Coupling method and coupling structure for hollow optical fiber, and optical fiber connector

Abstract

The present invention relates to the technical field of optical communication. Disclosed are a coupling method and coupling structure for a hollow optical fiber, and an optical fiber connector. The method of the present invention comprises the steps of: welding a first optical fiber with a first end surface of a bridge fiber, processing a second end surface of the bridge fiber into an inclined surface at a preset angle to serve as a coupling end surface, and fixing the overall structure obtained by welding the first optical fiber with the bridge fiber in a first sleeve to obtain a first intermediate; fixing the hollow optical fiber in a second sleeve to obtain a second intermediate; and clamping and fixing the first intermediate and the second intermediate by using an optical fiber coupling platform, adjusting the position of the first intermediate and / or the second intermediate, synchronously performing a powder test, and encapsulating and fixing coupling points when the coupling loss is at the minimum, thereby achieving the coupling of the hollow optical fiber and the first optical fiber. The present invention expands the application scenarios, and reduces the coupling loss and return loss.

Description

Coupling method and coupling structure of hollow-core fiber, and fiber connector TECHNICAL FIELD

[0001] The present application belongs to the technical field of optical communication, and more particularly relates to a coupling method and coupling structure of a hollow-core fiber, and a fiber connector. BACKGROUND

[0002] Hollow-core fiber (HCF) is currently the most promising new type of optical fiber, unlike the total internal reflection light guiding principle of traditional optical fibers in the glass core, the hollow-core fiber is a hollow structure and guides light in air. Due to the ultra-low nonlinear coefficient and Rayleigh scattering signal of air, the hollow-core fiber can realize ultra-low loss and low nonlinear signal transmission, and is considered to be the best choice for the next generation of optical fiber communication technology.

[0003] The existing coupling mode of the partial hollow-core fiber is only applicable to the coupling connection between the hollow-core fiber and the laser, or only applicable to the connection between the hollow-core fiber and the hollow-core fiber, and the application scene is limited, and cannot be applied to the connection between the hollow-core fiber and the single-mode fiber, nor can it be applied to the connection between the hollow-core fiber and other types of optical fibers. In addition, the coupling mode of part of the existing hollow-core fiber has low butt coupling efficiency and high coupling loss. Due to the strong centering design of the connector adapter, part of the existing hollow-core fiber connector causes the optical path to be unadjustable, and cannot obtain extremely low insertion loss.

[0004] In particular, considering that the current network application is basically based on standard single-mode fiber (SSMF), in order to realize the application of HCF in the current network, the interconnection of HCF and SSMF is essential. Since the attenuation of HCF itself is extremely low, when a short length of low-loss HCF (such as a length less than 1 km) is used, the HCF-SSMF coupling loss may become the main contributor to the total loss of the entire line, so the HCF-SSMF coupling loss must be reduced. The interconnection of the hollow-core fiber and the single-mode fiber is generally realized by fusion or coupling, but due to the hollow structure of the hollow-core fiber, direct butt joint of the end face will produce strong Fresnel reflection, resulting in high return loss, which cannot meet the transmission requirements. SUMMARY

[0005] The present application provides a coupling method and coupling structure of a hollow-core fiber, and a fiber connector, which solves the problem of limited application scene and high coupling loss or return loss of the coupling mode of the hollow-core fiber in the prior art.

[0006] In a first aspect, the present application provides a coupling method of a hollow core fiber, comprising the following steps: fusing a first fiber with a first end face of a bridge fiber, processing a second end face of the bridge fiber into a bevel with a preset angle and serving as a coupling end face, fixing the whole structure of the fused first fiber and bridge fiber in a first sleeve to obtain a first intermediate body; fixing a hollow core fiber in a second sleeve to obtain a second intermediate body; clamping and fixing the first intermediate body and the second intermediate body by using a fiber coupling platform, adjusting the position of the first intermediate body and / or the second intermediate body, and synchronously performing power detection, packaging and fixing the coupling point when the coupling loss is the lowest, and realizing the coupling of the hollow core fiber and the first fiber.

