optical fiber connector further comprises a shell. The shell is provided with a cavity for accommodating the first optical fiber 1, the second optical fiber 2 and the connecting part 3. Exemplarily, the shell can be made of rigid material as the main material. By this embodiment, the first optical fiber 1, the second optical fiber 2 and the connecting part 3 can be protected by the shell, so that the fixed connection between the connecting part 3 and the first optical fiber 1 or the fixed connection between the connecting part 3 and the second optical fiber 2 can be prevented from being bent. Thus, the risk of failure of the fixed connection between the connecting part 3 and the first optical fiber 1 or the fixed connection between the connecting part 3 and the second optical fiber 2 can be reduced, and the structural stability of the optical fiber connector 300 can be improved.

[0083] FIG. 5 is another structure sectional view of the optical fiber connector 300 along the direction of the optical fiber according to an embodiment of the present application.

[0084] In some optional embodiments, the distance between the end of the connecting part 3 and the first end is equal to the distance between the other end of the connecting part 3 and the second end. Thus, the structural stability of the optical fiber connector 300 can be improved by the symmetry of the optical fiber connection based on the connecting part 3. For example, the size of the connecting part 3 for sleeving the first optical fiber 1 can be equal to the size of the connecting part 3 for sleeving the second optical fiber 2, so that the same or similar fixing effects on the first optical fiber 1 and the second optical fiber 2 can be ensured, and the stability of the fixed connection between the connecting part 3 and the first optical fiber 1 or the fixed connection between the connecting part 3 and the second optical fiber 2 can be improved.

[0085] In some alternative embodiments, the distance between the end of the connecting portion 3 and the first end is not equal to the distance between the other end of the connecting portion 3 and the second end.

[0086] In some alternative embodiments, the first distance in the above embodiments is equal to the second distance in the above embodiments. In this way, the structural stability of the fiber connector 300 can be improved by the symmetry of the positions for fixing the connection of the first optical fiber 1 and the second optical fiber 2.

[0087] For example, the length of the connecting portion 3 is 100 mm, the distance between the position where the first optical fiber 1 is fixedly connected to the connecting portion 3 and the first end 11 is 45 mm, and the distance between the position where the second optical fiber 2 is fixedly connected to the connecting portion 3 and the second end 22 is 45 mm.

[0088] In some alternative embodiments, the first distance is not equal to the second distance. For example, the first distance is greater than the second distance. In this way, the special requirements of optical signal transmission can be met by the specific position of the connecting portion 3, and the connecting portion 3 does not affect the normal transmission of optical signals as much as possible.

[0089] For example, the length of the connecting portion 3 is 100 mm, the distance between the position where the first optical fiber 1 is fixedly connected to the connecting portion 3 and the first end 11 is 55 mm, and the distance between the position where the second optical fiber 2 is fixedly connected to the connecting portion 3 and the second end 22 is 35 mm.

[0090] As shown in FIG. 5, in some alternative embodiments, the distance between the position where the connecting portion 3 is fixedly connected to the first optical fiber 1 and the end of the connecting portion 3 is greater than zero, or in other words, the end of the connecting portion 3 is not fixedly connected to the first optical fiber 1.

[0091] As shown in FIG. 5, the distance between the position where the connecting portion 3 is fixedly connected to the second optical fiber 2 and the end of the connecting portion 3 is greater than zero, or in other words, the end of the connecting portion 3 is not fixedly connected to the second optical fiber 2.

[0092] In some alternative embodiments, the end of the connecting portion 3 is fixedly connected to the first optical fiber 1, and the other end of the connecting portion 3 is fixedly connected to the second optical fiber 2.

[0093] In some alternative embodiments, the ratio of the distance between the position where the connecting portion 3 is fixedly connected to the first optical fiber 1 and the end of the connecting portion 3 to the length of the connecting portion 3 is less than one half. For example, the ratio of the distance between the position where the connecting portion 3 is fixedly connected to the first optical fiber 1 and the end of the connecting portion 3 to the length of the connecting portion 3 includes but is not limited to one of the following: 0, 1 / 10, 1 / 5, 3 / 10, 2 / 5.

[0094] As shown in FIG. 5, in some optional embodiments, the mode field diameter of the second end 22 of the second optical fiber 2 is not equal to the mode field diameter of the third end 23 of the second optical fiber 2. Herein, the second end 22 and the third end 23 are located at opposite ends of the second optical fiber 2.

[0095] Exemplarily, the mode field diameter of the second end 22 of the second optical fiber 2 is greater than the mode field diameter of the third end 23 of the second optical fiber 2. Alternatively, the diameter of the core 2R of the second end 22 of the second optical fiber 2 is greater than the diameter of the core 2R of the third end 23 of the second optical fiber 2.

[0096] In some optional embodiments, the type of the second optical fiber 2 can include but is not limited to a tapered fiber, a heat-expanded core fiber (as shown in FIG. 2) or a graded-index fiber. The above-mentioned types of optical fibers are all solid-core optical fibers.

