Energy transmitting optical fiber, laser and processing equipment

Abstract

The utility model discloses an energy transmitting optical fiber, a laser and a processing device, the energy transmitting optical fiber comprises a main fiber core, the main fiber core comprises a first section, a first transition section and a second section, the diameter of the first section is larger than that of the second section, and the first transition section is connected with the first section and the second section; and the side fiber cores are periodically and spirally arranged around the main fiber core. According to the embodiment of the utility model, high Raman rejection ratio and high light beam quality can be ensured while high-brightness laser can be output.

Description

Technical Field

[0001] This utility model relates to the field of laser processing technology, and in particular to an optical fiber for transmitting energy, a laser, and processing equipment. Background Technology

[0002] Fiber lasers possess unique advantages such as high conversion efficiency, good beam quality, and compact structure, demonstrating broad application prospects in fields such as earth science, strong-field physics, atomic and molecular physics, frequency conversion, beam combining, and industrial processing. When applying fiber lasers, beam brightness and beam quality are crucial to their performance. However, increasing beam brightness, achieving a high Raman suppression ratio, and improving beam quality are, to some extent, contradictory. Therefore, finding a way to ensure both beam quality and beam brightness to a certain degree remains a pressing issue. Utility Model Content

[0003] This utility model provides a power transmission fiber, a laser, and a processing device that can output high-brightness laser while ensuring a high Raman suppression ratio and high beam quality.

[0004] The power transmission optical fiber proposed in this utility model includes: a main fiber core, the main fiber core including a first segment, a first transition segment and a second segment, the diameter of the first segment being larger than the diameter of the second segment, and the first transition segment connecting the first segment and the second segment;

[0005] Side fiber cores are arranged in a periodic spiral around the main fiber core.

[0006] Optionally, the transmission modes of the main fiber core and the side fiber core meet a quasi-phase matching condition, wherein the quasi-phase matching condition is:

[0007]

[0008] Wherein, β0 represents the beam propagation constant within the main fiber core, β1 represents the beam propagation constant within the side fiber core, h represents the center distance between the side fiber core and the main fiber core, p represents the axial helical period of the side fiber core, and l represents the azimuth order of the specific mode of the main fiber core.

[0009] Optionally, the diameter of the first segment is greater than or equal to 25 μm.

[0010] Optionally, the diameter of the second segment is less than or equal to 20 μm.

[0011] Optionally, the main fiber core further includes a third segment and a second transition segment, the second transition segment connecting the third segment and the first segment, and the diameter of the first segment being larger than the diameter of the third segment.

[0012] Optionally, the diameter of the third segment is greater than or equal to 20 μm.

[0013] Optionally, the power transmission optical fiber further includes a double cladding, with both the main fiber core and the side fiber core disposed within the double cladding.

[0014] Optionally, the ratio of the diameter of the double cladding layer at the periphery of the first segment to the diameter of the double cladding layer at the periphery of the second segment is the same as the ratio of the diameter of the first segment to the diameter of the second segment.

[0015] This invention also proposes a laser comprising the power transmission optical fiber as described in any of the above embodiments.

[0016] This utility model also proposes a processing device, including a laser as described in the above embodiments.

[0017] The power transmission fiber, laser, and processing equipment provided in this embodiment of the invention have the following advantages: the first segment has a larger diameter, which effectively improves the Raman threshold and ensures beam quality; the second segment has a smaller diameter, which ensures high brightness of the output laser; in addition, the side core can couple higher-order modes in the main core to the side core, and the energy of the higher-order modes is radiated out of the power transmission fiber due to bending loss caused by the spiral structure of the side core, while the lower-order modes are retained in the main core, effectively reducing the impact of higher-order modes on beam quality and reducing the pressure on the second segment caused by higher-order modes generated by mode field adaptation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of an embodiment of the power transmission optical fiber of this utility model;

[0020] Figure 2 This is a schematic diagram of another embodiment of the power transmission optical fiber of this utility model;

[0021] Figure 3 This is a cross-sectional view of the power transmission optical fiber of this utility model;

[0022] Figure 4 This is a schematic diagram of the structure of an embodiment of the laser of this utility model.

[0023] Explanation of icon numbers:

[0024] 100mm power transmission fiber;

[0025] Main fiber core 10, first section 11, first transition section 13, second section 15, third section 17, second transition section 19;

[0026] Side fiber core 20;

[0027] Double-layered 30;

[0028] Laser 1000;

[0029] High-reflectivity grating 200, active fiber 300, low-reflectivity grating 400, reverse pump combiner 500, reverse pump source 600, cladding power stripper 700.

[0030] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0033] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0034] It should be understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0036] Please see Figure 1 This utility model provides a power transmission optical fiber 100, including a main fiber core 10 and side fiber cores 20. The main fiber core 10 includes a first segment 11, a first transition segment 13, and a second segment 15. The diameter of the first segment 11 is larger than the diameter of the second segment 15. The first transition segment 13 connects the first segment 11 and the second segment 15. The side fiber cores 20 are periodically spirally arranged around the main fiber core 10.

