Manufacturing method and device for high-SBS-threshold multi-core fiber, and use of high-SBS-threshold multi-core fiber

Abstract

Provided are a manufacturing method and device for a high-SBS-threshold multi-core fiber, and a use of a high-SBS-threshold multi-core fiber. The manufacturing method comprises: S1. using a multi-core fiber as a raw material and perform preparatory work before drawing; S2. controlling the drawing speed for the multi-core 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 for the multi-core fiber to gradually decrease from 25 m / min to 14 m / min; S4. alternately performing steps S2 and S3 until the whole multi-core fiber is successfully drawn; and S5. cutting the multi-core fiber obtained in step S4 to manufacture tapered multi-core fibers in batches. The provided technical solution solves the technical problems of complicated equipment, cumbersome operations and relatively high costs caused by mode selection methods used in existing multi-core fiber manufacturing.

Description

A method, equipment, and application for manufacturing high SBS threshold multi-core optical fiber Technical Field

[0001] This invention relates to the field of optical fiber manufacturing and application technology, specifically to a method, equipment, and application for manufacturing high SBS threshold multi-core optical fiber. Background Technology

[0002] Multi-core optical fibers can be used to manufacture high-power single-frequency fiber lasers. However, high-power single-frequency fiber lasers often encounter the effect of stimulated Brillouin scattering (SBS) during operation. The SBS effect can lead to power instability, limit the output power of the laser, and may cause laser mode jumping, 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 well known, increasing the fiber core area can improve the SBS threshold, and increasing the number of cores in the inner cladding can increase the effective area. However, in multi-core fibers, each core operates in a single-mode state, forming multiple modes through mutual coupling. For multi-core fiber lasers and amplifiers, it is necessary to maximize the proportion of in-phase modes in the output power to ensure better beam quality. Currently, mode selection methods are commonly used to suppress the output of other modes and increase the output power of in-phase modes, such as the Talbert cavity mode selection method. Specifically, when a coherent beam illuminates a periodically arranged object, its own image appears after a certain distance; this distance is called the Talbert distance. This distance is related to its distribution period and wavelength. Therefore, different supermodes have different Talbert distances due to their different distribution periods. If a total internal reflection plane mirror is placed at an appropriate distance Z that favors the reflection of a certain mode, that 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, thus the mode can be selected. However, this method involves complex equipment, cumbersome operation, and high cost. It also requires determining a high-precision Talbot distance. Therefore, multi-core optical fibers manufactured using this method for mode selection are time-consuming, labor-intensive, and costly. Summary of the Invention

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

[0005] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for manufacturing a high SBS threshold multi-core optical fiber, the method comprising the following steps:

[0007] S1, Preparatory work before drawing using multi-core optical fiber as raw material;

[0008] S2, control the drawing speed of the multi-core optical fiber to gradually increase from 14m / min to 25m / min;

[0009] S3, after the drawing speed reaches 25m / min, control the drawing speed of the multi-core optical fiber to gradually decrease from 25m / min to 14m / min;

[0010] S4, alternate between steps S2 and S3 until the entire multi-core optical fiber is drawn;

[0011] S5, the multi-core optical fiber obtained in step S4 is cut and mass-produced into tapered multi-core optical fibers.

[0012] In some embodiments, step S1 includes the following sub-steps:

[0013] S11, clamp one end of the optical fiber preform onto the feeding device;

[0014] S12, place the other end of the optical fiber preform in a drawing furnace to produce a multi-core optical fiber;

[0015] S13, the multi-core optical fiber coming out of the drawing furnace is wound onto the drawing wheel;

[0016] S14. The multi-core optical fiber coming out of the drawing wheel is wound onto the take-up reel.

[0017] In some embodiments, step S1 further includes:

[0018] S15, a bare fiber diameter gauge, a primary coating and curing assembly, a secondary coating and curing assembly, a fiber diameter gauge, and a tension measuring instrument are sequentially arranged on the multi-core optical fiber between the drawing furnace and the drawing wheel.

[0019] In some embodiments, step S1 further includes:

[0020] S16 connects to various instrument components via a computer.

[0021] In some embodiments, steps S2 and S3 specifically involve controlling the speed of the drawing wheel via the computer to control the wire drawing speed.

