Manufacturing method, equipment and application of multi-core optical fiber with high SBS threshold value

Abstract

The invention discloses a manufacturing method and device for a multi-core optical fiber with a high SBS threshold value and application. The manufacturing method comprises the steps that S1, preparation work before drawing is conducted with the multi-core optical fiber as a raw material; s2, the wire drawing speed of the multi-core optical fiber is controlled to be gradually increased to 25 m / min from 14 m / min; s3, after the wire drawing speed reaches 25 m / min, the wire drawing speed of the multi-core optical fiber is controlled to be gradually reduced to 14 m / min from 25 m / min; s4, alternately carrying out the step S2 and the step S3 until the whole multi-core optical fiber is drawn; and S5, cutting the multi-core optical fiber prepared in the step S4 to prepare the conical multi-core optical fibers in batches. According to the technical scheme provided by the invention, the technical problems of complex equipment, tedious operation and relatively high cost existing in a mode selection mode adopted in manufacturing of the multi-core optical fiber in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber manufacturing and application, and in particular to a manufacturing method, equipment and application of a high SBS threshold multi-core optical fiber. Background Art

[0002] Multi-core optical fiber can be used to manufacture high-power single-frequency fiber lasers. However, when working, high-power single-frequency fiber lasers are often affected by stimulated Brillouin scattering (SBS). The SBS effect can cause the power of the laser to be unstable, limit the output power of the laser, and may cause the laser mode to jump, affecting the single-mode stability of the laser. Therefore, it is necessary to suppress the SBS effect in high-power single-frequency fiber lasers, that is, to suppress the SBS effect in multi-core optical fibers.

[0003] As is known to all, the SBS threshold can be increased by increasing the area of ​​the fiber core, and the effective area can be increased by increasing the number of cores in the inner cladding. However, each core in a multi-core fiber operates in a single-mode state, and multiple modes are formed by mutual coupling. For multi-core fiber lasers and amplifiers, it is necessary to maximize the proportion of the same-phase mode in the output power to ensure better beam quality. The existing mode selection method is often used to suppress the output of other modes and increase the output power of the same-phase mode, such as the Talbot cavity mode selection method. Specifically, when a coherent light beam illuminates a periodically arranged object, its own image will appear after a certain distance of transmission. This distance is called the Talbot distance. This distance is related to its distribution period and wavelength. Therefore, different supermodes have different Talbot distances due to different distribution periods. If a total reflection plane mirror is placed at an appropriate distance Z that is conducive to the reflection of a certain mode, the mode will obtain a large feedback coefficient, while the feedback of other modes will be suppressed to varying degrees. After reflection, the image of the supermode itself is coupled into the laser, and the mode can be selected. However, this method requires complex equipment, cumbersome operation, high cost, and also requires determination of a high-precision Talbot distance. Therefore, the multi-core optical fiber manufactured by this method of mode selection is time-consuming, labor-intensive, and costly. Summary of the invention

[0004] In view of this, the present invention proposes a method, device and application for manufacturing a high SBS threshold multi-core optical fiber, so as to solve the technical problems of complex equipment, cumbersome operation and high cost existing in the existing mode selection method used in manufacturing multi-core optical fibers.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a method for manufacturing a high SBS threshold multi-core optical fiber, the manufacturing method comprising the following steps: S1, preparation work before drawing multi-core optical fiber as raw material; S2, controlling the drawing speed of the multi-core optical fiber to gradually increase from 14 m / min to 25 m / min; S3, when the drawing speed reaches 25 m / min, controlling the drawing speed of the multi-core optical fiber to gradually decrease from 25 m / min to 14 m / min; S4, alternately performing step S2 and step S3 until the entire multi-core optical fiber is drawn; S5, cutting the multi-core optical fibers obtained in step S4 to make tapered multi-core optical fibers in batches.

