Single-lens coupling assembly, single-lens mode field conversion device and connector

Abstract

The invention discloses a single-lens coupling assembly, a single-lens mode field conversion device and a connector. The single-lens coupling assembly comprises a first optical fiber with a first mode field diameter; a second optical fiber having a second mode field diameter; the sleeve is provided with a hollow tube cavity with two through ends, and one end of the first optical fiber and one end of the second optical fiber respectively extend into the hollow tube cavity from openings in the two ends of the sleeve; and the lens is positioned in the sleeve between the first optical fiber and the second optical fiber and is used for realizing conversion of mode field diameters between the first optical fiber and the second optical fiber. Conversion of different mode fields between the first optical fiber and the second optical fiber is achieved through the single lens, and therefore reliable and stable connection between the optical fibers is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber communication, and particularly relates to a single-lens coupling component, a single-lens mode field conversion device, and a connector. Background Art

[0002] Hollow anti-resonant fiber (hereinafter simply referred to as hollow fiber) realizes hollow light guiding through the anti-resonant reflection optical waveguide mechanism, and has advantages such as low delay, low dispersion, low nonlinearity, high damage threshold, broadband light guiding, low thermal sensitivity, and radiation resistance. Therefore, it has great application prospects in the fields of optical communication, high-power laser transmission, ultrafast optics, nonlinear optics, fiber sensing, etc., and is very suitable for harsh environments such as space radiation.

[0003] To improve the compatibility between hollow fiber and traditional fiber device systems, or between fiber and optical waveguide, achieving low insertion loss, high return loss, and high stability connection between different fibers is the core problem to be solved. However, there are often large structural and mode field differences between them, making it difficult to achieve efficient and reliable coupling. The fiber mode field conversion device can change the mode field characteristics of the transmitted light, thereby breaking through the coupling bottleneck between hollow fiber and traditional single-mode fiber, realizing the high-efficiency integration of fiber optic devices, and bringing more possibilities for its development and application. Facing the upcoming large-scale application demands of hollow fiber in the fields of high-speed large-capacity optical communication, high-power laser transmission, fiber sensing, and special-scenario optical transmission in the future, it is necessary to develop fiber mode field conversion devices and hollow fiber connectors with mode field diameter conversion functions.

[0004] Develop a hollow-core fiber mode field diameter conversion device to achieve efficient connection between hollow-core fibers and traditional solid-core single-mode fibers widely used in existing optical transmission systems. There are mainly three technical bottleneck problems as follows. Firstly, when the transmission wavelength of traditional solid-core single-mode fiber is 1310nm, the mode field diameter is about 9.2μm, while the mode field diameter of hollow-core fiber is generally 20 - 40μm. The mode field sizes of the two are seriously mismatched, resulting in high coupling loss. For example, for a hollow-core fiber with a mode field diameter of 20μm, the coupling loss with a single-mode fiber is not less than 1.9dB; for a hollow-core fiber with a mode field diameter of 40μm, the coupling loss will be at least as high as 6.6dB. In addition, the mode field mismatch at the coupling interface of the two may also excite high-order modes in the hollow-core fiber, affecting the quality of the transmitted light beam. Therefore, matching the mode field characteristics of the two fibers is one of the key technical bottleneck problems to be solved. Secondly, there is an air structure in the core of the hollow-core fiber, and the air-glass interface at the coupling interface between the traditional solid-core single-mode fiber and the hollow-core fiber will also generate strong Fresnel reflection, thus increasing the insertion loss and bringing back reflection. Therefore, effective suppression of Fresnel reflection at the interface is the second technical bottleneck problem to be solved. Thirdly, for hollow-core fibers with internal microstructures, since the fiber itself relies on the internal microstructures to achieve low-loss optical transmission, ensuring the integrity of the internal microstructures of the fiber during coupling is also a key technical bottleneck problem to be solved.

[0005] In the prior art, for fiber coupling, an optical waveguide module is often fixed on the fiber to achieve the conversion of the mode field diameter of the fiber. However, the size of the optical waveguide module is small, so the size control is difficult and it is not easy to process. Moreover, in order to improve the return loss, a certain tilt angle is required at the end of the module that realizes the optical waveguide, which further increases the processing difficulty and the difficulty of realizing coupling. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems in the related art to some extent.

[0007] To this end, an embodiment of one aspect of the present invention provides a single-lens coupling assembly. The present invention realizes the conversion of different mode fields between the first fiber and the second fiber through a single lens, so as to achieve a reliable and stable connection between the first fiber and the second fiber. At the same time, the internal structure of a mode field conversion device of the present invention is designed according to the characteristics of the hollow-core fiber and the requirements of low insertion loss and high return loss.

[0008] One of the purposes of the present invention is to provide a single-lens coupling assembly, including

[0009] a first fiber having a first mode field diameter;

[0010] a second fiber having a second mode field diameter;

[0011] A sleeve, the sleeve having a hollow lumen that penetrates through both ends, and one end of each of the first optical fiber and the second optical fiber extends into the hollow lumen through the openings at both ends of the sleeve;

[0012] A lens, located within the sleeve between the first optical fiber and the second optical fiber, for achieving the conversion of the mode field diameter between the first optical fiber and the second optical fiber.

[0013] As a preferred solution, the end faces of the lens facing the optical fibers at both ends are both arc-shaped structures.

[0014] As a preferred solution, the first end of the first optical fiber is a bare optical fiber segment, and this bare optical fiber segment is arranged within the hollow lumen of the first ferrule to form a first optical fiber component. The first end of the second optical fiber is a bare optical fiber segment, and this bare optical fiber segment is arranged within the hollow lumen of the second ferrule to form a second optical fiber component.

[0015] As a preferred solution, the sleeve is a hollow cylindrical structure. The sleeve includes a first sub-suite and a second sub-suite. The ends of the first sub-suite and the second sub-suite are butt-jointed and arranged coaxially. One end of the lens extends into the lumen of the first sub-suite, and the second end of the lens extends into the lumen of the second sub-suite.

[0016] As a preferred solution, an inclined cut surface is formed at the end of the first optical fiber component facing the lens, and the inclined cut surface is not perpendicular to the axial direction of the first ferrule.

[0017] As a preferred solution, an anti-reflection film is provided on the inclined cut surface, and an anti-reflection film is provided on the arc-shaped structure on the side of the lens opposite to the first optical fiber component.

[0018] As a preferred solution, it further includes a connector ferrule. The bare optical fiber segment at the head end of the first optical fiber is arranged within the hollow lumen of the connector ferrule, and the bare optical fiber segment at the tail end of the first optical fiber is arranged within the hollow lumen of the first ferrule.

[0019] As a preferred solution, it further includes a flange. The flange has a cavity three along the central axis. The head end of the cavity three is used for fixedly installing the connector ferrule; the tail end of the cavity three is used for fixedly installing and accommodating one end of the first ferrule, and the other end of the first ferrule extends into the hollow lumen of the sleeve.

[0020] As a preferred solution, the flange includes a large-diameter section and a small-diameter section. An external prism is formed on the cylindrical surface of the large-diameter section, and the external prism is used for anti-rotation cooperation with the internal prism cavity of the connector housing.

[0021] As a preferred solution, it further includes a protective sleeve. The protective sleeve has a cavity four that penetrates through both ends. The sleeve and the flange are inserted into the cavity four of the protective sleeve, and the butt joint seam between the flange and the sleeve is placed inside the cavity four.

[0022] As a preferred solution, the first optical fiber is a solid-core single-mode optical fiber, and the second optical fiber is a hollow-core optical fiber.

[0023] A second object of the present invention is to provide a single-lens mode field conversion device, including a single-lens coupling assembly as described above.

