Combined optical fiber and preparation method thereof

Abstract

The invention relates to a combined optical fiber and a preparation method, and relates to the technical field of optical fiber preparation, and the combined optical fiber comprises an anti-resonance hollow-core optical fiber having a first mode field diameter; the single-mode optical fiber has a second mode field diameter, and the first mode field diameter is larger than the second mode field diameter; one end of the bridging optical fiber is connected with the anti-resonance hollow-core optical fiber and is matched with the mode field of the anti-resonance hollow-core optical fiber, and the other end of the bridging optical fiber is connected with the single-mode optical fiber and is matched with the mode field of the single-mode optical fiber. The anti-resonance hollow-core optical fiber and the single-mode optical fiber are connected through the bridging optical fiber, and the two ends of the bridging optical fiber are matched with the anti-resonance hollow-core optical fiber and the single-mode optical fiber respectively, so that compared with a direct fused biconical taper single-mode optical fiber, the bridging optical fiber is lower in operation difficulty, better in connection performance and capable of being replaced even if misoperation occurs, and the combined optical fiber is convenient to prepare; the problem that in the prior art, a combined optical fiber with an anti-resonance hollow-core optical fiber is difficult to prepare conveniently is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber preparation, and in particular to a combined optical fiber and a preparation method thereof. Background Art

[0002] Antiresonant hollow core fiber (AR-HCF) has gained wide attention in many fields in recent years due to its broadband and low-loss transmission characteristics. Antiresonant hollow core fiber is a new type of optical fiber that uses the antiresonance effect when light propagates in a hollow core to achieve ultra-low loss transmission. Compared with traditional quartz solid core optical fiber, it has a lower attenuation coefficient, shorter delay time and higher transmission bandwidth, and supports ultraviolet and mid-infrared light transmission. It is of great significance to optical communications, high-power lasers, nonlinear optics, biophotonics, quantum optics, fiber optic sensing and other fields. If antiresonant hollow core fiber is to be used in the current traditional single-mode solid core optical fiber transmission system, the problem of fusion with single-mode optical fiber must also be solved.

[0003] The mode field characteristics of antiresonant hollow core fiber (HC-ARF) are one of its unique advantages. Through its special structural design, antiresonant hollow core fiber can confine most of the light in the core, thereby significantly reducing material loss. In the study of fusion splicing of HC-ARF and single-mode fiber, since the mode field diameter of HC-ARF is different from that of ordinary single-mode fiber, direct fusion splicing may result in greater losses. Mode field matching is one of the key factors to achieve effective transmission of optical signals in optical fibers, especially when fusion splicing hollow core antiresonant fiber (HC-ARF) with single-mode fiber.

[0004] The main reasons for the large loss when antiresonant hollow core fiber (HC-ARF) and single-mode fiber are as follows: 1. Special capillary pore structure: The cladding of HC-ARF has a special capillary pore structure, which is easy to collapse during the welding process, resulting in increased welding loss; 2. Different mode field diameter: The mode field diameter of HC-ARF is different from that of ordinary single-mode fiber, which leads to large losses during direct welding due to mode field mismatch; 3. High requirements for welding technology: Due to the particularity of HC-ARF, the technical requirements for welding are high, and improper operation may lead to increased welding losses.

[0005] In the prior art, a common single-mode optical fiber is generally thermally expanded and then fused with a hollow-core optical fiber, or a graded-index multimode optical fiber is introduced to perform mode field matching with the hollow-core optical fiber and then fused with the single-mode optical fiber.

[0006] However, thermal expansion of single-mode optical fiber will only expand the mode field to a limited extent and is not suitable for all hollow-core optical fibers, as the degree of mode field matching varies. When gradient-index multimode optical fiber is introduced, the optical fiber length is relatively sensitive, and an increase in length will cause the generation of higher-order modes. This method also increases the difficulty and complexity of fusion splicing, and there is a problem that it is difficult to conveniently prepare a combined optical fiber with an antiresonant hollow-core optical fiber. Summary of the invention

[0007] The present application provides a combined optical fiber and a preparation method, which can solve the problem that the thermal expansion of single-mode optical fiber in the prior art will only expand the mode field to a limited extent, is not suitable for all hollow-core optical fibers, and has different degrees of mode field matching; and the introduction of gradient refractive index multimode optical fiber is sensitive to optical fiber length, and an increase in length will cause the generation of higher-order modes, and this method increases the difficulty and complexity of fusion splicing, and both have the problem of being difficult to conveniently prepare a combined optical fiber with an antiresonant hollow-core optical fiber.

