Multi-core transmission optical fiber and laser

Abstract

The utility model discloses a multi-core transmission optical fiber and a laser, and belongs to the technical field of lasers. The multi-core transmission optical fiber comprises an inner core and an outer wrapping layer arranged outside the inner core, the inner core comprises a first fiber core, a second fiber core and an inner wrapping layer, the first fiber core is arranged in the middle of the inner core, and the second fiber core is arranged on the periphery of the first fiber core; the refractive index of the first fiber core is n1, the refractive index of the inner cladding is n2, the refractive index of the second fiber core is n3, the refractive index of the outer cladding is n4, n1 > = n3 = n4 > n2, the cutting speed is high, the cutting section quality is good, and the taper is small.

Description

Technical Field

[0001] This utility model relates to the field of laser technology, and in particular to a multi-core transmission optical fiber and a laser. Background Technology

[0002] Thick carbon steel plates (40mm and above) are essential materials frequently used in industries such as shipbuilding. Currently, the main methods for cutting plates of this thickness are flame cutting and conventional laser cutting. Flame cutting offers advantages such as good cutting quality and small cross-sectional taper in the aforementioned thick plate applications, but it also has drawbacks including slow cutting speed, large amounts of metal fumes, high operational requirements, difficulty in piercing, a large heat-affected zone, and limitations in the materials it can cut (only suitable for cutting thick carbon steel plates). Conventional laser cutting, on the other hand, offers advantages such as relatively fast cutting speed and relatively small heat-affected zone in the same thick plate cutting process, but it suffers from poor cutting quality and a large cross-sectional taper.

[0003] like Figure 1 As shown by the solid line, existing ultra-high power lasers output a Gaussian distributed or a flat-topped laser beam 1' with uniformly controlled energy, which can meet the needs of normal cutting applications. However, in heavy industry and other applications involving thick plate cutting and welding, the aforementioned laser beams suffer from overly concentrated energy distribution and short Rayleigh lengths. Specifically, the Gaussian distributed laser beam 1' has a narrow waist in the middle along its length, resulting in a significant variation in the beam diameter. In thick plate cutting applications, this easily leads to problems such as an uneven end face of the plate to be cut 2', slag buildup at the bottom, and excessive taper at the cross-section 21'. In thick plate welding applications, it easily results in spattering weld slag, poor weld appearance, and insufficient penetration. Utility Model Content

[0004] The purpose of this invention is to provide a multi-core transmission optical fiber and laser that has a fast cutting speed, good cutting surface quality, and small taper.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A multi-core transmission optical fiber includes an inner core and an outer cladding disposed outside the inner core. The inner core includes a first fiber core, a second fiber core, and an inner cladding. The first fiber core is located at the middle of the inner core, and the second fiber core is located on the outer periphery of the first fiber core. The refractive index of the first fiber core is n1, the refractive index of the inner cladding is n2, the refractive index of the second fiber core is n3, and the refractive index of the outer cladding is n4, where n1 ≥ n3 = n4 > n2.

[0007] In some possible implementations, the second fiber core is provided with 2-6 fibers.

[0008] In some possible implementations, the diameters of the first fiber core and the second fiber core are both in the range of 10μm-100μm, and the diameters of the first fiber core and the second fiber core may be the same or different.

[0009] A laser comprising a multi-core transmission optical fiber as described in any of the preceding claims.

[0010] In some possible implementations, the system further includes a central optical path module, a sub-optical path module, an energy combiner, and an output head, with the multi-core transmission fiber disposed between the energy combiner and the output head. The energy combiner includes a central branch and an edge branch. The input end of the central branch is connected to the central optical path module, and the output end of the central branch is connected to the first fiber core. The input end of the edge branch is connected to the sub-optical path module, and the output end of the edge branch is connected to the second fiber core.

[0011] In some possible implementations, the number of sub-optical path modules and the number of the second fiber cores are equal, and at least one of each is provided. The second fiber core and the sub-optical path modules are each provided in a one-to-one correspondence with the edge branch.

