A high-efficiency and high-stability special optical fiber coupling system and method

Abstract

The present invention discloses a high-efficiency and high-stability special optical fiber coupling system and method. The system comprises a glass tube with openings at both ends, a solid double-clad optical fiber connected to each other with the connection point located at the center of the glass tube, and a special optical fiber. The method comprises etching the cladding of the double-clad solid optical fiber to the inner cladding region so that its diameter matches the core of the special optical fiber, then inserting the corroded portion of the solid optical fiber into the core of the special optical fiber, curing the connection entrance with optical glue, so that the special optical fiber forms a vacuum-sealed environment; or customizing a solid optical fiber core rod matching the effective mode field diameter of the special optical fiber, applying a coating layer to the outside of the core rod to form a waveguide structure, then inserting the solid optical fiber into the core of the special optical fiber, and heating and ablating the entrance connection end of the special optical fiber to achieve high-efficiency and high-stability coupling of the special optical fiber.

Description

Technical Field

[0001] The present invention relates to the technical field of optical communication devices, and in particular to a high-efficiency and high-stability special optical fiber coupling system and method. Background Art

[0002] As the market share of fiber lasers in industrial applications increases year by year, fiber laser technology is also constantly being updated. High-power narrow-linewidth fiber lasers are limited by the nonlinear effects of fiber materials such as stimulated Brillouin scattering and stimulated Raman scattering, which leads to the inability to achieve both narrow linewidth and high power at the same time. Special optical fibers (such as hollow-core optical fibers) have great application prospects in high-power narrow-linewidth lasers due to their low nonlinear coefficients and high damage thresholds. However, the core of special optical fibers is air, and when fused with traditional solid optical fibers, there will be problems such as collapse of the fusion point and high fusion loss. In order to reduce transmission loss, special optical fibers need to be stored and used in a vacuum environment.

[0003] In existing technologies, high-power laser coupling transmission can be achieved through lenses, but the spatial coupling efficiency is not high, and there is a thermal lens effect at high power. The device needs to be fine-tuned to maintain the coupling efficiency. The operation is complicated and the risk factor is high. Therefore, although special optical fibers have excellent performance, they are still in laboratory research and have not been put into large-scale industrial laser applications. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-efficiency and high-stability special optical fiber coupling system and method. The system is fully optical fiber-based and has higher stability than spatial coupling. Because the core diameter of the customized solid optical fiber matches the effective mode field diameter of the special optical fiber, the coupling efficiency can reach the theoretical limit of 96% by physical splicing, realizing high-efficiency and high-stability transmission of lasers.

[0005] According to a first aspect of the present invention, a high-efficiency and high-stability special optical fiber coupling system is provided, comprising a packaging device and a coupling device, wherein the packaging device comprises a metal packaging base and a metal packaging cover; the coupling device comprises:

[0006] Double-clad solid optical fiber, including a core, an inner cladding, an outer cladding and a coating;

[0007] Specialty optical fibers connected to double-clad solid optical fibers; and,

[0008] There are openings at both ends for wrapping the glass tube at the connection between the double-clad solid optical fiber and the special optical fiber; the special optical fiber and the double-clad solid optical fiber are fixedly connected under vacuum conditions using optical glue or heating ablation, and high-efficiency and high-stability laser transmission is achieved through all-fiber physical splicing.

[0009] Furthermore, the inner diameter of the glass tube is slightly larger than the coating diameter of the double-clad solid optical fiber and the special optical fiber used.

[0010] Furthermore, the system can further improve the coupling efficiency by coating the output end face of the double-clad solid optical fiber with an anti-reflection film.

[0011] Furthermore, the core diameter of the double-clad solid optical fiber is 5-50 μm.

[0012] Furthermore, the core diameter of the special optical fiber is 2-3 mm larger than the core diameter of the double-clad solid optical fiber.

[0013] Furthermore, the special optical fiber includes but is not limited to antiresonant hollow core optical fiber.

