Optical fiber connector and optical communication system

Abstract

The embodiment of the invention provides an optical fiber connector and an optical communication system, relates to the technical field of optical transmission, and aims to improve the connection performance between a hollow-core optical fiber and a solid-core optical fiber. The optical fiber connector comprises a first optical fiber, a second optical fiber and a connecting part. 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 the first end of the first optical fiber and the second end of the second optical fiber. And the connecting part is fixedly connected with the circumferential surface of the first optical fiber and is fixedly connected with the circumferential surface of the second optical fiber, so that relative fixation of the first optical fiber and the second optical fiber can be realized. The connecting part is not fixedly connected with the first end or the second end, so that the connection between the connecting part and the first optical fiber or the second optical fiber is prevented from damaging the optical fiber connection part, the optical fiber connection is ensured to have low insertion loss and high return loss, and the connection performance between the hollow-core optical fiber and the solid-core optical fiber is improved.

Description

Technical Field

[0001] This application relates to the field of optical transmission technology, and more particularly to an optical fiber connector and an optical communication system. Background Technology

[0002] Compared to traditional solid-core optical fibers, hollow-core optical fibers offer advantages such as low latency, high laser damage threshold, weak nonlinearity, low dispersion, and ultra-low loss. Therefore, hollow-core optical fibers are increasingly being used in long-distance optical communication systems. Furthermore, they also show promising applications in numerous fields, including light-gas or liquid interactions, fiber optic sensing, high-power laser transmission, and pulse compression.

[0003] When hollow-core and solid-core optical fibers are used in the same scenario, splicing between them is often necessary. For example, long-distance optical cables can use hollow-core fibers, while pigtails connecting optical communication equipment to the outside world typically use traditional solid-core fibers. To achieve optical communication, hollow-core and solid-core fibers need to be connected. The structures of hollow-core and solid-core optical fibers differ. For instance, the mode field diameter of hollow-core fibers differs from that of solid-core fibers, requiring appropriate adaptation methods for the connection. Furthermore, various application scenarios place specific demands on the connection performance between hollow-core and solid-core fibers. For example, in bidirectional optical fiber communication scenarios, the connection between hollow-core and solid-core fibers needs to maintain low insertion loss and high return loss.

[0004] Therefore, how to improve the connection performance between hollow-core optical fibers and solid-core optical fibers is a problem that technical personnel need to solve. Summary of the Invention

[0005] This application provides an optical fiber connector and an optical communication system, the main purpose of which is to improve the connection performance between hollow optical fibers and solid optical fibers.

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

[0007] In a first aspect, embodiments of this application provide an optical fiber connector, which 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 the circumferential surface of the first optical fiber and also fixedly connected to the circumferential surface of the second optical fiber. Alternatively, the connecting portion may not be fixedly connected to either the first end or the second end.

[0008] The fiber optic connector provided in the above-described embodiments of the first aspect uses a connecting portion to fixably connect the first and second optical fibers, thereby improving the structural stability of the fiber optic connector. Since the connecting portion is not fixedly connected to the first or second end used to establish the fiber optic connection, damage to the structural characteristics of the first or second end can be avoided, which helps improve the connection performance between hollow-core and solid-core optical fibers. For example, if the connecting portion is fixedly connected to the first optical fiber and the second optical fiber through fusion splicing, but the connecting portion is not fixedly connected to the first or second end used to establish the fiber optic connection, damage to the first or second end caused by the high temperature of fusion splicing can be avoided. This allows the fiber optic connection between hollow-core and solid-core optical fibers to achieve both low insertion loss and high return loss, which helps improve the transmission capability of the optical communication system.

[0009] In conjunction with the first aspect, in one possible implementation, the first optical fiber includes a first segment with a first end. The circumferential surface of the first segment has a first recess for accommodating a connector. In this implementation, taking into full account that the diameter of the first optical fiber, which is a hollow fiber, is often larger than the diameter of a solid fiber, the first recess at the end of the first optical fiber facilitates the connection between the first optical fiber and the second optical fiber via the connector.

[0010] In conjunction with the first aspect, in one possible implementation, the connector is fixedly connected to the circumferential surface of the second end and is an integral structure with the second optical fiber. The connector is not fixedly connected to the first end. In this implementation, the connector and the second optical fiber can be fabricated as an integral structure in advance, and then the connector is connected to the first optical fiber. Since the connector is not fixedly connected to the first end, it is also possible to avoid affecting the part where the optical fiber connection is established between the first end and the second end. For example, it is possible to avoid damage to the optical fiber connection caused by the high temperature of the fusion splicing process.

[0011] In conjunction with the first aspect, in one possible implementation, the second optical fiber includes a second segment with a second end. The circumferential surface of the second segment has a second recess for accommodating the connector. This allows the connector to be embedded in the second recess of the second optical fiber, improving the fit between the connector and the second optical fiber, and also enhancing the integrity of the connector and the second optical fiber when they are integrally structured.

[0012] In conjunction with the first aspect, in one possible implementation, the mode field diameter at the second end of the second optical fiber is not equal to the mode field diameter at the third end of the second optical fiber. The second and third ends are located at opposite ends of the second optical fiber. In this implementation, the mode field diameter at the second end of the second optical fiber can be matched with the mode field diameter at the first end of the first optical fiber, while the mode field diameter at the third end of the second optical fiber can be matched with the mode field diameter of the solid-core transmission fiber in the optical communication system. The mode field diameter at the first end of the first optical fiber can be matched with the mode field diameter of the hollow-core transmission fiber in the optical communication system, thereby improving the coupling efficiency in the optical communication system, achieving lower insertion loss, and meeting the chain transmission requirements of the optical communication system.

[0013] In conjunction with the first aspect, in one possible implementation, the fiber optic connector further includes a third fiber. The third end of the second fiber is optically connected to the fourth end of the third fiber, with the second and third ends located at opposite ends of the second fiber. The mode field diameter of the fourth end of the third fiber is not equal to the mode field diameter of the fifth end of the third fiber, with the fourth and fifth ends located at opposite ends of the third fiber. In this implementation, the second and third fibers can be used as fiber optic adapters between hollow-core and solid-core fibers. Exemplarily, the second fiber is a solid-core fiber with a mode field diameter matched to that of the first fiber, and the third fiber is a fiber with different mode field diameters at both ends, such as a tapered fiber or a thermally expanded fiber. Thus, the mode field diameter of the fourth end of the third fiber can be matched with the mode field diameter of the second fiber, and the mode field diameter of the fifth end of the third fiber can be matched with the mode field diameter of the solid-core transmission fiber in the optical communication system, improving the coupling efficiency in the optical communication system and achieving lower insertion loss.

[0014] In conjunction with the first aspect, in one possible implementation, the connecting portion surrounds the circumferential surface of the first end and the circumferential surface of the second end. The connecting portion is fixedly connected to an annular surface along the circumferential direction of the first optical fiber or to an annular surface along the circumferential direction of the second optical fiber. Thus, exemplarily, the connecting portion is a cylindrical structure, which can be connected to the annular surfaces along the circumferential direction of the first optical fiber and the second optical fiber, improving the structural stability of the connecting portion being fixedly connected to the first and second optical fibers respectively. Furthermore, taking the cylindrical structure of the connecting portion as an example, this implementation can also cover the circumferential surfaces of the first and second ends, sealing the first and second ends relative to the outside of the optical fiber connector, preventing contaminants such as dust and moisture from entering the optical fiber connection, and improving the operational stability of the optical communication system.