[0097] Herein, the graded-index fiber is also known as a self-focusing fiber. The refractive index of the center part of the fiber is the highest, and decreases along the radial direction. When the light beam propagates in the fiber, it can be automatically focused without dispersion.

[0098] In the embodiments of the present application, by adjusting the refractive index of each part of the fiber, the fibers of different sections can have different mode field diameters, so that the mode field diameter of the second end 22 is not equal to the mode field diameter of the third end 23.

[0099] In some optional embodiments, the mode field diameter of the second end 22 of the second optical fiber 2 is equal to the mode field diameter of the first end 11 of the first optical fiber 1.

[0100] Through the above embodiments, the mode field diameter of the second end 22 of the second optical fiber 2 can be matched with the mode field diameter of the first end 11 of the first optical fiber 1, the mode field diameter of the third end 23 of the second optical fiber 2 can be matched with the mode field diameter of the solid-core transmission optical fiber in the optical communication system 1000, and the mode field diameter of the first end 11 of the first optical fiber 1 can be matched with the mode field diameter of the hollow-core transmission optical fiber in the optical communication system 1000, so as to improve the coupling efficiency in the optical communication system 1000, realize lower insertion loss, and meet the chain transmission requirement of the optical communication system 1000.

[0101] As shown in FIG. 5, in some optional embodiments, the first optical fiber 1 includes a first section with the first end 11 as an end. The circumferential surface of the first section has a first recess, and the first recess is used for accommodating the connecting part 3.

[0102] In some optional embodiments, the first recess is an annular recess along the circumference of the first section, and the connecting part 3 is a cylindrical structure.

[0103] In some examples, the diameter of the columnar structure formed by the bottom surface of the annular recess is equal to the diameter of the inner wall surface of the connecting portion 3 having the cylindrical structure, so that the connecting portion 3 is fitted with the first recess, thereby improving the structural stability of the fixed connection of the first optical fiber 1 with the connecting portion 3.

[0104] In yet some examples, the diameter of the columnar structure formed by the bottom surface of the annular recess is slightly larger than the diameter of the inner wall surface of the connecting portion 3 having the cylindrical structure. In this way, the assembly of the connecting portion 3 with the first section of the first optical fiber 1 can be facilitated. The "slightly larger" between the numerical value M and the numerical value N can be selected to be the difference between the numerical value M and the numerical value N, and the ratio between the numerical value M and the numerical value N is between 0 and 5%.

[0105] In some optional embodiments, the first recess can be formed by polishing the circumferential surface of the first section.

[0106] In the above embodiments, considering that the diameter of the first optical fiber 1 as a hollow optical fiber is generally larger than that of a solid core optical fiber, the first recess is arranged at the end of the first optical fiber 1, the diameter of the first optical fiber 1 at the first recess is reduced compared to the original diameter of the first optical fiber 1, and the connecting portion 3 is embeddedly sleeved with the first recess, so that the connecting position of the connecting portion 3 with the first optical fiber 1 and the second optical fiber 2 is flush, thereby facilitating the structural connection between the first optical fiber 1 and the second optical fiber 2 through the connecting portion 3.

[0107] FIG. 6 is another structural cross-sectional view of the optical fiber connector 300 along the fiber extension direction according to an embodiment of the present application.

[0108] As shown in FIG. 6, in some optional embodiments, the connecting portion 3 is fixedly connected with the circumferential surface of the second end 22 and is an integral structure with the second optical fiber 2.

[0109] Specifically, in actual applications, the integral structure of the connecting portion 3 and the second optical fiber 2 can be obtained by etching a groove on the radial surface of the end of the solid core optical fiber. In this way, the material of the connecting portion 3 can be the same as the material of the cladding of the second optical fiber 2.

[0110] The connecting portion 3 is not fixedly connected with the first end 11. For example, the connecting portion 3 is fixedly connected with the circumferential surface of the first recess of the first optical fiber 1, and the distance between the part where the connecting portion 3 is fixedly connected with the first optical fiber 1 and the first end 11 is greater than zero.

[0111] Through the above embodiment, the connection part 3 and the second optical fiber 2 can be made into an integrated structure in advance, skipping the process of fusion splicing the connection part 3 and the second optical fiber 2, and avoiding the adverse effects on the optical performance of the radial surface of the second end 22 for establishing the optical fiber connection. Moreover, the connection part 3 is fixedly connected with the first optical fiber 1 but not fixedly connected with the first end 11, which can also avoid the adverse effects on the optical performance of the radial surface of the second end 22 for establishing the optical fiber connection, for example, the high temperature of the fusion splicing process or the glue of the bonding process can change the optical properties of the optical fiber connection.

[0112] As shown in FIG. 6, in the second example provided in the above embodiment, the first optical fiber 1 is a hollow core optical fiber, the cladding diameter of the first optical fiber 1 is 235 μm, and the mode field diameter of the first optical fiber 1 is 24 μm. The first section of the first optical fiber 1 with the first end 11 as the end is provided with a first recess.

[0113] In the second example, the size of the first section is 20 mm in the direction of the fiber extension, the depth of the first recess is 30 μm, and the cladding diameter of the first optical fiber 1 at the first recess is 175 μm.