[0024] As a preferred solution, it further includes a first fixing assembly and a second fixing assembly. The first fixing assembly includes a first outer housing, and the second fixing assembly includes a second outer housing. The docking ends of the first outer housing and the second outer housing are connected to form a housing structure, and a cavity for accommodating the single-lens coupling assembly is provided inside the housing structure. A first fixing sleeve fixes the first optical fiber at the end of the first outer housing, and a second fixing sleeve fixes the second optical fiber at the end of the second outer housing.

[0025] As a preferred solution, pressure joints for cooperating with the fixing sleeves are provided at the opposite ends of the first outer housing and the second outer housing.

[0026] As a preferred solution, at least one annular sealing connection groove is provided on the outer cylindrical surface of the pressure joint.

[0027] As a preferred solution, the first fixing assembly further includes a flange and a retaining ring. The flange is a cylindrical structure, and a cavity for accommodating the first optical fiber component is formed along the axial direction of the flange. A limiting boss is provided on the outer wall near the first end of the flange, and a groove for installing the retaining ring is provided on the outer wall near the second end of the flange. The flange is fixedly connected to the first optical fiber component. The first end of the flange cooperates with a stop platform inside the first outer housing through the limiting boss to limit the position of the flange relative to the first outer housing along the first axial direction. The second end of the flange cooperates with the retaining ring through the groove to limit the position of the flange relative to the first outer housing along the second axial direction, where the first axial direction and the second axial direction are opposite directions.

[0028] A third object of the present invention is to provide a connector, including the single-lens coupling assembly described in any one of the above.

[0029] As a preferred solution, it further includes a connector housing. The connector housing is arranged outside the single-lens coupling assembly. The connector housing includes a connector housing Ⅰ and a connector housing Ⅱ. The docking ends of the connector housing Ⅰ and the connector housing Ⅱ are fixedly connected. A stop platform Ⅰ is formed on the inner wall of the cavity of the connector housing Ⅰ, and the stop platform Ⅰ is used to form a stop limit for the axial movement of the single-lens coupling assembly relative to the connector housing in the head-end direction.

[0030] As a preferred solution, it further includes an elastic member. The elastic member is arranged in the accommodating cavity of the connector housing. The first end of the elastic member can abut against the circumferential step on the outer periphery of the flange, and the second end of the elastic member abuts against a stop platform Ⅱ inside the connector housing Ⅱ.

[0031] As a preferred solution, an inner sleeve is arranged inside the connector housing II, and the head end of the inner sleeve is used to abut against the elastic member, and its tail end extends out of the connector housing.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] First, through the improvement of the structure, the structure of the fiber optic coupling component is optimized. By setting a special lens, it is convenient to process the lens in batches, which reduces the processing difficulty of the fiber optic coupling component to a certain extent. At the same time, after the structural improvement, it uses a single special lens to realize the conversion of different mode fields between two fibers with different mode field diameters, reducing the insertion loss of the hollow core fiber. The return loss is improved by processing and coating the fiber bevel. Since Fresnel reflection occurs when light is incident on the interface of two media with different refractive indices, the present solution suppresses Fresnel reflection by coating anti-reflection films on the end faces of the first fiber and the lens. By setting a first pin at the end of the first fiber and a second pin at the end of the second fiber, the reinforcement of the fiber end is achieved, and at the same time, it is convenient to adjust the position of the fiber during subsequent debugging. By arranging a first fixing component and a second fixing component outside the two fibers with different mode field diameters to form a housing, the internal structure is fixed and effectively protected.

[0034] Second, the present solution also provides a connector. By integrating the single-lens coupling component inside the connector housing, the connector has the function of mode field diameter conversion, realizing the efficient connection between the hollow core fiber and the traditional solid-core single-mode fiber widely used in the existing optical transmission system, which helps to meet the large-scale application requirements of hollow core fibers in the fields of high-speed large-capacity optical communication, high-power laser transmission, fiber sensing, and optical transmission in special scenarios. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0036] Figure 1 It is the overall structure external view of the single-lens mode field conversion device of the present invention;

[0037] Figure 2 It is the overall structure cross-sectional view of the single-lens mode field conversion device of the present invention;

[0038] Figure 3 It is the external structure view of the single-lens coupling component of the present invention;

[0039] Figure 4 Cross-sectional view of the single-lens coupling component of the present invention;

[0040] Figure 5 Partial enlarged view of the connection between the solid-core end housing and the hollow-core end housing of the present invention;

[0041] Figure 6 Partial enlarged view of the connection between the solid-core pin optical fiber component and the solid-core end housing of the present invention;

[0042] Figure 7 Partial enlarged view of the connection between the hollow-core pin optical fiber component and the hollow-core end housing of the present invention;

[0043] Figure 8 Schematic diagram of the connection between the solid-core single-mode optical fiber and the solid-core pin of the present invention;

[0044] Figure 9 Schematic diagram of the connection between the hollow-core optical fiber and the hollow-core pin of the present invention;

[0045] Figure 10 Schematic diagram of the connection between the lens and the first sub-assembly of the present invention;

[0046] Figure 11 Schematic diagram of the connection between the lens and the second sub-assembly of the present invention;

[0047] Figure 12 Schematic diagram of the working principle of the mode field conversion of the single-lens mode field conversion device of the present invention;

[0048] Figure 13 Schematic diagram of the structure of the single-lens mode field conversion device in the specific embodiment of the present invention;

[0049] Figure 14 Simulation diagram in the specific embodiment of the present invention: solid-core single-mode optical fiber - hollow-core optical fiber;

[0050] Figure 15 Simulation diagram in the specific embodiment of the present invention: hollow-core optical fiber - solid-core single-mode optical fiber;

[0051] Figure 16 Structure diagram of the single-lens coupling component in the connector of the present invention;

[0052] Figure 17 Appearance structure diagram of the connector in the present invention;

[0053] Figure 18 Cross-sectional view of the connector housing in the present invention;

[0054] Figure 19 Cross-sectional view of the connector in the present invention;

[0055] Figure 20 It is a cross-sectional view of the flange in the connector of the present invention;

[0056] Figure 21 It is a three-dimensional view of the flange in the connector of the present invention;

[0057] Figure 22 It is a structural diagram of the connector pin in the present invention;

[0058] Markings in the figure: 1, solid-core single-mode optical fiber, 11, solid-core single-mode optical fiber I, 12, solid-core single-mode optical fiber II, 2, hollow optical fiber, 3, sleeve, 31, first sub-assembly, 311, cavity one, 32, second sub-assembly, 321, cavity two, 4, lens, 41, lens I, 42 lens II, 5, solid-core pin, 51, tapered insertion hole, 52, beveled surface, 6, hollow pin, 7, solid-core end housing, 8, hollow end housing, 82, locking block, 9, solid-core end fixing sleeve, 10, hollow end fixing sleeve, 13, flange, 131, limiting boss, 132, groove, 133, stop surface, 134, cavity three, 135, large-diameter cavity, 136, small-diameter cavity, 137, circumferential step on the outer periphery, 138, large-diameter section, 139, small-diameter section, 14, retaining ring, 15, connector pin, 151, hollow cavity, 152, tapered opening, 16, elastic member, 18, protective sleeve, 19, inner sleeve, 100, solid-core optical fiber component, 111, compression joint, 112, annular groove, 200, hollow optical fiber component, 300, single-lens coupling assembly, 400, solid-core end fixing assembly, 500, hollow end fixing assembly, 600, beam transmission, 700, connector housing, 701, stop platform I, 702, card hole, 703, connector housing I, 704, connector housing II, 705, stop platform II, 706, accommodation cavity, 707, locking block, 708, prism cavity, 101, solid-core optical fiber outer sheath layer, 102, solid-core bare optical fiber section, 103, solid-core optical fiber coating layer, 104, solid-core optical fiber protection layer, 105, solid-core optical fiber strengthening element, 201, hollow optical fiber outer sheath layer, 202, hollow bare optical fiber section, 203, hollow optical fiber coating layer, 204, hollow optical fiber strengthening element, A, adhesive location. Detailed implementation manners

[0059] The present invention will be specifically described below through exemplary implementation manners. However, it should be understood that, without further description, the elements, structures and features in one implementation manner can also be beneficially combined into other implementation manners.