[0007] Preferably, the first sleeve and the second sleeve are both glass capillary tubes, or the first sleeve and the second sleeve are both fiber arrays; the whole structure of the fused first fiber and bridge fiber is inserted into the first sleeve, so that the first sleeve covers the fusion point of the first fiber and the bridge fiber, and the coupling end face of the bridge fiber exceeds the first sleeve by a first distance; the hollow core fiber is inserted into the second sleeve, and the end face of the hollow core fiber for coupling exceeds the second sleeve by a second distance.

[0008] Preferably, the external dimensions of the first sleeve and the second sleeve are completely the same, the inner side of the first sleeve is provided with a hole for accommodating the oblique insertion of the fiber, and the inner side of the second sleeve is provided with a hole for accommodating the transverse insertion of the hollow core fiber; the whole structure of the fused first fiber and bridge fiber is inserted into the first sleeve, so that the first sleeve covers the fusion point of the first fiber and the bridge fiber, and after the coupling end face of the bridge fiber exceeds the first side face of the first sleeve, the section of the coupling end face exceeding the first sleeve is cut off, and the coupling end face and the first side face are processed into a bevel with a preset angle.

[0009] Preferably, the end face of the hollow core fiber for coupling is cut into a flat angle end face.

[0010] Preferably, an anti-reflection film is plated on the coupling end face of the bridge fiber.

[0011] Preferably, the bridge fiber is one of a graded-index fiber, a thermal expansion core fiber, and a fiber combination.

[0012] Preferably, the first fiber is a single-mode fiber.

[0013] In a second aspect, the present application provides a coupling structure of a hollow core fiber, which is prepared by using the above-mentioned coupling method of a hollow core fiber.

[0014] Preferably, the two ends of the hollow core fiber are coupled with two single-mode optical fibers respectively by using the coupling method of the hollow core fiber, so as to prepare a coupling structure for connecting into a single-mode optical fiber network.

[0015] In a third aspect, the present application provides an optical fiber connector, comprising: a ferrule and the coupling structure of the hollow core fiber; the coupling structure of the hollow core fiber is inserted into the ferrule, and the optical fiber connector is obtained after point gluing and end face grinding.

[0016] The one or more technical solutions provided in the present application have at least the following technical effects or advantages:

[0017] In the present application, the first optical fiber is fused with the first end face of the bridge fiber, the bridge fiber acts as a mode field conversion optical fiber to match the mode field of the first optical fiber and the hollow core fiber, the second end face of the bridge fiber is processed into a bevel with a preset angle and acts as a coupling end face, in the prior art, the coupling of two end optical fibers is usually flat angle coupling, but due to the characteristics of the air core of the hollow core fiber, the light transmission is from glass to air, and a large Fresnel reflection will occur at the coupling face, which will cause the line transmission bit error rate to be too high, in the present application, the coupling end face of the bridge fiber is a bevel, and the angle coupling can greatly reduce the Fresnel reflection of the coupling face, reduce the return loss, the overall structure of the first optical fiber and the bridge fiber after being fused is fixed in the first sleeve to obtain a first intermediate body, the hollow core fiber is fixed in the second sleeve to obtain a second intermediate body, the first intermediate body and the second intermediate body are clamped and fixed by using an optical fiber coupling platform, the position of the first intermediate body and / or the second intermediate body is adjusted, and power detection is performed synchronously, the coupling point is fixed and packaged when the coupling loss is the lowest, the coupling of the hollow core fiber and the first optical fiber is realized, the coupling loss of the present application is low, and the demand of line transmission is fully met; based on the intermediate body, the position adjustment can be more conveniently performed on the optical fiber coupling platform; the coupling method provided by the present application can not only realize the low-loss connection between the hollow core fiber and the single-mode optical fiber, but also realize the connection between the hollow core fiber and other types of optical fibers by using different bridge fibers, so the application scenarios are expanded compared with the prior art. On the basis of the above coupling method, the corresponding coupling structure can also be obtained, and the optical fiber connector can also be obtained in combination with the ferrule, and the obtained optical fiber connector can be connected to the conventional connector through an adapter. BRIEF DESCRIPTION OF DRAWINGS

[0018] Fig. 1 is a structure diagram of the first optical fiber and the bridge fiber fused in the coupling method of the hollow core fiber provided by the embodiment 1 of the present application, and the structure of the hollow core fiber;

[0019] Fig. 2 is a structure diagram of the first intermediate body and the second intermediate body in the coupling method of the hollow core fiber provided by the embodiment 1 of the present application;

[0020] Figure 3 is a schematic diagram of the use of an outer sleeve for encapsulation in a hollow-core fiber coupling method according to an embodiment of the present application;

[0021] Figure 4 is a schematic diagram of the insertion of a first optical fiber and a bridge fiber into a first sleeve in a hollow-core fiber coupling method according to an embodiment of the present application;

[0022] Figure 5 is a schematic diagram of the structure of a first intermediate body and a second intermediate body in a hollow-core fiber coupling method according to an embodiment of the present application. Embodiments of the present application

[0023] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with the accompanying drawings and specific embodiments.