[0015] In conjunction with the first aspect, in one possible implementation, an anti-reflection coating is provided on the radial surface of the second end. In this implementation, the anti-reflection coating helps reduce back reflection, thereby achieving high return loss of the optical fiber connection. Since the connector is not fused to the second end used to establish the optical fiber connection, the high temperature of the fusion splice can be avoided from damaging the anti-reflection coating located at the second end, ensuring high return loss of the optical fiber connection.

[0016] In conjunction with the first aspect, in one possible implementation, the angle between the radial surface of the first end and the radial surface of the second end is greater than zero. In this implementation, 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, which is a solid-core optical fiber, is tilted, which can reduce back reflection and thus further increase the high return loss of the optical fiber connection.

[0017] In conjunction with the first aspect, in one possible implementation, the material of the connector includes any one of phosphate, vanadate, bismuthate, and silicon dioxide. This facilitates fusion splicing of the connector to the first or second optical fiber, achieving a fixed connection.

[0018] Secondly, embodiments of this application provide an optical communication system, which includes a first transmission optical fiber, a second transmission optical fiber, and an optical fiber connector as described in any 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 to the first transmission optical fiber, and the second optical fiber is connected to the second transmission optical fiber.

[0019] The technical effects of the design methods provided in the second aspect can be seen in the technical effects of the different design methods in the first aspect, which will not be repeated here. Attached Figure Description

[0020] Figure 1 An architecture diagram of an optical communication system provided in this application embodiment;

[0021] Figure 2 A cross-sectional view of the fiber optic connector provided in an embodiment of this application along the fiber extension direction;

[0022] Figure 3 for Figure 2 A cross-sectional view of the fiber optic connector in the illustrated embodiment along the AA' direction.

[0023] Figure 4 for Figure 2 A cross-sectional view of the fiber optic connector in the illustrated embodiment along the BB' direction.

[0024] Figure 5 Another structural cross-sectional view of the fiber optic connector provided in the embodiment of this application along the fiber extension direction;

[0025] Figure 6 Another structural cross-sectional view of the fiber optic connector provided in the embodiments of this application along the fiber extension direction;

[0026] Figure 7 Another structural cross-sectional view of the fiber optic connector provided in the embodiments of this application along the fiber extension direction;

[0027] Figure 8 Another structural cross-sectional view of the fiber optic connector provided in the embodiments of this application along the fiber extension direction;

[0028] Figure 9 This is another structural cross-sectional view of the fiber optic connector provided in the embodiments of this application along the fiber extension direction. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0030] To facilitate a clear description of the technical solutions in the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different.

[0031] In describing some embodiments, the term "connection" and its derivative expressions are used. The term "connection" should be interpreted broadly; for example, "connection" can be a fixed connection, a detachable connection, or an integral part of a structure. "Connection" can be a direct link or an indirect link through an intermediate medium. In specific contexts, "connection" has corresponding meanings. For example, "connection" can refer to an optical fiber connection between two optical fibers, specifically a connection method for transmitting signals via optical fibers.

[0032] In the embodiments of this application, the positional relationships described by terms such as "inner" and "outer" can be relative concepts, and are not limited to the definitions derived from the indicated placement of components in the accompanying drawings. The specific meanings of these directional terms can change accordingly depending on the placement of the components in the accompanying drawings. In the accompanying drawings, for clarity, the thickness of layers and regions is exaggerated, and the dimensional proportions between the parts in the drawings do not reflect the actual dimensional proportions.

[0033] Figure 1 This is an architecture diagram of an optical communication system provided in an embodiment of this application.

[0034] like Figure 1As shown in the figure, this application provides an optical communication system 1000, which includes a first transmission optical fiber 100, a second transmission optical fiber 200, and an optical fiber connector 300.

[0035] In some optional embodiments, the first transmission fiber 100 is a hollow-core fiber, and the second transmission fiber 200 is a solid-core fiber. The fiber optic connector 300 is used to connect the first transmission fiber 100 and the second transmission fiber 200. In some optional embodiments, the fiber optic connector 300 can be connected to the first transmission fiber 100 or the second transmission fiber 200 via a cold splice. Exemplarily, the cold splice method may include, but is not limited to, mechanical cold splicing, fiber breakage cold splicing, and optical bonding. Taking mechanical cold splicing as an example, the two fibers can be precisely aligned using a mechanical device and fixed using a mechanical clamp or mechanical connector to achieve the fiber optic connection.

[0036] Optionally, the first transmission fiber 100 may also include a solid fiber. In some examples, the second transmission fiber 200 is a combination of hollow and solid fibers to achieve long-distance signal transmission.

[0037] In some optional embodiments, the first transmission fiber 100 can be an optical cable used for long-distance transmission in the optical communication system 1000, and the second transmission fiber 200 can be a pigtail used by the optical communication equipment in the optical communication system 1000 to connect with the outside world.

[0038] In the embodiments of this application, hollow-core optical fiber is an optical fiber with a cylindrical hollow structure in its core or core layer, and the hollow structure is used for optical transmission. Solid-core optical fiber is an optical fiber with a solid core or core layer, and the solid structure is used for optical transmission.

[0039] The fiber optic connector 300 includes a first optical fiber and a second optical fiber. The first optical fiber is a hollow-core optical fiber, and the second optical fiber is a solid-core optical fiber. The first optical fiber is connected to the first transmission optical fiber 100, and the second optical fiber is connected to the second transmission optical fiber 200.

[0040] 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.

[0041] In the embodiments of this application, "equal" includes absolute equality and approximate equality, wherein approximate equality can be, for example, the difference between two equal persons being less than or equal to 5% of either one.

[0042] In some optional examples, such as Figure 1As shown, the optical communication system 1000 may further include a transmitter 400 and a receiver 500. The transmitter 400 is equipped with optical communication equipment for transmitting optical signals, and the receiver 500 is equipped with optical communication equipment for receiving optical signals. The pigtails of both the transmitter 400 and receiver 500 are second transmission optical fibers 200, and the optical cable used for long-distance transmission is a first transmission optical fiber 100. For example, the transmitter 400 is connected to an optical fiber connector 300 via the first transmission optical fiber 100. This connector 300 is connected to one end of the second transmission optical fiber 200, and the other end of the second transmission optical fiber 200 is connected to the first transmission optical fiber 100 (which serves as the pigtail of the receiver 500) via another optical fiber connector 300. This combines solid-core and hollow-core optical fibers to form a complete optical transmission link in the optical communication system 1000.

[0043] Through the above embodiments, the first optical fiber, which is a hollow fiber in the optical fiber connector 300, can be matched and connected with the first transmission optical fiber 100, which is a hollow fiber in the optical communication system 1000, and the second optical fiber, which is a solid fiber in the optical fiber connector 300, can be matched and connected with the second transmission optical fiber 200, which is a solid fiber in the optical communication system 1000. Thus, when the optical cable in the optical communication system 1000 uses hollow fiber and the pigtail of the optical communication equipment uses solid fiber, the optical communication connection between the optical cable and the optical communication equipment can be achieved efficiently and quickly.