[0008] In a first aspect, an embodiment of the present application provides a combined optical fiber, comprising:

[0009] an antiresonant hollow core optical fiber having a first mode field diameter;

[0010] A single-mode optical fiber having a second mode field diameter, wherein the first mode field diameter is greater than the second mode field diameter;

[0011] A bridging optical fiber, one end of which is connected to the antiresonant hollow core optical fiber and matches the mode field of the antiresonant hollow core optical fiber, and the other end of which is connected to the single mode optical fiber and matches the mode field of the single mode optical fiber.

[0012] In one embodiment, the bridge optical fiber includes a connecting section and a fused-taper section, the connecting section is connected to the antiresonant hollow-core optical fiber, and the fused-taper section is connected to the single-mode optical fiber.

[0013] In one embodiment, the fused taper section is formed by taper processing the bridge optical fiber using an optical fiber taper machine or an optical fiber fusion splicer with a taper function to form a tapered transition structure with a smaller cladding diameter and mode field diameter.

[0014] In one embodiment, the fused taper section includes a cone section and a flat section, the large diameter end of the cone section is connected to the connecting section, the small diameter end is connected to one end of the flat section, and the other end of the flat section is connected to the single-mode optical fiber.

[0015] In one embodiment, a fiber outer protective shell is provided at the connection between the antiresonant hollow core fiber and the bridge fiber.

[0016] In one embodiment, one end of the bridge optical fiber connected to the antiresonant hollow core optical fiber is configured to be in a truncated cone shape and extends into the outer protective shell of the optical fiber to form a conical lens.

[0017] In one embodiment, one end of the bridge optical fiber connected to the antiresonant hollow-core optical fiber is configured as a bevel, and the end face corresponding to the antiresonant hollow-core optical fiber matches the bevel.

[0018] In a second aspect, an embodiment of the present application further provides a method for preparing a combined optical fiber, which is used to prepare the above-mentioned combined optical fiber, comprising the following steps:

[0019] Obtain a first mode field diameter and a second mode field diameter;

[0020] According to the first mode field diameter and the second mode field diameter, obtaining the mode field diameters at both ends of the bridge optical fiber and the initial mode field diameter of the bridge optical fiber;

[0021] A bridge fiber is prepared according to the initial mode field diameter, the first mode field diameter and the second mode field diameter of the bridge fiber, and the antiresonant hollow core fiber and the single mode fiber are connected through the bridge fiber.

[0022] In one embodiment, the method of preparing a bridge fiber according to the initial mode field diameter, the first mode field diameter, and the second mode field diameter of the bridge fiber, and connecting the antiresonant hollow core fiber and the single-mode fiber through the bridge fiber, comprises:

[0023] According to the first mode field diameter, the second mode field diameter, and the initial mode field diameter, determining the end portion where the bridge optical fiber is connected to the antiresonant hollow core optical fiber;

[0024] The connecting section is connected to the anti-resonant hollow core optical fiber, and a fiber taper machine or a fiber fusion splicer with a taper function is used to perform a taper process on the fused taper section until the end of the fused taper section matches the mode field of the single-mode optical fiber.

[0025] In one embodiment, the connection section is connected to an antiresonant hollow core optical fiber, and a fiber taper machine or a fiber fusion splicer with a taper function is used to perform a taper process on the fused taper section until the end of the fused taper section matches the mode field of the single-mode optical fiber, including:

[0026] Based on the preset taper parameters, a fiber taper machine or a fiber fusion splicer with a taper function is used to heat and taper the fused taper section, and the cladding diameter of the single-mode optical fiber is estimated during the taper process until the cladding diameter at the end of the fused taper section is close to or larger than the single-mode optical fiber.