[0060] It should be noted that: Unless otherwise defined, the technical terms or scientific terms used in this article shall have the ordinary meanings understood by those with ordinary skills in the field to which this invention belongs. The words such as "a", "an" or "the" used in the description and claims of this patent application for invention do not express a limitation of quantity, but mean that there is at least one. Words such as "comprising" or "including" indicate that the elements or objects appearing before "comprising" or "including" cover the elements or objects listed after "comprising" or "including" and their equivalents, but do not exclude other elements or objects with the same functions.

[0061] In the embodiments of this solution, the coupling of a solid-core single-mode fiber and a hollow-core fiber is taken as an example for illustration. It should be noted that the first fiber of this solution is not limited to a solid-core single-mode fiber, and the second fiber is not limited to a hollow-core fiber either. The coupling of the first fiber and the second fiber with different mode field diameters is applicable to this solution.

[0062] Embodiment 1

[0063] As Figure 1-15 shown, in a preferred embodiment of this solution, a single-lens coupling component is provided, which includes a solid-core single-mode fiber 1, a hollow-core fiber 2, a sleeve 3, and a lens 4. In this embodiment, the first fiber uses the solid-core single-mode fiber 1, and the second fiber uses the hollow-core fiber 2; the mode field diameters of the solid-core single-mode fiber 1 and the hollow-core fiber 2 are different. The solid-core single-mode fiber 1 has a first mode field diameter, and the hollow-core fiber 2 has a second mode field diameter, and the mode field diameter of the hollow-core fiber 2 is larger than that of the solid-core single-mode fiber 1. The sleeve 3 is a glass tube with a hollow cavity, and the lens 4 is arranged in the hollow cavity of the sleeve 3. The first end portions of the solid-core single-mode fiber 1 and the hollow-core fiber 2 respectively extend into its inner cavity from the two open ends of the sleeve 3, and the solid-core single-mode fiber 1 and the hollow-core fiber 2 are oppositely arranged at both ends of the lens 4; the lens 4 is a separately provided component, which is convenient for batch and separate processing. The two ends of the lens 4 corresponding to the solid-core single-mode fiber 1 and the hollow-core fiber 2 are arc-shaped convex surface structures.

[0064] According to different beam transmission directions, this solution specifically includes the following two situations: The first end of the lens 4 close to the small-mode-field solid-core single-mode fiber 1 is used to expand and collimate the light emitted by the solid-core single-mode fiber 1, and the second end of the lens 4 close to the large-mode-field hollow-core fiber 2 is used to focus the collimated light to a spot mode field size matching that of the large-mode-field hollow-core fiber 2. Or, the second end of the lens 4 close to the large-mode-field hollow-core fiber 2 is used to expand and collimate the light emitted by the hollow-core fiber 2, and the first end of the lens 4 close to the small-mode-field solid-core single-mode fiber 2 is used to focus the collimated light to a spot mode field size matching that of the small-mode-field solid-core single-mode fiber 1.

[0065] In this solution, to facilitate the installation of the lens 4 more conveniently, the sleeve 3 is disconnected into two parts along the cross-section perpendicular to its axis, namely the first sub-assembly 31 and the second sub-assembly 32. The first arcuate convex end of the lens 4 is arranged in the cavity one 311 of the first sub-assembly 31, and the second arcuate convex end of the lens 4 is arranged in the cavity two 321 of the second sub-assembly 32. The cavity one 311 and the cavity two 321 have the same shape and inner diameter size. The purpose of such a setting is considered as follows: If the sleeve 3 is integrally formed, the lens 4 needs to extend into its cavity from one side port of the sleeve 3 and enter the position near the middle section of the sleeve 3. Since the cylindrical surface of the lens 4 is coated with glue for bonding, such glue will adhere to the inner wall of the sleeve 3 during the installation of the lens 4, which will contaminate the inner wall of the sleeve 3. Since the sleeve 3 in this solution is pre-designed to be disconnected into two parts, during the installation of the lens, only one end of the lens 4 needs to be first extended into the hollow cavity of the first sub-assembly 31 and fixed with glue, and the other end of the lens 4 is extended into the hollow cavity of the second sub-assembly 32 and fixed with glue. In this way, the contamination of the inner wall of the sleeve 3 can be avoided.

[0066] In a typical embodiment of the present invention, the first pin is a solid pin 5, and the second pin is a hollow pin 6; the solid pin 5 is a hollow cylindrical glass tube, and a tapered insertion hole 51 is arranged at the cavity port of the solid pin 5. The arrangement of the tapered insertion hole 51 can more conveniently guide the end of the solid single-mode optical fiber 1 to be inserted into the pin cavity, and at the same time can be used to accommodate glue, making the connection between the optical fiber and the pin more firm. One end of the solid pin 5 facing the lens 4 forms an inclined plane 52, and an anti-reflection film is plated on the inclined plane 52. The hollow pin 6 is a cylindrical glass tube, and both ends thereof are flat end faces. The arrangement of the solid pin 5 and the hollow pin 6 can, on the one hand, play a role in strengthening the end of the optical fiber, and on the other hand, can facilitate a series of optical fiber position adjustments during the production and debugging of subsequent conversion devices.

[0067] In this solution, taking the solid single-mode optical fiber 1 and the hollow optical fiber 2 as examples, the solid bare fiber section 102 of the solid single-mode optical fiber 1 without the coating layer 101 is passed through the solid pin 5 and fixed with glue, and the end faces of the combination of the solid single-mode optical fiber 1 and the solid pin 5 are ground and an anti-reflection film is plated, thereby forming the first optical fiber component. The first optical fiber component in this embodiment is also the solid optical fiber component 100; the hollow bare fiber section 202 of the hollow optical fiber 2 without the coating layer 201 is passed through the hollow pin 6, the end of the hollow optical fiber 2 extending out of the hollow pin 6 is cut flat by using an optical fiber cutter, and then the end face of the hollow optical fiber 2 is pulled back into the cavity of the hollow pin 6, and the hollow bare fiber section of the hollow optical fiber 2 and the hollow pin 6 are fixed with glue, thereby forming the second optical fiber component. The second optical fiber component in this embodiment is also the hollow optical fiber component 200. The solid optical fiber component 100 and the hollow optical fiber component 200 extend into the sleeve 3 from both ends of the sleeve 3 and realize the conversion and matching of the two optical fiber mode fields.

[0068] In this embodiment, since Fresnel reflection occurs when light is incident on the interface between two media with different refractive indices, this solution suppresses Fresnel reflection by coating antireflection films on the end faces of the small mode field solid core single-mode fiber 1 and the lens 4. The principle of designing the antireflection film is that two reflected light beams on the upper and lower surfaces of the film undergo destructive interference. Therefore, the optical path difference between the two reflected lights should be an odd multiple of half a wavelength, and the optical thickness of the film layer (the product of the actual thickness and the refractive index of the material) must be an odd multiple of a quarter wavelength.

[0069] In this solution, in order to further improve the return loss, the end face of the small mode field solid core single-mode fiber 1 assembly is ground into an inclined section 52, which can reflect a part of the reflected light at a certain angle to the cladding, thereby reducing more reflected light in the core from returning to the light source and increasing the return loss.