[0044] In various applications of hollow-core optical fibers, coupling with traditional solid-core optical fibers is unavoidable. Taking the aforementioned optical communication system 1000 as an example, the hollow-core optical fiber used as the first transmission fiber 100 has low-loss anti-resonance characteristics, and its core diameter is generally around 30 μm. However, the mode field diameter of the solid-core optical fiber used as the second transmission fiber 200 is around 10 μm. The mode fields of the larger-diameter hollow-core fiber and the smaller-diameter solid-core fiber do not match. Therefore, by connecting the two ends of the optical fiber connector 300 to the first transmission fiber 100 and the second transmission fiber 200, mode field matching between the hollow-core and solid-core optical fibers in the optical communication system 1000 can be achieved.

[0045] In the embodiments of this application, the matching between optical fibers, or the matching between the mode fields or mode field diameters of optical fibers, can refer to the fact that the mode field diameters of the two connected optical fibers are equal or similar at the optical fiber connection point.

[0046] 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.

[0047] 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.

[0048] Therefore, the transmission capability of the aforementioned optical communication system 1000 needs to be improved.

[0049] Figure 2 This is a cross-sectional view of the fiber optic connector 300 provided in an embodiment of this application along the fiber extension direction. Figures 3-4 for Figure 2 Some structural cross-sectional views of the fiber optic connector 300 in the illustrated embodiment along the radial direction of the fiber.

[0050] In view of this, embodiments of this application propose an optical fiber connector 300, such as... Figure 2 As shown, the fiber optic 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.

[0051] 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.

[0052] like Figure 3 As shown, 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.

[0053] In this embodiment, "circumferential direction" can be selectively defined as the direction surrounding the optical axis of the optical fiber, and the "circumferential direction" of the optical fiber intersects with the extension direction of the optical fiber. For example, the "circumferential direction" of the optical fiber is perpendicular to the extension direction of the optical fiber.

[0054] In some optional embodiments, the size of the area where the connector 3 is fixedly connected to the circumferential surface of the first optical fiber 1 along the extension direction of the optical fiber (including the first optical fiber 1 and the second optical fiber 2) is not less than 0.5 mm and not more than 10 mm. For example, the size of the area where the connector 3 is fixedly connected to the circumferential surface of the first optical fiber 1 along the extension direction of the optical fiber may include, but is not limited to, the following: 0.5 mm, 1 mm, 3 mm, 5 mm, 10 mm.

[0055] like Figure 4 As shown, the connecting part 3 is fixedly connected to the circumferential surface of the second optical fiber 2. P2 is the location where the connecting part 3 is fixedly connected to the circumferential surface of the second optical fiber 2.

[0056] In some optional embodiments, the size of the area where the connector 3 is fixedly connected to the circumferential surface of the second optical fiber 2 along the extension direction of the optical fiber is not less than 0.5 mm and not more than 10 mm. For example, the size of the area where the connector 3 is fixedly connected to the circumferential surface of the second optical fiber 2 along the extension direction of the optical fiber may include, but is not limited to, the following: 0.5 mm, 1 mm, 3 mm, 5 mm, 10 mm.

[0057] In some optional embodiments, the connecting part 3 is fixedly connected to the circumferential surface of the first optical fiber 1 by fusion splicing or bonding, and the connecting part 3 is fixedly connected to the circumferential surface of the second optical fiber 2 by fusion splicing or bonding. Fusion splicing is a technique that connects two or more objects together by heating or applying pressure.

[0058] In some examples, the material of the connector 3 can be a material whose melting point is not higher than that of the first optical fiber 1 or the second optical fiber 2. The material of the connector 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 connector 3 can be different from the material of the first optical fiber 1 or the second optical fiber 2.

[0059] An optical fiber comprises a core and a cladding that surrounds the core, with the cladding material being the primary material. Unless otherwise specified, the material of the optical fiber refers to the material of the cladding, and the circumferential surface of the cladding is fixedly connected to the connector 3. For example, the core 1R of the first optical fiber has a diameter of 30 μm, and the cladding diameter is 235 μm. Similarly, the core 2R of the second optical fiber has a diameter of 10 μm, and the cladding diameter is 235 μm.

[0060] In some alternative embodiments, the material of the connecting portion 3 includes any one of phosphate, vanadate, bismuthate, and silicon dioxide.

[0061] In some alternative embodiments, the material of the first optical fiber 1 may include, but is not limited to, silicon dioxide, and the material of the second optical fiber 2 may include, but is not limited to, silicon dioxide.

[0062] For example, the main materials of the first optical fiber 1, the second optical fiber 2, and the connecting part 3 are all silicon dioxide. By heating a specific part of the circumferential surface of the connecting part 3 and the first optical fiber 1 at high temperature, the connecting part 3 and the circumferential surface of the first optical fiber 1 can be fixedly connected. Similarly, by heating a specific part of the circumferential surface of the connecting part 3 and the second optical fiber 2 at high temperature, the connecting part 3 and the circumferential surface of the second optical fiber 2 can be fixedly connected.

[0063] In some alternative embodiments, the connector 3 has a cylindrical structure. Thus, the connector 3 can be sleeved onto the location where the first optical fiber 1 and the second optical fiber 2 establish an optical fiber connection, thereby forming a ring-shaped cover over the circumferential surfaces of the first optical fiber 1 and the second optical fiber 2, which helps to improve the structural stability of the connection and the sealing of the optical fiber connection.

[0064] In some alternative embodiments, the cross-sectional shape of the connector 3 is C-shaped along the radial direction of the optical fiber. The structural stability of the connector 3 in fixing the first optical fiber 1 and the second optical fiber 2 can also be improved by matching the shape of the circumferential surfaces of the connector 3 with those of the first optical fiber 1 and the second optical fiber 2. Exemplarily, the connector 3 is a three-quarter sleeve, and the cross-sectional shape of the connector 3 is three-quarter circular along the radial direction of the optical fiber.

[0065] In some alternative embodiments, one end of the connector 3 along the fiber extension direction is fixedly connected to the circumferential surface of the first optical fiber 1, and the other end of the connector 3 along the fiber extension direction is fixedly connected to the circumferential surface of the second optical fiber 2.

[0066] In some alternative embodiments, the distance between the portion of the connector 3 that is fixedly connected to the first optical fiber 1 and both ends of the connector 3 along the optical fiber extension direction is greater than zero. Similarly, the distance between the portion of the connector 3 that is fixedly connected to the second optical fiber 2 and both ends of the connector 3 along the optical fiber extension direction is greater than zero.

[0067] Traditional fiber optic cold splicing methods typically use mechanical clamps or connectors to fix solid-core and hollow-core optical fibers. Compared to traditional fiber optic cold splicing methods, the fiber optic connector 300 in the above embodiment uses the connecting part 3 to fix the first optical fiber 1 and the second optical fiber 2 together, which can improve the structural stability and reliability of the fiber optic connector 300.

[0068] In some alternative embodiments, the connector 3 is not fixedly connected to the first end 11. Specifically, the portion of the first optical fiber 1 that is fixedly connected to the connector 3 has a first distance greater than zero from the first end 11.