[0014] According to a second aspect of the present invention, a high-efficiency and high-stability special optical fiber coupling method is provided, comprising:

[0015] S100, using a fiber cleaver to strip the coating and outer cladding of the double-clad solid optical fiber used, with a stripping length of 2-5 cm, and etching the inner cladding of the solid optical fiber with hydrofluoric acid so that the inner cladding diameter is approximately 2 µm larger than the core diameter;

[0016] S200: Place the etched solid optical fiber and the special optical fiber into a fusion splicer. Set the corresponding optical fiber parameters in the fusion splicer program. After the optical fiber cores are aligned, manually advance the solid optical fiber on the left side using the fusion splicer motor according to the image on the fusion splicer screen until the core of the solid optical fiber enters the core of the special optical fiber.

[0017] S300: After the fusion splicing is completed, open the windshield of the fusion splicer, take out the optical fiber, and evacuate the output end on the right side of the special optical fiber.

[0018] S400, use optical glue to seal and secure the inlet port on the left side of the special optical fiber to prevent air from entering the core and cladding of the special optical fiber;

[0019] S500. Place the connection point between the two optical fibers at the center of the glass tube, and perform vacuum sealing on the opening of the glass tube. The glass tube is used to fix the optical fibers and protect the exposed solid optical fiber core and cladding, while also providing secondary protection against air intrusion into the special optical fiber.

[0020] S600, placing the sealed glass tube in the metal packaging base, and then sealing and fixing the metal packaging base with the metal packaging cover to further improve the stability of the coupling device.

[0021] Furthermore, the solid optical fiber core can be customized according to the effective mode field diameter of the special optical fiber, and a coating layer can be added to the core to replace the traditional double-clad optical fiber.

[0022] Furthermore, the refractive index of the coating layer is lower than the refractive index of the core, forming a waveguide structure.

[0023] Furthermore, after the solid optical fiber is inserted into the special optical fiber, it can be sealed and fixed by heating and ablating the inlet connection end of the special optical fiber.

[0024] Beneficial effects of the present invention:

[0025] 1. This invention proposes a high-efficiency, high-stability special fiber coupling system that uses all-fiber coupling and a metal packaging device for packaging and fixation. Compared with traditional spatial coupling devices, it has higher stability.

[0026] 2. This invention proposes a high-efficiency, high-stability specialty fiber coupling system. This system uses a customized solid fiber with a core diameter that matches the effective mode field diameter of the specialty fiber. Physical splicing is used for transmission coupling, resulting in a transmission efficiency that reaches the theoretical limit of 96%. This efficiency can be further improved by coating the output end face of the solid fiber with an anti-reflection coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0028] Figure 1 This is a schematic diagram of a packaging device for a high-efficiency and high-stability special optical fiber coupling system according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of a coupling device of a high-efficiency and high-stability special optical fiber coupling system according to an embodiment of the present invention;

[0030] Figure 3 This is a flow chart of a high-efficiency and high-stability special optical fiber coupling method according to an embodiment of the present invention;

[0031] Figure 4 This is a flow chart of the second method of high-efficiency and high-stability special optical fiber coupling in an embodiment of the present invention;

[0032] In the present invention, the same reference numerals represent the same structural elements, specifically:

[0033] 1- solid double-clad optical fiber, 2- glass tube, 3- special optical fiber;

[0034] 4-metal packaging base, 5-metal packaging cover. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0036] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0037] Those skilled in the art will understand that, unless otherwise stated, the singular forms "a," "an," "said," and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of this application refers to the presence of the stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0038] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as those generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless specifically defined as in the examples of this application.

[0039] The embodiments of the present application provide a high-efficiency and high-stability special optical fiber coupling system and method, which can effectively solve the problem of high splicing loss between solid optical fiber and special optical fiber, while taking into account the mode field matching of solid optical fiber and special optical fiber, and realizing high-efficiency and high-stability transmission of special optical fiber.

[0040] Example 1

[0041] This embodiment provides a high-efficiency and high-stability special optical fiber coupling system, including a packaging device and a coupling device.

[0042] like Figure 1 As shown, the packaging device includes a metal packaging base 4 and a metal packaging cover 5, which can be used to place a coupling device to further increase the stability of the system.

[0043] like Figure 2As shown, the coupling device includes:

[0044] A double-clad solid optical fiber 1, comprising: a core, an inner cladding, an outer cladding, and a coating;

[0045] A special optical fiber 3 connected to the double-clad solid optical fiber 1, wherein the special optical fiber 3 is fixedly connected to the double-clad solid optical fiber 1 under vacuum conditions by optical glue or heating ablation; and

[0046] A glass tube 2 with openings at both ends, covering the connection between the two optical fibers;

[0047] Furthermore, the double-clad solid optical fiber 1 includes a core, an inner cladding, an outer cladding and a coating layer.