[0070] Embodiment 2

[0071] As shown in the figure, this solution also provides a single-lens mode field conversion device, including the single-lens coupling assembly 300 of the above-mentioned Embodiment 1. A first fixing component is arranged on the periphery of the solid core end of the single-lens coupling assembly 300. In this embodiment, the first fixing component is a solid core end fixing component 400. A second fixing component is arranged on the periphery of the hollow core end of the single-lens coupling assembly 300. In this embodiment, the second fixing component is a hollow core end fixing component 500; and the solid core end fixing component 400 and the hollow core end fixing component 500 are connected by threads. A first fixing sleeve is sleeved outside the connection part between the solid core end fixing component 400 and the solid core optical fiber component 100. The first fixing sleeve is a solid core end fixing sleeve 9, and the solid core end fixing sleeve 9 is used to fixedly press the solid core single-mode fiber 1 at the crimping end of the solid core end fixing component 400. A second fixing sleeve is sleeved outside the connection part between the hollow core end fixing component 500 and the hollow core optical fiber component 100. The second fixing sleeve is a hollow core end fixing sleeve 10, which is used to fixedly press the hollow core optical fiber 2 at the crimping end of the hollow core end fixing component 500.

[0072] In a typical embodiment of the present invention, the solid core end fixing component 400 includes a first outer shell, and the first outer shell is a solid core end outer shell 7. The hollow core end fixing component 500 includes a second outer shell, and the second outer shell is a hollow core end outer shell 8. Both the solid core end outer shell 7 and the hollow core end outer shell 8 are rotary cylinder structures with hollow cavities arranged along their respective central axes. Inner thread parts and outer thread parts are correspondingly arranged at the opposite connection ends of the solid core end outer shell 7 and the hollow core end outer shell 8. Therefore, the opposite ends of the solid core end outer shell 7 and the hollow core end outer shell 8 can be fixedly connected by threads. After the solid core end outer shell 7 and the hollow core end outer shell 8 are threadedly connected, a complete outer shell structure is formed, and an accommodation cavity for accommodating the single-lens coupling assembly 300 is formed inside this outer shell structure.

[0073] In a preferred embodiment of this solution, compression joints 111 are provided at the opposite ends of the solid-core end housing 7 and the hollow-core end housing 8. At least one annular groove 112 is formed on the compression joint 111 along the axial direction. The function of setting the annular groove 112 is to cooperate with the solid-core end fixing sleeve 9 and the hollow-core end fixing sleeve 10. For example, if the fixing sleeve is fixed by shrinkage crimping, after the fixing sleeve deforms and tightens, it will be fastened at the position of the annular groove 112. The annular groove 112 can increase the relative frictional force between the fixing sleeve and the compression joint 111 along the axial direction and enhance the sealing effect. If the fixing sleeve is fixed by gluing, the annular groove 112 can be used to hold glue, playing a role in increasing the firmness of bonding and enhancing the sealing effect.

[0074] In the present invention, the structures of the solid-core end fixing sleeve 9 and the hollow-core end fixing sleeve 10 are the same or similar, both being annular sleeves, including a large-diameter end and a small-diameter end. The large-diameter end of the solid-core end fixing sleeve 9 fixes or bonds the solid-core optical fiber outer sheath layer 103 of the solid-core single-mode optical fiber 1 whose end is stripped to the compression joint 111 of the solid-core end housing 7. The small-diameter end of the solid-core end fixing sleeve 9 is used to connect with the solid-core single-mode optical fiber 1. The hollow-core end fixing sleeve 10 fixes or bonds the hollow-core optical fiber outer sheath layer 203 of the hollow-core optical fiber 2 to the compression joint 111 of the hollow-core end housing 8.

[0075] In a typical embodiment of the present invention, the solid end fixing assembly 400 also includes a flange 13 and a retaining ring 14 for fixing the position of the flange 13, wherein the main body of the flange 13 is a hollow cylindrical structure, the tail end of the solid pin 5 is fixed to the inner wall of the flange 13 by glue, and the head end of the solid pin 5 extends into the interior of the sleeve 3 and corresponds to the lens 4. A limiting boss 131 is provided on the outer wall near the first end of the flange 13, and a stopper is formed at the connection between the accommodating cavity of the solid core end outer shell 7 and the crimping joint 101, and the stopper can cooperate with the limiting boss 131, so as to limit the relative position between the solid core optical fiber component 100 and the solid core end outer shell 7 along the first axial direction of the A axis, and a groove 132 for installing the retaining ring 14 is provided on the outer wall near the second end of the flange 13, and after the retaining ring 14 is installed, it is located at the outer end of the crimping joint 111 of the solid core end outer shell 7, so as to limit the relative position between the solid core optical fiber component 100 and the solid core end outer shell 7 along the second axial direction of the A axis through the retaining ring 14, and the first axial direction and the second axial direction are In the opposite direction, specifically, the spacing between the retaining ring 14 and the limiting boss 131 is equal to the axial length of the crimping joint 111 of the solid core end outer shell 7 accommodated therein, thereby being able to limit the axial position of the solid core optical fiber component 100 relative to the solid core end outer shell 11 from both ends. It should be pointed out that after the retaining ring 14 is installed, it is basically flush with the outer cylindrical surface of the crimping joint 101 of the solid core end outer shell 7, thereby facilitating the installation of the solid core end fixing sleeve 9. Since the solid core end fixing component 400 and the hollow core end fixing component 500 are threadedly connected, the limiting cooperation of the limiting boss 131 and the retaining ring 14 can realize the limitation of the relative position of the single lens coupling component 300 and the overall shell along the axial direction.

[0076] In this solution, the solid core single mode optical fiber 1 includes, from outside to inside, a solid core optical fiber outer sheath layer 101, a solid core optical fiber reinforcement element 105, a solid core optical fiber protective layer 104, a solid core optical fiber coating layer 103 and a solid core optical fiber bare fiber segment 102, wherein the solid core optical fiber bare fiber segment 102 includes a cladding and a core portion. The hollow core optical fiber 2 includes, from outside to inside, a hollow core optical fiber outer sheath layer 201, a hollow core optical fiber reinforcement element 204, a hollow core optical fiber coating layer 203 and a hollow core optical fiber bare fiber segment 202.

[0077] The manufacturing method of the single-lens mode field conversion device of the present invention comprises the following steps:

[0078] The uncoated solid core bare fiber segment 102 of the solid core single mode optical fiber 1 is inserted into the cavity of the solid core pin 5 and fixed to form a solid core optical fiber component 100; the uncoated hollow core bare fiber segment 202 of the hollow core optical fiber 2 is inserted into the cavity of the hollow core pin 6 and fixed to form a hollow core optical fiber component 200;

[0079] In this step, the solid-core optical fiber coating layer 103 outside the optical fiber cladding at the first end of the solid-core single-mode optical fiber 1 is removed. The solid-core bare optical fiber section 102 of the solid-core single-mode optical fiber 1 with the stripped solid-core optical fiber coating layer 103 is inserted into the hollow lumen of the solid-core ferrule 5 and fixed with glue. The end face of the combination of the solid-core single-mode optical fiber 1 and the solid-core ferrule 5 is polished to form an inclined section 52 that is not perpendicular to its axis, and an anti-reflection film is deposited on the arc convex surface opposite to the lens 4 on the inclined section 52 to form the solid-core optical fiber component 100.