[0022] In some embodiments, the core diameter of the tapered multi-core optical fiber in step S5 gradually decreases from 6.4 μm to 1 μm, and the core spacing gradually decreases from 35 μm to 5.5 μm.

[0023] In some embodiments, the manufacturing method further includes:

[0024] S6, the computer controls the drawing cycle to return to the initial drawing speed, retaining a section of head fiber and tail fiber for easy connection with other structures.

[0025] Secondly, the present invention provides a manufacturing apparatus for a high SBS threshold multi-core optical fiber, used to implement a manufacturing method for a high SBS threshold multi-core optical fiber provided in the first aspect of the present invention, the manufacturing apparatus comprising:

[0026] feeding device;

[0027] A wire drawing furnace, wherein the feed end of the wire drawing furnace faces the feeding device;

[0028] A wire drawing wheel, wherein the feeding end of the wire drawing wheel faces the discharge end of the wire drawing furnace;

[0029] The take-up reel has its feeding end facing the unloading end of the drawing wheel.

[0030] In some embodiments, the manufacturing equipment further includes a bare fiber diameter gauge, a primary coating and curing assembly, a secondary coating and curing assembly, a fiber diameter gauge, and a tension measuring instrument, wherein the bare fiber diameter gauge, the primary coating and curing assembly, the secondary coating and curing assembly, the fiber diameter gauge, and the tension measuring instrument are arranged sequentially according to the fiber drawing process direction.

[0031] Thirdly, the present invention provides an application of a high SBS threshold multi-core optical fiber, including the application of the high SBS threshold multi-core optical fiber manufactured by the manufacturing method provided in the first aspect of the present invention in the manufacture of a high-power single-frequency fiber laser.

[0032] Compared with existing technologies, the manufacturing method of this invention reduces the diameter of each core and the distance between them by controlling the drawing speed during the multi-core fiber drawing process, thereby enabling multiple cores to form a fundamental mode and thus improving the SBS threshold. Therefore, the manufacturing method and equipment provided by this invention are simple to operate, low in cost, and can greatly improve production efficiency. Furthermore, the multi-core fiber obtained using the manufacturing method and equipment of this invention has the advantages of high and stable output power when used to manufacture high-power single-frequency fiber lasers. Attached Figure Description

[0033] Figure 1 is a flowchart of the manufacturing method of the present invention;

[0034] Figure 2 is a flowchart of step S1 of the manufacturing method of the present invention;

[0035] Figure 3 is an overall schematic diagram of the manufacturing equipment described in this invention;

[0036] Figure 4 is a schematic diagram of the structure of the multi-core optical fiber obtained by the manufacturing method described in this invention.

[0037] Figure 5 is a schematic diagram (O) of one of the tapered multi-core optical fibers cut from the multi-core optical fiber obtained by the present invention.

[0038] The annotations in the attached figures are explained as follows:

[0039] 100. Feeding device; 200. Fiber drawing furnace; 300. Fiber drawing wheel; 310. First fiber drawing wheel; 320. Second fiber drawing wheel; 400. Take-up reel; 500. Bare optical fiber diameter gauge; 600. Primary coating and curing assembly; 610. Primary coater; 620. Primary UV curing oven; 700. Secondary coating and curing assembly; 710. Secondary coater; 720. Secondary UV curing oven; 800. Fiber diameter gauge; 900. Tension measuring instrument.

[0040] A is an optical fiber preform, and B is a multi-core optical fiber. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0042] To address the technical problems of complex equipment, cumbersome operation, and high cost associated with existing mode selection methods used in manufacturing multi-core optical fibers, this invention provides a manufacturing method, equipment, and application for high SBS threshold multi-core optical fibers.

[0043] It should be noted that the basic principle upon which this invention is based is:

[0044] According to the micro-core diameter mode selection theory, by reducing the radius of each core in a multi-core fiber, each single core cannot independently output a single mode due to its small core diameter. Furthermore, by reducing the core spacing, the coupling between the cores is strengthened. When the radius and core spacing of each core are reduced to a certain value, it is equivalent to outputting a single mode overall. Since the single mode of a multi-core fiber has a larger mode area than that of a single-core fiber, the SBS threshold can be increased.