[0027] The beneficial effects brought by the technical solution provided in the embodiments of the present application include:

[0028] When manufacturing the combined optical fiber, the antiresonant hollow-core optical fiber has a first mode field diameter, the single-mode optical fiber has a second mode field diameter, and the first mode field diameter is greater than the second mode field diameter. One end of the bridging optical fiber is connected to the antiresonant hollow-core optical fiber and matches the mode field of the antiresonant hollow-core optical fiber. The other end of the bridging optical fiber is connected to the single-mode optical fiber and matches the mode field of the single-mode optical fiber. First, a first mode field diameter and a second mode field diameter are obtained; based on the first mode field diameter and the second mode field diameter, the mode field diameters at both ends of the bridge fiber and the initial mode field diameter of the bridge fiber are obtained; based on the initial mode field diameter, the first mode field diameter and the second mode field diameter of the bridge fiber, a bridge fiber is prepared, and the antiresonant hollow core fiber and the single-mode fiber are connected through the bridge fiber. Since the antiresonant hollow core fiber and the single-mode fiber are connected through the bridge fiber, the two ends of the bridge fiber are matched with the antiresonant hollow core fiber and the single-mode fiber respectively. Compared with the direct fusion tapered single-mode fiber, the bridge fiber is less difficult to operate and has better connection performance. It can also be replaced in case of operation errors, which is convenient for preparing the combined optical fiber. This solves the problem that the thermal expansion of single-mode optical fiber in the prior art will only expand the mode field to a limited extent, is not suitable for all hollow core optical fibers, and has different degrees of mode field matching. When a gradient refractive index multimode optical fiber is introduced, the optical fiber length is relatively sensitive, and an increase in length will cause the generation of higher-order modes. In addition, this method increases the difficulty and complexity of fusion splicing, and both methods have the problem of difficulty in conveniently preparing a combined optical fiber with an antiresonant hollow core optical fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a schematic structural diagram of a combined optical fiber embodiment of the present invention.

[0031] Figure 2 It is a schematic structural diagram of a truncated cone-shaped connecting end in an embodiment of a combined optical fiber of the present invention.

[0032] Figure 3 It is a schematic structural diagram of the bevel connection end in an embodiment of a combined optical fiber of the present invention.

[0033] In the figure: 1. Antiresonant hollow core optical fiber; 2. Single mode optical fiber; 3. Bridge optical fiber; 31. Connecting section; 32. Fused taper section; 321. Cone section; 322. Flat section; 4. Optical fiber outer protective shell. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] The embodiments of the present application provide a combined optical fiber and a preparation method, which can solve the problem that the thermal expansion of single-mode optical fiber in the prior art will only expand the mode field to a limited extent, is not suitable for all hollow-core optical fibers, and has different degrees of mode field matching; and the introduction of gradient refractive index multimode optical fiber is sensitive to optical fiber length, and an increase in length will cause the generation of higher-order modes, and this method increases the difficulty and complexity of fusion splicing, and both have the problem of difficulty in conveniently preparing a combined optical fiber with an antiresonant hollow-core optical fiber.

[0036] like Figure 1 As shown, on the one hand, the present application provides a combined optical fiber, which includes:

[0037] An antiresonant hollow core optical fiber 1 having a first mode field diameter;

[0038] A single-mode optical fiber 2, which has a second mode field diameter, and the first mode field diameter is larger than the second mode field diameter;

[0039] One end of the bridge fiber 3 is connected to the antiresonant hollow core fiber 1 and matches the mode field of the antiresonant hollow core fiber 1 , and the other end of the bridge fiber 3 is connected to the single mode fiber 2 and matches the mode field of the single mode fiber 2 .