[0114] In the second example, the connection part 3 is fixedly connected with the circumferential surface of the first optical fiber 1 at the first recess by fusion splicing, wherein the position P1 where the connection part 3 is fixedly connected with the first optical fiber 1 is a fusion splicing area.

[0115] In the second example, the connection part 3 is an integrated structure with the second optical fiber 2. The size of the connection part 3 is 40 mm in the direction of the fiber extension. The inner surface diameter of the connection part 3 is 175 μm, and the outer surface diameter is 235 μm.

[0116] In the second example, the mode field diameters of the two ends of the second optical fiber 2 are different. As shown in FIG. 6, the second optical fiber 2 is a hot-drawn core optical fiber, and the second section of the second optical fiber 2 with the second end 22 as the end is provided with a second recess, and the depth of the second recess is 30 μm. Half of the connection part 3 is sleeved on the first section of the first optical fiber 1, and the other half of the connection part 3 is sleeved on the second section of the second optical fiber 2, and the connection part 3 is an integrated structure with the second section. The size of the second section is 20 mm in the direction of the fiber extension, and the cladding diameter of the second optical fiber 2 at the second recess is 175 μm. The cladding diameter of the section of the second optical fiber 2 with the second end 22 as the end, which is not provided with the second recess, is 235 μm. The mode field diameter of the second end 22 of the second optical fiber 2 is 24 μm, and the mode field diameter of the third end 23 of the second optical fiber 2 is 9 μm.

[0117] In the second example, the single-mode solid core optical fiber with a cladding diameter of 125 μm and a mode field diameter of 9 μm can be selected as the solid core optical fiber for connecting with the second end 22 of the second optical fiber 2 in the optical communication system.

[0118] Fig. 7 is another sectional view of the optical fiber connector 300 along the optical fiber extension direction according to an embodiment of the present application.

[0119] As shown in Fig. 7, in some optional embodiments, the second optical fiber 2 comprises a second section with the second end 22 as an end. The circumferential surface of the second section has a second recess for accommodating the connecting part 3.

[0120] In some optional embodiments, the second recess is an annular recess along the circumference of the second section, and the connecting part 3 has a cylindrical structure.

[0121] As shown in Fig. 7, in some examples, the first optical fiber 1 is provided with the first recess, and the second optical fiber 2 is provided with the second recess, so that the connecting part 3 can be embedded in the first recess and the second recess.

[0122] In some optional embodiments, the second recess can be formed by polishing the circumferential surface of the second section.

[0123] Through the above embodiments, the connecting part 3 can be embedded in the second recess of the second optical fiber 2, the fit of the connecting part 3 and the second optical fiber 2 is improved, and the structural stability of the connecting part 3 and the second optical fiber 2 is improved.

[0124] In yet some examples, the connecting part 3 can be connected with the bottom surface of the second recess as an integrated structure,

[0125] In some examples, the diameter of the cylindrical structure formed by the bottom surface of the annular recess is equal to the diameter of the inner wall surface of the connecting part 3 with the cylindrical structure. The diameter of the outer wall surface of the connecting part 3 with the cylindrical structure is equal to the diameter of the first optical fiber 1. Thus, it is convenient to etch a groove on the radial surface of the end of the solid core optical fiber to obtain an integrated structure formed by the connecting part 3 and the second optical fiber 2 (as shown in Fig. 6).

[0126] Through the above embodiments, the integration of the connecting part 3 and the second optical fiber 2 can be improved when the connecting part 3 and the second optical fiber 2 are an integrated structure, and the manufacturing of the integrated structure formed by the connecting part 3 and the second optical fiber 2 is facilitated.

[0127] As shown in Fig. 7, in the third example provided in the above embodiments, the first optical fiber 1 is a hollow core optical fiber, the cladding diameter of the first optical fiber 1 is 235 μm, and the mode field diameter of the first optical fiber 1 is 24 μm.

[0128] In the third example, the first section of the first optical fiber 1 with the first end 11 as the end is provided with a first recess. The size of the first section is 50 mm in the direction of the fiber extension, the depth of the first recess is 30 μm, and the cladding diameter of the first optical fiber 1 at the first recess is 175 μm.

[0129] In the third example, the connecting part 3 is fixedly connected with the circumferential surface of the first optical fiber 1 at the first recess by means of fusion splicing, wherein the position P1 at which the connecting part 3 is fixedly connected with the first optical fiber 1 is a fusion splicing area.

[0130] In the third example, the connecting part 3 is a glass sleeve, and the size of the connecting part 3 is 100 mm in the direction of the fiber extension. The inner surface diameter of the connecting part 3 is 175 μm, and the outer surface diameter is 235 μm.