[0024] The present application first provides a hollow-core fiber coupling method, comprising the following steps: fusion splicing a first end face of a first optical fiber and a bridge fiber, machining a second end face of the bridge fiber into a bevel of a preset angle and taking it as a coupling end face, fixing the whole structure after fusion splicing of the first optical fiber and the bridge fiber in a first sleeve to obtain a first intermediate body; fixing a hollow-core fiber in a second sleeve to obtain a second intermediate body; clamping and fixing the first intermediate body and the second intermediate body by using an optical fiber coupling platform, adjusting the position of the first intermediate body and / or the second intermediate body, and simultaneously performing power detection, encapsulating and fixing a coupling point when the coupling loss is the lowest, and realizing the coupling of the hollow-core fiber and the first optical fiber.

[0025] Correspondingly, the present application also provides a hollow-core fiber coupling structure prepared by using the above-mentioned hollow-core fiber coupling method.

[0026] The following will be further described in combination with Embodiments 1 and 2.

[0027] Embodiment 1

[0028] Embodiment 1 provides a hollow-core fiber coupling method and a corresponding coupling structure thereof, and the following first describes the coupling method.

[0029] The hollow-core fiber coupling method provided by Embodiment 1, as shown in Figures 1 to 3, comprises the following steps:

[0030] Step 1: fusion splicing a first end face of a first optical fiber 110 and a bridge fiber 120, machining a second end face of the bridge fiber 120 into a bevel of a preset angle and taking it as a coupling end face 121, fixing the whole structure after fusion splicing of the first optical fiber 110 and the bridge fiber 120 in a first sleeve 10, the first sleeve 10 being a glass capillary or an optical fiber array, to obtain a first intermediate body. Fixing a hollow-core fiber 130 in a second sleeve 20, the second sleeve 20 being a glass capillary or an optical fiber array, to obtain a second intermediate body.

[0031] The whole structure after the first optical fiber 110 and the bridge fiber 120 are fused is inserted into the first sleeve 10, the first sleeve 10 covers the fusion point of the first optical fiber 110 and the bridge fiber 120, and the coupling end face 121 of the bridge fiber 120 exceeds the first sleeve 10 by a first distance. That is, the optical fiber obtained after the first optical fiber 110 and the bridge fiber 120 are fused is inserted into the first sleeve 10 and a small section of the optical fiber (for example, within 2 mm) is exposed, and then ultraviolet curing and heat curing are performed on the optical fiber and the first sleeve 10 by using ultraviolet glue, and the whole structure after curing is taken as the first intermediate body.

[0032] For example, the first sleeve 10 and the second sleeve 20 are glass capillary tubes, the inner diameters of the glass capillary tubes match the corresponding optical fibers respectively, the outer diameters of the glass capillary tubes are preferably the same, and the materials of the glass capillary tubes can be high borosilicon or silica.

[0033] When the first sleeve 10 is an optical fiber array, the inside of the optical fiber array can be made into an angle-shaped inner groove, and the optical fiber is attached to the groove.

[0034] The end face of the hollow core optical fiber 130 used for coupling is cut into a flat angle end face, the hollow core optical fiber 130 is inserted into the second sleeve 20, and the end face of the hollow core optical fiber 130 used for coupling exceeds the second sleeve 20 by a second distance. That is, the hollow core optical fiber 130 is inserted into the second sleeve 20 and a small section of the optical fiber (for example, within 2 mm) is exposed, and then ultraviolet curing and heat curing are performed on the hollow core optical fiber 130 and the second sleeve 20 by using ultraviolet glue, and the whole structure after curing is taken as the second intermediate body.