[0012] In some possible implementations, the number of edge branches is greater than or equal to the number of the second fiber cores.

[0013] In some possible implementations, the diameter of the first fiber core is larger than the diameter of the central branch, and / or the numerical aperture of the first fiber core is larger than the numerical aperture of the central branch.

[0014] In some possible implementations, a cladding stripper is also included, disposed between the multi-core transmission fiber and the output head, wherein the outer cladding of the multi-core transmission fiber forms cladding light, and the cladding stripper is used to strip the cladding light.

[0015] In some possible implementations, a laser control system is also included, through which the central optical path module and the sub-optical path modules are independently controlled.

[0016] The beneficial effects of this utility model are:

[0017] This invention provides a multi-core transmission optical fiber and a laser. By setting a first core and a second core, laser transmission can be performed separately, thereby forming separate light spots. Based on this multi-core transmission optical fiber, a laser with combined light spot output is realized. Furthermore, the refractive index of the first core is equal to or higher than that of the second core, which helps improve the uniformity of the light spot after passing through the external optical path. This enables control over the energy distribution of the ultra-high power light spot, improving the laser beam's narrow waist and increasing the Rayleigh length. The multi-core transmission optical fiber and the laser based on it achieve combined light spot output, ensuring fast cutting speed, good cutting surface quality, and small taper. This is beneficial for improving the cutting or welding effect of thick plates, especially significantly improving the taper and quality of the cut surface. In actual welding, it can better suppress welding spatter and achieve a beautiful weld. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a Gaussian distributed laser beam (solid line) in the prior art and a laser beam (dashed line) provided in one embodiment of the present invention cutting a plate to be cut;

[0019] Figure 2 This is a cross-sectional schematic diagram of a multi-core transmission optical fiber provided in a specific embodiment of this utility model;

[0020] Figure 3 This is a schematic diagram of the refractive index distribution of a multi-core transmission optical fiber provided in a specific embodiment of this utility model;

[0021] Figure 4 This is a schematic diagram of the optical path of a laser provided in a specific embodiment of this utility model;

[0022] Figure 5 This is a cross-sectional view of the coupling between the energy combiner and the multi-core transmission optical fiber provided in a specific embodiment of this utility model.

[0023] In the picture:

[0024] 1' Laser beam; 2' Plate to be cut; 21' Cross-section; 1. Laser beam; 21. Cross-section;

[0025] 100. Multi-core transmission fiber; 110. Outer cladding; 120. Inner core; 122. Inner cladding; 123. First fiber core; 124. Second fiber core; 200. Central optical path module; 300. Sub-optical path module; 400. Energy combiner; 410. Spare edge branch; 500. Output head; 600. Laser control system; 700. Cladding optical stripper. Detailed Implementation

[0026] To make the technical problems solved by this utility model, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of this utility model will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] like Figure 1 dotted line section Figure 2 and Figure 3 As shown, this embodiment provides a multi-core transmission optical fiber, including an inner core 120 and an outer cladding 110 disposed outside the inner core 120. The inner core 120 includes an inner cladding 122, a first fiber core 123, and a second fiber core 124. The first fiber core 123 is located in the middle of the inner core 120, and the second fiber core 124 is located on the outer periphery of the first fiber core 123. The inner cladding 122 is disposed between the second fiber core 124 and the outer cladding 110. The refractive index of the first fiber core 123 is n1, the refractive index of the inner cladding 122 is n2, the refractive index of the second fiber core 124 is n3, and the refractive index of the outer cladding 110 is n4, where n1 ≥ n3 = n4 > n2. Preferably, n1 > n3.

[0030] By setting the first fiber core 123 and the second fiber core 124, laser transmission can be performed separately, thereby forming light spots for energy distribution. A laser with combined light spot output is realized based on this multi-core transmission fiber.

