Optical fiber coupler

Abstract

The invention discloses an optical fiber coupler, and relates to an optical fiber laser coupling technology, the optical fiber coupler comprises an optical fiber coupling body, the optical fiber coupling body comprises a liquid core optical fiber coupling end and a liquid core optical fiber receiving end, the liquid core optical fiber coupling end is a hollow-core optical fiber coupling body formed by fusing and coupling N fluorine-doped capillary quartz glass tube bundles, kerr medium liquid is injected into a multi-fiber end hollow area of the hollow-core fiber coupling body; the liquid core optical fiber receiving end is processed into an inner cone, and the inner cone angle is gt; at 90 degrees, the inner cone is filled with Kerr liquid to form a liquid core optical fiber receiving end; the optical fiber coupling body is formed by matching, fusing and coupling liquid core end surfaces of the liquid core optical fiber coupling end and the liquid core optical fiber receiving end; and the adaptive coupling sealing structure is used for placing the optical fiber coupling body, and the input end and the output end of the adaptive coupling sealing structure are respectively matched with the liquid core optical fiber adapters, so that an integrated multi-path coupling adaptive sealing structure is formed, and the optical fiber coupler is formed. The optical fiber laser coupling technology is improved, and high-power laser beam power coupling is achieved.

Description

Technical Field

[0001] This application relates to the field of fiber laser technology, and particularly to an optical fiber coupler. Background Art

[0002] Fiber lasers are widely used in fields such as laser space long-distance communication. However, with the further increase in the demand for laser power, the increase in the power of fiber lasers requires higher costs and is unstable. If the method of using a microlens to focus is adopted to increase the laser pulse power, then under the irradiation of strong laser, the focusing microlens is extremely easy to be damaged and the focal spot is relatively large, which is not conducive to further coupling into an optical fiber or for other applications. By utilizing the focusing effect of strong laser in a highly nonlinear medium and using a liquid-core fiber with a liquid core as a Kerr medium with a high nonlinear coefficient for the focusing of strong laser, compared with focusing microlenses or lens groups or directly increasing the power of fiber lasers, it has the characteristics of low cost, small focusing spot, and laser fiber output.

[0003] A liquid-core fiber is filled with a transparent liquid with a high refractive index into the core of a hollow-core fiber. Laser light can be confined to propagate forward within the fiber core layer. It is different from silica fibers and polymer fibers and has its unique properties. When the liquid-core fiber is bent, since the core is filled with flowing liquid inside, the stress on the liquid will be quickly released to the surrounding, so it will not cause large bending losses like the above-mentioned fibers when bent, has a large bending radius, and the liquid-core fiber has excellent heat dissipation performance and can transmit hundreds of watts of optical power without being damaged. Due to the special structure of the liquid-core fiber different from traditional fibers, it has many unique properties: large core diameter, large numerical aperture, wide spectrum, high transmission efficiency, long service life, etc. In recent years, by filling various liquids such as rare-earth ions, dyes, azo, etc. into hollow-core fibers to produce various functional liquid-core fibers, extensive attention has been obtained. How to quickly detect the optical signal amplification performance of these liquid-core fibers containing different liquids is a very urgent need.

[0004] Liquid-core optical fibers and optical waveguides have been the subject of continuous research and development work for decades because, within a certain range of applications, they are applicable to an increasingly favorable effect. Various applications of liquid-filled hollow-core optical fibers are known, and typically depend on the properties of the liquid used to fill the core and the specific properties of the optical fiber employed. For example, liquid-core optical fibers are used to observe and study the Raman effect generated at the other end of the optical fiber when the material filling the core is excited by a laser source coupled to one end of the optical fiber. Such an assembly requires that optical couplers or connectors for transmitting light be placed at the input and output of the optical fiber so that the excitation signal emitted by the laser source can be injected into the optical fiber, and requires analyzing the properties of the signal output from the optical fiber. To perform the desired analysis, the described applications require that the optical fiber be filled with liquid and optically coupled to the optical fiber, which assumes that the optical fiber can be filled with liquid without limitation and that the liquid inserted into the optical fiber can be changed. In addition, optical fibers known as "microstructured" optical fibers or sometimes "photonic crystal fibers" have been developed for various applications such as telecommunications, nonlinear optical devices, etc. for several years, and have such favorable properties that their use has spread rapidly. A microstructured optical fiber is an optical fiber that contains microstructures that exhibit the form of cavities extending along the length of the optical fiber, and the cross-section of the optical fiber forms the matrix of the cavities, thereby defining the microstructures.