[0035] The core of the hollow core optical fiber 130 is an air core, and the cladding is a plurality of glass capillary rings, which can be single, double or multiple rings, and can be regularly arranged or irregularly arranged, and can be single-layer or multi-layer.

[0036] The bridge fiber 120 serves as a mode field conversion optical fiber and matches the mode field of the first optical fiber 110 and the hollow core optical fiber 130. After the first optical fiber 110 and the bridge fiber 120 are fused, the mode field of one end of the bridge fiber 120 matches the mode field of the first optical fiber 110, and the mode field of the other end of the bridge fiber 120 matches the mode field of the hollow core optical fiber 130, and coupling with the hollow core optical fiber 130 can obtain extremely low coupling loss. In order to reduce the return loss, the bridge fiber 120 needs to be ground or cut at a certain angle.

[0037] The bridge fiber 120 can be one of a graded-index fiber, a hot-deformed core fiber (for example, a single-mode fiber hot-deformed core fiber), or a fiber combination. In addition, the bridge fiber 120 can also be any other fiber, lens, or device that can perform mode field conversion. By changing the type of the bridge fiber 120, the hollow core fiber 130 can be coupled to any other mode field fiber.

[0038] In a preferred embodiment, an anti-reflection film is coated on the coupling end face of the bridge fiber 120. Specifically, one or more layers of anti-reflection film are coated on the coupling end face 121 of the bridge fiber 120. The anti-reflection film has high anti-reflection properties, which can reduce the connection loss caused by the coupling and improve the return loss.

[0039] In the preferred embodiment, the second end face of the bridge fiber 120 is processed into a bevel with a preset angle and serves as the coupling end face 121. The preset angle is less than 8 degrees, and the specific angle is determined according to the required return loss. The greater the angle, the lower the return loss. The design of the bevel can greatly reduce the Fresnel reflection of the coupling surface, thereby reducing the return loss. In combination with the coating process, the return loss can be below -60 dB. Under the precise adjustment of the coupling platform, the coupling loss of a single point can be within 0.4 dB, fully meeting the requirements of line transmission. For example, the return loss of a 2-degree angle with end face coating can be below -50 dB, and the return loss of a 4-degree angle with end face coating can be below -60 dB.

[0040] Step 2: The first intermediate body and the second intermediate body are clamped and fixed by using a fiber coupling platform. The position of the first intermediate body and / or the second intermediate body is adjusted (i.e., the relative positions of the two end fibers are adjusted), and power detection is performed synchronously. When the coupling loss is the lowest, the coupling point is encapsulated and fixed, thereby achieving the coupling between the hollow core fiber 130 and the first fiber 110, i.e., obtaining the coupling structure of the hollow core fiber 130 and the first fiber 110.

[0041] In step 2, the first intermediate body and the second intermediate body are coupled. Specifically, the fiber coupling platform used is a six-axis coupling platform, which includes a left-axis adjustment frame, a right-axis adjustment frame, and a power monitoring device. The first intermediate body is fixed on the left-axis adjustment frame, and the second intermediate body is fixed on the right-axis adjustment frame. The positions of the six axes X, Y, Z, θx, θy, and θz of the left and right adjustment frames are adjusted, and power detection is performed synchronously. When the coupling efficiency is the highest, the coupling point is encapsulated and fixed. That is, the positions of the six axes X, Y, Z, θx, θy, and θz of the input and output fibers are adjusted, so that the optical signal of the input end can be completely coupled into the coupling output end, and the coupling loss is the lowest.

[0042] In the coupling process, the distance between the two coupled optical fibers is controlled within 10 um, and the spacing should be as small as possible but not in contact to avoid damage to the fiber end face and affect the coupling efficiency.

[0043] When the coupling point is packaged and fixed, an outer sleeve 30 can be used for packaging, for example, the two intermediates are fixed by an outer metal or glass sleeve, specifically, an outer sleeve 30 of metal or glass with a length shorter than the total length of the two intermediates and a diameter slightly larger than the size of the intermediate is sleeved between the first intermediate and the second intermediate, a small amount of ultraviolet glue is filled at both ends of the outer sleeve 30, and ultraviolet curing and thermal curing are performed. The present application does not need to grind or specially treat the end face of the hollow core optical fiber 130, the outer sleeve 30 can also seal the hollow core optical fiber 130, which can avoid damage to the end face of the hollow core optical fiber 130 and can avoid the influence of water vapor on the hollow core optical fiber 130 for a long time in the air. When the present application performs optical connection, the hollow core optical fiber 130 does not need to be in direct contact with other optical fibers, which effectively improves the coupling efficiency of the optical fiber butt joint and has good anti-pollution ability and excellent environmental performance.