[0048] Furthermore, the core diameter of the special optical fiber 3 is adapted to the core diameter of the solid optical fiber 1 used, that is, it is 2-3 mm larger than the core diameter of the solid optical fiber.

[0049] Specifically, the outer diameter of the coating of the two optical fibers is generally less than 1 mm. The glass tube 2 with open ends is used to fix the two optical fibers. The inner diameter of the glass tube 2 is slightly larger than the coating diameter of the solid optical fiber and special optical fiber used to ensure that the two optical fibers can be inserted into the glass tube.

[0050] Furthermore, the special optical fiber used in this embodiment is an anti-resonant hollow-core optical fiber.

[0051] Example 2

[0052] This embodiment provides a high-efficiency and high-stability special optical fiber coupling method, the flow chart of which is as follows: Figure 3 Shown, including:

[0053] S100, using an optical fiber cutter to strip the coating and outer cladding of the double-clad solid optical fiber 1 used, with a stripping length of 2-5 cm, and corroding the inner cladding of the solid optical fiber 1 with hydrofluoric acid so that the inner cladding diameter is about 2 μm larger than the core diameter.

[0054] Furthermore, for the commonly used double-clad solid optical fibers of 20 / 400µm, 25 / 400µm, and 30 / 400µm, the core diameter of the special optical fiber used in this embodiment is 35µm;

[0055] S200, put the corroded solid optical fiber and special optical fiber into the fusion splicer, set the corresponding optical fiber parameters in the fusion splicer program, such as: optical fiber core diameter, cladding diameter, cutting length, etc., and change the default fusion splicing mode in the program to left-side push, and the alignment mode to manual alignment. After the program settings are completed, cover the windshield, press the set key, and let the fusion splicer determine the cutting end face angle. If the cutting angle is greater than 1°, it needs to be re-cut. After the optical fiber cores on both sides are aligned, since the inner cladding diameter of the corroded solid optical fiber on the left is smaller than the core diameter of the special optical fiber, and the core of the special optical fiber is air, it is necessary to manually advance the solid optical fiber on the left through the fusion splicer motor according to the imaging on the fusion splicer screen until the core of the solid optical fiber enters the core of the special optical fiber;

[0056] S300: After the fusion splicing is completed, open the windshield of the fusion splicer, take out the optical fiber, and evacuate the output end on the right side of the special optical fiber.

[0057] S400, use optical glue to seal and secure the inlet port on the left side of the special optical fiber to prevent air from entering the core and cladding of the special optical fiber;

[0058] S500. Place the connection point between the two optical fibers at the center of the glass tube, and perform vacuum sealing on the opening of the glass tube. The glass tube is used to fix the optical fibers and protect the exposed solid optical fiber core and cladding, while also providing secondary protection against air intrusion into the special optical fiber.

[0059] S600 , placing the sealed glass tube in the metal packaging base 4 , and then sealing and fixing the metal packaging base 4 with the metal packaging cover 5 to further increase the stability of the system.

[0060] Example 3

[0061] The present invention provides another high-efficiency and high-stability special optical fiber coupling method. The flowchart of the method is as follows: Figure 4 Shown, including:

[0062] S100, based on the effective mode field diameter of the special optical fiber, customize the solid optical fiber core rod with a core diameter that matches the mode field diameter of the special optical fiber;

[0063] Furthermore, the core diameter of the specialty optical fiber is 2-3 mm larger than the core diameter of the solid optical fiber;

[0064] S200, adding a coating layer to the core rod of the solid optical fiber to replace the traditional double-clad optical fiber, making the refractive index of the coating layer lower than that of the core rod, forming a waveguide structure;

[0065] Furthermore, the waveguide structure can reduce the transmission loss of the device;

[0066] S300. Place the solid fiber and the special fiber into the fusion splicer. Set the corresponding fiber parameters in the fusion splicer program, such as fiber core diameter, cladding diameter, cutting length, etc., and change the default fusion splicing mode in the program to left-side push and the alignment mode to manual alignment. After the program settings are completed, cover the windshield and press the set button to let the fusion splicer determine the cutting end face angle. If the cutting angle is greater than 1°, re-cutting is required. After the fiber cores are aligned, according to the imaging on the fusion splicer screen, manually advance the solid fiber on the left through the fusion splicer motor until the core of the solid fiber enters the core of the special fiber.