[0006] In some embodiments, step S1 includes the following sub-steps: S11, clamping one end of the optical fiber preform on a feeding device; S12, placing the other end of the optical fiber preform in a drawing furnace to produce a multi-core optical fiber; S13, winding the drawn multi-core optical fiber coming out of the drawing furnace onto a drawing wheel; S14, winding the multi-core optical fiber coming out of the spinning wheel onto a take-up reel.

[0007] In some embodiments, step S1 further includes: S15, sequentially arranging a bare fiber diameter gauge, a primary coating and curing assembly, a secondary coating and curing assembly, an optical fiber diameter gauge and a tension measuring instrument on the drawing of the multi-core optical fiber between the drawing furnace and the drawing wheel.

[0008] In some embodiments, step S1 further includes: S16, establish signal connection with each instrument component through the computer.

[0009] In some embodiments, steps S2 and S3 specifically control the speed of the drawing wheel by the computer to control the drawing speed.

[0010] In some embodiments, the core diameter of the tapered multi-core optical fiber in step S5 is gradually reduced from 6.4 μm to 1 μm, and the core distance is gradually reduced from 35 μm to 5.5 μm.

[0011] In some embodiments, the manufacturing method further comprises: S6, controlling the drawing wheel to return to the initial drawing speed through the computer, retaining a section of the head fiber and the tail fiber for easy connection with other structures.

[0012] In a second aspect, the present invention provides a manufacturing device for a high SBS threshold multi-core optical fiber, which is used to implement a manufacturing method for a high SBS threshold multi-core optical fiber provided in the first aspect of the present invention, and the manufacturing device comprises: Feeding device; A wire drawing furnace, wherein the feeding end of the wire drawing furnace faces the feeding device; A drawing wheel, wherein a feeding end of the drawing wheel faces a discharging end of the drawing furnace; A wire take-up drum, wherein a feeding end of the wire take-up drum faces a feeding end of the spinning wheel.

[0013] In some embodiments, the manufacturing equipment also includes a bare fiber diameter gauge, a primary coating curing component, a secondary coating curing component, a fiber diameter gauge and a tension measuring instrument, and the bare fiber diameter gauge, the primary coating curing component, the secondary coating curing component, the fiber diameter gauge and the tension measuring instrument are arranged in sequence according to the direction of the fiber drawing process.

[0014] In a third aspect, the present invention provides an application of a high SBS threshold multi-core optical fiber, comprising applying the high SBS threshold multi-core optical fiber produced by the manufacturing method provided by the first aspect of the present invention to the manufacture of a high-power single-frequency optical fiber laser.

[0015] Compared with the prior art, the manufacturing method of the present invention reduces the diameter of each core in the multi-core optical fiber and the distance between each core by controlling the drawing speed during the drawing process of the multi-core optical fiber, so that multiple cores form a fundamental mode, thereby increasing the SBS threshold. It can be seen that the manufacturing method and manufacturing equipment provided by the present invention are simple to operate and low in cost, and can greatly improve production efficiency. At the same time, the multi-core optical fiber obtained by the manufacturing method and manufacturing equipment of the present invention to manufacture a high-power single-frequency optical fiber laser has the advantages of large output power and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a flow chart of the manufacturing method of the present invention; Figure 2 is a flow chart of step S1 of the manufacturing method of the present invention; Figure 3 is an overall schematic diagram of the manufacturing equipment of the present invention; Figure 4 is a schematic structural diagram of a multi-core optical fiber manufactured by the manufacturing method of the present invention; Figure 5 It is a schematic structural diagram (at O) of one of the tapered multi-core optical fibers cut from the obtained multi-core optical fiber according to the present invention.