[0040] When manufacturing the combined optical fiber, the antiresonant hollow-core optical fiber 1 has a first mode field diameter, the single-mode optical fiber 2 has a second mode field diameter, and the first mode field diameter is greater than the second mode field diameter. One end of the bridging optical fiber 3 is connected to the antiresonant hollow-core optical fiber 1 and matches the mode field of the antiresonant hollow-core optical fiber 1. The other end of the bridging optical fiber 3 is connected to the single-mode optical fiber 2 and matches the mode field of the single-mode optical fiber 2. First, obtain a first mode field diameter and a second mode field diameter; according to the first mode field diameter and the second mode field diameter, obtain the mode field diameters at both ends of the bridge optical fiber 3 and the initial mode field diameter of the bridge optical fiber 3; according to the initial mode field diameter, the first mode field diameter and the second mode field diameter of the bridge optical fiber 3, prepare the bridge optical fiber 3, and connect the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 through the bridge optical fiber 3. Since the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 are connected through the bridge optical fiber 3, the two ends of the bridge optical fiber 3 are matched with the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 respectively. Compared with the direct melting and tapering of the single-mode optical fiber 2, the bridge optical fiber 3 is less difficult to operate and has better connection performance. It can also be replaced in case of operating errors, which is convenient for preparing the combined optical fiber. It solves the problem that the thermal expansion of the single-mode optical fiber in the prior art will only expand the mode field to a limited extent, is not suitable for all hollow-core optical fibers, and has different degrees of mode field matching. When introducing a gradient refractive index multimode optical fiber, the optical fiber length is relatively sensitive, and the increase in length will cause the generation of high-order modes. In addition, this method increases the difficulty and complexity of fusion splicing, and there is a problem that it is difficult to conveniently prepare a combined optical fiber with an antiresonant hollow core optical fiber.

[0041] In this example, the core of the antiresonant hollow core optical fiber 1 is an air medium, and the core has a negative curvature profile, which can confine most of the light in the core, thereby significantly reducing material loss.

[0042] like Figure 1 As shown, in some optional embodiments, the bridge optical fiber 3 includes a connecting section 31 and a fused-taper section 32 , the connecting section 31 is connected to the antiresonant hollow-core optical fiber 1 , and the fused-taper section 32 is connected to the single-mode optical fiber 2 .

[0043] In this embodiment, the structure of the bridge optical fiber 3 is specifically described. The bridge optical fiber 3 includes a connecting section 31 and a fused-taper section 32, wherein the connecting section 31 is connected to the antiresonant hollow-core optical fiber 1, and the fused-taper section 32 is connected to the single-mode optical fiber 2. The structure is simple and the division is reasonable.

[0044] In this example, a high temperature resistant anti-reflection film is plated on the end face of the fused taper section 32, which can reduce the reflectivity of the optical fiber end face. The connection section 31 and the antiresonant hollow core optical fiber 1, and the fused taper section 32 and the single-mode optical fiber 2 are fused and connected, and the connection method is simple and efficient. The mode field diameters at both ends of the connection section 31 are the same, ensuring the structural stability of the connection section 31.

[0045] In some optional embodiments, the fused taper section 32 is formed by taper processing the bridge optical fiber 3 using an optical fiber taper machine or an optical fiber fusion splicer with a taper function to form a tapered transition structure with a smaller cladding diameter and mode field diameter.

[0046] In this embodiment, the fused taper segment 32 is formed by tapering the bridge optical fiber 3 using an optical fiber taper machine or an optical fiber fusion splicer with a taper function to form a conical transition structure with a smaller cladding diameter and mode field diameter. The preparation method of the fused taper segment 32 is specifically described to improve the preparation efficiency of the fused taper segment 32, thereby improving the preparation efficiency of the combined optical fiber.

[0047] like Figure 1 As shown, in some optional embodiments, the fused taper section 32 includes a cone section 321 and a flat section 322, the large diameter end of the cone section 321 is connected to the connecting section 31, the small diameter end is connected to one end of the flat section 322, and the other end of the flat section 322 is connected to the single-mode optical fiber 2.

[0048] In this embodiment, the structure of the fused tapered section 32 is specifically described. The fused tapered section 32 includes a cone section 321 and a flat section 322, wherein the large diameter end of the cone section 321 is connected to the connecting section 31, the small diameter end is connected to one end of the flat section 322, and the other end of the flat section 322 is connected to the single-mode optical fiber 2, so that the connection is more convenient and the stability is better.

[0049] like Figure 2 or Figure 3 As shown, in some optional embodiments, a fiber outer protective shell 4 is provided at the connection between the antiresonant hollow core fiber 1 and the bridge fiber 3 .

[0050] In this embodiment, an optical fiber outer protective shell 4 is provided at the connection between the antiresonant hollow core optical fiber 1 and the bridge optical fiber 3, which improves the connection effect and plays a protective role.

