Transmission optical fiber and laser

Abstract

The utility model discloses a transmission optical fiber and a laser, and belongs to the technical field of optical fibers. The transmission optical fiber comprises a fiber core and a wrapping layer wrapping the fiber core, the wrapping layer comprises a first isolation layer, a first transmission layer, a second isolation layer and an outer side layer which are sequentially arranged from inside to outside, and the fiber core and the first transmission layer can transmit laser; the refractive index of the fiber core is n1, the refractive indexes of the first isolation layer and the second isolation layer are n2, the refractive index of the first transmission layer is n3, n1 is larger than n2 and smaller than n3, the thick plate cutting and welding application scene can be matched, and the operation effect is improved.

Description

Technical Field

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

[0002] Ultra-high power fiber lasers have wide applications in materials processing. For example... Figure 1 As shown by the solid line, existing ultra-high power lasers output a Gaussian distributed or a flat-topped laser beam 100' 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 beam has an overly concentrated energy distribution and a short Rayleigh length. Specifically, the Gaussian distributed laser beam 100' 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 cut surface, slag buildup at the bottom, and an excessively large taper at the 210' section. In thick plate welding applications, it easily results in slag spatter, poor weld appearance, and insufficient penetration. Utility Model Content

[0003] The purpose of this invention is to provide a transmission optical fiber and laser that can be matched with the above-mentioned thick plate cutting and welding application scenarios, thereby improving the work efficiency.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] An optical fiber includes a fiber core and a cladding covering the fiber core. The cladding includes a first isolation layer, a first transmission layer, a second isolation layer, and an outer layer arranged sequentially from the inside to the outside. Both the fiber core and the first transmission layer are capable of transmitting laser light. The refractive index of the fiber core is n1, the refractive indices of the first isolation layer and the second isolation layer are both n2, and the refractive index of the first transmission layer is n3, wherein n2 < n1 < n3.

[0006] In some possible implementations, the refractive index of the first transport layer is greater than the refractive index of the fiber core, and the difference in refractive index between the fiber core and the first transport layer is in the range of 0.01-0.06.

[0007] In some possible implementations, the numerical aperture of the fiber core is in the range of 0.05-0.21; and / or, the numerical aperture of the first transmission layer is in the range of 0.06-0.22.

[0008] In some possible implementations, the cladding layer further includes a second transmission layer and a third isolation layer disposed sequentially from the inside out between the second isolation layer and the outer layer.

[0009] In some possible implementations, the refractive index of the third isolation layer is equal to that of the first isolation layer; and / or, the refractive index of the second transport layer is equal to that of the fiber core.

[0010] In some possible implementations, the cladding layer further includes M intermediate transport layers and M intermediate isolation layers arranged alternately from the inside to the outside between the third isolation layer and the outer layer, wherein M is an integer greater than or equal to 1.

[0011] In some possible implementations, the refractive indices of the M intermediate isolation layers are all equal to the refractive index of the first isolation layer; when M is an odd number, the refractive index of the Mth intermediate transport layer is equal to the refractive index of the first transport layer, and when M is an even number, the refractive index of the Mth intermediate transport layer is equal to the refractive index of the second transport layer.

[0012] In some possible implementations, the diameter of the fiber core is 14 μm-100 μm; and / or, the thickness of the first isolation layer and the second isolation layer ranges from 5 μm to 20 μm; and / or, the thickness of the first transmission layer and the outer layer ranges from 20 μm to 100 μm.

[0013] A laser comprising a transmission optical fiber as described in any of the preceding claims.

[0014] In some possible implementations, the laser further includes a cladding light stripper for filtering out cladding light transmitted from the outer cladding layer.

[0015] The beneficial effects of this utility model are:

[0016] This invention provides a transmission optical fiber and laser. By adding a first transmission layer to the outside of the fiber core, the fiber core and the first transmission layer each form a beam spot, thus creating a double-ring beam spot. Since the refractive index of the first transmission layer is greater than that of the optical fiber, the energy density of the double-ring beam spot is more uniform, enabling control over the energy distribution of the ultra-high power beam. The resulting laser beam improves the performance of thin-waisted beams, increases Rayleigh length, and reduces taper, ideally achieving taper-free cutting. 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 more aesthetically pleasing weld. Attached Figure Description

[0017] 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;

[0018] Figure 2This is a schematic diagram of the refractive index distribution of the transmission optical fiber provided in one embodiment of this utility model;

[0019] Figure 3 This is a schematic cross-sectional view of the transmission optical fiber provided in one embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the refractive index distribution of the transmission optical fiber provided in another embodiment of the present invention;

[0021] Figure 5 This is a cross-sectional schematic diagram of the transmission optical fiber provided in another embodiment of the present invention.

