Anti-resonant hollow core fiber connection structure

Abstract

The utility model discloses a kind of anti-resonance hollow-core optical fiber connecting structure, it is characterized by: including positioning tube, first optical fiber and second optical fiber;The positioning tube has inner hole extending along axial direction;The first optical fiber is hollow-core optical fiber, and the first end of first optical fiber is inserted into the inner hole;The second optical fiber is hollow-core optical fiber or solid-core optical fiber, and the first end of second optical fiber is inserted into the inner hole from the other end of inner hole, and contact with the first end of first optical fiber;When second optical fiber is solid-core optical fiber, the first end of second optical fiber is conical end face;The both ends of positioning tube are fixed between first optical fiber and second optical fiber by sealing structure respectively;The utility model has the characteristics of simple structure, stable and reliable, low loss and excellent echo loss performance.

Description

Technical Field

[0001] This utility model relates to the field of optical fiber communication technology, and in particular to an anti-resonant hollow optical fiber connection structure. Background Technology

[0002] Anti-resonant hollow fiber has shown great application potential in high-speed communication, data centers, fiber optic sensing, and fiber lasers due to its ultra-low transmission loss, low optical transmission delay, ultra-low dispersion, excellent bandwidth characteristics, and ultra-low optical nonlinear effects.

[0003] However, behind its numerous advantages lie many drawbacks, among which fiber optic connections are one of the key challenges restricting its practical deployment. This type of fiber cannot be directly fused with solid-core fibers, and even fusion with itself is extremely difficult. The main reason is its hollow internal structure, containing a precisely arranged array of capillaries. If traditional high-temperature fusion splicing methods are used, the fusion temperature is far higher than the melting point of pure silica, causing deformation or collapse of the precision capillaries, resulting in significant fusion loss. Even with high-end polarization-maintaining fusion splicers, actual verification shows that not only is the fusion time extremely long (approximately 12 minutes to fusion a single point), but the splice joint is also quite fragile, requiring careful protection on the outside to prevent breakage.

[0004] Furthermore, the fusion splicing of hollow-core and solid-core optical fibers presents a physical interface mismatch problem. Nearly 4% of the light is reflected back at the interface between the two media, resulting in a return loss of only about 14dB, while communication systems typically require at least 50dB. To address this issue, one existing solution is to grind the end face of the solid-core fiber at a 6-8 degree bevel. Figure 5 As shown, this achieves a return loss of 50dB. However, this results in a large gap between the hollow and solid fibers, approximately 12-16µm, significantly increasing the splicing loss between the two types of fibers. To address the splicing and return loss issues, existing technology coats the end face of the solid fiber with an antireflection coating. However, this only brings the reflectivity close to 0.1%, or approximately 30dB, so the return loss is still nearly 20dB short of the actual requirement, failing to meet the requirements. Furthermore, some commercially available structures employ more complex spatial optical path designs, which are not only bulky and unstable but also expensive to produce, making them impractical. Utility Model Content

[0005] To address the shortcomings of existing technologies, this invention provides an anti-resonant hollow fiber connection structure, which features simple structure, stability and reliability, low loss and excellent return loss performance.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An anti-resonant hollow fiber connection structure, characterized in that it includes a positioning tube, a first optical fiber, and a second optical fiber; The positioning tube has an inner hole extending axially; The first optical fiber is a hollow optical fiber, and the first end of the first optical fiber is inserted into the inner hole; The second optical fiber is a hollow optical fiber or a solid optical fiber. The first end of the second optical fiber is inserted into the inner hole from the other end of the inner hole and contacts the first end of the first optical fiber. When the second optical fiber is a solid-core optical fiber, the first end of the second optical fiber is a conical end face; The two ends of the positioning tube are fixed to the first optical fiber and the second optical fiber respectively through a sealing structure.

[0007] Preferably, the inner hole has a three-section structure, consisting of a middle positioning section and end positioning sections located at both ends of the middle positioning section; The inner diameter of the intermediate positioning section matches the diameter of the first and second optical fibers after the coating is removed. The inner diameter of the end positioning section matches the diameter of the first and second optical fibers when they are coated.

[0008] Preferably, the cone angle of the conical end face is between 164 and 168°.

[0009] Preferably, the positioning tube is a pure silica capillary tube or a ceramic insert.

[0010] The advantages of this utility model are: 1. By designing the first end of the solid fiber inserted into the positioning tube as a conical end face at a specific angle, an optical tilt interface is formed when it contacts the planar end face of the hollow fiber, which can improve the return loss to more than 50dB and meet the system requirements. 2. The "cold connection" method completely avoids the damage of high temperature to the precision structure of hollow optical fiber; the axial tension of more than 100 kpsi is provided by the encapsulation to form a high-strength and durable mechanical connection. 3. Simple structure and mature technology such as fiber polishing and encapsulation, without the need for expensive and time-consuming special fusion splicing equipment, making it especially suitable for field construction and large-scale deployment, significantly reducing connection costs, time and operation difficulty. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the anti-resonant hollow fiber connection structure provided in this embodiment; Figure 2 This embodiment shows the docking structure of solid-core optical fiber and hollow-core optical fiber in the intermediate positioning segment. Figure 3 This embodiment shows the docking structure of two hollow optical fibers in the intermediate positioning section. Figure 4 This is a schematic diagram of the positioning tube provided in this embodiment; Figure 5 This is a schematic diagram of a solid fiber end being ground at an 8-degree angle and connected to a hollow fiber in the prior art. Detailed Implementation

[0012] Combination Figures 1 to 4 The anti-resonant hollow fiber connection structure of this utility model will be further described.