[0080] In this step, part of the hollow-core optical fiber coating layer 203 outside the optical fiber cladding in the hollow-core optical fiber 200 is removed. The hollow-core bare optical fiber section 202 of the hollow-core optical fiber 2 with the stripped hollow-core optical fiber coating layer 203 is passed through the hollow lumen of the hollow-core ferrule 6, and the end of the hollow-core bare optical fiber section 202 at the penetrated end is cut flat using an optical fiber cutter. The hollow-core bare optical fiber section 202 is pulled back into the hollow lumen of the hollow-core ferrule 6 and fixed with glue to form the hollow-core optical fiber component 200.

[0081] It should be noted that in this solution, the outer solid-core optical fiber outer sheath layer 101 that is stripped is only separated from the solid-core bare optical fiber section 102, while the stripped solid-core optical fiber outer sheath layer 101 and the non-stripped solid-core optical fiber outer sheath layer 101 at the rear end are still connected together. The outer hollow-core outer sheath layer 201 that is stripped is only separated from the hollow-core bare optical fiber section 202, while the stripped hollow-core optical fiber outer sheath layer 201 and the non-stripped hollow-core optical fiber outer sheath layer 201 at the rear end are still connected together.

[0082] The lens 4 is inserted into the lumen of the sleeve 3 and fixed. The solid-core optical fiber component 100 and the hollow-core optical fiber component 200 are respectively inserted through the opposite end ports of the sleeve 3. After passing the optical alignment test, the positions of the solid-core optical fiber component 100 and the hollow-core optical fiber component 200 are bonded and fixed to form the single-lens coupling assembly 300.

[0083] In this step, the lens 4 is inserted into the body of the sleeve 3 and fixed. The solid-core optical fiber component 100 and the hollow-core optical fiber component 200 are inserted into the predetermined theoretical design positions in the sleeve 3, and the optical alignment test is carried out online. By finely adjusting the axial and radial positions of the solid-core optical fiber component 100 and the hollow-core optical fiber component 200, when the coupling loss is minimized, the positions of the solid-core optical fiber component 100 and the hollow-core optical fiber component 200 are fixed to form the single-lens coupling assembly 300. Since the ends of the solid-core optical fiber component 100 and the hollow-core optical fiber component 200 are both arranged in the ferrule components made of glass material, during the optical alignment test process, while strengthening the optical fiber, it is very convenient to accurately adjust the position to achieve an efficient coupling effect.

[0084] In this step, preferably, the sleeve 3 includes a first sub-assembly 31 and a second sub-assembly 32. First, insert the first end of the lens 4 into the lumen of the first sub-assembly 31 and bond it in place. Then, insert the second end of the lens 4 into the lumen of the second sub-assembly 32 and bond it in place. Next, insert the solid-core optical fiber component 100 and the hollow-core optical fiber component 200 through the opposite end ports of the sleeve 3 respectively. After optical transmission debugging, bond and fix the positions of the solid-core optical fiber component 100 and the hollow-core optical fiber component 200 when the coupling loss is minimized to form a single-lens coupling assembly 300. In this way, when installing the lens 4, only need to first insert one end of the lens 4 into the hollow cavity of the first sub-assembly 31 and fix it with adhesive, and insert the other end of the lens 4 into the hollow cavity of the second sub-assembly 32 and fix it with adhesive, which will effectively avoid contaminating the inner wall of the sleeve 3.

[0085] Fix the docking ends of the solid-core end fixing component 400 sleeved outside the solid-core end of the single-lens coupling assembly 300 and the hollow-core end fixing component 500 sleeved outside the hollow-core end of the single-lens coupling assembly 300 in a fixed connection;

[0086] In this step, fixedly connect the solid-core optical fiber component 100 of the single-lens coupling assembly 300 obtained in the above step to the flange 13 by means of adhesive, and then sleeve a solid-core end outer housing 7 outside one end of the flange 13 of the single-lens coupling assembly 300, and use a retaining ring 14 to block and limit the axial relative sliding between the flange 13 and the solid-core end outer housing 7. Specifically, the retaining ring 14 abuts against the end of the solid-core end outer housing 7. Sleeve a hollow-core end outer housing 8 on the hollow-core end of the single-lens coupling assembly 300, and threadedly connect the solid-core end outer housing 7 and the hollow-core end outer housing 8.

[0087] Fix the solid-core optical fiber outer sheath layer 101 stripped from the solid-core single-mode optical fiber 1 on the solid-core end fixing 400 through a solid-core end fixing sleeve 9, and fix the hollow-core optical fiber outer sheath layer 201 stripped from the hollow-core optical fiber 2 on the hollow-core end fixing component 500 through a hollow-core end fixing sleeve 10;

[0088] In this step, specifically, the large-diameter end of the solid-core end fixing sleeve 9 fixes the stripped outer sheath and aramid fiber of the solid-core single-mode optical fiber 1 between the solid-core end fixing sleeve 9 and the crimping head 111 of the solid-core end outer housing 7 by means of crimping or bonding. At the same time, the stripped outer sheath layer and aramid fiber of the hollow-core optical fiber 2 are fixed between the hollow-core end fixing sleeve 10 and the crimping head 111 of the hollow-core end outer housing 8 by means of crimping or bonding. It should be noted that the solid-core end fixing sleeve 9 and the solid-core end outer housing 7 are pre-sleeved on the solid-core optical fiber component 100, while the hollow-core end fixing sleeve 10 and the hollow-core end outer housing 8 are pre-sleeved on the hollow-core optical fiber component 200.

[0089] The following is an illustration with specific embodiments: This specific embodiment adopts the above manufacturing method. Specifically, this embodiment is a solid-core single-mode fiber - hollow-core fiber - solid-core single-mode fiber transmission optical path, including two optical paths: solid-core single-mode fiber I 11 - hollow-core fiber 2 and hollow-core fiber 2 - solid-core single-mode fiber II 12. Both optical paths are subjected to mode field coupling through the above structure. Among them, the mode field of the solid-core single-mode fiber 11 - hollow-core fiber 2 is converted from a small mode field diameter to a large mode field diameter, so that the coupling of the solid-core single-mode fiber 11 - hollow-core fiber 2 is realized through lens I 41. The mode field of the hollow-core fiber 2 - solid-core single-mode fiber II 12 is converted from a large mode field diameter to a small mode field diameter, as Figure 13-15 .

[0090] In this embodiment, the distance between the solid-core single-mode fiber I 11 and the first end of lens I 41 is L1 (1.4 - 1.5 mm), the distance between the second end of lens I 41 and the first end of the hollow-core fiber 2 is L2 (3.6 - 3.7 mm), the distance between the second end of the hollow-core fiber 2 and the first end of lens II 42 is L3 (3.7 - 3.8 mm), and the distance between the second end of lens II 42 and the adjacent end of the solid-core single-mode fiber II 12 is L4 (1.4 - 1.5 mm). Specifically, in this solution, the mode field diameters of the solid-core single-mode fiber I 11 and the solid-core single-mode fiber 12 are equal, both being 9.2 μm; the mode field diameter of the hollow-core fiber 2 is 20 μm (@1310 nm).

[0091] In this embodiment, taking lens I 41 as the zero point, the radial deviation value of the solid-core single-mode fiber I 11 on the left side of lens I 41 is 0.066 mm, and the radial deviation value of the hollow-core fiber 2 on the right side of lens I 41 is 0.155 mm. There is no radial deviation in the optical path components from the hollow-core fiber 2 through lens II 42 to the solid-core single-mode fiber II 12.

[0092] The parameters of lens I and lens II in this solution are the same, specifically as follows: Material N-SF11, lens curvature: the radius of one end is 1.15 mm, and the other end, lens length 4.85 mm. The circular convex surfaces with a curvature radius of 1.15 mm of the two lenses (lens I and lens II) are respectively arranged facing the solid-core single-mode fiber I 11 and the solid-core single-mode fiber II 12, while the circular convex surfaces with a curvature radius of 2.52 mm of the two lenses are correspondingly arranged facing: the direction of the hollow-core fiber 2.