[0044] In the above operation, it is necessary to ensure that the optical fiber and the sleeve (including the overall structure after the first optical fiber 110 and the bridge fiber 120 are fused and the first sleeve 10, the hollow core optical fiber 130 and the second sleeve 20), the sleeve and the outer sleeve 30 (including the first sleeve 10 and the outer sleeve 30, the second sleeve 20 and the outer sleeve 30) have good concentricity, small gap redundancy, avoid large amount of filling glue, and thus can avoid the situation that the optical fiber deviates or deflects due to large stress, and the loss increases. In addition, since the stress generated by the glue curing will cause the optical fiber to deflect or deviate, the present application selects ultralow stress ultraviolet glue to avoid the influence of stress and ensure that the loss change before and after curing is within 0.1 dB.

[0045] Using the above coupling method, the coupling structure obtained by example 1 is shown in FIG. 3, which includes a first intermediate, a second intermediate and an outer sleeve 30, wherein, referring to FIG. 2, the first intermediate includes the overall structure after the first optical fiber 110 and the bridge fiber 120 are fused and the first sleeve 10, and the second intermediate includes the hollow core optical fiber 130 and the second sleeve 20.

[0046] Example 2:

[0047] Example 2 provides a coupling method of a hollow core optical fiber and a corresponding coupling structure, which will be described first.

[0048] The coupling method of the hollow core optical fiber provided by example 2 is shown in FIGS. 4-5, which includes the following steps:

[0049] Step 1: fuse the first optical fiber 110 with the first end face of the bridge fiber 120, process the second end face of the bridge fiber 120 into a bevel with a preset angle and as a coupling end face, fix the whole structure after fusing the first optical fiber 110 with the bridge fiber 120 in the first sleeve 11, and obtain a first intermediate body; fix the hollow core optical fiber 130 in the second sleeve 12, and obtain a second intermediate body; wherein the external dimensions of the first sleeve 11 and the second sleeve 12 are completely the same, the inner side of the first sleeve 11 is provided with a hole for accommodating the optical fiber to tilt through, and the inner side of the second sleeve 12 is provided with a hole for accommodating the hollow core optical fiber 130 to pass through laterally; pass the whole structure after fusing the first optical fiber 110 with the bridge fiber 120 into the first sleeve 11, so that the first sleeve 11 covers the fusion point of the first optical fiber 110 and the bridge fiber 120, cut the section of the coupling end face of the bridge fiber 120 beyond the first side face of the first sleeve 11, and process the coupling end face and the first side face into bevels with a preset angle; cut the end face of the hollow core optical fiber 130 for coupling into a flat angle end face, pass the hollow core optical fiber 130 into the second sleeve 12, and the end face of the hollow core optical fiber 130 for coupling exceeds the second sleeve 12 by a distance.

[0050] Step 2: clamp and fix the first intermediate body and the second intermediate body by using a fiber coupling platform, adjust the position of the first intermediate body and / or the second intermediate body, and simultaneously perform power detection, encapsulate and fix the coupling point when the coupling loss is the lowest, and realize the coupling of the hollow core optical fiber and the first optical fiber.