[0069] In some alternative embodiments, the connector 3 is not fixedly connected to the second end 22. Specifically, the portion of the second optical fiber 2 that is fixedly connected to the connector 3 has a second distance greater than zero from the second end 22.

[0070] For example, the connecting part 3 is not fixedly connected to the first end 11 and not fixedly connected to the second end 22.

[0071] Through the above embodiments, the first end 11 and the second end 22 are used to establish an optical fiber connection. The connection part 3 is not fixedly connected to the first end 11 or the second end 22 for establishing the optical fiber connection, which can reduce the damage to the structural characteristics of the first end 11 or the second end 22 and help improve the connection performance between hollow optical fiber and solid optical fiber.

[0072] For example, if the connection between the connector 3 and the first optical fiber 1 and the connector 3 and the second optical fiber 2 are fixedly connected by fusion splicing, and the connector 3 is not fixedly connected to 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 from damaging the first end 11 or the second end 22. This allows the optical fiber connection between the hollow optical fiber and the solid optical fiber to take into account both low insertion loss and high return loss, which helps to improve the transmission capability of the optical communication system 1000.

[0073] In some alternative embodiments, such as Figure 3 As shown, the connecting portion 3 surrounds the circumferential surface of the first end 11. Figure 4 As shown, the connecting part 3 surrounds the circumferential surface of the second end 22.

[0074] In the embodiments of this application, the connecting part 3 is fixedly connected to the annular surface along the circumference of the first optical fiber 1, or fixedly connected to the annular surface along the circumference of the second optical fiber 2.

[0075] For example, the connecting part 3 is a cylindrical structure, which can be connected to 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, thereby improving the structural stability of the connecting part 3 being fixedly connected to the first optical fiber 1 and the second optical fiber 2 respectively.

[0076] Taking the connection part 3 as a cylindrical structure as an example, in this embodiment of the application, the connection part 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, preventing dust, water vapor and other pollutants from entering the optical fiber connection and improving the working stability of the optical communication system 1000.

[0077] like Figure 2 As shown, in the first example provided in the above embodiment, the first optical fiber 1 is a hollow-core optical fiber with a cladding diameter of 235 μm and a mode field diameter of 24 μm. The connector 3 is fixedly connected to the circumferential surface of the first optical fiber 1 by fusion splicing, wherein the portion P1 where the connector 3 is fixedly connected to the first optical fiber 1 is the fusion splice area.

[0078] In the first example, the connector 3 is a glass sleeve, and its dimensions are 100 mm along the direction of optical fiber extension. The inner surface diameter of the connector 3 is 235 μm, and the outer surface diameter is 300 μm.

[0079] In the first example, the mode field diameters at the two ends of the second optical fiber 2 are different. The second optical fiber 2 is a thermally expanded core optical fiber, the cladding diameter of the second optical fiber 2 is 235 μm, the mode field diameter at the second end 22 of the second optical fiber 2 is 24 μm, and the mode field diameter at the third end 23 of the second optical fiber 2 is 9 μm.

[0080] In the first example, the solid fiber used in the communication system to connect to the third end 23 of the second optical fiber 2 can be a single-mode solid fiber with a cladding diameter of 125 μm and a mode field diameter of 9 μm.

[0081] In some optional embodiments, the fiber optic connector further includes a housing. The housing has a cavity for accommodating the first optical fiber 1, the second optical fiber 2, and the connector 3. Exemplarily, the housing can be made of a rigid material as its primary material. This embodiment allows the housing to protect the first optical fiber 1, the second optical fiber 2, and the connector 3, thereby preventing bending at the fixed connection between the connector 3 and the first optical fiber 1, or between the connector 3 and the second optical fiber 2. This reduces the risk of failure in the fixed connection between the connector 3 and the first optical fiber 1, or between the connector 3 and the second optical fiber 2, thus improving the structural stability of the fiber optic connector 300.

[0082] Figure 5 Another structural cross-sectional view of the fiber optic connector 300 provided in the embodiment of this application along the fiber extension direction.

[0083] In some optional embodiments, the distance between one end of the connecting portion 3 and the first end is equal to the distance between the other end of the connecting portion 3 and the second end. This allows for improved structural stability of the fiber optic connector 300 by leveraging the symmetry of the connecting portion 3 at the fiber optic connection point. For example, the size of the connecting portion 3 for fitting the first fiber 1 can be made equal to the size for fitting the second fiber 2, thereby ensuring that the fixing effect on the first fiber 1 and the second fiber 2 is the same or similar, improving the stability of the fixed connection between the connecting portion 3 and the first fiber 1, and the fixed connection between the connecting portion 3 and the second fiber 2.

[0084] 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.

[0085] In some optional embodiments, the first spacing in the above embodiments is equal to the second spacing in the above embodiments. Therefore, the structural stability of the fiber optic connector 300 can be improved by utilizing the symmetry of the portions used for fixed connection in the first fiber 1 and the second fiber 2.

[0086] For example, the length of the connecting part 3 is 100mm, the distance between the part where the first optical fiber 1 is fixedly connected to the connecting part 3 and the first end 11 is 45mm, and the distance between the part where the second optical fiber 2 is fixedly connected to the connecting part 3 and the second end 22 is 45mm.

[0087] In some alternative embodiments, the first spacing and the second spacing are not equal. For example, the first spacing is greater than the second spacing. Thus, by setting the connection part 3 at a specific position, the special requirements for optical signal transmission can be met, and the connection part 3 can be made to minimize its impact on the normal transmission of optical signals.

[0088] For example, the length of the connector 3 is 100mm, and the distance between the part of the first optical fiber 1 that is fixedly connected to the connector 3 and the first end 11 is 55mm. The distance between the part of the second optical fiber 2 that is fixedly connected to the connector 3 and the second end 22 is 35mm.

[0089] like Figure 5 As shown, in some optional embodiments, the distance between the part of the connecting portion 3 that 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.

[0090] like Figure 5 As shown, the distance between the part of the connecting part 3 that is fixedly connected to the second optical fiber 2 and the end of the connecting part 3 is greater than zero, or in other words, the end of the connecting part 3 is not fixedly connected to the second optical fiber 2.

[0091] In some alternative embodiments, one end of the connector 3 is fixedly connected to the first optical fiber 1, and the other end of the connector 3 is fixedly connected to the second optical fiber 2.

[0092] In some optional embodiments, the ratio of the distance between the portion of the connector 3 that is fixedly connected to the first optical fiber 1 and the end of the connector 3 to the length of the connector is less than one-half. For example, the ratio of the distance between the portion of the connector 3 that is fixedly connected to the first optical fiber 1 and the end of the connector 3 to the length of the connector is, but is not limited to, one of the following: 0, 1 / 10, 1 / 5, 3 / 10, or 2 / 5.

[0093] like Figure 5 As shown, 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. The second end 22 and the third end 23 are located at opposite ends of the second optical fiber 2.

[0094] For example, 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.

[0095] In some alternative implementations, the type of the second optical fiber 2 may include, but is not limited to, tapered optical fiber, thermally expanded core optical fiber (e.g., Figure 2 (As shown) or graded-index fiber. All of the above types of optical fibers are solid-core fibers.

[0096] Among them, graded-index fiber, also known as self-focusing fiber, has the highest refractive index at the center of the fiber, which decreases radially. When a beam of light propagates in the fiber, it can automatically focus without dispersion.