[0093] In the above embodiment, through theoretical simulation, the coupling loss from the solid-core single-mode fiber I 11 to the hollow-core fiber 2 is 0.17 dB, the coupling loss from the hollow-core fiber 2 to the solid-core single-mode fiber II 12 is 0.23 dB, and the return loss exceeds 45 dB, meeting the usage requirements.

[0094] The present solution also provides a comparative example. All parameters of the solid-core single-mode fiber and the hollow-core fiber used in the comparative example are the same as those in the above embodiments. The difference lies in that: the single-lens mode field conversion device of the present solution is not included in the comparative example. Instead, the above solid-core single-mode fiber 1 and the hollow-core fiber 2 are directly connected by a conventional fusion splicing method in the prior art. The mode field diameter of the solid-core single-mode fiber 1 is 9.2 μm; the mode field diameter of the hollow-core fiber 2 is 20 μm (@1310 nm). The coupling loss in this comparative example is higher than 2.4 dB, and the return loss is about 15 dB.

[0095] In this solution, the manufacturing process of the single-lens mode field conversion device is optimized. By cooperating with the specific structure of the above single-lens mode field conversion device and strictly implementing the manufacturing process, it is possible to avoid the contamination of the internal components of the conversion device. At the same time, the processing difficulty is reduced to a certain extent, and the coupling effect of the manufactured product is improved. In this solution, through a specific pin structure, the solid-core fiber component 100 and the hollow-core fiber component 200 are respectively introduced from both ends of the sleeve 3, which is convenient for light passing debugging and adjusting the position of the optical fiber, and realizing the precise coupling effect of the two optical fibers with different mode field diameters, so as to achieve a reliable and stable connection effect between the two optical fibers with different mode field diameters.

[0096] Embodiment 3

[0097] As Figure 16-22 shown, this embodiment provides a single-lens coupling assembly for a connector, including a solid-core single-mode fiber 1, a hollow-core fiber 2, a sleeve 3, and a lens 4. In this embodiment, the first optical fiber uses the solid-core single-mode fiber 1, and the second optical fiber uses the hollow-core fiber 2; the first optical fiber and the second optical fiber have different mode field diameters. The mode field diameters of the solid-core single-mode fiber 1 and the hollow-core fiber 2 are different. Among them, the solid-core single-mode fiber 1 has a first mode field diameter, and the hollow-core fiber 2 has a second mode field diameter, and the mode field diameter of the hollow-core fiber 2 is larger than that of the solid-core single-mode fiber 1. The sleeve 3 is a glass tube with a hollow cavity, and the lens 4 is arranged in the hollow cavity of the sleeve 3. The first end portions of the solid-core single-mode fiber 1 and the hollow-core fiber 2 respectively extend into its inner cavity from the two openings at both ends of the sleeve 3, and the solid-core single-mode fiber 1 and the hollow-core fiber 2 are arranged opposite to each other at both ends of the lens 4; the lens 4 is a separately arranged component, which is convenient for batch and separate processing. The two ends of the lens 4 corresponding to the solid-core single-mode fiber 1 and the hollow-core fiber 2 are arc-shaped convex surface structures.

[0098] In this solution, to make the installation and debugging of the lens 4 more convenient, the sleeve 3 is disconnected into two parts along the cross-section perpendicular to its axis, namely the first sub-assembly 31 used as a solid-core end sleeve and the second sub-assembly 32 used as a hollow-core end sleeve. The first arc convex end of the lens 4 is arranged in the cavity 311 of the first sub-assembly 31, and the second arc convex end of the lens 4 is arranged in the cavity 321 of the second sub-assembly 32. The shapes and inner diameter sizes of the cavity 311 and the cavity 321 are the same. The purpose of such a setting is considered as follows: If the sleeve 3 is integrally formed, the lens 4 needs to extend into its cavity from one side port of the sleeve 3 and enter the position near the middle section of the sleeve 3. Since the cylindrical surface of the lens 4 is coated with glue for bonding, such glue will adhere to the inner wall of the sleeve 3 when the lens 4 is installed, which will contaminate the inner wall of the sleeve 3. Since the sleeve 3 in this solution is pre-designed to be disconnected into two parts, when the lens 4 is installed, only one end of the lens 4 needs to be first inserted into the hollow cavity of the first sub-assembly 31 and fixed with glue, and the other end of the lens 4 is inserted into the hollow cavity of the second sub-assembly 32 and fixed with glue, so as to avoid contaminating the inner wall of the sleeve 3. In addition, from the perspective of debugging, the first sub-assembly 31 is first fixed to one end of the lens 4, while the second sub-assembly 32 and the lens 4 are connected but not fixed first, so as to facilitate the subsequent adjustment of the relative positions of the solid-core optical fiber component 100 and the hollow-core optical fiber component 200 and reduce the difficulty of debugging operations. When the overall loss of the two reaches the optimum during the debugging process, the second sub-assembly 32 and the lens 4 are fixedly connected by an adhesive.

[0099] In this embodiment, the first pin is a solid-core pin 5, and the second pin is a hollow-core pin 6; the solid-core pin 5 is a hollow cylindrical glass tube, and a tapered insertion hole 51 is arranged at the cavity port of the solid-core pin 5. The arrangement of the tapered insertion hole 51 can more conveniently guide the end of the solid-core single-mode optical fiber 1 to be inserted into the pin cavity, and at the same time can be used to accommodate glue, making the connection between the optical fiber and the pin more firm. One end of the solid-core pin 5 facing the lens 4 forms an inclined plane 52 that is not perpendicular to its axis, and an anti-reflection film is plated on the inclined plane 52. The hollow-core pin 6 is a cylindrical glass tube with flat end faces at both ends. The arrangement of the solid-core pin 5 and the hollow-core pin 6 can play a role in strengthening the end of the optical fiber on the one hand, and can facilitate a series of optical fiber position adjustments during the production and debugging of subsequent conversion devices on the other hand.

[0100] This solution also includes a connector pin 15. Taking the solid-core single-mode fiber 1 and the hollow-core fiber 2 as examples, by removing the protective layers at both ends of the solid-core single-mode fiber 1 so that both ends are solid-core bare fiber segments, the tail-end solid-core bare fiber segment of the solid-core single-mode fiber 1 is inserted into the cavity inside the solid-core pin 5 and fixed by adhesive. The head-end solid-core bare fiber segment of the solid-core single-mode fiber 1 is inserted into the hollow cavity 151 at the tail end of the connector pin 15 and fixed by adhesive. Specifically, the connector pin 15 is formed with a through hollow cavity 151 along the central axis direction. A tapered opening 152 is formed at the tail end of the hollow cavity 151. The tapered opening 152 is used to fill the adhesive, making the fixation between the connector pin 15 and the solid-core single-mode fiber 1 more firm. Grind the end face of the combination of the solid-core single-mode fiber 1 and the solid-core pin 5 and coat an anti-reflection film to form the first optical fiber component, which is the solid-core optical fiber component 100. Pass the uncoated hollow-core bare fiber segment of the hollow-core fiber 2 through the hollow-core pin 6. Use an optical fiber cutter to cut the end of the hollow-core fiber 2 extending out of the hollow-core pin 6 flat, and then pull the end face of the hollow-core fiber 2 back into the cavity of the hollow-core pin 6 to form the second optical fiber component, which is the hollow-core optical fiber component 200. The solid-core pin 5 and the hollow-core pin 6 extend into the inside of the sleeve 3 from both ends of the sleeve 3 respectively, and realize the mode field conversion and matching of the two optical fibers. In this solution, the end of the single-lens coupling component 300 with the connector pin 15 is defined as the head end.