[0131] In the third example, the mode field diameters of the two ends of the second optical fiber 2 are not equal. As shown in FIG. 7, the second optical fiber 2 is a tapered optical fiber, and the second section of the second optical fiber 2 with the second end 22 as the end is provided with a second recess, and the depth of the second recess is 30 μm. The size of the second section or the second recess is 50 mm in the direction of the fiber extension, and the cladding diameter of the second optical fiber 2 at the second recess is 175 μm. The cladding diameter of the section of the second optical fiber 2 with the second end 22 as the end and without the second recess is 235 μm. The cladding diameter of the second optical fiber 2 at the third end 23 is 125 μm. The second end 22 is an untapered end, and the third end 23 is a tapered end. The mode field diameter of the second end 22 of the second optical fiber 2 is 24 μm, and the mode field diameter of the third end 23 of the second optical fiber 2 is 9 μm.

[0132] In the third example, the single-mode solid core optical fiber used for connecting with the second end 22 of the second optical fiber 2 in the optical communication system can be selected. The cladding diameter of the solid core optical fiber is 125 μm, and the mode field diameter of the solid core optical fiber is 9 μm.

[0133] FIG. 8 is another structure sectional view of the optical fiber connector 300 in the direction of the fiber extension according to an embodiment of the present application.

[0134] As shown in FIG. 8, in some optional embodiments, the optical fiber connector 300 further includes a third optical fiber 4. The third end 23 of the second optical fiber 2 is optically connected with the fourth end 44 of the third optical fiber 4, and the second end 22 and the third end 23 are located at opposite ends of the second optical fiber 2. The mode field diameter of the fourth end 44 of the third optical fiber 4 is not equal to the mode field diameter of the fifth end 45 of the third optical fiber 4, and the fourth end 44 and the fifth end 45 are located at opposite ends of the third optical fiber 4.

[0135] In some optional embodiments, the second optical fiber 2 is a solid core optical fiber, and the mode field diameter of the second optical fiber 2 matches the mode field diameter of the first optical fiber 1. The third optical fiber 4 is a solid core optical fiber, and the mode field diameters of the two ends of the third optical fiber 4 are different.

[0136] For example, the mode field diameter of the fourth end 44 of the third optical fiber 4 is greater than the mode field diameter of the fifth end 45 of the third optical fiber 4. Alternatively, the diameter of the core 4R of the fourth end 44 of the third optical fiber 4 is greater than the diameter of the core 4R of the fifth end 45 of the third optical fiber 4.

[0137] In some examples, the type of the third optical fiber 4 can include but is not limited to a tapered fiber, a heat-expanded core fiber (as shown in FIG. 8), or a graded index fiber. Among them, the type of the optical fiber is different, and the characteristics of the core of the optical fiber or the characteristics of the cladding are different.

[0138] For example, as shown in FIG. 7, along the direction of the fiber extension, the core diameter of the tapered fiber can first remain unchanged and then gradually decrease, and the cladding diameter of the tapered fiber matches the core diameter. Specifically, the core diameter of the tapered fiber remains unchanged, and the diameter of the cladding surrounding the part of the core remains unchanged. The core diameter of the tapered fiber gradually decreases, and the diameter of the cladding surrounding the part of the core gradually decreases.

[0139] For another example, as shown in FIG. 8, along the direction of the fiber extension, the core diameter of the heat-expanded core fiber can first remain unchanged and then gradually decrease, and the diameter of the cladding of the heat-expanded core fiber remains unchanged (not considering the case where the fiber is provided with a recess).

[0140] Through the above examples, the second optical fiber 2 and the third optical fiber 4 can be used as a fiber adapter between the hollow core optical fiber and the solid core optical fiber. In this way, the mode field diameter of the fourth end 44 of the third optical fiber 4 can match the mode field diameter of the second optical fiber 2, and the mode field diameter of the fifth end 45 of the third optical fiber 4 can match the mode field diameter of the solid core transmission optical fiber in the optical communication system 1000, thereby improving the coupling efficiency in the optical communication system 1000 and achieving lower insertion loss.

[0141] As shown in FIG. 8, in a fourth example provided in the above examples, the first optical fiber 1 is a hollow core optical fiber, the cladding diameter of the first optical fiber 1 is 235 μm, and the mode field diameter of the first optical fiber 1 is 24 μm.

[0142] In the fourth example, the connecting part 3 is fixedly connected with the circumferential surface of the first optical fiber 1 by fusion, and the part P1 where the connecting part 3 is fixedly connected with the first optical fiber 1 is a fusion zone.

[0143] In the fourth example, the connecting part 3 is a glass sleeve, and the size of the connecting part 3 along the direction of the fiber extension is 100 mm. The inner surface diameter of the connecting part 3 is 235 μm, and the outer surface diameter is 300 μm.

[0144] In the fourth example, the mode field diameters of the second fiber 2 at both ends are the same. The cladding diameter of the second fiber 2 is 235 μm, and the mode field diameter of the second fiber 2 is 24 μm. The radial surface of the second end 22 of the second fiber 2 is provided with an anti-reflection film layer. The connecting part 3 is fixedly connected with the circumferential surface of the second fiber 2 by fusion, wherein the part of the second fiber 2 used for fusion is the outer surface of the cladding of the second fiber 2, and the part P2 where the connecting part 3 is fixedly connected with the second fiber 2 is the fusion zone.