[0051] like Figure 2 As shown, in some optional embodiments, one end of the bridging optical fiber 3 connected to the antiresonant hollow-core optical fiber 1 is configured to be truncated cone-shaped and extends into the optical fiber outer protective shell 4 to form a conical lens.

[0052] In this embodiment, one end of the bridge optical fiber 3 connected to the antiresonant hollow core optical fiber 1 is configured to be truncated cone-shaped and extends into the optical fiber outer protective shell 4 to form a cone lens, which can not only improve the coupling efficiency but also reduce back reflection.

[0053] like Figure 3 As shown, in some optional embodiments, one end of the bridge optical fiber 3 connected to the antiresonant hollow core optical fiber 1 is set as a bevel, and the corresponding end face of the antiresonant hollow core optical fiber 1 matches the bevel.

[0054] In this embodiment, one end of the bridge optical fiber 3 connected to the antiresonant hollow core optical fiber 1 is set as a bevel, and the corresponding end face of the antiresonant hollow core optical fiber 1 matches the bevel, which can reduce back reflection.

[0055] In this example, the inclination angle of the inclined surface ranges from 4 to 8 degrees.

[0056] On the other hand, the present application also provides a method for preparing a combined optical fiber, which is used to prepare the above-mentioned combined optical fiber, comprising the following steps:

[0057] Obtain a first mode field diameter and a second mode field diameter;

[0058] According to the first mode field diameter and the second mode field diameter, the mode field diameters at both ends of the bridge optical fiber 3 and the initial mode field diameter of the bridge optical fiber 3 are obtained;

[0059] The bridge optical fiber 3 is prepared according to the initial mode field diameter, the first mode field diameter and the second mode field diameter of the bridge optical fiber 3 , and the antiresonant hollow core optical fiber 1 and the single mode optical fiber 2 are connected via the bridge optical fiber 3 .

[0060] When manufacturing the combined optical fiber, the antiresonant hollow-core optical fiber 1 has a first mode field diameter, the single-mode optical fiber 2 has a second mode field diameter, and the first mode field diameter is greater than the second mode field diameter. One end of the bridging optical fiber 3 is connected to the antiresonant hollow-core optical fiber 1 and matches the mode field of the antiresonant hollow-core optical fiber 1. The other end of the bridging optical fiber 3 is connected to the single-mode optical fiber 2 and matches the mode field of the single-mode optical fiber 2. First, obtain a first mode field diameter and a second mode field diameter; according to the first mode field diameter and the second mode field diameter, obtain the mode field diameters at both ends of the bridge optical fiber 3 and the initial mode field diameter of the bridge optical fiber 3; according to the initial mode field diameter, the first mode field diameter and the second mode field diameter of the bridge optical fiber 3, prepare the bridge optical fiber 3, and connect the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 through the bridge optical fiber 3. Since the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 are connected through the bridge optical fiber 3, the two ends of the bridge optical fiber 3 are matched with the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 respectively. Compared with the direct melting and tapering of the single-mode optical fiber 2, the bridge optical fiber 3 is less difficult to operate and has better connection performance. It can also be replaced in case of operating errors, which is convenient for preparing the combined optical fiber. It solves the problem that the thermal expansion of the single-mode optical fiber in the prior art will only expand the mode field to a limited extent, is not suitable for all hollow-core optical fibers, and has different degrees of mode field matching. When introducing a gradient refractive index multimode optical fiber, the optical fiber length is relatively sensitive, and the increase in length will cause the generation of high-order modes. In addition, this method increases the difficulty and complexity of fusion splicing, and there is a problem that it is difficult to conveniently prepare a combined optical fiber with an antiresonant hollow core optical fiber.

[0061] In some optional embodiments, the method of preparing the bridge optical fiber 3 according to the initial mode field diameter, the first mode field diameter, and the second mode field diameter of the bridge optical fiber 3, and connecting the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 through the bridge optical fiber 3 includes:

[0062] According to the first mode field diameter, the second mode field diameter and the initial mode field diameter, determining the end portion where the bridge optical fiber 3 is connected to the antiresonant hollow core optical fiber 1;

[0063] The connecting section 31 is connected to the antiresonant hollow core optical fiber 1, and a fiber taper machine or a fiber fusion splicer with a taper function is used to perform a taper process on the fused taper section 32 until the end of the fused taper section 32 matches the mode field of the single-mode optical fiber 2.