[0017] The following are the descriptions of the reference numerals: 100, feeding device; 200, wire drawing furnace, 300, wire drawing wheel, 310, first wire drawing wheel, 320, second wire drawing wheel, 400, take-up reel, 500, bare optical fiber diameter gauge, 600, primary coating and curing assembly, 610, primary coating device, 620, primary UV curing oven, 700, secondary coating and curing assembly, 710, secondary coating device, 720, secondary UV curing oven, 800, optical fiber diameter gauge, 900, tension measuring instrument; A is the optical fiber preform rod, and B is the multi-core optical fiber. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] In view of the technical problems of complex equipment, cumbersome operation and high cost in the existing mode selection method used in manufacturing multi-core optical fibers, the present invention provides a method, equipment and application for manufacturing a high SBS threshold multi-core optical fiber.

[0020] It should be noted that the basic principle of the present invention is: According to the micro-core mode selection theory, by reducing the radius of each core in the multi-core optical fiber, each single core cannot independently output single mode due to the small core diameter, and then by reducing the core distance, the coupling between the cores is strengthened; when the radius and core distance of each core are reduced to a certain value, it is equivalent to outputting single mode overall, and the single mode of the multi-core optical fiber has a larger mode area than the single-core optical fiber, so the SBS threshold can be increased.

[0021] According to the above principle, firstly, Figure 1 As shown, the present invention proposes a method for manufacturing a high SBS threshold multi-core optical fiber, the manufacturing method comprising the following steps: S1, using the multi-core optical fiber B as raw material to perform preparation work before drawing; S2, controlling the drawing speed of the multi-core optical fiber B to gradually increase from 14 m / min to 25 m / min; S3, when the drawing speed reaches 25 m / min, the drawing speed of the multi-core optical fiber B is controlled to gradually decrease from 25 m / min to 14 m / min; S4, alternately performing step S2 and step S3 until the entire multi-core optical fiber B is drawn; S5, cutting the multi-core optical fiber B obtained in step S4 into tapered multi-core optical fibers in batches.

[0022] Different from the prior art, the manufacturing method of the present invention reduces the diameter of each core in the multi-core optical fiber and the distance between each core by controlling the drawing speed during the drawing process of the multi-core optical fiber, so that multiple cores form a fundamental mode, thereby increasing the SBS threshold. It can be seen that the manufacturing method and manufacturing equipment provided by the present invention are simple to operate and low in cost, and can greatly improve production efficiency. At the same time, the multi-core optical fiber obtained by the manufacturing method and manufacturing equipment of the present invention to manufacture a high-power single-frequency optical fiber laser has the advantages of large and stable output power.

[0023] The following is a detailed step-by-step description of a method for manufacturing a high SBS threshold multi-core optical fiber provided by the present invention, which specifically includes: S1, using multi-core optical fiber for drawing; Figure 2 As shown, step S1 specifically includes: S11, clamping one end of the optical fiber preform A on the feeding device 100; S12, placing the other end of the optical fiber preform A in a drawing furnace 200; S13, drawing and winding the multi-core optical fiber B coming out of the drawing furnace 200 onto the drawing wheel 300; S14, winding the multi-core optical fiber B coming out of the spinning wheel 300 onto the take-up reel 400; S15, sequentially arranging a bare fiber diameter gauge 500, a primary coating and curing assembly 600, a secondary coating and curing assembly 700, a fiber diameter gauge 800 and a tension measuring instrument 900 on the drawing of the multi-core optical fiber B between the drawing furnace 200 and the drawing wheel 300; S16, connecting signals with various instrument components through the computer; In step S1, firstly, a multi-core optical fiber B is manufactured from an optical fiber preform rod A, and then a high-power and high-SBS threshold multi-core optical fiber is manufactured from the multi-core optical fiber B.