[0145] In the fourth example, the mode field diameters of the third fiber 4 at both ends are different. The third fiber 4 is a hot-drawn core fiber, the cladding diameter of the third fiber 4 is 125 μm, the mode field diameter of the fourth end 44 of the third fiber 4 is 24 μm, and the mode field diameter of the fifth end 45 of the third fiber 4 is 9 μm.

[0146] In the fourth example, the single-mode solid core fiber used for connecting with the fifth end 45 of the third fiber in the optical communication system can be selected as follows: the cladding diameter of the solid core fiber is 125 μm, and the mode field diameter of the solid core fiber is 9 μm.

[0147] In the fifth example provided by the above-mentioned embodiments, the main difference from the above-mentioned fourth example is that the connecting part 3 is in one-piece structure with the second fiber 2. In the fifth example, the first fiber 1 is a hollow core fiber, the cladding diameter of the first fiber 1 is 235 μm, and the mode field diameter of the first fiber 1 is 24 μm.

[0148] In the fifth example, the first recess is arranged in the first section of the first fiber 1 with the first end 11 as the end.

[0149] In the fifth example, the size of the first section along the direction of fiber extension is 20 mm, the depth of the first recess is 30 μm, and the cladding diameter of the first fiber 1 at the first recess is 175 μm.

[0150] In the fifth example, the connecting part 3 is fixedly connected with the circumferential surface of the first fiber 1 at the first recess by fusion, wherein the part P1 where the connecting part 3 is fixedly connected with the first fiber 1 is the fusion zone.

[0151] In the fifth example, the connecting part 3 is in one-piece structure with the second fiber 2. The size of the connecting part 3 along the direction of fiber extension is 40 mm. The inner diameter of the connecting part 3 is 175 μm, and the outer diameter of the connecting part 3 is 235 μm.

[0152] In the fifth example, the mode field diameters of the second fiber 2 at both ends are the same, and the mode field diameter of the second fiber 2 is 24 μm. The second section of the second fiber 2 with the second end 22 as the end is provided with a second recess, and the depth of the second recess is 30 μm. Half of the sections of the connecting part 3 are sleeved on the first section of the first fiber 1, and the other half of the sections of the connecting part 3 are sleeved on the second section of the second fiber 2, and the connecting part 3 is in an integral structure with the second section. In the extension direction of the fiber, the size of the second section is 20 mm, and the cladding diameter of the second fiber 2 at the second recess is 175 μm. In the section of the second fiber 2 with the second end 22 as the end, the cladding diameter without the second recess is 235 μm.

[0153] In the fifth example, the mode field diameters of the third fiber 4 at both ends are different. The third fiber 4 is a hot-drawn fiber or a tapered fiber, the maximum cladding diameter of the third fiber 4 is 125 μm, the mode field diameter of the fourth end 44 of the third fiber 4 is 24 μm, and the mode field diameter of the fifth end 45 of the third fiber 4 is 9 μm.

[0154] In the sixth example provided by the above embodiment, the main difference from the above-mentioned fourth example is that the first fiber 1 and the second fiber 2 are provided with recesses for accommodating the connecting part 3. In the sixth example, the first fiber 1 is a hollow core fiber, the cladding diameter of the first fiber 1 is 235 μm, and the mode field diameter of the first fiber 1 is 24 μm.

[0155] In the sixth example, the first section of the first fiber 1 with the first end 11 as the end is provided with a first recess. In the extension direction of the fiber, the size of the first section is 50 mm, the depth of the first recess is 30 μm, and the cladding diameter of the first fiber 1 at the first recess is 175 μm.

[0156] In the sixth example, the connecting part 3 is fixedly connected with the circumferential surface of the first fiber 1 at the first recess by means of fusion, and the part P1 where the connecting part 3 is fixedly connected with the first fiber 1 is a fusion zone.

[0157] In the sixth example, the connecting part 3 is a glass sleeve, and in the extension direction of the fiber, the size of the connecting part 3 is 100 mm. The inner diameter of the connecting part 3 is 175 μm, and the outer diameter is 235 μm.

[0158] In the sixth example, the mode field diameters of the second fiber 2 at both ends are the same, and the mode field diameter of the second fiber 2 is 24 μm. The second section of the second fiber 2 with the second end 22 as the end is provided with a second recess, and the depth of the second recess is 30 μm. Half of the sections of the connecting part 3 are sleeved on the first section of the first fiber 1, and the other half of the sections of the connecting part 3 are sleeved on the second section of the second fiber 2. In the extension direction of the optical fiber, the size of the second section is 50 mm, and the cladding diameter of the second fiber 2 at the second recess is 175 μm. In the section of the second fiber 2 with the second end 22 as the end, the cladding diameter without the second recess is 235 μm.

[0159] In the sixth example, the mode field diameters of the third fiber 4 at both ends are different. The third fiber 4 is a hot-drawn core fiber or a tapered fiber, the maximum cladding diameter of the third fiber 4 is 125 μm, the mode field diameter of the fourth end 44 of the third fiber 4 is 24 μm, and the mode field diameter of the fifth end 45 of the third fiber 4 is 9 μm.