[0097] In this embodiment of the application, by adjusting the refractive index of different parts of the optical fiber, different sections of the optical fiber can be made to 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.

[0098] In some alternative 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.

[0099] 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, while 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 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 transmission optical fiber in the optical communication system 1000. This improves the coupling efficiency in the optical communication system 1000, achieves lower insertion loss, and meets the chain transmission requirements of the optical communication system 1000.

[0100] like Figure 5 As shown, in some optional embodiments, the first optical fiber 1 includes a first segment with a first end 11 at its end. The circumferential surface of the first segment has a first recess for accommodating the connector 3.

[0101] In some alternative embodiments, the first recess is an annular recess along the circumference of the first section, and the connecting part 3 is a cylindrical structure.

[0102] In some examples, the diameter of the columnar structure formed on the bottom surface of the annular recess is equal to the diameter of the inner wall of the connector 3 with the cylindrical structure, so that the connector 3 fits into the first recess, thereby improving the structural stability of the fixed connection between the first optical fiber 1 and the connector 3.

[0103] In some other 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 of the connecting part 3, which is a cylindrical structure. This facilitates the assembly of the connecting part 3 with the first segment of the first optical fiber 1. The phrase "the value M is slightly larger than the value N" can selectively refer to the difference between the value M and the value N, with the ratio between M and N being between 0% and 5%.

[0104] In some alternative implementations, the first recess may be formed by polishing the circumferential surface of the first section.

[0105] Through the above embodiments, considering that the diameter of the first optical fiber 1, which is a hollow optical fiber, is often larger than the diameter of the solid optical fiber, a first recess is provided at the end of the first optical fiber 1. The diameter of the first optical fiber 1 at the first recess is smaller than the original diameter of the first optical fiber 1. The connecting part 3 is embedded in the first recess, so that the connecting part 3 is flush with the connection position of the first optical fiber 1 and the second optical fiber 2, thereby facilitating the connection of the structure between the first optical fiber 1 and the second optical fiber 2 through the connecting part 3.

[0106] Figure 6 This is another structural cross-sectional view of the fiber optic connector 300 provided in the embodiments of this application along the fiber extension direction.

[0107] like Figure 6 As shown, in some optional embodiments, the connecting part 3 is fixedly connected to the circumferential surface of the second end 22 and is an integral structure with the second optical fiber 2.

[0108] Specifically, in practical applications, the integrated structure formed by the connector 3 and the second optical fiber 2 can be obtained by etching grooves into the radial surface of the end of the solid optical fiber. Therefore, the material of the connector 3 can be the same as the cladding material of the second optical fiber 2.

[0109] The connecting portion 3 is not fixedly connected to the first end 11. For example, the connecting portion 3 is fixedly connected to the circumferential surface of the first recess of the first optical fiber 1, and the distance between the part of the connecting portion 3 that is fixedly connected to the first optical fiber 1 and the first end 11 is greater than zero.

[0110] Through the above embodiments, the connector 3 and the second optical fiber 2 can be prefabricated as an integral structure, skipping the fusion splicing process between the connector 3 and the second optical fiber 2, thus avoiding adverse effects on the optical properties of the radial surface of the second end 22 used to establish the optical fiber connection. Furthermore, by fixing the connector 3 to the first optical fiber 1 instead of to the first end 11, adverse effects on the optical properties of the radial surface of the second end 22 used to establish the optical fiber connection can also be avoided. For example, the high temperature of the fusion splicing process or the adhesive of the bonding process can be prevented from altering the optical characteristics of the optical fiber connection.

[0111] like Figure 6 As shown, 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. A first recess is provided in the first segment of the first optical fiber 1 with the first end 11 as the end.

[0112] In the second example, along the direction of fiber extension, the size of the first segment 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.

[0113] In the second example, the connector 3 is fixedly connected to the circumferential surface of the first optical fiber 1 at the first recess by means of fusion splicing, wherein the part P1 where the connector 3 is fixedly connected to the first optical fiber 1 is the fusion splice area.

[0114] In the second example, the connector 3 and the second optical fiber 2 are integrally formed. The connector 3 has a dimension of 40 mm along the direction of optical fiber extension. The inner surface diameter of the connector 3 is 175 μm, and the outer surface diameter is 235 μm.

[0115] In the second example, the mode field diameters at the two ends of the second fiber 2 are different. For example... Figure 6 As shown, the second optical fiber 2 is a thermally expanded core optical fiber. A second recess with a depth of 30 μm is provided in the second section of the second optical fiber 2, with the second end 22 as its end point. Half of the connector 3 is fitted onto the first section of the first optical fiber 1, and the other half of the connector 3 is fitted onto the second section of the second optical fiber 2, with the connector 3 and the second section forming an integral structure. Along the fiber's extension direction, the second section has a dimension of 20 mm, and the cladding diameter of the second optical fiber 2 at the second recess is 175 μm. In the section of the second optical fiber 2 with the second end 22 as its end point, the cladding diameter at the point without the second recess is 235 μm. The mode field diameter at the second end 22 of the second optical fiber 2 is 24 μm, and the mode field diameter at the third end 23 of the second optical fiber 2 is 9 μm.

[0116] In the second example, the solid fiber used in the optical communication system to connect to the second end 22 of the second optical fiber 2 can be a single-mode solid fiber with a cladding diameter of 125 μm and a mode field diameter of 9 μm.

[0117] Figure 7 This is another structural cross-sectional view of the fiber optic connector 300 provided in the embodiments of this application along the fiber extension direction.

[0118] like Figure 7 As shown, in some optional embodiments, the second optical fiber 2 includes a second segment with a second end 22 at its end. The circumferential surface of the second segment has a second recess for accommodating the connector 3.

[0119] In some alternative embodiments, the second recess is an annular recess along the circumference of the second section, and the connecting part 3 is a cylindrical structure.

[0120] like Figure 7 As shown, in some examples, the first optical fiber 1 is provided with a first recess and the second optical fiber 2 is provided with a second recess, so the connector 3 can be embedded in the first recess and the second recess.

[0121] In some alternative implementations, the second recess may be formed by polishing the circumferential surface of the second section.

[0122] Through the above embodiments, the connecting part 3 can be embedded in the second recess of the second optical fiber 2, thereby improving the fit between the connecting part 3 and the second optical fiber 2 and thus improving the structural stability of the connection between the connecting part 3 and the second optical fiber 2.

[0123] In some other examples, the connecting part 3 can be integrated with the bottom surface of the second recess as a single structure.

[0124] 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 of the connector 3 with the cylindrical structure. The diameter of the outer wall of the connector 3 with the cylindrical structure is equal to the diameter of the first optical fiber 1. Therefore, it is convenient to obtain an integral structure formed by connecting the connector 3 and the second optical fiber 2 by etching grooves into the radial surface of the end of the solid optical fiber (e.g., ...). Figure 6 (As shown).

[0125] 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 integrated into one structure, and the fabrication of the integrated structure formed by connecting the connecting part 3 and the second optical fiber 2 can be facilitated.

[0126] like Figure 7As shown, in the third example provided in the above embodiment, the first optical fiber 1 is a hollow 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.