[0064] In this embodiment, the bridge optical fiber 3 is prepared according to the initial mode field diameter, the first mode field diameter and the second mode field diameter of the bridge optical fiber 3, and the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 are connected through the bridge optical fiber 3. Specifically, the end of the bridge optical fiber 3 connected to the antiresonant hollow core optical fiber 1 is judged according to the size of the first mode field diameter, the second mode field diameter and the initial mode field diameter, the connecting section 31 is connected to the antiresonant hollow core optical fiber 1, and a fiber taper machine or a fiber fusion splicer with a taper function is used to perform a taper process on the fused taper section 32 until the end of the fused taper section 32 matches the mode field of the single-mode optical fiber 2, so as to facilitate the preparation of the combined optical fiber.

[0065] In some optional embodiments, the connecting section 31 is connected to the antiresonant hollow core optical fiber 1, and a fiber taper machine or a fiber fusion splicer with a taper function is used to perform a taper process on the fused taper section 32 until the end of the fused taper section 32 matches the mode field of the single-mode optical fiber 2, including:

[0066] Based on the preset taper parameters, a fiber taper machine or a fiber fusion splicer with a taper function is used to heat and taper the fused taper segment 32. The cladding diameter of the single-mode optical fiber 2 is estimated during taper drawing until the cladding diameter at the end of the fused taper segment 32 is close to or greater than the single-mode optical fiber 2.

[0067] In this embodiment, the connecting section 31 is connected to the antiresonant hollow core optical fiber 1, and a fiber taper machine or a fiber fusion splicer with a taper function is used to perform a taper process on the fused taper section 32 until the end of the fused taper section 32 matches the mode field of the single-mode optical fiber 2. Specifically, based on preset taper parameters, the fiber taper machine or the fiber fusion splicer with a taper function is used to heat and taper the fused taper section 32, and the cladding diameter of the single-mode optical fiber 2 is estimated during the taper process until the cladding diameter of the end of the fused taper section 32 is close to or greater than the single-mode optical fiber 2.

[0068] In summary, when manufacturing the combined optical fiber, the antiresonant hollow-core optical fiber 1 has a first mode field diameter, the single-mode optical fiber 2 has a second mode field diameter, and the first mode field diameter is greater than the second mode field diameter, one end of the bridging optical fiber 3 is connected to the antiresonant hollow-core optical fiber 1 and matches the mode field of the antiresonant hollow-core optical fiber 1, and the other end of the bridging optical fiber 3 is connected to the single-mode optical fiber 2 and matches the mode field of the single-mode optical fiber 2. First, obtain a first mode field diameter and a second mode field diameter; according to the first mode field diameter and the second mode field diameter, obtain the mode field diameters at both ends of the bridge optical fiber 3 and the initial mode field diameter of the bridge optical fiber 3; according to the initial mode field diameter, the first mode field diameter and the second mode field diameter of the bridge optical fiber 3, prepare the bridge optical fiber 3, and connect the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 through the bridge optical fiber 3. Since the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 are connected through the bridge optical fiber 3, the two ends of the bridge optical fiber 3 are matched with the antiresonant hollow core optical fiber 1 and the single-mode optical fiber 2 respectively. Compared with the direct melting and tapering of the single-mode optical fiber 2, the bridge optical fiber 3 is less difficult to operate and has better connection performance. It can also be replaced in case of operating errors, which is convenient for preparing the combined optical fiber. It solves the problem that the thermal expansion of the single-mode optical fiber in the prior art will only expand the mode field to a limited extent, is not suitable for all hollow-core optical fibers, and has different degrees of mode field matching. When introducing a gradient refractive index multimode optical fiber, the optical fiber length is relatively sensitive, and the increase in length will cause the generation of high-order modes. In addition, this method increases the difficulty and complexity of fusion splicing, and there is a problem that it is difficult to conveniently prepare a combined optical fiber with an antiresonant hollow core optical fiber.