[0022] In the picture:

[0023] 100', laser beam; 210', cross-section; 100, laser beam; 200, plate to be cut; 210, cross-section;

[0024] 1. Fiber core; 2. Cladding; 21. First isolation layer; 22. First transmission layer; 23. Second isolation layer; 24. Outer layer; 25. Third isolation layer; 26. Second transmission layer. Detailed Implementation

[0025] 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.

[0026] 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.

[0027] 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.

[0028] like Figure 1 dotted line section Figure 2 and Figure 3 As shown, this embodiment provides a transmission optical fiber, including a fiber core 1 and a cladding 2 covering the fiber core 1. The cladding 2 includes a first isolation layer 21, a first transmission layer 22, a second isolation layer 23, and an outer layer 24 arranged sequentially from the inside out, that is, the cladding 2 has four layers. Both the fiber core 1 and the first transmission layer can transmit laser light, and beams can be output from the fiber core 1 and the first transmission layer 22, respectively. The refractive index of the fiber core 1 is n1, the refractive indices of the first isolation layer 21 and the second isolation layer 23 are both n2, and the refractive index of the first transmission layer 22 is n3, where n2 < n1 < n3.

[0029] By adding a first transmission layer 22 to the outside of the fiber core 1, the fiber core 1 and the first transmission layer 22 each form a beam spot, thus forming a double-ring beam spot. Since the refractive index of the first transmission layer 22 is greater than that of the fiber core 1, the energy density of the double-ring beam spot is more uniform, thus achieving control over the energy distribution of the ultra-high power beam spot. The resulting laser beam 100 improves the narrow waist condition and increases the Rayleigh length. When applied to thick plate cutting, it reduces the taper of the cut surface 210, ideally resulting in taper-free cutting. This is beneficial for improving the cutting or welding effect of thick plate materials, especially significantly improving the taper and quality of the cut surface 210 after cutting the plate 200. In actual welding, it can better suppress welding spatter and achieve a beautiful weld seam.

[0030] Optionally, the refractive index difference between the fiber core 1 and the first transmission layer 22 can range from 0.01 to 0.06. The refractive index of the first transmission layer 22 can be slightly greater than that of the fiber core 1. A refractive index difference that is too large or too small will affect the uniformity of the light spot. For example, the difference can be 0.01, 0.02, 0.03, 0.04, 0.05, or 0.06, etc.

[0031] The numerical aperture has the same relationship as the refractive index, meaning the numerical aperture of the first transport layer 22 is slightly larger than that of the fiber core 1. Optionally, the numerical aperture of the fiber core 1 ranges from 0.05 to 0.21; and / or, the numerical aperture of the first transport layer 22 ranges from 0.06 to 0.22. Optionally, the numerical aperture of the fiber core 1 ranges from 0.05 to 0.10, 0.10 to 0.15, or 0.15 to 0.21, etc.; optionally, the numerical aperture of the first transport layer 22 ranges from 0.06 to 0.10, 0.10 to 0.15, or 0.15 to 0.22, etc.; optionally, the numerical aperture of the fiber core 1 ranges from 0.05 to 0.10, and the numerical aperture of the first transport layer 22 ranges from 0.10 to 0.15. Alternatively, the numerical aperture of fiber core 1 can range from 0.10 to 0.15, and the numerical aperture of the first transmission layer 22 can range from 0.15 to 0.22. Optionally, the numerical aperture of fiber core 1 can be 0.05, 0.10, 0.15, or 0.20, while the numerical aperture of the first transmission layer 22 can be 0.06, 0.11, 0.16, or 0.21 respectively. Taking the numerical aperture of fiber core 1 as an example of 0.15, the numerical aperture of fiber core 1 determines the critical angle of total internal reflection of the laser within fiber core 1. The numerical aperture of fiber core 1 is NA, that is, NA = 0.15, and the critical angle of total internal reflection of the laser is θc, where θc = arcsin(NA). If the divergence angle of the laser exceeds the critical angle of total internal reflection θc, that is, the divergence angle of the laser exceeds arcsin0.15, the laser will leak to the adjacent isolation layer and then to the transmission layer. If the numerical aperture of fiber core 1 and the numerical aperture of the first transmission layer 22 are too large or too small, it will cause the laser to be unable to leak to the transmission layer or to leak too much to the transmission layer, neither of which can meet the requirements.