[0160] FIG. 9 is another structure sectional view of the optical fiber connector 300 provided by the embodiment of the present application in the extension direction of the optical fiber.

[0161] As shown in FIG. 9, in some optional embodiments, the radial surface of the second end 22 is provided with the anti-reflection film layer 5. The anti-reflection film layer 5 helps to reduce the back reflection, thereby achieving high return loss of the optical fiber connection.

[0162] In the above embodiments, the second fiber 2 is a solid core fiber, and the anti-reflection film layer 5 is arranged on the radial surface of the second end 22 of the second fiber 2. The anti-reflection film layer 5 is arranged on the end surface of the solid core fiber, which is less difficult than arranging the anti-reflection film layer 5 on the end surface of the hollow core fiber, thereby facilitating the manufacturing of the anti-reflection film layer 5.

[0163] In the above embodiments, the anti-reflection film layer 5 can be formed by any one of the following methods: chemical plating, physical vapor plating, and magnetron sputtering plating.

[0164] In the above embodiments, the connecting part 3 is not fused with the second end 22 for establishing the optical fiber connection, which can avoid the damage of the high temperature of the fusion to the anti-reflection film layer located on the second end 22, thereby ensuring the high return loss of the optical fiber connection. For example, the return loss of the optical fiber connector 300 is greater than 40 dB.

[0165] In some optional embodiments, the anti-reflection film layer 5 can also be arranged on the radial surface of the first end 11 of the first fiber 1.

[0166] As shown in FIG. 9, in some optional embodiments, the included angle between the radial surface of the first end 11 and the radial surface of the second end 22 is greater than zero.

[0167] In some examples, the laying direction of the radial surface of the second end 22 is not perpendicular to the extension direction of the second optical fiber 2 at the second end 22, or in other words, the end face of the second optical fiber 2 as a solid core optical fiber is inclined.

[0168] Exemplarily, the included angle between the radial surface of the first end 11 and the radial surface of the second end 22 is not less than 2° and not greater than 8°. For example, the angle between the laying direction of the radial surface of the second end 22 and the extension direction of the second optical fiber 2 at the second end 22 is not less than 2° and not greater than 8°.

[0169] Through the above-mentioned embodiments, the included angle between the end face of the first optical fiber 1 and the end face of the second optical fiber 2 can be utilized to further reduce the back reflection, and then increase the high return loss of the optical fiber connection. For example, the return loss of the optical fiber connector 300 is greater than 40 dB.

[0170] The embodiments of the present application also provide an optical communication system 1000, which comprises the optical fiber connector 300 in any of the above-mentioned embodiments. In this way, the low insertion loss and high return loss of the connection between the hollow core optical fiber and the solid core optical fiber in the optical communication system 1000 can be guaranteed, and then the transmission performance of the optical communication system 1000 is improved.

[0171] The embodiments of the present application also provide a manufacturing method of the optical fiber connector 300 in some of the above-mentioned embodiments, which can be used to manufacture the optical fiber connector 300 in the embodiment shown in FIG. 2, for example. The method comprises:

[0172] In step S201, a second initial optical fiber is provided, the second initial optical fiber is a solid core optical fiber, the second initial optical fiber is heat-expanded, the mode field diameter of one end of the heat-expanded second initial optical fiber is matched with the mode field diameter of the hollow core optical fiber in the optical communication system, and the second optical fiber 2 is formed. The mode field diameter of the second initial optical fiber is matched with the mode field diameter of the solid core optical fiber in the optical communication system.

[0173] The above-mentioned step S201 selects a heat expansion mode to form the second optical fiber 2 with unequal mode field diameters at two ends. Alternatively, the above-mentioned step S201 can select a fiber tapering mode to form the second optical fiber 2. Specifically, one end of the second initial optical fiber is tapered, the mode field diameter of the tapered end of the second initial optical fiber is matched with the mode field diameter of the solid core optical fiber in the optical communication system, and the second optical fiber 2 is formed. The mode field diameter of the second initial optical fiber is matched with the mode field diameter of the hollow core optical fiber in the optical communication system.

[0174] Step S202, in the case that the second optical fiber is a hot-drawn fiber, the end of the second optical fiber 2 that is not hot-drawn is taken as the second end 22. In the case that the second optical fiber is a taper fiber, the end of the second optical fiber 2 that is not tapered is taken as the second end 22. An anti-reflection film layer is formed on the second end 22 of the second optical fiber 2. Exemplarily, the anti-reflection film layer 5 can be formed by sputtering.

[0175] Step S203, a connecting part 3 is provided, and the second end 22 of the second optical fiber 2 is inserted into one end of the connecting part 3. Exemplarily, the connecting part 3 can be a glass sleeve. For example, the second end 22 of the second optical fiber 2 can be inserted into the connecting part 3 to the middle position of the connecting part 3.