[0045] Based on the above principles, in a first aspect, as shown in Figure 1, this invention proposes a method for manufacturing a high SBS threshold multi-core optical fiber, the method comprising the following steps:

[0046] S1, Preparatory work before drawing using multi-core optical fiber B as raw material;

[0047] S2, control the drawing speed of the multi-core optical fiber B to gradually increase from 14m / min to 25m / min;

[0048] S3, after the drawing speed reaches 25m / min, control the drawing speed of the multi-core optical fiber B to gradually decrease from 25m / min to 14m / min;

[0049] S4, alternate between steps S2 and S3 until the entire multi-core optical fiber B is pulled;

[0050] S5, the multi-core optical fiber B obtained in step S4 is cut and mass-produced into tapered multi-core optical fibers.

[0051] Unlike existing technologies, the manufacturing method of this invention reduces the diameter of each core and the distance between them by controlling the drawing speed during the multi-core fiber drawing process, thereby enabling multiple cores to form a fundamental mode and thus increasing the SBS threshold. Therefore, the manufacturing method and equipment provided by this invention are simple to operate, low in cost, and can greatly improve production efficiency. Furthermore, the multi-core fiber obtained using the manufacturing method and equipment of this invention has the advantages of high and stable output power when used to manufacture high-power single-frequency fiber lasers.

[0052] 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, specifically including:

[0053] S1, using multi-core optical fiber for drawing; as shown in Figure 2, step S1 specifically includes:

[0054] S11, clamp one end of the optical fiber preform A onto the feeding device 100;

[0055] S12, the other end of the optical fiber preform A is placed in the drawing furnace 200;

[0056] S13, the multi-core optical fiber B that comes out of the drawing furnace 200 is drawn and wound onto the drawing wheel 300;

[0057] S14. The multi-core optical fiber B that comes out from the drawing wheel 300 is wound onto the take-up reel 400.

[0058] S15, 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 are sequentially arranged on the drawing surface of the multi-core optical fiber B between the drawing furnace 200 and the drawing wheel 300.

[0059] S16 connects to various instrument components via a computer;

[0060] In step S1, firstly, multi-core fiber B is fabricated using fiber preform A, and then multi-core fiber B with high power and high SBS threshold is fabricated using multi-core fiber B.

[0061] S2, by controlling the drawing speed of the multi-core optical fiber B to gradually increase from 14m / min to 25m / min, the diameter of the multi-core optical fiber B gradually decreases from 125μm to 21μm, and the minimum distance between the core and the ground gradually decreases from 35μm to 5.5μm.

[0062] S3, when the drawing speed reaches 25m / min, the drawing speed of the multi-core optical fiber B is gradually reduced from 25m / min to 14m / min, and the diameter of the optical fiber gradually increases from 21μm to 125μm.

[0063] S4, alternate between steps S2 and S3 until the entire multi-core optical fiber B is drawn, as shown in Figure 4. The axial length a of a single cone region of the tapered multi-core optical fiber is 15-20m, and each cone region is set at equal distances. The axial center distance b between two adjacent cone regions is 15-20m.

[0064] S5, the multi-core fiber B obtained in step S4 is cut and batch-produced into tapered multi-core fibers, as shown in Figure 5. The core diameter of the tapered multi-core fiber gradually decreases from 6.4 μm to 1 μm, and the core spacing gradually decreases from 35 μm to 5.5 μm.

[0065] S6, the computer controls the drawing wheel 300 to return to the initial drawing speed, retaining a section of head fiber and tail fiber for easy connection with other structures.

[0066] In one embodiment, steps S2 and S3 specifically involve controlling the speed of the drawing wheel 300 via the computer to control the wire drawing speed.

[0067] In one embodiment, the drawing wheel 300 includes a first drawing wheel 310 and a second drawing wheel 320, and the speeds between the first drawing wheel 310 and the second drawing wheel 320, as well as between the drawing wheel 320 and the take-up reel 400, are matched by the computer control.

[0068] In the above technical solution, the primary coating and curing component 600 includes a primary coater 610 and a primary UV curing oven; the secondary coating and curing component 700 includes a secondary coater 710 and a secondary UV curing oven 720; the drawing wheel 300 includes a first drawing wheel 310 and a second drawing wheel 320, wherein the diameter of the first drawing wheel 310 is larger than the diameter of the second drawing wheel 320.