[0024] S2, controlling the drawing speed of the multi-core optical fiber B to gradually increase from 14 m / min to 25 m / min, so that the diameter of the multi-core optical fiber B gradually decreases from 125 μm to 21 μm, and the minimum distance between the cores gradually decreases from 35 μm to 5.5 μm; S3, when the drawing speed reaches 25 m / min, the drawing speed of the multi-core optical fiber B is controlled to gradually decrease from 25 m / min to 14 m / min, and the diameter of the optical fiber gradually increases from 21 μm to 125 μm; S4, alternately perform step S2 and step S3 until the entire multi-core optical fiber B is drawn. Figure 4As shown, the axial length a of a single cone region of the tapered multi-core optical fiber is 15-20 m, the cone regions are arranged at equal distances, and the axial center distance b between two adjacent cone regions is 15-20 m; S5, cutting the multi-core optical fiber B obtained in step S4 into tapered multi-core optical fibers in batches, such as Figure 5 As shown, the core diameter of the tapered multi-core optical fiber gradually decreases from 6.4 μm to 1 μm, and the core distance gradually decreases from 35 μm to 5.5 μm; S6, the computer controls the spinning wheel 300 to return to the initial drawing speed, retaining a section of the head fiber and the tail fiber for connection with other structures.

[0025] In one embodiment, the steps S2 and S3 are specifically to control the speed of the drawing wheel 300 by the computer to control the drawing speed.

[0026] In one embodiment, the spinning wheel 300 includes a first spinning wheel 310 and a second spinning wheel 320, and the speeds of the first spinning wheel 310 and the second spinning wheel 320, and the speeds of the spinning wheel 320 and the take-up drum 400 are matched by controlling by the computer.

[0027] In the above technical scheme, the first-level coating and curing component 600 includes a first-level coater 610 and a first-level UV curing furnace; the second-level coating and curing component 700 includes a second-level coater 710 and a second UV curing furnace 720; the spinning wheel 300 includes a first spinning wheel 310 and a second spinning wheel 320, and the diameter of the first spinning wheel 310 is greater than the diameter of the second spinning wheel 320.

[0028] It should be noted that the faster the drawing speed, the smaller the diameter of the optical fiber, and the slower the drawing speed, the larger the diameter of the optical fiber.

[0029] Second, as Figure 3 As shown, the present invention provides a manufacturing device for high-power and high-SBS threshold multi-core optical fiber, which is used to implement the manufacturing method provided in the first aspect of the present invention. The manufacturing device includes a feeding device 100, a drawing furnace 200, a drawing wheel 300, a take-up reel 400, a bare optical fiber diameter gauge 500, a primary coating and curing assembly 600, a secondary coating and curing assembly 700, an optical fiber diameter gauge 800 and a tension measuring instrument 900. The feeding end of the drawing furnace 200 faces the feeding device 100, the loading end of the drawing wheel 300 faces the discharging end of the drawing furnace 200, and the loading end of the take-up reel 400 faces the unloading end of the drawing wheel 300.

[0030] When using the above-mentioned manufacturing equipment to manufacture multi-core optical fibers, first, one end of the optical fiber preform is fixed on the feeding device 100, and the other end is set in the drawing furnace 200. Then, the optical fiber filament coming out of the drawing furnace 200 is wound on the straight take-up drum 400 under the action of the drawing wheel 300. In this process, the diameter of the bare optical fiber can be measured by the bare optical fiber diameter gauge 500, the optical fiber can be coated and cured multiple times by the primary coating and curing assembly 600 and the secondary coating and curing assembly 700, the diameter of the optical fiber can be measured by the optical fiber diameter gauge 800, the tension of the optical fiber is controlled by the tension measuring instrument 900, and the optical fiber is stored on the take-up drum 400 by the drawing wheel 300; at the same time, through the signal connection between the computer and various electrical components, the speed of the drawing wheel 300 is adjusted under the measurement and monitoring of the bare optical fiber diameter gauge 500 and the optical fiber diameter gauge 800, so that the drawing speed of the optical fiber changes according to a certain periodic law, thereby obtaining a multi-core optical fiber whose optical fiber diameter changes periodically along the axial direction. The obtained multi-core optical fiber is as follows. Figure 4 As shown, the obtained multi-core optical fiber is finally cut to obtain a tapered multi-core optical fiber, as shown in Figure 5 shown.