[0037] In this embodiment of the invention, since the first segment 11 has a larger diameter, it can effectively improve the Raman threshold and ensure beam quality; while the second segment 15 has a smaller diameter, ensuring high brightness of the output laser; in addition, the side core 20 can couple the higher-order modes in the main core 10 to the side core 20, and the energy of the higher-order modes is radiated out of the power transmission fiber 100 due to the bending loss generated by the spiral structure of the side core 20, while the lower-order modes are retained in the main core 10, effectively reducing the influence of higher-order modes on beam quality, and also reducing the pressure on the first transition segment 13 caused by higher-order modes generated by mode field adaptation.

[0038] Specifically, the brightness (B) of a beam is defined as the beam power (P) per unit area (A) and per unit solid angle (Ω), which can be expressed by the formula:

[0039]

[0040] Where r is the fiber core radius and NA is the fiber numerical aperture. Therefore, it can be seen that by reducing the fiber core radius, the beam brightness can be increased, thus achieving higher processing quality.

[0041] Specifically, the Raman threshold power generated when laser light propagates in an optical fiber can be expressed as:

[0042]

[0043] Among them, A eff g is the effective mode area of ​​the optical fiber. R (Ω) is the Raman gain coefficient of the optical fiber, L eff The effective length of the optical fiber is denoted as . The effective mode field area can be increased by increasing the core area, thereby raising the Raman threshold and reducing the impact of stimulated Raman scattering on the laser power.

[0044] As can be seen from the above, increasing the beam brightness requires reducing the fiber core radius, while increasing the Raman threshold requires increasing the fiber core radius. Therefore, this application proposes a power transmission fiber 100. When the first segment 11 transmits the beam, the larger radius of the first segment 11 effectively increases the Raman threshold. When the second segment 15 is about to output the beam, the core radius is reduced to increase the beam brightness. It is understood that the first transition segment 13 is used to connect the first segment 11 and the second segment 15 to connect fiber cores with different radii. It is also understood that when the beam passes through the first transition segment 13, mode field mismatch will generate higher-order modes, which may cause the first transition segment 13 to have a high temperature and affect the beam quality, thus affecting the reliability of the power transmission fiber 100. Therefore, this application surrounds the main fiber core 10 with side fiber cores 20 to eliminate the influence of higher-order modes and ensure the beam output quality.

[0045] Understandably, the first transition segment 13 is used to connect and transition the first segment 11 and the second segment 15, with the diameter of the first segment 11 and the diameter of the second segment 15 as the upper and lower limits of the diameter range.

[0046] Understandably, along the direction of light propagation, the first segment 11, the first transition segment 13, and the second segment 15 are set sequentially.

[0047] It is worth noting that there are many ways to manufacture the main fiber core 10. It can be drawn as an integral preform or drawn by tapering a thick optical fiber. This application does not impose any specific restrictions.

[0048] It is understandable that the cross-sectional shape of the main fiber core 10 can be many, such as circular, polygonal, elliptical, semi-circular, etc. This application does not impose any specific restrictions.

[0049] In this utility model embodiment, the transmission modes of the main fiber core 10 and the side fiber core 20 meet the quasi-phase matching condition, which is:

[0050]

[0051] Wherein, β0 represents the beam propagation constant within the main fiber core 10, β1 represents the beam propagation constant within the side fiber core 20, h represents the center distance between the side fiber core 20 and the main fiber core 10, p represents the axial spiral period of the side fiber core 20, and l represents the azimuth order of a specific mode of the main fiber core 10.

[0052] In this way, the modes in the main fiber core 10 and the side fiber core 20 can be coupled together, so that the higher-order modes in the main fiber core 10 can be coupled into the measurement core, thereby reducing the impact of higher-order modes on beam quality.

[0053] In the embodiment of the utility model, the diameter of the first segment 11 is greater than or equal to 25 μm.

[0054] This ensures a high Raman threshold to accommodate long-distance beam transmission.

[0055] Furthermore, the diameter of the second segment 15 is less than or equal to 20 μm.

[0056] Thus, the smaller core diameter ensures high brightness of the output laser.

[0057] Please see Figure 2 In the utility model embodiment, the main fiber core 10 further includes a third segment 17 and a second transition segment 19. The second transition segment 19 connects the third segment 17 and the first segment 11. The diameter of the first segment 11 is larger than the diameter of the third segment 17.

[0058] Thus, the third segment 17 can be connected to the device that inputs the beam. After the beam is input through the third segment 17, it passes through the second transition segment 19 with a gradually increasing diameter and reaches the first segment 11 with a larger diameter. The Raman threshold gradually increases to ensure the quality of beam transmission.

[0059] Understandably, the second transition segment 19 is used to transition and connect the third segment 17 and the first segment 11, and the diameter range of the second transition segment 19 is limited by the diameter of the first segment 11 and the diameter of the third segment 17.

[0060] Understandably, the diameter of the optical fiber of the device that inputs the beam may not correspond to the diameter of the first segment 11. Therefore, a third segment 17 that corresponds to the diameter of the light beam of the device that inputs the beam is set up to facilitate connection and input of the beam. After the beam is input, it is then transitioned to the first segment 11 through the second transition segment 19 and transmitted in the first segment 11 with a larger diameter to achieve a better beam transmission effect.