[0127] In the third example, a first recess is provided in a first segment of the first optical fiber 1 with the first end 11 as the end. Along the direction of optical fiber extension, the size of the first segment is 50 mm, 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.

[0128] In the third example, the connector 3 is fixedly connected to the circumferential surface of the first optical fiber 1 at the first recess by means of fusion splicing, wherein the part P1 where the connector 3 is fixedly connected to the first optical fiber 1 is the fusion splice area.

[0129] In the third example, the connector 3 is a glass sleeve, and its dimensions are 100 mm along the direction of optical fiber extension. The inner surface diameter of the connector 3 is 175 μm, and the outer surface diameter is 235 μm.

[0130] In the third example, the mode field diameters at both ends of the second fiber 2 are not equal. For example... Figure 7 As shown, the second optical fiber 2 is a tapered optical fiber. A second recess is provided in the second section of the second optical fiber 2 at its second end 22, with a depth of 30 μm. Along the extension direction of the fiber, the dimension of the second section or the second recess is 50 mm, and the cladding diameter of the second optical fiber 2 at the second recess is 175 μm. In the section of the second optical fiber 2 at its second end 22, the cladding diameter at the point without the second recess is 235 μm. The cladding diameter of the second optical fiber 2 at its third end 23 is 125 μm. The second end 22 is the non-tapered end, and the third end 23 is the tapered end. The mode field diameter at the second end 22 of the second optical fiber 2 is 24 μm, and the mode field diameter at the third end 23 of the second optical fiber 2 is 9 μm.

[0131] In the third example, the solid fiber used in the optical communication system to connect to the second end 22 of the second optical fiber 2 can be a single-mode solid fiber with a cladding diameter of 125 μm and a mode field diameter of 9 μm.

[0132] Figure 8 This is another structural cross-sectional view of the fiber optic connector 300 provided in the embodiments of this application along the fiber extension direction.

[0133] like Figure 8As shown, in some optional embodiments, the fiber optic connector 300 further includes a third fiber 4. The third end 23 of the second fiber 2 is optically connected to the fourth end 44 of the third fiber 4, with the second end 22 and the third end 23 located at opposite ends of the second fiber 2. The mode field diameter of the fourth end 44 of the third fiber 4 is not equal to the mode field diameter of the fifth end 45 of the third fiber 4, with the fourth end 44 and the fifth end 45 located at opposite ends of the third fiber 4.

[0134] In some alternative 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 at its two ends are different.

[0135] 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.

[0136] In some examples, the type of the third fiber 4 can include, but is not limited to, tapered fiber, thermally expanded fiber (e.g., Figure 8 (As shown) or graded-index optical fiber. Different types of optical fibers exhibit differences in the characteristics of their core or cladding.

[0137] For example, such as Figure 7 As shown, along the direction of fiber extension, the core diameter of a tapered fiber can initially remain constant and then gradually decrease, with the cladding diameter matching the core diameter. Specifically, if the core diameter of the tapered fiber remains constant, the diameter of the cladding surrounding that portion of the core remains constant; if the core diameter of the tapered fiber gradually decreases, the diameter of the cladding surrounding that portion of the core gradually decreases.

[0138] For example, such as Figure 8 As shown, along the direction of fiber extension, the core diameter of the thermally expanded fiber can remain constant at first and then gradually decrease, while the cladding diameter of the thermally expanded fiber remains constant (without considering the fiber recess).

[0139] Through the above embodiments, the second optical fiber 2 and the third optical fiber 4 can be used as optical fiber adapters between hollow-core and solid-core optical fibers. Therefore, the mode field diameter of the fourth end 44 of the third optical fiber 4 can be matched with 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 be matched with the mode field diameter of the solid-core transmission optical fiber in the optical communication system 1000. This improves the coupling efficiency in the optical communication system 1000 and achieves lower insertion loss.

[0140] like Figure 8As shown, in the fourth example provided in the above embodiment, the first optical fiber 1 is a hollow 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.

[0141] In the fourth example, the connector 3 is fixedly connected to the circumferential surface of the first optical fiber 1 by fusion splicing, wherein the part P1 where the connector 3 is fixedly connected to the first optical fiber 1 is the fusion splice area.

[0142] In the fourth example, connector 3 is a glass sleeve, and its dimensions are 100 mm along the direction of optical fiber extension. The inner surface diameter of connector 3 is 235 μm, and the outer surface diameter is 300 μm.

[0143] In the fourth example, the mode field diameters at both ends of the second optical fiber 2 are the same. The cladding diameter of the second optical fiber 2 is 235 μm, and the mode field diameter is 24 μm. An anti-reflection coating is provided on the radial surface of the second end 22 of the second optical fiber 2. The connecting part 3 is fixedly connected to the circumferential surface of the second optical fiber 2 by fusion splicing. The fusion splicing area of ​​the second optical fiber 2 is the outer surface of the cladding, and the fixed connection point P2 between the connecting part 3 and the second optical fiber 2 is the fusion splice area.

[0144] In the fourth example, the mode field diameters at both ends of the third fiber 4 are different. The third fiber 4 is a thermally expanded core fiber, with a cladding diameter of 125 μm, a mode field diameter of 24 μm at its fourth end 44, and a mode field diameter of 9 μm at its fifth end 45.

[0145] In the fourth example, the solid fiber used in the optical communication system to connect to the fifth end 45 of the third fiber can be a single-mode solid fiber with a cladding diameter of 125 μm and a mode field diameter of 9 μm.

[0146] In the fifth example provided by the above embodiments, the main difference from the fourth example is that the connector 3 and the second optical fiber 2 are an integral structure. In the fifth example, 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.

[0147] In the fifth example, a first recess is provided in the first section of the first optical fiber 1 with the first end 11 as the end.

[0148] In the fifth example, along the direction of fiber extension, the size of the first segment 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.

[0149] In the fifth example, the connector 3 is fixedly connected to the circumferential surface of the first optical fiber 1 at the first recess by means of fusion splicing, wherein the part P1 where the connector 3 is fixedly connected to the first optical fiber 1 is the fusion splice area.

[0150] In the fifth example, the connector 3 and the second optical fiber 2 are integrally formed. The connector 3 has a dimension of 40 mm along the direction of optical fiber extension. The inner surface diameter of the connector 3 is 175 μm, and the outer surface diameter is 235 μm.

[0151] In the fifth example, the mode field diameters at both ends of the second optical fiber 2 are the same, and the mode field diameter of the second optical fiber 2 is 24 μm. A second recess is provided in the second section of the second optical fiber 2 with the second end 22 as its end, and the depth of the second recess is 30 μm. Half of the connector 3 is fitted onto the first section of the first optical fiber 1, and the other half of the connector 3 is fitted onto the second section of the second optical fiber 2, and the connector 3 and the second section are integrally formed. Along the extension direction of the optical fiber, the size of the second section is 20 mm, and the cladding diameter of the second optical fiber 2 at the second recess is 175 μm. In the section of the second optical fiber 2 with the second end 22 as its end, the cladding diameter at the section without the second recess is 235 μm.

[0152] In the fifth example, the mode field diameters at both ends of the third fiber 4 are different. The third fiber 4 is a thermally expanded core fiber or a tapered fiber, the maximum cladding diameter of the third fiber 4 is 125 μm, the mode field diameter at the fourth end 44 of the third fiber 4 is 24 μm, and the mode field diameter at the fifth end 45 of the third fiber 4 is 9 μm.