[0031] In one embodiment, the spinning wheel 300 includes a first spinning wheel 310 and a second spinning wheel 320; the first-level coating and curing assembly 600 includes a first-level coater 610 and a first-level UV curing oven 620; the second-level coating and curing assembly 700 includes a second-level coater 710 and a second-level UV curing oven 720.

[0032] In one of the embodiments, the feeding device 100, the drawing furnace 200, the bare fiber diameter gauge 500, the primary coater 610, the primary UV curing furnace 620, the secondary coater 710, the secondary UV curing furnace 720, the fiber diameter gauge 800, the tension measuring instrument 900, the first drawing wheel 310, the second drawing wheel 320 and the take-up reel 400 are arranged in sequence according to the direction of the optical fiber drawing process.

[0033] In a third aspect, the present invention provides an application of a high-power high SBS threshold multi-core optical fiber, comprising applying the high-power high SBS threshold multi-core optical fiber produced by the manufacturing method described in the first aspect of the present invention to the manufacture of a high-power single-frequency optical fiber laser.

[0034] In the prior art, high-power single-frequency fiber lasers are often affected by the SBS effect when they are working. The stimulated Brillouin scattering gain bandwidth is generally 10 7Hz, which is much larger than the spectral linewidth of a single-frequency fiber laser source. Factors such as higher optical power density and longer interaction length in the fiber core also indicate that optical fiber may not be suitable for use as a gain medium for a high-power single-frequency laser source. The main reason is that the above factors will reduce the stimulated Brillouin scattering threshold, causing the energy of the signal light to transfer to the reverse Stokes signal. At the same time, the reverse Stokes signal will cause certain damage to the device, thereby limiting the increase in the output power of the single-frequency laser source.

[0035] In order to suppress the SBS effect in high-power single-frequency fiber lasers, increasing the effective mode field area of ​​the optical fiber is a common method. The threshold of SBS can be increased by increasing the core area of ​​the optical fiber. In recent years, research on multi-core optical fibers has gradually attracted attention. The advantage of multi-core optical fibers is that the effective area can be increased by increasing the number of cores in the inner cladding, thereby increasing the threshold of nonlinear effects such as stimulated Brillouin scattering and stimulated Raman scattering, and thus helping to increase the output power of single-frequency high-power fiber amplifiers. Each core in a multi-core optical fiber operates in a single-mode state, and multiple modes are formed through mutual coupling. According to the coupled mode theory, the total number of modes equal to the number of cores can be obtained, such as 7 and 19 modes in 7-core and 19-core optical fibers, respectively. The mode with the largest transmission constant has the same phase in the complex amplitude in each core, so it is called the in-phase mode, and its corresponding beam quality factor M 2 Close to limit 1, it has the best beam quality compared with several other modes. Therefore, for multi-core fiber lasers and amplifiers, it is necessary to maximize the proportion of the in-phase mode in the output power to ensure better beam quality. Usually, the mode selection method is used to suppress the output of other modes and increase the output power of the in-phase mode. The Talbot cavity mode selection method is currently the most widely used and important mode selection method. When a coherent light beam illuminates a periodically arranged object, its own image will appear after a certain distance of transmission. This distance is called the Talbot distance. This distance is related to its distribution period and wavelength. Therefore, different supermodes have different Talbot distances due to different distribution periods. If a total reflection plane mirror is placed at an appropriate distance Z that is conducive to the reflection of a certain mode, the mode will obtain a large feedback coefficient, while the feedback of other modes will be suppressed to varying degrees. After reflection, the image of the supermode itself is coupled into the laser, and the mode can be selected, but this method has complex equipment, cumbersome operation, high cost, and requires the determination of a high-precision Talbot distance.