[0069] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0070] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0071] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A combined optical fiber, characterized in that: include: An antiresonant hollow core optical fiber (1) having a first mode field diameter; A single-mode optical fiber (2), which has a second mode field diameter, and the first mode field diameter is larger than the second mode field diameter; A bridging optical fiber (3) has one end connected to the antiresonant hollow core optical fiber (1) and matched with the mode field of the antiresonant hollow core optical fiber (1), and the other end of the bridging optical fiber (3) is connected to the single-mode optical fiber (2) and matched with the mode field of the single-mode optical fiber (2).

2. A combined optical fiber according to claim 1, characterized in that: The bridging optical fiber (3) comprises a connecting section (31) and a fused taper section (32); the connecting section (31) is connected to the antiresonant hollow core optical fiber (1); and the fused taper section (32) is connected to the single-mode optical fiber (2).

3. A combined optical fiber according to claim 2, characterized in that: The fused taper section (32) is a fiber taper machine or a fiber fusion splicer with a taper function that performs a taper process on the bridge optical fiber (3) to form a tapered transition structure with a smaller cladding diameter and mode field diameter.

4. A combined optical fiber according to claim 2, characterized in that: The fused cone section (32) comprises a cone section (321) and a flat section (322), wherein the large diameter end of the cone section (321) is connected to the connecting section (31), the small diameter end is connected to one end of the flat section (322), and the other end of the flat section (322) is connected to the single-mode optical fiber (2).

5. A combined optical fiber according to claim 2, characterized in that: An optical fiber outer protective shell (4) is provided at the connection point between the anti-resonance hollow core optical fiber (1) and the bridge optical fiber (3).

6. A combined optical fiber according to claim 5, characterized in that: One end of the bridging optical fiber (3) connected to the anti-resonance hollow-core optical fiber (1) is arranged in a truncated cone shape and extends into the optical fiber outer protective shell (4) to form a cone lens.

7. A combined optical fiber according to claim 5, characterized in that: One end of the bridging optical fiber (3) connected to the antiresonant hollow-core optical fiber (1) is arranged as a bevel, and the corresponding end face of the antiresonant hollow-core optical fiber (1) matches the bevel.

8. A method for preparing a combined optical fiber, characterized in that: The method for preparing a combined optical fiber as claimed in any one of claims 1 to 7 comprises the following steps: Obtain a first mode field diameter and a second mode field diameter; According to the first mode field diameter and the second mode field diameter, the mode field diameters at both ends of the bridge optical fiber (3) and the initial mode field diameter of the bridge optical fiber (3) are obtained; A bridge optical fiber (3) is prepared according to the initial mode field diameter, the first mode field diameter and the second mode field diameter of the bridge optical fiber (3), and the antiresonant hollow core optical fiber (1) and the single mode optical fiber (2) are connected via the bridge optical fiber (3).

9. A method for preparing a combined optical fiber according to claim 8, characterized in that: The method of preparing a bridge optical fiber (3) according to the initial mode field diameter, the first mode field diameter and the second mode field diameter of the bridge optical fiber (3), and connecting the antiresonant hollow core optical fiber (1) and the single-mode optical fiber (2) via the bridge optical fiber (3) comprises: According to the first mode field diameter, the second mode field diameter and the initial mode field diameter, determining the end portion where the bridge optical fiber (3) is connected to the antiresonant hollow core optical fiber (1); The connecting section (31) is connected to the anti-resonant hollow core optical fiber (1), and a fiber taper machine or a fiber fusion splicer with a taper function is used to perform a taper process on the fused taper section (32) until the end of the fused taper section (32) matches the mode field of the single-mode optical fiber (2).

10. The method for preparing a combined optical fiber according to claim 8, characterized in that: The connecting section (31) is connected to the anti-resonant hollow core optical fiber (1), and a fiber taper machine or a fiber fusion splicer with a taper function is used to perform a taper process on the fused taper section (32) until the end of the fused taper section (32) matches the mode field of the single-mode optical fiber (2), including: Based on preset taper parameters, a fiber taper machine or a fiber fusion splicer with a taper function is used to heat and taper the fused taper section (32), and the cladding diameter of the single-mode optical fiber (2) is estimated during the taper process until the cladding diameter at the end of the fused taper section (32) is close to or greater than the single-mode optical fiber (2).

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