[0005] Patent CN102324688A proposes a high-power laser light source. The patent states that the present invention provides a high-power laser fiber light source, belonging to the field of fiber technology. In particular, it relates to the technical problem solved by the laser fiber light source, which is to utilize the laser focusing effect in the liquid-core optical fiber to achieve the focused emission of the laser emitted by the fiber laser in the liquid-core optical fiber. It provides a high-power laser fiber light source, which is characterized by consisting of a fiber laser, a quartz optical fiber, an optical fiber connector, and a liquid-core optical fiber. The liquid-core optical fiber is connected to the quartz optical fiber through an optical fiber adapter. The laser emitted by the fiber laser is transmitted through a common quartz optical fiber and enters the liquid-core optical fiber. The liquid in the liquid-core optical fiber is a liquid with a high nonlinear coefficient. By utilizing the focusing effect of high-power laser in a high-nonlinear medium, the focusing of the laser is achieved, and the focused high-power laser is emitted from the liquid-core optical fiber. This light source meets the requirements of various applications that demand a high-power fiber light source. However, this patent does not consider how to solve the problem of multi-channel high-power laser coupling.

[0006] Patent CN104737047A proposes an optical device with a liquid-core optical fiber and a method for manufacturing such a device. The connection device for the liquid-core optical fiber of the present invention includes a sleeve, which is penetrated by a channel including a plurality of connected and superimposed conduits. The first conduit is formed from one end of the sleeve and is arranged to receive one end of the optical fiber in a sealed manner at the corresponding end of the sleeve, and the second conduit is formed to communicate with the first conduit and a closing device, and the closing device hermetically seals the end of the second conduit opposite to the end communicating with the first conduit. The sleeve further includes a third conduit, which is used to fill the internal volume of the second conduit when the second conduit is closed at one end by the closing device and the optical fiber is inserted into the first conduit. The third conduit laterally connects the outside of the sleeve to the inside of the second conduit and a sealing plug, and the sealing plug is used to hermetically seal the opening of the third conduit leading to the outside of the sleeve. However, this patent has problems such as poor single-path coupling sealing.

[0007] Patent CN110954296A also discloses a method for detecting the optical signal amplification performance of a liquid-core optical fiber and a detection device therefor. Invention method: The present invention relates to a method for detecting the optical signal amplification performance of a liquid-core optical fiber and a detection device therefor. By preparing a liquid-core optical fiber, testing the optical characteristics of the liquid-core optical fiber, adjusting the signal optical path, adjusting the pump optical path, synthesizing a focused light beam, aligning the focal point, and comparing the amplification performance diagrams of liquid-core optical fibers filled with different liquids, it is possible to perform a small amount of parameter adjustment according to the spectral characteristics of different liquid-core optical fibers, quickly detect and display the amplification effect of liquid-core optical fibers with different fillers on optical signals, thereby efficiently determining the amplification performance of the fillers of the liquid-core optical fiber, and further quickly identifying and detecting excellent liquid-core optical fiber filling materials. However, this patent only conducts innovative development in terms of materials and fails to elaborate in detail on functions and characteristic uses. Summary of the Invention

[0008] The embodiments of the present application provide an optical fiber coupler to achieve high-power laser beam power coupling and improve the optical fiber laser coupling technology.

[0009] The embodiments of the present application provide an optical fiber coupler, including: an optical fiber coupling body and an adaptive coupling and sealing structure, wherein,

[0010] The optical fiber coupling body includes a liquid-core optical fiber coupling end and a liquid-core optical fiber receiving end. The liquid-core optical fiber coupling end 2 is a hollow-core optical fiber coupling body formed by fusing and coupling 5 groups of N fluorine-doped capillary quartz glass tubes. A Kerr medium liquid is injected into the hollow region at the multi-fiber end of the hollow-core optical fiber coupling body. The 5 groups of N fluorine-doped capillary quartz glass tubes at the liquid-core optical fiber coupling end 2 are vertically arranged upward, filled, and sealed.

[0011] The liquid-core fiber optic receiving end 3 is processed into an inner cone with an inner cone angle > 90°. The inner cone is filled with Kerr liquid and sealed to form the liquid-core fiber optic receiving end.

[0012] The fiber optic coupler is formed by the liquid-core end faces of the liquid-core fiber optic coupling end and the liquid-core fiber optic receiving end being matched and fusion-coupled.