[0153] In the sixth example provided by the above embodiments, the main difference from the fourth example is that the first optical fiber 1 and the second optical fiber 2 are provided with recesses for accommodating the connector 3. In the sixth example, the first optical fiber 1 is a hollow-core optical fiber with a cladding diameter of 235 μm and a mode field diameter of 24 μm.

[0154] In the sixth example, a first recess is provided in a first segment of the first optical fiber 1 with the first end 11 as the end. Along the direction of optical fiber extension, the size of the first segment is 50 mm, 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.

[0155] In the sixth example, the connector 3 is fixedly connected to the circumferential surface of the first optical fiber 1 at the first recess by means of fusion splicing, wherein the part P1 where the connector 3 is fixedly connected to the first optical fiber 1 is the fusion splice area.

[0156] In the sixth example, connector 3 is a glass sleeve, and its dimensions are 100 mm along the direction of optical fiber extension. The inner surface diameter of connector 3 is 175 μm, and the outer surface diameter is 235 μm.

[0157] In the sixth example, the mode field diameters at both ends of the second optical fiber 2 are the same, and the mode field diameter of the second optical fiber 2 is 24 μm. A second recess is provided in the second section of the second optical fiber 2 with the second end 22 as its end, and the depth of the second recess is 30 μm. Half of the connector 3 is fitted onto the first section of the first optical fiber 1, and the other half of the connector 3 is fitted onto the second section of the second optical fiber 2. Along the extension direction of the optical fiber, the size of the second section is 50 mm, and the cladding diameter of the second optical fiber 2 at the second recess is 175 μm. In the section of the second optical fiber 2 with the second end 22 as its end, the cladding diameter at the section without the second recess is 235 μm.

[0158] In the sixth example, the mode field diameters at both ends of the third fiber 4 are different. The third fiber 4 is a thermally expanded core fiber or a tapered fiber, the maximum cladding diameter of the third fiber 4 is 125 μm, the mode field diameter at the fourth end 44 of the third fiber 4 is 24 μm, and the mode field diameter at the fifth end 45 of the third fiber 4 is 9 μm.

[0159] Figure 9 This is another structural cross-sectional view of the fiber optic connector 300 provided in the embodiments of this application along the fiber extension direction.

[0160] like Figure 9 As shown, in some optional embodiments, an anti-reflection coating 5 is provided on the radial surface of the second end 22. The anti-reflection coating 5 helps reduce back reflection, thereby achieving high return loss in the optical fiber connection.

[0161] In this design, the second optical fiber 2 is a solid-core optical fiber, and the anti-reflective coating 5 is disposed on the radial surface of the second end 22 of the second optical fiber 2. Therefore, placing the anti-reflective coating 5 on the end face of the solid-core optical fiber is less challenging than placing it on the end face of a hollow-core optical fiber, thus facilitating the application of the anti-reflective coating.

[0162] For example, the antireflective coating 5 can be formed by any of the following methods: chemical coating, physical vapor deposition, and magnetron sputtering.

[0163] In conjunction with the above embodiments, the connector 3 is not fused with the second end 22 used to establish the optical fiber connection. This avoids the high temperature of the fusion splice from damaging the anti-reflective coating layer located at the second end 22, ensuring high return loss of the optical fiber connection. For example, the return loss of the optical fiber connector 300 is greater than 40 dB.

[0164] In some alternative embodiments, the antireflective coating 5 may also be disposed on the radial surface of the first end 11 of the first optical fiber 1.

[0165] like Figure 9As shown, in some optional embodiments, the angle between the radial surface of the first end 11 and the radial surface of the second end 22 is greater than zero.

[0166] 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, which is a solid optical fiber, is tilted.

[0167] For example, the 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 more than 8°. For instance, 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 more than 8°.

[0168] Through the above embodiments, the angle between the end face of the first optical fiber 1 and the end face of the second optical fiber 2 can be used to further reduce back reflection, thereby increasing the high return loss of the optical fiber connection. For example, the return loss of the optical fiber connector 300 can be made greater than 40dB.

[0169] This application also provides an optical communication system 1000, which includes the fiber optic connector 300 from any of the above embodiments. This ensures low insertion loss and high return loss in the connection between the hollow-core and solid-core optical fibers in the optical communication system 1000, thereby improving the transmission performance of the optical communication system 1000.

[0170] This application also provides a method for manufacturing the fiber optic connector 300 in some of the above embodiments, which can be used, for example, to manufacture... Figure 2 The fiber optic connector 300 in the illustrated embodiment includes a method comprising:

[0171] Step S201: Provide a second initial optical fiber, which is a solid-core optical fiber. Perform thermal expansion on the second initial optical fiber so that the mode field diameter at one end of the thermally expanded core matches the mode field diameter of the hollow-core optical fiber in the optical communication system, forming a second optical fiber 2. The mode field diameter of the second initial optical fiber matches the mode field diameter of the solid-core optical fiber in the optical communication system.

[0172] In step S201 above, a second optical fiber 2 with unequal mode field diameters at both ends is formed by thermal expansion. Alternatively, step S201 above can be used to form the second optical fiber 2 by tapering the fiber. Specifically, this includes tapering one end of the second initial optical fiber so that the mode field diameter of the taper end of the second initial optical fiber matches the mode field diameter of the solid-core optical fiber in the optical communication system. Wherein, the mode field diameter of the second initial optical fiber matches the mode field diameter of the hollow-core optical fiber in the optical communication system.

[0173] Step S202: If the second optical fiber is a thermally expanded fiber, the thermally expanded end of the second optical fiber 2 is designated as the second end 22. If the second optical fiber is a tapered fiber, the untapered end of the second optical fiber 2 is designated as the second end 22. An anti-reflective coating is formed at the second end 22 of the second optical fiber 2. Exemplarily, the anti-reflective coating 5 can be formed by sputtering deposition.

[0174] Step S203: Provide a connector 3, and insert the second end 22 of the second optical fiber 2 into one end of the connector 3. Exemplarily, the connector 3 can be a glass sleeve. For example, the second end 22 of the second optical fiber 2 can be inserted into the connector 3 to the middle position of the connector 3.

[0175] Step S204: Fix the connector 3 to the second optical fiber 2. In some examples, the connector 3 is not fixedly connected to the second end 22 of the second optical fiber 2. For example, the connector 3 is fixedly connected to the second optical fiber 2 by fusion splicing, and the connector 3 is not fused to the second end 22 of the second optical fiber 2.

[0176] Step S205: Provide the first optical fiber 1 and insert the first end 11 of the first optical fiber 1 into the other end of the connector 3. Exemplarily, step S54 can selectively adjust the relative position between the connector 3 and the first optical fiber 1 so that the contact position between the connector 3 and the outer surface of the cladding of the first optical fiber 1 is located at the discharge position of the fusion splicing device.

[0177] Step S206: Adjust 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 to reduce the fiber optic splicing loss between the first optical fiber 1 and the second optical fiber 2. 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 be established 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 be, but is not limited to, any of the following values: 5μm, 10μm, 20μm, 50μm, 100μm.