[0176] Step S204, the connecting part 3 is fixedly connected with the second optical fiber 2. In some examples, the connecting part 3 is not fixedly connected with the second end 22 of the second optical fiber 2. For example, the connecting part 3 is fixedly connected with the second optical fiber 2 by fusion, and the connecting part 3 is not fused with the second end 22 of the second optical fiber 2.

[0177] Step S205, a first optical fiber 1 is provided, and the first end 11 of the first optical fiber 1 is inserted into the other end of the connecting part 3. Exemplarily, step S54 can selectively adjust the relative position between the connecting part 3 and the first optical fiber 1, so that the contact position of the connecting part 3 with the outer surface of the cladding of the first optical fiber 1 is located at the discharge position of the fusion equipment.

[0178] Step S206, the relative position between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2 is adjusted, and the fiber butt joint loss between the first optical fiber 1 and the second optical fiber 2 is reduced. In some examples, the distance between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2 can be equal to 0, or in other words, the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2 can establish fiber connection by direct contact. In other examples, the distance between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2 can be greater than 0. For example, the distance between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2 can include but is not limited to any of the following values: 5 μm, 10 μm, 20 μm, 50 μm, 100 μm.

[0179] Step S207, the connecting part 3 is fixedly connected with the first optical fiber 1. In some examples, the connecting part 3 is not fixedly connected with the first end 11 of the first optical fiber 1. For example, the connecting part 3 is fixedly connected with the first optical fiber 1 by fusion, and the connecting part 3 is not fused with the first end 11 of the first optical fiber 1.

[0180] The embodiments of the present application also provide a manufacturing method of the fiber connector 300 in some of the above-mentioned embodiments, for example, which can be used to manufacture the fiber connector 300 in the embodiment shown in FIG. 6. The method comprises:

[0181] Step S301, providing a first initial optical fiber, the first initial optical fiber being a hollow core optical fiber, a first recess is formed on a circumferential surface of a first section of the first initial optical fiber with a first end 11 as an end, to obtain a first optical fiber 1 with the first recess. Illustratively, a polishing manner can be selected to remove part of the cladding of the first initial optical fiber on the circumferential surface of the first section, so that the first optical fiber 1 with the first recess can be formed.

[0182] Step S302, providing a second initial optical fiber, the second initial optical fiber being a hot-drawn core optical fiber. A groove is formed on a radial surface of a hot-drawn core end of the second initial optical fiber, to obtain a second optical fiber 2 with the groove. The bottom of the groove is a second end 22 of the second optical fiber 2, and the sidewall part of the groove is a connecting part 3. Illustratively, a laser drilling manner can be selected to form the groove. For example, the size of the groove is the same as that of the first section along the direction of the fiber extension. The aperture of the groove is the same as the diameter of the first optical fiber 1 at the first recess.

[0183] Step S303, forming an anti-reflection film layer on the second end 22 of the second optical fiber 2.

[0184] Step S304, adjusting the relative position of the first optical fiber 1 and the second optical fiber 2 to reduce the fiber butt joint loss between the first optical fiber 1 and the second optical fiber 2. The connecting part 3 is fixedly connected with the first optical fiber 1. Or, the first optical fiber 1 and the second optical fiber 2 are fixedly connected.

[0185] The embodiments of the present application also provide a manufacturing method of the optical fiber connector 300 in some of the above-mentioned embodiments, which can be used to manufacture the optical fiber connector 300 in the embodiment shown in FIG. 7, and the method comprises:

[0186] Step S401, providing a first initial optical fiber, the first initial optical fiber being a hollow core optical fiber, a first recess is formed on a circumferential surface of a first section of the first initial optical fiber with a first end 11 as an end, to obtain a first optical fiber 1 with the first recess.

[0187] Step S402, providing a second initial optical fiber, the second initial optical fiber being a tapered optical fiber. A second recess is formed on a circumferential surface of a second section of the second initial optical fiber, to obtain a second optical fiber 2 with the second recess. The end of the second initial optical fiber which is not tapered is a second end 22, and the second section has the second end 22 as an end.

[0188] Step S403, forming an anti-reflection film layer on the second end 22 of the second optical fiber 2.

[0189] Step S404, providing a connecting part 3, and inserting the second end 22 of the second optical fiber 2 into one end of the connecting part 3.

[0190] Step S405, fixing the connection part 3 with the second optical fiber 2.

[0191] Step S406, inserting the first end 11 of the first optical fiber 1 into the other end of the connection part 3.

[0192] Step S407, adjusting the relative position between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2, reducing the fiber butt joint loss between the first optical fiber 1 and the second optical fiber 2.

[0193] Step S408, fixing the connection part 3 with the first optical fiber 1.

[0194] The embodiments of the present application also provide a manufacturing method of the optical fiber connector 300 in some of the above embodiments, for example, which can be used to manufacture the optical fiber connector 300 in the embodiment shown in FIG. 8. The method comprises:

[0195] Step S501, providing the second optical fiber 2, and forming an anti-reflection film layer on the second end 22 of the second optical fiber 2.

[0196] Step S502, providing the connection part 3, and inserting the second end 22 of the second optical fiber 2 into one end of the connection part 3.