[0067] S400: Synchronously move the motors on both sides of the fusion splicer to the right, so that the port of the special optical fiber is at the discharge center of the fusion splicer. Then, heat and ablate the port with the fusion splicer to create a sealed vacuum environment for the special optical fiber.

[0068] S500. Place the connection point between the two optical fibers at the center of the glass tube, and perform vacuum sealing on the opening of the glass tube. The glass tube is used to fix the optical fibers and protect the exposed solid optical fiber core and cladding, while also providing secondary protection against air intrusion into the special optical fiber.

[0069] S600 , placing the sealed glass tube in the metal packaging base 4 , and then sealing and fixing the metal packaging base 4 with the metal packaging cover 5 to further increase the stability of the system.

[0070] Furthermore, traditional specialty fiber coupling devices add a lens group behind the laser output end. By combining lenses of different focal lengths, the output laser parameters are matched to the specialty fiber parameters, thereby improving the specialty fiber coupling efficiency. Currently, the laser coupling efficiency of this method reportedly does not exceed 90%. This method is also costly, and the lens has a thermal lens effect at high power, which causes the light spot to shift. The spatial optical path debugging is complex and requires high operator skills. Therefore, this spatial coupling method is not engineering-capable. After vibration testing, the spatial optical path will shift, resulting in low reliability. The high-efficiency and high-stability specialty fiber coupling system proposed in this invention is fully fiber-optic, and thus has higher stability than spatial structures.

[0071] Furthermore, the high-efficiency and high-stability special optical fiber coupling device proposed by the present invention has a coupling efficiency that reaches the theoretical limit of 96%, because the core diameter of the customized solid optical fiber matches the effective mode field diameter of the special optical fiber. 4% of the loss comes from Fresnel reflection generated at the junction of the output end face of the solid optical fiber and the special optical fiber.

[0072] Furthermore, the present invention can also reduce Fresnel reflection by coating the output end face of the solid optical fiber with an antireflection film, thereby further improving the coupling efficiency.

[0073] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown in sequence as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps in the flowcharts of the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0074] The above description is only part of the implementation methods of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A high-efficiency and high-stability special optical fiber coupling method, comprising: S100, based on the effective mode field diameter of the special optical fiber, customize the solid optical fiber core rod with a core diameter that matches the mode field diameter of the special optical fiber; S200, adding a coating layer to the core rod of the solid optical fiber to replace the traditional double-clad optical fiber, so that the refractive index of the coating layer is lower than the refractive index of the core rod, thereby forming a waveguide structure, wherein the waveguide structure is used to reduce the transmission loss of the device; S300. Place the solid fiber and the special fiber into the fusion splicer. Set the corresponding fiber parameters in the fusion splicer program. After the fiber cores are aligned, manually advance the solid fiber on the left side using the fusion splicer motor according to the image on the fusion splicer screen until the core of the solid fiber enters the core of the special fiber. S400: Synchronously move the motors on both sides of the fusion splicer to the right, so that the port of the special optical fiber is at the discharge center of the fusion splicer. Then, heat and ablate the port with the fusion splicer to create a sealed vacuum environment for the special optical fiber. S500. Place the connection point between the two optical fibers at the center of the glass tube, and perform vacuum sealing on the opening of the glass tube. The glass tube is used to fix the optical fibers and protect the exposed solid optical fiber core and cladding, while also providing secondary protection against air intrusion into the special optical fiber. S600, placing the sealed glass tube in the metal packaging base, and then sealing and fixing the metal packaging base with the metal packaging cover to further increase the stability of the system; The output end face of the solid optical fiber is coated with an anti-reflection film to reduce Fresnel reflection and further improve coupling efficiency; The special optical fiber is an anti-resonant hollow-core optical fiber.

2. A high-efficiency and high-stability special optical fiber coupling method according to claim 1, characterized in that: After the solid optical fiber (1) is inserted into the special optical fiber (3), it can be sealed and fixed by heating and ablating the inlet connection end of the special optical fiber.

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