[0013] The adapter coupling and sealing structure 4 is used to place the fiber optic coupler, and the input end and the output end are respectively matched with liquid-core fiber optic adapters to form an integrated multi-channel coupling and matching sealing structure, constituting the fiber optic coupler.

[0014] Optionally, a transition cone region is added in the middle of the fusion splicing of the liquid-core fiber optic coupling end 2, and the end face of the transition cone region is fusion-spliced with the end face of the quartz fiber to form the fiber optic coupler.

[0015] Optionally, the liquid-core fiber optic receiving end 3 is located on the side with a smaller cross-sectional area of the transition cone region of the fiber optic bundle structure and is cut from one large-core diameter signal fiber.

[0016] Optionally, there is a planar coating 7 at the inner cone bottom of the inner cone, and the outlet is sealed after the planar coating 7 is completed.

[0017] Optionally, the input end and the output end of the adapter coupling and sealing structure 4 are both provided with adapter coupling fiber optic end faces.

[0018] In the embodiment of the present application, multi-channel high-power laser beams are coupled through the liquid-core fiber optic coupling end, the liquid-core fiber optic receiving end, and the adapter coupling and sealing structure, and are coupled through the cone region of the fiber optic cone structure, forming miniaturization of the coupling structure and stable output of high-power laser.

[0019] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the following specifically gives the specific implementation manners of the present application. Description of the Drawings

[0020] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. And throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0021] Figure 1 It is a schematic diagram of the external structure of the fiber optic coupler according to the embodiment of the present application;

[0022] Figure 2Schematic diagram of the liquid injection method for the liquid-core optical fiber coupling end of the optical fiber coupler according to the embodiment of the present application

[0023] Figure 3 Schematic diagram of the structure of the liquid-core optical fiber coupling module of the optical fiber coupler according to the embodiment of the present application;

[0024] Figure 4 Schematic diagram of the internal structure of the package of the liquid-core optical fiber coupling module of the optical fiber coupler according to the embodiment of the present application. Detailed implementation manners

[0025] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0026] The embodiment of the present application provides an optical fiber coupler. As shown in Figure 1 , Figure 2 , Figure 3 , the optical fiber coupler 1 according to the embodiment of the present application includes an optical fiber coupling body and an adaptive coupling sealing structure, wherein:

[0027] The optical fiber coupling body includes a liquid-core optical fiber coupling end and a liquid-core optical fiber receiving end. The liquid-core optical fiber coupling end 2 is a hollow optical fiber coupling body formed by melting and coupling 5 bundles of N fluorine-doped capillary quartz glass tubes. The hollow region at the multi-fiber end of the hollow optical fiber coupling body is injected with Kerr medium liquid, filled and sealed. In the present application, the liquid-core optical fiber coupling end of the optical fiber coupler 1 is formed by arranging and combining N hollow optical fibers, and through electrode melting and tapering, a coupled molten microstructure cone structure is formed. After cutting, both ends of the coupled molten cone are quartz-sealed, and the core structure inside the microstructure cone structure is in a hollow state, forming an inverted hollow optical fiber coupling body. The hollow optical fiber coupling body is formed by melting and coupling fluorine-doped capillary quartz tubes, and the fluorine-doped capillary quartz tubes have strong liquid corrosion resistance.

[0028] In a specific example, the liquid-core optical fiber coupling end 2 has a microstructure cone structure, and the multi-fiber end is placed vertically upward. Colloid is slowly injected from the lower end of the microstructure cone structure. Through the capillary effect, the microstructure cone structure is fully filled with colloid. The capillary phenomenon of filling the liquid helps to exclude the air in the internal space of the microstructure cone structure, and at the same time is beneficial to reducing the injection bubbles generated during the colloid injection process. After the liquid-core optical fiber coupling end is filled with Kerr liquid, the laser transmits linearly in the liquid core and will not deviate. In a specific example, the liquid Kerr medium is carbon disulfide (CS2), which has a large nonlinear polarization coefficient and good transparency.

[0029] For example, in an optional embodiment, the inner diameter of N capillary fused silica tubes 5 is 100 μm and the outer diameter is 800 μm. The N fluorine-doped capillary fused silica tubes 5 are grouped by a professional bunching device. The grouped capillary glass tube bundle is melted and tapered by a three-electrode tapering machine, and the outer diameter of the tapered transition region formed by the grouped coupling is 400 μm. The tapered transition region is cut online by the online cutting knife of the three-electrode tapering machine, and the cutting angle is set to 0°, forming the liquid-core fiber coupling end, as Figure 2 shown.