[0032] The diameter of fiber core 1 is 14μm-100μm, the thickness of the first isolation layer 21 and the second isolation layer 23 ranges from 5μm to 20μm, and the thickness of the first transmission layer 22 and the outer layer 24 ranges from 20μm to 100μm. The 5μm-20μm thickness of the first isolation layer 21 or the second isolation layer 23 cannot confine the laser, while the 20μm-100μm thickness of the first transmission layer 22 and the outer layer 24 allow the coupled laser to transmit normally. Therefore, the laser will pass through the first isolation layer 21 into the first transmission layer 22 for normal transmission, and it can also pass through the second isolation layer 23 into the outer layer 24 for transmission, but it will be filtered out by the cladding optical stripper.

[0033] The outermost layer 24 has a coating layer on its outer side, the refractive index of which is lower than that of the fiber core 1. On one hand, this coating layer protects the cladding 2 from the influence of the external environment. It is made of materials such as polyimide, acrylate, and silicone rubber, possessing good weather resistance, abrasion resistance, and insulation, preventing mechanical damage, chemical corrosion, and moisture erosion of the transmission optical fiber. On the other hand, the use of a low-refractive-index coating layer ensures total internal reflection at the boundary between the fiber core 1 and the cladding 2, ensuring that light is confined within the cladding 2 and the fiber core 1, preventing optical signals from leaking to the outside of the transmission optical fiber, thereby achieving efficient and stable transmission.

[0034] The laser also includes a cladding light stripper to filter out the cladding light transmitted through the outer layer 24. The laser outputs a double-ring light spot through the fiber core 1 and the first transmission layer 22, making the laser output more stable and pure.

[0035] In the second embodiment, such as Figure 4 and Figure 5 As shown, cladding 2 also includes a second transmission layer 26 and a third isolation layer 25, arranged sequentially from the inside to the outside between the second isolation layer 23 and the outer layer 24. The fiber core 1, the first transmission cladding 22, and the second transmission cladding 26 can all transmit laser light, meaning cladding 2 has six layers. By increasing the number of transmission layers (the second transmission layer 26), the laser beam 100 is controlled to pass through more transmission layers for output, further making the energy density of the ring-shaped light spot more uniform, further increasing the Rayleigh length, and reducing the taper of the cut section 210. After the cladding light of the outer layer 24 is stripped using a cladding stripper, the laser outputs a three-ring light spot through the fiber core 1, the first transmission layer 22, and the second transmission layer 26.

[0036] Furthermore, the refractive index of the third isolation layer 25 is equal to that of the first isolation layer 21; and / or, the refractive index of the second transmission layer 26 is equal to that of the fiber core 1, further improving the uniformity of the energy density of the annular light spot.

[0037] In the third embodiment, the cladding 2 further includes M intermediate transmission layers and M intermediate isolation layers arranged alternately from the inside to the outside between the third isolation layer 25 and the outer layer 24, where M is an integer greater than or equal to 1; the refractive index of each of the M intermediate isolation layers is equal to the refractive index of the first isolation layer 21; when M is odd, the refractive index of the Mth intermediate transmission layer is equal to the refractive index of the first transmission layer 22, and when M is even, the refractive index of the Mth intermediate transmission layer is equal to the refractive index of the second transmission layer 26. The laser can be transmitted through the fiber core 1 and the cladding 2 of the transmission fiber, i.e., the cladding 2 has eight or more layers, and the transmission layers have four or more layers. When a cladding optical stripper is used, the laser outputs a four-ring or multi-ring spot through the fiber core 1, the first transmission layer 22 and the outer layer 24, the second transmission layer 26, and the M-1 intermediate transmission layers. Optionally, M can be 1, 2, 3, 4, 5, or 6, etc., without limitation.