[0197] Step S503, fixing the connection part 3 with the second optical fiber 2.

[0198] Step S504, providing the first optical fiber 1, and inserting the first end 11 of the first optical fiber 1 into the other end of the connection part 3.

[0199] Step S505, adjusting the relative position between the first end 11 of the first optical fiber 1 and the second end 22 of the second optical fiber 2, reducing the fiber butt joint loss between the first optical fiber 1 and the second optical fiber 2.

[0200] Step S506, fixing the connection part 3 with the first optical fiber 1. In some examples, the connection part 3 is not fixed with the first end 11 of the first optical fiber 1.

[0201] Step S507, fixing the third end 23 of the second optical fiber 2 with the fourth end 44 of the third optical fiber 4. For example, the third end 23 of the second optical fiber 2 and the fourth end 44 of the third optical fiber 4 are fixed by fusion splicing. For example, the mode field diameter of the third end 23 of the second optical fiber 2 matches the mode field diameter of the fourth end 44 of the third optical fiber 4. For example, the third optical fiber 4 is a hot expanded core optical fiber, and the mode field diameter of the fourth end 44 of the third optical fiber 4 is larger than the mode field diameter of the fifth end 45 of the third optical fiber 4.

[0202] The mode field diameter of the first end 11 of the first optical fiber 1 in the optical fiber connector 300 in the above embodiment matches the mode field diameter of the hollow core optical fiber in the optical communication system, and the mode field diameter of the fifth end 45 of the third optical fiber 4 matches the mode field diameter of the solid core optical fiber in the optical communication system. The first end 11 of the first optical fiber 1 can be used to establish an optical fiber connection with the hollow core optical fiber in the optical communication system, and the fifth end 45 of the third optical fiber 4 can be used to establish an optical fiber connection with the solid core optical fiber in the optical communication system, for example, the optical fiber connection between the optical fiber connector 300 and the remaining optical fibers can be established in a cold-connection manner.

[0203] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can think of changes or replacements within the technical range disclosed in the present application, which should be covered in the protection scope of the present application. With the evolution of architecture and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

Claims

1. An optical fiber connector, characterized by, The optical fiber connector comprises: a first optical fiber, the first optical fiber being a hollow core optical fiber; a second optical fiber, the second optical fiber being a solid core optical fiber; an optical fiber connection is established between a first end of the first optical fiber and a second end of the second optical fiber; a connecting portion, the connecting portion being fixedly connected with a circumferential surface of the first optical fiber and fixedly connected with a circumferential surface of the second optical fiber; the connecting portion is not fixedly connected with the first end or not fixedly connected with the second end.

2. The fiber optic connector of claim 1, wherein, The first optical fiber comprises a first section with the first end as an end portion; a circumferential surface of the first section has a first recess for accommodating the connecting portion.

3. The fiber optic connector of claims 1 or 2, wherein, The connecting portion is fixedly connected with a circumferential surface of the second end and is an integral structure with the second optical fiber; the connecting portion is not fixedly connected with the first end.

4. The fiber optic connector of any one of claims 1-3, wherein, The second optical fiber comprises a second section with the second end as an end portion; a circumferential surface of the second section has a second recess for accommodating the connecting portion.

5. The fiber optic connector of any one of claims 1-4, wherein, A mode field diameter of the second end of the second optical fiber is not equal to a mode field diameter of a third end of the second optical fiber; wherein the second end and the third end are located at opposite ends of the second optical fiber.

6. The fiber optic connector of any one of claims 1-4, wherein, The optical fiber connector further comprises a third optical fiber; a third end of the second optical fiber is optically connected with a fourth end of the third optical fiber, the second end and the third end being located at opposite ends of the second optical fiber; a mode field diameter of the fourth end of the third optical fiber is not equal to a mode field diameter of a fifth end of the third optical fiber, the fourth end and the fifth end being located at opposite ends of the third optical fiber.

7. The fiber optic connector of any one of claims 1-6, wherein, The connecting portion surrounds a circumferential surface of the first end and surrounds a circumferential surface of the second end; The connecting portion is fixedly connected with an annular surface along a circumference of the first optical fiber or fixedly connected with an annular surface along a circumference of the second optical fiber.

8. The fiber optic connector of any one of claims 1-7, wherein, A radial surface of the second end is provided with an anti-reflection film layer.

9. The fiber optic connector of any one of claims 1-8, wherein, An included angle between a radial surface of the first end and a radial surface of the second end is greater than zero.

10. The fiber optic connector of any one of claims 1-9, wherein, The material of the connecting portion comprises any one of phosphate, vanadate, bismuthate, and silicon dioxide.

11. An optical communication system, characterized by The optical communication system comprises: a first transmission optical fiber, the first transmission optical fiber being a hollow core optical fiber; a second transmission optical fiber, the second transmission optical fiber being a solid core optical fiber; The optical fiber connector according to any one of claims 1-10; wherein the first optical fiber is connected with the first transmission optical fiber, and the second optical fiber is connected with the second transmission optical fiber.

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