[0030] The liquid-core fiber receiving end 3 is processed into an inner cone, and the inner cone angle > 90°. The inner cone is filled with Kerr liquid and sealed to form the liquid-core fiber receiving end. The laser maintains high-quality transmission inside the liquid-core fiber, maintaining the original mode of the laser. When passing through the inner cone surface of the fiber with an angle greater than 90°, the laser will undergo a refraction phenomenon. Multiple beams of laser are combined into one beam of laser after refraction through the cone surface, and finally power combination is achieved through the output end. The liquid-core coupling structure of the present application can achieve laser combination.

[0031] In some embodiments, the liquid-core fiber receiving end 3 is located on the side with a small cross-sectional area of the transition cone region of the fiber bundle structure. It is formed by cutting a large-core diameter signal fiber with a large-core diameter fiber. It includes a fiber cone and liquid filling, and beam coupling is formed on the side of the fiber cone. The microstructured cone structure is filled with Kerr dielectric liquid, and the relevant liquid mechanism is formed after filling the Kerr dielectric liquid, forming a multi-channel coupling power structure. Thus, power coupling output is formed, and multi-channel laser combination is achieved. When transmitting through the low-refractive-index liquid, due to the excellent heat dissipation performance of the liquid-core fiber, it can transmit hundreds of watts of optical power without being damaged. Due to the special structure of the liquid-core fiber different from traditional fibers, it has many unique characteristics: large core diameter, large numerical aperture, wide spectrum, high transmission efficiency, long service life, etc.

[0032] The fiber coupler is formed by the liquid-core end faces of the liquid-core fiber coupling end and the liquid-core fiber receiving end being matched and fused. The adapter coupling and sealing structure 4 is used to place the fiber coupler, and the input end and the output end are respectively matched with the liquid-core fiber adapters to form an integrated multi-channel coupling and adapting sealing structure, constituting the fiber coupler. In some embodiments, the adapter coupling and sealing structure 4 includes input and output adapting interfaces, forming an integrated module structure. The adapting interfaces can be directly connected to the adapters, with a simple structure, which is beneficial to the application and development in the direction of device engineering. Through the microstructured cone structure, the number of input fiber optical paths can be controlled in a timely manner. After adjustment, an integrated liquid-core microstructured package is formed, forming a new type of fiber coupler.

[0033] In the embodiments of the present application, multiple high-power laser beams are coupled through a liquid-core fiber coupling end, a liquid-core fiber receiving end, and an adaptive coupling and sealing structure, and are coupled through the tapered region of a fiber taper structure, so as to miniaturize the coupling structure and stably output high-power laser.

[0034] In some embodiments, in the middle of the fusion splicing of the liquid-core fiber coupling end 2, a transition tapered region is added, and the end face of the transition tapered region is fused with the end face of a quartz fiber to form the fiber coupler. In a specific example, as Figure 2 shown, the fiber bundle structure includes a hollow fiber coupler formed by fusing 5 groups of N fluorine-doped capillary quartz tubes. After adding the transition tapered region in the middle of the fusion splicing, the end face of the transition tapered region is fused with the end face of a quartz fiber to form a pure liquid-core fiber coupling module, and the fiber coupling module is fixed in the adaptive coupling and sealing structure 4 by using an ultraviolet curing adhesive. In a specific example, the liquid-core fiber coupling module is fixed in the adaptive coupling and sealing structure by using an ultraviolet curing adhesive. Both the input end and the output end of the adaptive coupling and sealing structure 4 are composed of adaptive coupling fiber end faces, and the liquid-core fiber coupling module is fixed in the adaptive coupling and sealing structure 4 to form an independent novel fiber coupler.

[0035] In some embodiments, both the input end and the output end of the adaptive coupling and sealing structure 4 are provided with adaptive coupling fiber end faces.

[0036] In some embodiments, for the liquid-core fiber receiving end 3, the inner and outer claddings of its end face adopt a uniform laser etching method to microprocess the fiber core into an inner and outer in-tapered structure 6, and its inner taper angle > 90°. Or, use a CO 2 laser to microprocess the fiber end face to form an inner-tapered transition structure part, and then use a laser to uniformly micro-polish the inner side of the taper. The formed end face is flat and free of burrs.

[0037] In some embodiments, the inner bottom of the inner cone of the inner cone has a planar coating 7, and the outlet is sealed after the planar coating 7 is completed. After the coating 7 is completed, the outlet is sealed, and the rear side of the inner cone is fused with the output fiber end to form the liquid-core fiber receiving end 3, as Figure 4 shown.