[0038] In the transmission optical fiber, since the first transmission layer 22, the outer layer 24, the second transmission layer 26 and the Mth intermediate transmission layer, in addition to the fiber core 1, all have the function of transmitting signals, the transmission optical fiber in this embodiment has increased its ability to withstand lasers compared to ordinary optical fibers where only the fiber core 1 has the function of transmitting signals. The laser can generate an output beam of 80kW-160kW, realizing ultra-high power spot output.

[0039] This embodiment also provides a laser, including an optical module, an output coupler, a cladding optical stripper, and the aforementioned transmission optical fiber. The optical module, such as a pump source, generates an optical signal, which is transmitted through the transmission optical fiber. The beam is then coupled through the output coupler, and the cladding optical stripper strips the laser from the outer layer 24, preventing the transmission of large numerical aperture laser light through the cladding from affecting the laser's reliability and application performance. Finally, a laser beam 100 is output for cutting or welding. The aforementioned transmission optical fiber enables the output of double-ring, triple-ring, or multi-ring beams. On one hand, it allows for control of the ultra-high power beam energy distribution, resulting in a laser beam 100 that improves the narrow waist, increases the Rayleigh length, and reduces the taper, which is beneficial for improving the cutting or welding effect of thick plates. On the other hand, the transmission optical fiber increases the laser's load-bearing capacity, enabling the laser to generate an output beam of 80kW-160kW, achieving ultra-high power beam output.

[0040] 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 transmission optical fiber, characterized in that, The optical fiber comprises a core (1) and a cladding (2) covering the core (1), the cladding (2) comprises a first isolation layer (21), a first transmission layer (22), a second isolation layer (23) and an outer layer (24) arranged in sequence from inside to outside, the core (1) and the first transmission layer (22) can transmit laser; the refractive index of the core (1) is n1, the refractive index of the first isolation layer (21) and the second isolation layer (23) is n2, and the refractive index of the first transmission layer (22) is n3, wherein n2 < n1 < n3.

2. The transmission optical fiber according to claim 1, characterized in that, The refractive index of the first transmission layer (22) is greater than the refractive index of the core (1), and the difference between the refractive indices of the core (1) and the first transmission layer (22) ranges from 0.01 to 0.

06.

3. The transmission optical fiber according to claim 2, characterized in that, The numerical aperture of the core (1) ranges from 0.05 to 0.21; and / or, the numerical aperture of the first transmission layer (22) ranges from 0.06 to 0.

22.

4. The transmission optical fiber according to claim 1, characterized in that, The cladding (2) further comprises a second transmission layer (26) and a third isolation layer (25) arranged in sequence from inside to outside between the second isolation layer (23) and the outer layer (24).

5. The transmission optical fiber according to claim 4, characterized in that, The refractive index of the third isolation layer (25) is equal to the refractive index of the first isolation layer (21); and / or, the refractive index of the second transmission layer (26) is equal to the refractive index of the core (1).

6. The transmission optical fiber according to claim 4, characterized in that, The cladding (2) further comprises M intermediate transmission layers and M intermediate isolation layers arranged alternately between the third isolation layer (25) and the outer layer (24) from inside to outside, wherein M is an integer greater than or equal to 1.

7. The transmission optical fiber according to claim 6, characterized in that, The refractive index of the M intermediate isolation layers is equal to the refractive index of the first isolation layer (21); when M is odd, the refractive index of the Mth intermediate transmission layer is equal to the refractive index of the first transmission layer (22), and when M is even, the refractive index of the Mth intermediate transmission layer is equal to the refractive index of the second transmission layer (26).

8. The transmission optical fiber according to any of claims 1-7, characterized in that, The diameter of the core (1) ranges from 14 μm to 100 μm; and / or, the thickness of the first isolation layer (21) and the second isolation layer (23) ranges from 5 μm to 20 μm; and / or, the thickness of the first transmission layer (22) and the outer layer (24) ranges from 20 μm to 100 μm.

9. A laser characterized by, The laser further comprises a cladding light stripper for filtering out cladding light transmitted by the outer layer (24).

10. The laser of claim 9, wherein, The laser further comprises a cladding light stripper for filtering out cladding light transmitted by the outer layer (24).

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