[0178] Step S207: Fix the connector 3 to the first optical fiber 1. In some examples, the connector 3 is not fixedly connected to the first end 11 of the first optical fiber 1. For example, the connector 3 is fixedly connected to the first optical fiber 1 by fusion splicing, and the connector 3 is not fused to the first end 11 of the first optical fiber 1.

[0179] This application also provides a method for manufacturing the fiber optic connector 300 in some of the above embodiments, which can be used, for example, to manufacture... Figure 6The fiber optic connector 300 in the illustrated embodiment includes a method comprising:

[0180] Step S301: Provide a first initial optical fiber, which is a hollow-core optical fiber. Form a first depression on the circumferential surface of a first segment of the first initial optical fiber with the first end 11 as the end point, to obtain a first optical fiber 1 with the first depression. For example, polishing can be selected to remove part of the cladding on the circumferential surface of the first initial optical fiber in the first segment, thereby forming the first optical fiber 1 with the first depression.

[0181] Step S302: Provide a second initial optical fiber, which is a thermally expanded core optical fiber. A groove is formed on the radial surface of one end of the thermally expanded core of the second initial optical fiber to obtain a second optical fiber 2 with a groove. The bottom of the groove is the second end 22 of the second optical fiber 2, and the sidewall of the groove is the connecting portion 3. Exemplarily, the groove can be formed by laser drilling. For example, along the direction of optical fiber extension, the size of the groove is the same as the size of the first segment. The aperture of the groove is the same as the diameter of the first optical fiber 1 at the first recess.

[0182] Step S303: An anti-reflection film is formed at the second end 22 of the second optical fiber 2.

[0183] Step S304: Adjust the relative positions of the first optical fiber 1 and the second optical fiber 2 to reduce the optical fiber splicing loss between them. Then, fix the connector 3 to the first optical fiber 1. Alternatively, fix the first optical fiber 1 to the second optical fiber 2.

[0184] This application also provides a method for manufacturing the fiber optic connector 300 in some of the above embodiments, which can be used, for example, to manufacture... Figure 7 The fiber optic connector 300 in the illustrated embodiment includes a method comprising:

[0185] Step S401: Provide a first initial optical fiber, which is a hollow optical fiber. Form a first depression on the circumferential surface of a first segment of the first initial optical fiber with the first end 11 as the end, to obtain a first optical fiber 1 with the first depression.

[0186] Step S402: Provide a second initial optical fiber, which is a tapered optical fiber. A second recess is formed on the circumferential surface of a second segment of the second initial optical fiber to obtain a second optical fiber 2 with the second recess. The untapered end of the second initial optical fiber is designated as the second end 22, and the second segment ends at the second end 22.

[0187] Step S403: An anti-reflection film is formed at the second end 22 of the second optical fiber 2.

[0188] Step S404: Provide a connector 3 and insert the second end 22 of the second optical fiber 2 into one end of the connector 3.

[0189] Step S405: Fix the connection part 3 to the second optical fiber 2.

[0190] Step S406: Insert the first end 11 of the first optical fiber 1 into the other end of the insertion connector 3.

[0191] Step S407: Adjust 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 to reduce the optical fiber splicing loss between the first optical fiber 1 and the second optical fiber 2.

[0192] Step S408: Fix the connecting part 3 to the first optical fiber 1.

[0193] This application also provides a method for manufacturing the fiber optic connector 300 in some of the above embodiments, which can be used, for example, to manufacture... Figure 8 The fiber optic connector 300 in the illustrated embodiment includes a method comprising:

[0194] Step S501: Provide a second optical fiber 2, and form an anti-reflection film layer at the second end 22 of the second optical fiber 2.

[0195] Step S502: Provide a connector 3, and insert the second end 22 of the second optical fiber 2 into one end of the connector 3 from one end of the connector 3.

[0196] Step S503: Fix the connection part 3 to the second optical fiber 2.

[0197] Step S504: Provide a first optical fiber 1 and insert the first end 11 of the first optical fiber 1 into the other end of the connector 3.

[0198] Step S505: Adjust 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 to reduce the optical fiber splicing loss between the first optical fiber 1 and the second optical fiber 2.

[0199] Step S506: Fix the connector 3 to the first optical fiber 1. In some examples, the connector 3 is not fixedly connected to the first end 11 of the first optical fiber 1.

[0200] Step S507: Fix the third end 23 of the second optical fiber 2 to 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 fixedly connected by fusion splicing. For instance, 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 instance, the third optical fiber 4 is a thermally 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.

[0201] In the above embodiment, the mode field diameter of the first end 11 of the first optical fiber 1 in the optical fiber connector 300 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 other optical fibers can be established by cold splicing.

[0202] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Furthermore, with the evolution of architectures and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

Claims

1. An optical fiber connector, characterized in that, The fiber optic connector includes: The first optical fiber is a hollow-core optical fiber. The second optical fiber is a solid optical fiber; an optical fiber connection is established between the first end of the first optical fiber and the second end of the second optical fiber. The connecting part is fixedly connected to the circumferential surface of the first optical fiber and to the circumferential surface of the second optical fiber; the connecting part is not fixedly connected to the first end or not fixedly connected to the second end.

2. The fiber optic connector according to claim 1, characterized in that, The first optical fiber includes a first segment with the first end as its end; The circumferential surface of the first section has a first recess for accommodating the connecting portion.

3. The fiber optic connector according to claim 1 or 2, characterized in that, The connecting part is fixedly connected to the circumferential surface of the second end and is an integral structure with the second optical fiber; the connecting part is not fixedly connected to the first end.

4. The fiber optic connector according to any one of claims 1 to 3, characterized in that, The second optical fiber includes a second segment with the second end as its end; The circumferential surface of the second section has a second recess for accommodating the connecting portion.

5. The fiber optic connector according to any one of claims 1 to 4, characterized in that, The mode field diameter at the second end of the second optical fiber is not equal to the mode field diameter at 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.

6. The fiber optic connector according to any one of claims 1 to 4, characterized in that, The fiber optic connector also includes a third fiber optic cable; The third end of the second optical fiber is optically connected to the 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; The mode field diameter at the fourth end of the third optical fiber is not equal to the mode field diameter at the 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.

7. The fiber optic connector according to any one of claims 1 to 6, characterized in that, The connecting portion surrounds the circumferential surface of the first end and the circumferential surface of the second end; The connecting part is fixedly connected to the annular surface along the circumference of the first optical fiber, or fixedly connected to the annular surface along the circumference of the second optical fiber.

8. The fiber optic connector according to any one of claims 1 to 7, characterized in that, An anti-reflective coating is provided on the radial surface of the second end.

9. The fiber optic connector according to any one of claims 1 to 8, characterized in that, The angle between the radial surface of the first end and the radial surface of the second end is greater than zero.

10. The fiber optic connector according to any one of claims 1 to 9, characterized in that, The material of the connecting part includes any one of phosphate, vanadate, bismuthate, and silicon dioxide.

11. An optical communication system, characterized in that, The optical communication system includes: The first transmission optical fiber is a hollow-core optical fiber. The second transmission optical fiber is a solid-core optical fiber; The fiber optic connector as described in any one of claims 1 to 10; The first optical fiber is connected to the first transmission optical fiber, and the second optical fiber is connected to the second transmission optical fiber.

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