[0036] Therefore, the high-power single-frequency fiber laser manufactured by the high SBS threshold multi-core optical fiber obtained by the manufacturing method and manufacturing equipment of the present invention has a large output power, is less affected by the SBS effect, and has high stability.

[0037] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for manufacturing a high SBS threshold multi-core optical fiber, characterized in that: The manufacturing method comprises the following steps: S1, preparation work before drawing multi-core optical fiber as raw material; S2, during the drawing process, controlling the drawing speed of the multi-core optical fiber to gradually increase from 14 m / min to 25 m / min; S3, when the drawing speed reaches 25 m / min, controlling the drawing speed of the multi-core optical fiber to gradually decrease from 25 m / min to 14 m / min; S4, alternately performing step S2 and step S3 until the entire multi-core optical fiber is drawn; S5, cutting the multi-core optical fibers obtained in step S4 to produce tapered multi-core optical fibers in batches.

2. The method for manufacturing a high SBS threshold multi-core optical fiber according to claim 1, characterized in that: The step S1 comprises the following sub-steps: S11, clamping one end of the optical fiber preform on a feeding device; S12, placing the other end of the optical fiber preform in a drawing furnace to produce a multi-core optical fiber; S13, winding the drawn multi-core optical fiber coming out of the drawing furnace onto a drawing wheel; S14, winding the multi-core optical fiber coming out of the spinning wheel onto a take-up reel.

3. The method for manufacturing a high SBS threshold multi-core optical fiber according to claim 2, characterized in that: The step S1 further comprises: S15, sequentially arranging a bare fiber diameter gauge, a primary coating and curing assembly, a secondary coating and curing assembly, an optical fiber diameter gauge and a tension measuring instrument on the drawing of the multi-core optical fiber between the drawing furnace and the drawing wheel.

4. The method for manufacturing a high SBS threshold multi-core optical fiber according to claim 3, characterized in that: The step S1 further comprises: S16, establish signal connection with each instrument component through the computer.

5. The method for manufacturing a high SBS threshold multi-core optical fiber according to claim 4, characterized in that: The steps S2 and S3 specifically control the speed of the drawing wheel by the computer to control the drawing speed.

6. The method for manufacturing a high SBS threshold multi-core optical fiber according to claim 5, characterized in that: In step S5, the core diameter of the tapered multi-core optical fiber gradually decreases from 6.4 μm to 1 μm, and the core distance gradually decreases from 35 μm to 5.5 μm.

7. The method for manufacturing a high SBS threshold multi-core optical fiber according to claim 6, characterized in that: The manufacturing method further comprises: S6, controlling the drawing wheel to return to the initial drawing speed through the computer, retaining a section of the head fiber and the tail fiber for easy connection with other structures.

8. A manufacturing device for a high SBS threshold multi-core optical fiber, used to implement the manufacturing method for a high SBS threshold multi-core optical fiber according to any one of claims 1 to 7, characterized in that: The manufacturing equipment comprises: feeding device; A wire drawing furnace, wherein the feeding end of the wire drawing furnace faces the feeding device; A drawing wheel, wherein a feeding end of the drawing wheel faces a discharging end of the drawing furnace; A wire take-up drum, wherein a feeding end of the wire take-up drum faces a feeding end of the spinning wheel.

9. The manufacturing equipment for high SBS threshold multi-core optical fiber according to claim 8, characterized in that: The manufacturing equipment also includes a bare fiber diameter gauge, a primary coating curing component, a secondary coating curing component, a fiber diameter gauge and a tension measuring instrument. The bare fiber diameter gauge, the primary coating curing component, the secondary coating curing component, the fiber diameter gauge and the tension measuring instrument are arranged in sequence according to the direction of the fiber drawing process.

10. An application of a high SBS threshold multi-core optical fiber, characterized in that: The method comprises applying the high SBS threshold multi-core optical fiber manufactured by the manufacturing method described in any one of claims 1 to 7 to the manufacture of a high-power single-frequency optical fiber laser.

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