[0031] The numerical aperture has the same relationship as the refractive index. The numerical aperture determines the critical angle for total internal reflection of the laser within the first core 123. The numerical aperture of the first core 123 is NA, and the critical angle for total internal reflection of the laser is θc, where θc = arcsin(NA). If the divergence angle of the laser exceeds the critical angle for total internal reflection θc, that is, if the divergence angle of the laser exceeds arcsin(NA), then the laser will leak into the adjacent second core 124. In one embodiment, n1 > n3 = n4, that is, the numerical aperture of the first core 123 is the largest, followed by the numerical apertures of the second core 124 and the outer cladding 110. In another embodiment, n1 = n3 = n4, that is, the numerical apertures of the first core 123, the second core 124, and the outer cladding 110 are equal. Since the inner cladding 122 has the smallest numerical aperture, when the divergence angle of the laser passing through the first fiber core 123 exceeds the critical angle of total internal reflection, the laser will leak into the second fiber core 124 and the outer cladding 110. When the divergence angle of the laser passing through the second fiber core 124 exceeds the critical angle of total internal reflection, the laser will leak into the outer cladding 110, thereby further improving the uniformity of energy density.

[0032] By setting a first fiber core 123 and a second fiber core 124, with the refractive index of the first fiber core 123 being equal to or higher than the refractive index of the second fiber core 124, it is beneficial to improve the uniformity of the light spot after passing through the external optical path, thereby achieving control over the energy distribution of the ultra-high power light spot. Figure 1 In the dashed section, the formed laser beam 1 improves the narrow waist condition, increases the Rayleigh length, and significantly improves the taper and quality of the cut surface 21 after cutting the plate 2'. The multi-core transmission optical fiber and the laser based on it achieve combined beam output, ensuring high cutting speed, good cut surface quality, and small taper, which is beneficial for improving the cutting or welding effect of thick plates, especially significantly improving the taper and quality of the cut surface. In actual welding, it can better suppress welding spatter and achieve a beautiful weld.

[0033] The second fiber core 124 is provided with 2 to 6 fibers, such as 2, 3, 4, 5, or 6. For example, if there are 2 second fiber cores 124, then 3 fiber cores will transmit laser light separately, thereby providing three combined light spots. For example, if there are 3 or more second fiber cores 124, then the first fiber core 123 and the 3 or more second fiber cores 124 will transmit laser light separately, thereby providing multiple combined light spots. By increasing the number of second fiber cores 124, the number of light spots is increased. Furthermore, by providing multiple second fiber cores 124 surrounding the outer periphery of the first fiber core 123, the uniformity of energy density can be further improved.

[0034] The diameter of the first fiber core 123 and the diameter of the second fiber core 124 both range from 10μm to 100μm. The diameter of the first fiber core 123 and the diameter of the second fiber core 124 may be the same or different. For example, the diameter of the first fiber core 123 and the diameter of the second fiber core 124 are the same, and are 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm, etc. Alternatively, the diameters of the first fiber core 123 and the second fiber core 124 may differ. The diameter of the first fiber core 123 may be 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, or 90μm, while the diameter of the second fiber core 124 may be 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, or 100μm, for example, the diameter of the first fiber core 123 may be 10μm and the diameter of the second fiber core 124 may be 20μm. When multiple second fiber cores 124 are provided, the diameters of the multiple second fiber cores 124 may be the same or different. For example, if there are three second fiber cores 124, the diameter of the first fiber core 123 is 10 μm, the diameter of the first second fiber core 124 is 20 μm, the diameter of the second second fiber core 124 is 30 μm, and the diameter of the third second fiber core 124 is 40 μm. By setting different sizes of fiber cores, different light spot energy distributions can be provided.

[0035] Optionally, the outer cladding 110 is coated with a coating layer whose refractive index is lower than that of the first fiber core 123 and the second fiber core 124. On one hand, this coating layer protects the outer cladding 110 from the influence of the external environment. It is made of materials such as polyimide, acrylate, and silicone rubber, which have good weather resistance, abrasion resistance, and insulation, preventing mechanical damage, chemical corrosion, and moisture erosion of the transmission optical fiber. On the other hand, using a low-refractive-index coating layer ensures total internal reflection at the boundary between the inner core 120 and the outer cladding 110, ensuring that light is confined within the inner core 120 and the outer cladding 110, preventing optical signals from leaking outside the multi-core transmission optical fiber 100, thereby achieving efficient and stable transmission.