[0069] It should be noted that the faster the fiber drawing speed, the smaller the diameter of the optical fiber, while the slower the fiber drawing speed, the larger the diameter of the optical fiber.

[0070] Secondly, as shown in Figure 3, the present invention provides a manufacturing equipment for high-power, high SBS threshold multi-core optical fibers, which is used to implement the manufacturing method provided in the first aspect of the present invention. The manufacturing equipment 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 feeding end of the drawing wheel 300 faces the discharge end of the drawing furnace 200, and the feeding end of the take-up reel 400 faces the unloading end of the drawing wheel 300.

[0071] When manufacturing multi-core optical fibers using the aforementioned manufacturing equipment, one end of the optical fiber preform is first fixed to the feeding device 100, and the other end is placed in the drawing furnace 200. Then, the optical fiber filaments emerging from the drawing furnace 200 are wound onto the take-up reel 400 by the drawing wheel 300. During this process, the diameter of the bare optical fiber can be measured by the bare fiber diameter gauge 500, and multiple coating and curing processes can be performed on the optical fiber 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 fiber diameter gauge 800, and the tension of the optical fiber can be controlled by the tension measuring instrument 900. The fiber is then taken onto the take-up reel 400 by the drawing wheel 300. Simultaneously, through signal connections between the computer and various electrical components, the speed of the drawing wheel 300 is adjusted under the measurement and monitoring of the bare fiber diameter gauge 500 and the fiber diameter gauge 800, causing the fiber drawing speed to change according to a certain periodic pattern, thereby obtaining a multi-core optical fiber with a periodic variation in fiber diameter along the axial direction. The resulting multi-core optical fiber is shown in Figure 4. Finally, the multi-core optical fiber is cut to obtain a tapered multi-core optical fiber, as shown in Figure 5.

[0072] In one embodiment, the drawing wheel 300 includes a first drawing wheel 310 and a second drawing wheel 320; the primary coating and curing assembly 600 includes a primary coater 610 and a primary UV curing oven 620; and the secondary coating and curing assembly 700 includes a secondary coater 710 and a secondary UV curing oven 720.

[0073] In one embodiment, the feeding device 100, drawing furnace 200, bare optical fiber diameter gauge 500, primary coating device 610, primary UV curing furnace 620, secondary coating device 710, secondary UV curing furnace 720, optical fiber diameter gauge 800, tension measuring instrument 900, first drawing wheel 310, second drawing wheel 320 and take-up reel 400 are arranged sequentially according to the optical fiber drawing process direction.

[0074] Thirdly, the present invention provides an application of a high-power, high-SBS-threshold multi-core optical fiber, including the application of the high-power, high-SBS-threshold multi-core optical fiber manufactured by the manufacturing method described in the first aspect of the present invention in the manufacture of a high-power, single-frequency fiber laser.

[0075] In existing technologies, high-power single-frequency fiber lasers often encounter the Stimulated Brillouin (SBS) effect during operation. The bandwidth of the stimulated Brillouin scattering gain is typically 10. 7 The Hz value is much higher than the spectral linewidth of a single-frequency fiber laser source. Factors such as the high optical power density in the fiber core and the long interaction length also indicate that optical fiber may not be suitable as a gain medium for high-power single-frequency laser sources. The main reason is that the above factors will reduce the stimulated Brillouin scattering threshold, causing the energy of the signal light to be transferred to the reverse Stokes signal. At the same time, the reverse Stokes signal will cause certain damage to the device, thus limiting the improvement of the output power of the single-frequency laser source.