[0051] The difference between Example 2 and Example 1 is that Example 2 first determines the tilt angle θ of the bridge fiber 120 required for coupling, and then customizes a square fiber array or a cylindrical glass tube as the first sleeve 11 and the second sleeve 12. Among them, the first sleeve 11 is penetrated by a hole that can accommodate the tilt of the fiber, and the overall structure after the first fiber 110 is fused with the bridge fiber 120 is inserted into the first sleeve 11, and the bridge fiber 120 penetrates out of a section of the first side of the first sleeve 11, wherein the length from the fusion point of the first fiber 110 and the bridge fiber 120 to the first side of the first sleeve 11 needs to be accurately controlled to ensure that the mode field diameter of the section of the bridge fiber 120 and the first side of the first sleeve 11 matches the mode field of the hollow core fiber 130. Point the glue between the fiber and the hole to fix it, cut off the exposed section of the bridge fiber 120, grind the first side, process the bridge fiber 120 and the section of the first side into a bevel with a preset angle, and perform the same coating treatment on the first side as in Example 1 to obtain the first intermediate body. The outer dimensions of the second sleeve 12 used by the hollow core fiber 130 are the same as the outer dimensions of the first sleeve 11. When packaging, the bottom surfaces of the first intermediate body and the second intermediate body can be fixed by a piece of sheet with glue, or an outer sleeve with a slightly larger size can be used to fix them, and the inner size of the outer sleeve is close to the outer size of the intermediate body. Fill the gap with ultraviolet glue or heat-curable glue for ultraviolet curing and heat curing.

[0052] When coupling in Step 2 of Example 2, the first intermediate body and the second intermediate body do not need to be adjusted in angle under power detection. Since the outer dimensions of the first intermediate body and the second intermediate body are completely the same (or it can be understood that the outer dimensions of the first sleeve 11 and the second sleeve 12 are completely the same), only slight adjustment in the XYZ three directions is needed to achieve perfect coupling of the optical fibers at both ends and achieve a lower coupling efficiency. Compared with Example 1, Example 2 can achieve the same coupling effect, but the further optimization of the first sleeve 11 and the second sleeve 12 in Example 2 makes the coupling easier. The first sleeve 11 fixes the position of the bevel of the overall structure after the first fiber 110 is fused with the bridge fiber 120, and there is no need to rotate the angle to find the best bevel alignment position during optical fiber coupling, which greatly improves the coupling efficiency.

[0053] Using the above coupling method, the coupling structure obtained by Example 2 includes a first intermediate body, a second intermediate body and an outer sleeve. Referring to FIG. 5, the first intermediate body includes the overall structure after the first fiber 110 is fused with the bridge fiber 120 and the first sleeve 11, and the second intermediate body includes the hollow core fiber 130 and the second sleeve 12.

[0054] In the basis of the embodiment 1 or the embodiment 2, when the first optical fiber 110 adopts a single-mode optical fiber, the two ends of the hollow core optical fiber 130 are coupled with two single-mode optical fibers respectively, and a coupling structure for connecting into a single-mode optical fiber network can be prepared.

[0055] Specifically, the same coupling structure is prepared at the two ends of the hollow core optical fiber 130, the two ends of the hollow core optical fiber 130 are converted into single-mode optical fibers, the whole section of the hollow core optical fiber 130 is connected into a single-mode optical fiber, that is, the hollow core optical fiber 130 with the coupling structure at the two ends is made into a connector with the two ends connected, and the connector can be connected into a conventional single-mode optical fiber network to replace part of the conventional single-mode optical fiber. In the application of a data center, the loss of the whole section of the optical fiber is within 1 dB, the return loss is less than -50 dB, in the transmission test of a 400G optical module, the transmission bit error rate is similar to that of a conventional single-mode optical fiber, and low-loss transmission of an optical signal from a single-mode optical fiber to the hollow core optical fiber and then to a single-mode optical fiber can be realized.

[0056] In addition, in the basis of the embodiment 1 or the embodiment 2, two sections of the hollow core optical fiber can be butted to realize optical signal transmission between the hollow core optical fibers.

[0057] Embodiment 3:

[0058] The embodiment 3 provides an optical fiber connector, which comprises a ferrule and the coupling structure of the hollow core optical fiber as described in the embodiment 1 or the embodiment 2; the coupling structure of the hollow core optical fiber is inserted into the ferrule, and the optical fiber connector is obtained after point gluing and end face grinding.

[0059] That is, the assembled coupling structure can be used as a connector assembly, the whole coupling structure is inserted into a ferrule with a customized size, point gluing is performed, end face grinding is performed, and a conventional connector structure is assembled and prepared, so that the conventional single-mode optical fiber can be conventionally butted.