[0036] like Figure 4 and Figure 5 As shown, this embodiment also provides a laser, including the multi-core transmission optical fiber 100 as described above. The laser based on the multi-core transmission optical fiber achieves combined beam output, ensuring high cutting speed, good cutting surface quality, and small taper, solving the problems of flame cutting and conventional laser cutting in industries such as shipbuilding where carbon steel plates thicker than 40mm are cut.

[0037] The laser also includes a central optical path module 200, a sub-optical path module 300, an energy combiner 400, and an output head 500. A multi-core transmission fiber 100 is disposed between the energy combiner 400 and the output head 500. The energy combiner 400 includes a central branch and an edge branch. The input end of the central branch is connected to the central optical path module 200, and the output end of the central branch is connected to the first fiber core 123. The input end of the edge branch is connected to the sub-optical path module 300, and the output end of the edge branch is connected to the second fiber core 124. The energy combiner 400 is used for relay coupling of the central optical path module 200, the sub-optical path module 300, and the multi-core transmission fiber 100. The output laser of the central optical path module 200 is formed into the central optical path module laser after passing through the central branch of the energy combiner 400, and then connected to the first fiber core 123. The output laser from the sub-optical path module 300 passes through the edge branch of the energy combiner 400 to form the sub-optical path module laser, which is then connected to the second fiber core 124. That is, the energy combiner 400 can couple the lasers from the central optical path module 200 and the sub-optical path module 300 to the first fiber core 123 and the second fiber core 124 of the multi-core transmission fiber 100, respectively, and output multiple light spots through the output head 500. Optionally, the section from the energy combiner 400 to the output head 500 is a complete multi-core transmission fiber 100 without any fusion splices.

[0038] The aforementioned single central optical path module 200 and sub-optical path module 300 can achieve a maximum high power output of 20kW, thus enabling an ultra-high power output of 80kW or higher based on the aforementioned laser.

[0039] The diameter of the first fiber core 123 is larger than the diameter of the central branch, and / or the numerical aperture of the first fiber core 123 is larger than the numerical aperture of the central branch, which facilitates the coupling of the output laser of the central optical path module 200 into the first fiber core 123 in the multi-core transmission fiber 100. The diameter of the second fiber core 124 is larger than the diameter of the edge branch, and / or the numerical aperture of the second fiber core 124 is larger than the numerical aperture of the edge branch, which facilitates the coupling of the output laser of the sub-optical path module 300 into the second fiber core 124 in the multi-core transmission fiber 100.

[0040] The number of sub-optical path modules 300 and second fiber cores 124 are equal, and at least one of each is provided. The second fiber core 124 and the sub-optical path module 300 are each provided in a one-to-one correspondence with the edge branches. Furthermore, the number of edge branches is greater than or equal to the number of second fiber cores 124 to ensure that the edge branches of the energy combiner 400 are aligned one-to-one with the fiber cores of the multi-core optical fiber.

[0041] The spacing between the first fiber core 123 and the second fiber core 124, the number of second fiber cores 124, and the spacing between the second fiber cores 124 can be adjusted according to the actual application scenario. Furthermore, the arrangement of the first fiber core 123 and the second fiber core 124 needs to be matched with the energy combiner 400. For example, the energy combiner 400 includes a central branch located at the center and six edge branches located around the central branch. Three second fiber cores 124 and three sub-optical path modules 300 are correspondingly configured with the output and input ends of the three edge branches, and the other three edge branches are unused edge branches 410. Correspondingly, the multi-core transmission fiber 100 includes a first fiber core 123 and three second fiber cores 124. One second fiber core 124 is located above the first fiber core 123, and the other two second fiber cores 124 are located on both sides of the first fiber core 123 to facilitate the connection between the first fiber core 123 and the central branch. The second fiber cores 124 are connected one-to-one with the sub-branches.