[0076] To suppress the SBS effect in high-power single-frequency fiber lasers, increasing the effective mode area of ​​the fiber is a common method. Increasing the fiber core area can raise the SBS threshold. In recent years, research on multi-core fibers has gradually gained attention. The advantage of multi-core fibers is that by increasing the number of cores in the inner cladding, the effective area can be increased, thereby raising the threshold of nonlinear effects such as stimulated Brillouin scattering and stimulated Raman scattering, thus helping to improve the output power of single-frequency high-power fiber amplifiers. In a multi-core fiber, each core operates in a single-mode state, forming multiple modes through mutual coupling. According to coupled-mode theory, the total number of modes is equal to the number of cores; for example, 7-core and 19-core fibers contain 7 and 19 modes, respectively. The mode with the largest transmission constant has the same phase in the complex amplitude of each core, hence it is called the in-phase mode, and its corresponding beam quality factor M... 2Approaching the limit 1, it possesses the best beam quality compared to other modes. Therefore, for multi-core fiber lasers and amplifiers, it is necessary to maximize the proportion of in-phase modes in the output power to ensure better beam quality. Mode selection is typically employed to suppress the output of other modes and increase the output power of in-phase modes. The Talbert cavity mode selection method is currently the most widely used and important mode selection method. When a coherent beam illuminates a periodically arranged object, its image appears after traveling a certain distance; this distance is called the Talbert distance. This distance is related to its distribution period and wavelength. Therefore, different supermodes have different Talbert distances due to their different distribution periods. If a total internal reflection plane mirror is placed at an appropriate distance Z that favors the reflection of a certain mode, that 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, thus selecting that mode. However, this method involves complex equipment, cumbersome operation, and high cost, requiring the determination of a highly accurate Talbert distance.

[0077] Therefore, the high-power single-frequency fiber laser manufactured by the high SBS threshold multi-core fiber obtained by the manufacturing method and equipment described in this invention has a large output power and is less affected by the SBS effect, resulting in high stability.

[0078] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method of manufacturing a high SBS threshold multicore optical fiber, characterized by, The manufacturing method includes the following steps: S1, Preparatory work before drawing using multi-core optical fiber as raw material; S2, during the drawing process, the drawing speed of the multi-core optical fiber is gradually increased from 14m / min to 25m / min; S3, after the drawing speed reaches 25m / min, control the drawing speed of the multi-core optical fiber to gradually decrease from 25m / min to 14m / min; S4, alternate between steps S2 and S3 until the entire multi-core optical fiber is drawn; S5, the multi-core optical fiber obtained in step S4 is cut and mass-produced into tapered multi-core optical fibers.

2. The method for manufacturing a high SBS threshold multi-core optical fiber according to claim 1, characterized in that, Step S1 includes the following sub-steps: S11, clamp one end of the optical fiber preform onto the feeding device; S12, place the other end of the optical fiber preform in a drawing furnace to produce a multi-core optical fiber; S13, the multi-core optical fiber coming out of the drawing furnace is wound onto the drawing wheel; S14. The multi-core optical fiber coming out of the drawing wheel is wound onto the take-up reel.

3. The method for manufacturing a high SBS threshold multi-core optical fiber according to claim 2, characterized in that, Step S1 further includes: S15, a bare fiber diameter gauge, a primary coating and curing assembly, a secondary coating and curing assembly, a fiber diameter gauge, and a tension measuring instrument are sequentially arranged on 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, Step S1 further includes: S16 connects to various instrument components via a computer.

5. The method for manufacturing a high SBS threshold multi-core optical fiber according to claim 4, characterized in that, Specifically, steps S2 and S3 involve controlling the speed of the drawing wheel via the computer to control the wire 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 spacing 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 includes: S6, the computer controls the drawing cycle to return to the initial drawing speed, retaining a section of head fiber and tail fiber for easy connection with other structures.

8. A manufacturing apparatus for high SBS threshold multi-core optical fiber, used to implement the manufacturing method of high SBS threshold multi-core optical fiber according to any one of claims 1-7, characterized in that, The manufacturing equipment includes: feeding device; A wire drawing furnace, wherein the feed end of the wire drawing furnace faces the feeding device; A wire drawing wheel, wherein the feeding end of the wire drawing wheel faces the discharge end of the wire drawing furnace; The take-up reel has its feeding end facing the unloading end of the drawing 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 optical 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. The bare optical fiber diameter gauge, the primary coating and curing assembly, the secondary coating and curing assembly, the optical fiber diameter gauge, and the tension measuring instrument are arranged sequentially according to the optical fiber drawing process direction.

10. Use of a high SBS threshold multicore optical fiber, characterized in that, This includes applying the high SBS threshold multicore fiber obtained by the manufacturing method described in any one of claims 1-7 to the manufacture of high-power single-frequency fiber lasers.

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