[0060] For example, the cylindrical coupling structure (such as the packaged whole structure shown in FIG. 3) obtained by using the embodiment 1 is used as the coupling structure, a ferrule with a corresponding inner diameter size is customized according to the size of the sleeve tube, the packaged coupling structure is inserted into and taken out of the corresponding ferrule, one end of the first optical fiber is exposed from the ferrule, the coupling structure is completely built-in in the ferrule, the process of a conventional optical fiber connector is performed on the end face of the ferrule, point gluing is performed, end face grinding is performed, and the required optical fiber connector (such as an FC type, an SC type, an LC type, etc.) is assembled. The obtained optical fiber connector can be butted with a conventional connector through an adapter, and the physical contact end face optical fiber is the first optical fiber.

[0061] Specifically, the ferrule and the coupling structure have good concentricity (concentricity ≤0.25um). The prepared optical fiber connector can perfectly realize the butt joint of hollow optical fiber and single-mode optical fiber. When the end faces are butt jointed, the physical contact surface is a single-mode optical fiber.

[0062] The present application can provide an insertion loss of not more than 0.5 dB at 1310 nm and 1550 nm wavelengths. The return loss at 1310 nm and 1550 nm wavelengths is not more than -50 dB.

[0063] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A method of coupling an optical hollow core fiber, characterized by, The method comprises the following steps: fusing the first optical fiber with the first end face of the bridge fiber, processing the second end face of the bridge fiber into a bevel with a preset angle and serving as a coupling end face, fixing the whole structure after fusing the first optical fiber with the bridge fiber in the first sleeve to obtain a first intermediate body; fixing the hollow core fiber in the second sleeve to obtain a second intermediate body; clamping and fixing the first intermediate body and the second intermediate body by using a fiber coupling platform, adjusting the position of the first intermediate body and / or the second intermediate body, and synchronously performing power detection, packaging and fixing the coupling point when the coupling loss is the lowest, and realizing the coupling of the hollow core fiber and the first optical fiber.

2. The method of coupling of a hollow core optical fiber according to claim 1, characterized in that, The first sleeve and the second sleeve are both glass capillary tubes, or the first sleeve and the second sleeve are both fiber arrays; the whole structure after fusing the first optical fiber with the bridge fiber is inserted into the first sleeve, so that the first sleeve covers the fusion point of the first optical fiber and the bridge fiber, and the coupling end face of the bridge fiber exceeds the first sleeve by a first distance; the hollow core fiber is inserted into the second sleeve, and the end face of the hollow core fiber for coupling exceeds the second sleeve by a second distance.

3. The method of claim 1, wherein the step of coupling the coreless optical fiber is performed by, The first sleeve and the second sleeve have the same external dimensions, the inner side of the first sleeve is provided with a hole for accommodating the oblique insertion of an optical fiber, and the inner side of the second sleeve is provided with a hole for accommodating the transverse insertion of the hollow core fiber; the whole structure after fusing the first optical fiber with the bridge fiber is inserted into the first sleeve, so that the first sleeve covers the fusion point of the first optical fiber and the bridge fiber, and the coupling end face of the bridge fiber exceeds the first side face of the first sleeve by a first distance, then the section of the coupling end face exceeding the first sleeve is cut off, and the coupling end face and the first side face are processed into a bevel with a preset angle.

4. The coupling method for hollow optical fiber according to claim 1, characterized in that, The end face of the hollow core fiber for coupling is cut into a flat end face.

5. The coupling method for hollow optical fiber according to claim 1, characterized in that, An anti-reflection film is coated on the coupling end face of the bridge fiber.

6. The coupling method for hollow optical fiber according to claim 1, characterized in that, The bridge fiber is one of a graded-index fiber, a hot-drawn core fiber and a fiber combination.

7. The coupling method for hollow optical fiber according to claim 1, characterized in that, The first optical fiber is a single-mode fiber.

8. A coupling structure of a hollow core optical fiber, characterized by, The coupling method is prepared by using any one of the hollow core fiber coupling methods in claims 1-7.

9. The coupling structure of a hollow core optical fiber according to claim 8, characterized by The coupling method of the hollow core fiber in claim 7 is used to couple two ends of the hollow core fiber with two single-mode fibers respectively, so as to prepare a coupling structure for connecting into a single-mode fiber network.

10. An optical fiber connector, characterized by, The method comprises: a ferrule and the coupling structure of the hollow core fiber in claim 8; the coupling structure of the hollow core fiber is inserted into the ferrule, and a fiber connector is obtained after point gluing and end face grinding.

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