[0038] In some embodiments, the liquid-core fiber coupling end 2 and the liquid-core fiber receiving end 3 are fused with each other to form an optical module of a fiber coupler, and a thermally conductive ultraviolet curing adhesive liquid is applied to the fixed area of the formed optical module of the fiber coupler, and potting glue is coated on the outside after curing. As Figure 3As shown, for the adapted coupling and sealing structure 4, through microfabrication of a thermally conductive metal structure, the coupling end of the liquid-core optical fiber and the connecting body of the liquid-core optical fiber receiving end are placed in the adapted coupling and sealing structure. Both the left and right ends of the adapted coupling and sealing structure are pre-inlaid and fixed by the adapted receiving end. A thermally conductive ultraviolet curable adhesive liquid is applied to the fixed area of the new fiber coupler optical module formed by the fusion splicing of the liquid-core optical fiber receiving end and the liquid-core optical fiber coupling end, and a layer of potting adhesive is applied again on the outside to enhance the reliability of the device. Epoxy resin adhesive is applied at the position of the output end of the structure to improve the impact resistance of the overall device.

[0039] In the embodiment of the present application, through the liquid-core optical fiber coupling end, the liquid-core optical fiber receiving end, and the adapted coupling and sealing structure, multiple high-power laser beams are coupled and coupled through the tapered area of the fiber cone structure. The liquid can output the combined laser beams of each branch, forming miniaturization of the coupling structure and stable output of high-power laser. Since the inside of the optical fiber is filled with liquid, during the process of high-speed aerospace pressure change, the optical fiber coupling device is stable and reliable during the transmission and use at a long distance in aerospace. Through the new fiber coupler, multiple high-power fiber lasers are efficiently coupled, effectively improving the coupling output efficiency of single-beam fiber laser synthesis, providing a new approach for the development of fiber lasers.

[0040] It should be noted that in each embodiment of the present application, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of another identical element in the process, method, article or device including that element.

[0041] The serial numbers of the above embodiments of the present application are only for description and do not represent the advantages or disadvantages of the embodiments.

[0042] The embodiments of the present application have been described above with reference to the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of these belong to the protection scope of the present application.

Claims

1. A fiber coupler, characterized in that: include: Optical fiber coupling body, matching coupling sealing structure, wherein: The optical fiber coupling body comprises a liquid core optical fiber coupling end and a liquid core optical fiber receiving end. The liquid core optical fiber coupling end (2) is a hollow core optical fiber coupling body formed by bundling and melting N fluorine-doped capillary quartz glass tubes (5). The hollow region of the multi-optical fiber end of the hollow core optical fiber coupling body is injected with Kerr medium liquid, filled and sealed. The liquid core optical fiber receiving end (3) is processed into an inner cone with an inner cone angle of >90°, and the inner cone is filled with Kerr liquid and sealed to form the liquid core optical fiber receiving end; The optical fiber coupling body is formed by matching and fusion coupling between the liquid core end faces of the liquid core optical fiber coupling end and the liquid core optical fiber receiving end; The adapting coupling sealing structure (4) is used to be placed in the optical fiber coupling body, and the input end and the output end are respectively matched with liquid core optical fiber adapters to form an integrated multi-channel coupling adapting sealing structure to constitute the optical fiber coupler.

2. The optical fiber coupler according to claim 1, wherein: The liquid core optical fiber coupling end (2) has a transition cone region added in the middle of the fusion splice, and the end face of the transition cone region is fusion spliced ​​with the end face of the quartz optical fiber to form the optical fiber coupling body.

3. The optical fiber coupler according to claim 2, wherein: The liquid core optical fiber receiving end (3) is located on the side with a smaller cross-sectional area of ​​the transition cone region of the optical fiber bundle structure, and is formed by cutting a large core diameter signal optical fiber.

4. The optical fiber coupler according to claim 1, wherein: The N fluorine-doped capillary quartz glass tubes (5) at the liquid core optical fiber coupling end (2) are bundled and arranged vertically upward.

5. The optical fiber coupler according to claim 1, wherein: The inner cone bottom of the inner cone is provided with a planar coating (7), and the outlet is sealed after the planar coating (7) is completed.

6. The optical fiber coupler according to claim 1, wherein: The input end and the output end of the adaptable coupling sealing structure (4) are both provided with adaptable coupling optical fiber end faces.

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