[0013] An anti-resonant hollow fiber connection structure is characterized by comprising a positioning tube 3, a first optical fiber 1, and a second optical fiber 2.

[0014] The positioning tube 3 is made of pure silica capillary or ceramic ferrule, and has an axially extending inner hole. This inner hole is used to allow the first end of the first optical fiber 1 and the first end of the second optical fiber 2 to be inserted from both ends, so as to limit the insertion of the first optical fiber 1 into the inner hole and the insertion of the second optical fiber 2 into the inner hole, so that the first end of the first optical fiber 1 and the first end of the second optical fiber 2 can be precisely aligned.

[0015] The first optical fiber 1 is a hollow-core optical fiber, and its first end is inserted into the inner hole. The second optical fiber 2 is either a hollow-core or solid-core optical fiber, and its first end is inserted into the inner hole from the other end. The first ends of the first optical fiber 1 and the first ends of the second optical fiber 2 are precisely matched and aligned within the inner hole by the limiting effect of the inner hole, enabling effective and stable light transmission between the first optical fiber 1 and the second optical fiber 2.

[0016] The two ends of the positioning tube 3 are fixed and sealed to the first optical fiber 1 and the second optical fiber 2 respectively with sealant, so that the tension between the first optical fiber 1 and the second optical fiber 2 exceeds 100kpsi, realizing a high-performance hard connection between the first optical fiber 1 and the second optical fiber 2, and ensuring that the first optical fiber 1 and the second optical fiber 2 can be stably connected in the inner hole.

[0017] The inner hole has a three-section structure, consisting of a middle positioning section 32 and end positioning sections 31 located at both ends of the middle positioning section 32. The inner diameter of the middle positioning section 32 matches the diameter of the first optical fiber 1 and the second optical fiber 2 after the coating is removed. The inner diameter of the end positioning sections 31 matches the diameter of the first optical fiber 1 and the second optical fiber 2 when they are coated. When the first optical fiber 1 and the second optical fiber 2 are mated, the first end face of the first optical fiber 1 and the first end face of the second optical fiber 2 are both inserted into the middle position of the inner hole to achieve mating. At the same time, the coated portions of the first optical fiber 1 and the second optical fiber 2 respectively fit into the end positioning sections 31.

[0018] There is a connecting section 33 between the intermediate positioning section 32 and the end positioning section 31. The inner diameter of the connecting section 33 gradually decreases from the end positioning section 31 to the intermediate positioning section 32. The inner hole is a smooth surface, so that the first ends of the first optical fiber 1 and the second optical fiber 2 can be inserted into the middle position of the intermediate positioning section 32 from the end positioning section 31 without obstruction.

[0019] In the first embodiment of the second optical fiber 2, the second optical fiber 2 is a solid-core optical fiber. The positioning tube 3 is a pure silica capillary tube. The first end of the first optical fiber 1 and the first end of the second optical fiber 2 are inserted into the positioning tube 3 from both ends, and the connection is completed at the middle position of the positioning tube 3. The end face of the first end of the second optical fiber 2 is a conical end face 21, and the cone angle of the conical end face 21 is between 164° and 168°. The two ends of the positioning tube 3 are sealed with the first optical fiber 1 and the second optical fiber 2 using sealant. In this structure, after the first optical fiber 1 and the second optical fiber 2 are connected, the conical end face 21 of the second optical fiber 2 can partially enter the first optical fiber 1, which can achieve zero-distance contact between the solid-core optical fiber and the hollow-core optical fiber, and at the same time suppress the return loss at the contact point, improve the stability of the connection and light transmission. This structure can be called an adapter cable.

[0020] In a second embodiment of the second optical fiber 2, the second optical fiber 2 is a hollow-core optical fiber. The positioning tube 3 is made of pure silica capillary. The first end of the first optical fiber 1 and the first end of the second optical fiber 2 are inserted into the positioning tube 3 from both ends, and the connection is completed at the middle position of the positioning tube 3. The two ends of the positioning tube 3 are sealed with the first optical fiber 1 and the second optical fiber 2 using sealant. This process is a cold connection and does not damage the precise capillary shape inside the hollow-core optical fiber. Therefore, precise capillary alignment of the two end faces is not required, and a low-loss connection between hollow-core optical fibers can be achieved within three minutes.

[0021] The above description is merely a preferred embodiment of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are protected by this utility model. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should also be considered within the protection scope of this utility model.

Claims

1. An anti-resonant hollow fiber connection structure, characterized in that: Includes a positioning tube, a first optical fiber, and a second optical fiber; The positioning tube has an inner hole extending axially; The first optical fiber is a hollow optical fiber, and the first end of the first optical fiber is inserted into the inner hole; The second optical fiber is a hollow optical fiber or a solid optical fiber. The first end of the second optical fiber is inserted into the inner hole from the other end of the inner hole and contacts the first end of the first optical fiber. When the second optical fiber is a solid-core optical fiber, the first end of the second optical fiber is a conical end face; The two ends of the positioning tube are fixed to the first optical fiber and the second optical fiber respectively through a sealing structure.

2. The anti-resonant hollow fiber connection structure according to claim 1, characterized in that: The inner hole has a three-section structure, consisting of a middle positioning section and end positioning sections located at both ends of the middle positioning section; The inner diameter of the intermediate positioning section matches the diameter of the first and second optical fibers after the coating is removed. The inner diameter of the end positioning section matches the diameter of the first and second optical fibers when they are coated.

3. The anti-resonant hollow fiber connection structure according to claim 1, characterized in that: The cone angle of the conical end face is between 164° and 168°.

4. The anti-resonant hollow fiber connection structure according to claim 1, characterized in that: The positioning tube is a pure silica capillary tube or a ceramic insert.

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