[0101] In this embodiment, the single-lens coupling component 300 further includes a flange 13. The flange 13 is formed with a through cavity three 134 along its central axis direction. Preferably, in order to match the outer dimensions of the connector pin 15 and the solid-core pin 5, an inner circumferential step is formed on the inner wall of the middle section of the cavity three 134. The inner circumferential step divides the inside of the cavity three 134 into a large-diameter cavity 135 and a small-diameter cavity 136. The inside of the large-diameter cavity 135 is used to accommodate and install the tail-end part of the connector pin 15. The small-diameter cavity 136 is used to install the first end of the hollow-core pin 5. The second end of the hollow-core pin 5 is located inside the sleeve 3. The connection position between the large-diameter cavity 135 and the small-diameter cavity 136 is used to fill the binder, so as to fix the connector pin 15 and the solid-core pin 5 at both ends of the cavity three 134 respectively. An outer circumferential step 137 is also provided on the outer cylindrical surface of the flange 13. The outer circumferential step 137 divides the flange 13 into a large-diameter section 138 and a small-diameter section 139. A stop surface 133 is formed at the head-end end of the large-diameter section 138. The purpose of the stop surface 133 is to be in stop cooperation with the stop platform I 701 inside the connector housing I 703, and is used to form a limit stop for the flange 13 to move in the head-end direction. The small-diameter section 139 is butted against the end of the sleeve 3. And preferably, the outer diameter of the small-diameter section 139 is the same as that of the sleeve 3. A protective sleeve 18 is sleeved outside the butt joint seam of the sleeve 3 and the flange 13. The small-diameter section 139 of the flange 13 and a part of the length of the sleeve 3 are located inside the protective sleeve 18.

[0102] Specifically, a cavity four is formed in the protection sleeve 18 along the central axis direction. The head end of the sleeve 3 and the tail end of the flange 13 are both inserted into the cavity four of the sleeve 18, so that the protection sleeve 18 can be used to fix the flange 13, the first sub-assembly 31 and the second sub-assembly 32, and reinforce the outside of the above components to increase their mechanical strength. At the same time, by arranging the protection sleeve 18 outside, the butt joint seam between the sleeve 3 and the flange 13 is placed inside the protection sleeve 18 to ensure the smoothness and no step of the column body where the elastic member 10 is installed, so as to prevent the axial misalignment butt joint of the sleeve 3 and the flange 13 from affecting the telescopic movement of the elastic member 10 through the protection sleeve 18.

[0103] The assembly method of the single-lens coupling component 300 of this solution is as follows: The specific steps are as follows:

[0104] Single-mode end assembly steps: Step 11: Remove the outer protective layers at both ends of the solid-core single-mode optical fiber 1 to form solid-core bare optical fiber segments, and insert the tail end of the solid-core single-mode optical fiber 1 into the hollow cavity 151 of the solid-core ferrule 5, and grind the end face of the solid-core ferrule 5 according to requirements;

[0105] Step 12: Insert the tail end of the connector ferrule 15 into and fix it in the large-diameter cavity 135 of the flange 13 to form a connector ferrule assembly;

[0106] Step 13: Insert the head-end solid-core bare optical fiber segment of the solid-core single-mode optical fiber 1 processed in Step 11 into the connector ferrule assembly processed in Step 12. Specifically, the head end of the solid-core single-mode optical fiber 1 penetrates through the small-diameter cavity 136 of the flange 13 and extends into the hollow cavity of the connector ferrule 15 for fixation. It should be noted that before the solid-core single-mode optical fiber 1 is inserted, an adhesive should be pre-filled in the cavity three 134 of the flange 13, and then the solid-core single-mode optical fiber 1 is inserted and then enters the hollow cavity of the connector ferrule 15, and is fixed by the adhesive to obtain a connector ferrule assembly;

[0107] Step 14: Assemble and fix the lens 4 with the first sub-assembly 31. Specifically, the head end of the lens 4 extends into the tail-end interior of the first sub-assembly 31 to assemble and form a solid-core end lens assembly;

[0108] Step 15: Assemble the solid-core end lens assembly obtained in Step 14 onto the connector ferrule assembly processed in Step 13. Specifically, the tail end of the solid-core ferrule 5 extends into the head-end end part of the first sub-assembly 31, thus completing the component assembly at one end of the solid-core single-mode optical fiber 1.

[0109] Hollow-core end assembly steps: Step 21: Insert the head end of the hollow-core optical fiber 2 into the hollow-core ferrule 4 to obtain a hollow-core ferrule assembly;

[0110] Step 22: Insert the head end of the hollow pin assembly obtained in Step 21 into the cavity of the second sub-assembly 32, without fixing the second sub-assembly 32 and the hollow pin 6 for the time being.

[0111] Debugging and assembly steps: Step 31: Fix the solid end component obtained in the single-mode end assembly step and the hollow end component obtained in the hollow end assembly step in two toolings of the adjusting frame respectively.

[0112] Step 32: By adjusting the relative positions of the solid optical fiber component 100 and the hollow optical fiber component 200, make the overall loss reach the optimal effect.

[0113] Step 33: At the position where the overall loss effect is optimal, bond and fix the second sub-assembly 32 to the lens 4, and bond and fix the hollow optical fiber component 200 to the second sub-assembly 32.

[0114] Step 34: Fix the pre-inserted protective sleeve 18 at the connection gap between the flange 13, the first sub-assembly 31 and the second sub-assembly 32, thereby obtaining the single-lens coupling assembly 300.

[0115] Embodiment 4

[0116] This solution also provides a connector, including the single-lens coupling assembly 300 for the connector in Embodiment 3 above and a connector housing 700. Taking the LC connector as an example, the connector housing 700 includes a connector housing I 703 and a connector housing II 704. The docking ends of the connector housing I 703 and the connector housing II 704 can be connected by a snap-fit method. Specifically, a snap hole 702 or a slot is provided on the side wall of the connector housing I 703, and a snap block 707 is provided on the side wall of the connector housing II 704. The snap block 707 cooperates with the snap hole 702 or the slot to realize the fixed connection of the connector housing I 703 and the connector housing II 704. An accommodation cavity 706 is formed inside the connector housing 700, and the single-lens coupling assembly 300 is installed in the accommodation cavity 706, that is, the head end of the single-lens coupling assembly 300 passes through the connector housing 700 and extends out through the head end of the connector housing 700.

[0117] In this solution, a stop platform I 701 is formed in the accommodation cavity of the connector housing I 703. The stop platform I 701 can cooperate with the stop surface 133 of the flange 13 of the single-lens coupling assembly 300, so as to form a stop effect on the single-lens coupling assembly 300 moving towards the head end direction. Specifically, in addition to the above stop effect, the head end stop part of the flange 13 has a structure with a small head end and a large tail end. When it cooperates with the tapered cavity formed by the stop surface 133, it can also realize a certain guiding and aligning effect on the single-lens coupling assembly 300 when it moves axially. Further, the outer cylindrical surface of the large-diameter section 138 of the flange 13 can be set as an outer prism structure 1310, and a prism cavity 708 that cooperates with the outer prism structure 1310 of the flange 13 is formed inside the accommodation cavity of the connector housing I 703. Thus, through the cooperation of the outer prism 1310 and the prism cavity 708, the relative anti-rotation effect between the single-lens coupling part 300 and the connector housing 700 is realized. An insertion pin hole for the connector insertion pin 15 to pass through is formed on the head end face of the connector housing I 703.