[0042] Optionally, the laser also includes a laser control system 600. The central optical path module 200 and the sub-optical path modules 300 are independently controlled by the laser control system 600, allowing the output power of both the central optical path module 200 and the sub-optical path modules 300 to be adjustable. This enables adjustment of the energy distribution of the multi-ring spot to meet different application scenarios and improves the processing effect of the laser in the laser processing of thick plates. Optionally, the sub-optical path module 300 includes at least one. The laser control system 600 can adjust the number of couplings of the sub-optical path modules 300 to adjust the energy distribution of the multi-ring spot to meet different application scenarios and improve the processing effect of the laser in the laser processing of thick plates. For example, through the laser control system, a combined spot of the laser output from the above four fiber cores can be realized, or only the central optical path module 200 can be turned on, specifically for cutting medium and thin plates; or the central optical path module 200 and the three sub-optical path modules 300 can be turned on, specifically for cutting thick plates, thus being compatible with the processing of medium and thin plates.

[0043] The laser transmitted through the multi-core transmission fiber 100 passes through the inner core 120 and enters the outer cladding 110 for normal transmission, forming cladding light. The laser also includes a cladding light stripper 700 disposed between the multi-core transmission fiber 100 and the output head 500. The cladding light stripper 700 is used to strip and filter out the cladding light, making the laser output more stable and pure.

[0044] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A multi-core transmission optical fiber, characterized in that, The device includes an inner core (120) and an outer cladding (110) disposed outside the inner core (120). The inner core (120) includes a first fiber core (123), a second fiber core (124), and an inner cladding (122). The first fiber core (123) is disposed in the middle of the inner core (120), and the second fiber core (124) is disposed on the outer periphery of the first fiber core (123). The refractive index of the first fiber core (123) is n1, the refractive index of the inner cladding (122) is n2, the refractive index of the second fiber core (124) is n3, and the refractive index of the outer cladding (110) is n4, where n1 ≥ n3 = n4 > n2.

2. The multi-core transmission optical fiber according to claim 1, characterized in that, The second fiber core (124) has 2-6 fibers.

3. The multi-core transmission optical fiber according to claim 1, characterized in that, The diameter of the first fiber core (123) and the diameter of the second fiber core (124) are both in the range of 10μm-100μm. The diameter of the first fiber core (123) and the diameter of the second fiber core (124) may be the same or different.

4. A laser, characterized in that, Including the multi-core transmission optical fiber as described in any one of claims 1-3.

5. The laser according to claim 4, characterized in that, It also includes a central optical path module (200), a sub-optical path module (300), an energy combiner (400), and an output head (500). The multi-core transmission fiber is disposed between the energy combiner (400) and the output head (500). The energy combiner (400) includes a central branch and an edge branch. The input end of the central branch is connected to the central optical path module (200), and the output end of the central branch is connected to the first fiber core (123). The input end of the edge branch is connected to the sub-optical path module (300), and the output end of the edge branch is connected to the second fiber core (124).

6. The laser according to claim 5, characterized in that, The number of the sub-optical path module (300) and the second fiber core (124) are equal, and at least one of each is provided. The second fiber core (124) and the sub-optical path module (300) are each provided in a one-to-one correspondence with the edge branch.

7. The laser according to claim 5, characterized in that, The number of edge branches is greater than or equal to the number of the second fiber core (124).

8. The laser according to claim 5, characterized in that, The diameter of the first fiber core (123) is greater than the diameter of the central branch, and / or the numerical aperture of the first fiber core (123) is greater than the numerical aperture of the central branch.

9. The laser according to claim 5, characterized in that, It also includes a cladding light stripper (700) disposed between the multi-core transmission optical fiber and the output head (500), wherein the outer cladding (110) of the multi-core transmission optical fiber forms cladding light, and the cladding light stripper (700) is used to strip the cladding light.

10. The laser according to any one of claims 5-9, characterized in that, It also includes a laser control system (600), through which the central optical path module (200) and the sub-optical path module (300) are independently controlled.

Images