[0118] In this solution, the elastic member 10 is sleeved on the outer cylindrical surface of the protective sleeve 18. The head end of the elastic member 10 abuts against the circumferential step 137 of the flange 13, and the tail end of the elastic member 10 abuts against the stop platform II 705 in the accommodation cavity 706 of the connector housing 700. A pre-tightening force towards the head end direction is applied to the single-lens coupling assembly 300 through the elastic member 10, so that the single-lens coupling assembly 300 can be integrally abutted against the stop platform I 701. When the single-lens coupling assembly 300 is pressed, it can compress the elastic member 10 integrally towards the tail end direction, so as to realize the overall movement of the single-lens coupling assembly 300 towards the tail end. At the same time, the elastic member 10 provides an elastic pressure towards the head end direction for the single-lens coupling assembly 300.

[0119] In this embodiment, an inner sleeve 19 is further arranged inside the accommodation cavity 706 of the connector housing 700. The head end of the inner sleeve 19 extends into the connector housing II 704 and is fixed inside it. The stop platform II 705 formed at the head end of the inner sleeve 19 forms an abutting fit with the tail end of the elastic member 10. The tail end of the inner sleeve 19 extends out of the connector housing II 704 for fixed connection with external devices. The inner sleeve 19 forms a cavity along the central axis. The tail end part of the single-lens coupling assembly 300 is arranged in the cavity of the inner sleeve 19, and the hollow optical fiber 2 passes through the inner sleeve 19 towards the tail end direction.

[0120] The assembly method of the connector is as follows: The LC connector is used for illustration below:

[0121] Step 41: Sleeve the elastic member 10 and the connector housing II 704 on the single-lens coupling assembly 300 in Embodiment 3;

[0122] Step 42: Insert the end of the single-lens coupling component 300 with the connector pin 15 into the interior of the connector housing Ⅰ703 and extend it. Then, dock the connector housing Ⅰ703 and the connector housing Ⅱ704 in place, and achieve fixed clamping through the snap block and the snap hole, thereby obtaining the connector of this solution.

[0123] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A single-lens coupling component, characterized in that: Comprising a first optical fiber having a first mode field diameter; a second optical fiber having a second mode field diameter; a sleeve having a hollow lumen that penetrates through both ends, and one end of each of the first optical fiber and the second optical fiber extends into the hollow lumen through the openings at both ends of the sleeve; a lens located within the sleeve between the first optical fiber and the second optical fiber for achieving the conversion of the mode field diameter between the first optical fiber and the second optical fiber.

2. The single-lens coupling component according to claim 1, wherein: Both end faces of the lens facing the two optical fibers are arc-shaped structures.

3. The single-lens coupling component according to claim 2, characterized in that: The first end of the first optical fiber is a bare fiber segment, and this bare fiber segment is disposed within the hollow lumen of the first ferrule to form a first optical fiber component. The first end of the second optical fiber is a bare fiber segment, and this bare fiber segment is disposed within the hollow lumen of the second ferrule to form a second optical fiber component.

4. The single-lens coupling component according to claim 2, wherein: The sleeve is a hollow cylindrical structure, and the sleeve includes a first sub-assembly and a second sub-assembly. The ends of the first sub-assembly and the second sub-assembly are butt-jointed and coaxially arranged. One end of the lens extends into the lumen of the first sub-assembly, and the second end of the lens extends into the lumen of the second sub-assembly.

5. The single-lens coupling component according to claim 3, wherein: The end of the first optical fiber component facing the lens forms an inclined cut surface, and the inclined cut surface is not perpendicular to the axis of the first ferrule.

6. The single-lens coupling component according to claim 5, wherein: An anti-reflection film is provided on the inclined cut surface, and an anti-reflection film is provided on the arc-shaped structure on the side of the lens opposite to the first optical fiber component.

7. A single-lens coupling component according to any one of claims 1-6, characterized in that: It further includes a connector ferrule. The bare fiber segment at the head end of the first optical fiber is disposed within the hollow lumen of the connector ferrule, and the bare fiber segment at the tail end of the first optical fiber is disposed within the hollow lumen of the first ferrule.

8. The single-lens coupling component according to claim 7, wherein: It further includes a flange. The flange has a cavity three along the central axis. The head end of the cavity three is used for fixedly installing the connector ferrule; the tail end of the cavity three is used for fixedly installing and accommodating one end of the first ferrule, and the other end of the first ferrule extends into the hollow lumen of the sleeve.

9. The single-lens coupling component according to claim 8, wherein: The flange includes a large-diameter section and a small-diameter section. An external prism is formed on the cylindrical surface of the large-diameter section, and the external prism is used for anti-rotation cooperation with the internal prism cavity of the connector housing.

10. A single-lens coupling component according to claim 8, characterized in that: It further includes a protective sleeve. The protective sleeve has a cavity four that penetrates through both ends. The sleeve and the flange are inserted into the cavity four of the protective sleeve, and the butt joint seam between the flange and the sleeve is placed inside the cavity four.

11. The single-lens coupling component according to claim 1, wherein: The first optical fiber is a solid-core single-mode optical fiber, and the second optical fiber is a hollow-core optical fiber.

12. A single-lens mode field conversion device, characterized in that: Comprising a single-lens coupling assembly according to any one of claims 1-6.

13. A single-lens mode field conversion device according to claim 12, characterized in that: It further includes a first fixing assembly and a second fixing assembly. The first fixing assembly includes a first outer housing, and the second fixing assembly includes a second outer housing. The butt-jointed ends of the first outer housing and the second outer housing are connected to form a housing structure, and a cavity for accommodating the single-lens coupling assembly is provided within the housing structure. A first fixing sleeve fixes the first optical fiber at the end of the first outer housing, and a second fixing sleeve fixes the second optical fiber at the end of the second outer housing.

14. A single-lens mode field conversion device according to claim 13, characterized in that: Both opposite ends of the first outer housing and the second outer housing are provided with crimping heads for cooperation with the fixing sleeves.

15. A single-lens mode field conversion device according to claim 14, characterized in that: At least one annular seal connection groove is provided on the outer cylindrical surface of the crimping head.

16. A single-lens mode field conversion device according to claim 13, characterized in that: The first fixing component further includes a flange and a retaining ring. The flange is of a cylindrical structure, and a cavity for accommodating the first optical fiber component is formed along the axial direction of the flange. A limiting boss is provided on the outer wall near the first end of the flange, and a groove for installing the retaining ring is provided on the outer wall near the second end of the flange. The flange is fixedly connected to the first optical fiber component. The first end of the flange cooperates with a stop in the lumen of the first housing through the limiting boss to limit the position of the flange relative to the first housing in the first axial direction. The second end of the flange cooperates with the groove and the retaining ring to limit the position of the flange relative to the first housing in the second axial direction, where the first axial direction and the second axial direction are opposite directions.

17. A connector, characterized in that: Comprising the single-lens coupling component according to any one of claims 1-11.

18. A connector according to claim 17, characterized in that: It further includes a connector housing, which is arranged outside the single-lens coupling component. The connector housing includes a connector housing Ⅰ and a connector housing Ⅱ. The docking ends of the connector housing Ⅰ and the connector housing Ⅱ are fixedly connected. A stop Ⅰ is formed on the inner wall of the cavity of the connector housing Ⅰ, and the stop Ⅰ is used to form a stop limit for the axial movement of the single-lens coupling component relative to the connector housing in the head-end direction.

19. A connector according to claim 17 or 18, characterized in that: It further includes an elastic member, which is arranged in the accommodating cavity of the connector housing. The first end of the elastic member can abut against the circumferential step on the outer periphery of the flange, and the second end of the elastic member abuts against a stop Ⅱ in the connector housing Ⅱ.

20. A connector according to claim 18, characterized in that: An inner sleeve is arranged inside the connector housing Ⅱ, and the head end of the inner sleeve is used to abut against the elastic member, and its tail end extends out of the connector housing.

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