[0061] It is understandable that the length of the second transition segment 19 can be equal to the length of the first transition segment 13, or the length of the second transition segment 19 can be different from that of the first transition segment 13. The length of the first transition segment 13 and the length of the second transition segment 19 can be adjusted according to factors such as the diameter of the first segment 11, the diameter of the second segment 15, or the diameter of the third segment 17. This application does not impose specific restrictions.

[0062] Furthermore, the diameter of the third segment 17 is greater than or equal to 20 μm.

[0063] This ensures that the laser in the third segment 17 has a high Raman suppression ratio.

[0064] Please see Figures 1 to 3 In the utility model embodiment, the power transmission optical fiber 100 further includes a double cladding 30, with the main fiber core 10 and the side fiber core 20 both disposed within the double cladding 30.

[0065] Thus, the double cladding 30 can block the light beam in the main fiber core 10 and the side fiber core 20, ensuring the light beam transmission of the main fiber core 10. In addition, the double cladding 30 can still ensure the light beam transmission in the main fiber core 10 when the single cladding is damaged, improving fault tolerance and ensuring the light beam transmission.

[0066] It is understood that in other embodiments of this utility model, the power transmission optical fiber 100 may also include single cladding, triple cladding, multi-cladding, etc., which will not be described in detail in this application.

[0067] It is understandable that the cross-section of the double cladding 30 can be circular, polygonal, elliptical, semi-circular, etc., and this application does not impose specific restrictions.

[0068] Furthermore, the ratio of the diameter of the double cladding 30 located around the first segment 11 to the diameter of the double cladding 30 located around the second segment 15 is the same as the ratio of the diameter of the first segment 11 to the diameter of the second segment 15.

[0069] This makes it convenient to process the cladding and the main fiber core 10 together, reducing processing costs.

[0070] This utility model embodiment also provides a laser 1000, which includes a power transmission fiber 100. The specific structure of the power transmission fiber 100 is as described in the above embodiments. Since this laser 1000 adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0071] In this embodiment of the invention, the laser 1000 has a larger diameter in the first segment 11, which effectively increases the Raman threshold and ensures beam quality. The smaller diameter in the second segment 15 ensures high brightness of the output laser. Furthermore, the side fiber core 20 can couple higher-order modes from the main fiber core 10 into the side fiber core 20. The energy of the higher-order modes is radiated out of the power transmission fiber 100 due to bending losses caused by the spiral structure of the side fiber core 20, while the lower-order modes are retained in the main fiber core 10. This effectively reduces the impact of higher-order modes on beam quality and also reduces the pressure on the second segment 15 caused by higher-order modes generated by mode field adaptation.

[0072] For details, please refer to Figure 4 In one embodiment, the laser 1000 further includes a high-reflectivity grating 200, an active fiber 300, a low-reflectivity grating 400, a reverse pump combiner 500, and a cladding power stripper 700 connected in sequence. The laser 1000 also includes a reverse pump source 600 connected to the reverse pump combiner 500, and the cladding power stripper 700 is connected to the power transmission fiber 100.

[0073] This utility model embodiment also provides a processing device, which includes a laser 1000. The specific structure of the laser 1000 is as described in the above embodiments. Since this processing device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0074] In the processing equipment of this utility model embodiment, since the first segment 11 has a larger diameter, it can effectively improve the Raman threshold and ensure the beam quality; while the second segment 15 has a smaller diameter, ensuring the high brightness of the output laser; in addition, the side fiber core 20 can couple the higher-order modes in the main fiber core 10 into the side fiber core 20, and the energy of the higher-order modes is radiated out of the power transmission fiber 100 due to the bending loss generated by the spiral structure of the side fiber core 20, while the lower-order modes are retained in the main fiber core 10, effectively reducing the influence of higher-order modes on the beam quality, and also reducing the pressure on the second segment 15 caused by higher-order modes generated by mode field adaptation.

[0075] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A power transmission optical fiber, characterized in that, include: The main fiber core includes a first segment, a first transition segment, and a second segment. The diameter of the first segment is larger than the diameter of the second segment, and the first transition segment connects the first segment and the second segment. Side fiber cores are arranged in a periodic spiral around the main fiber core.

2. The power transmission optical fiber as described in claim 1, characterized in that, The transmission modes of the main fiber core and the side fiber core meet the quasi-phase matching condition, which is: Wherein, β0 represents the beam propagation constant within the main fiber core, β1 represents the beam propagation constant within the side fiber core, h represents the center distance between the side fiber core and the main fiber core, p represents the axial helical period of the side fiber core, and represents the azimuth order of a specific mode of the main fiber core.

3. The power transmission optical fiber as described in claim 1, characterized in that, The diameter of the first segment is greater than or equal to 25 μm.

4. The power transmission optical fiber as described in claim 3, characterized in that, The diameter of the second segment is less than or equal to 20 μm.

5. The power transmission optical fiber as described in claim 1, characterized in that, The main fiber core also includes a third segment and a second transition segment, the second transition segment connecting the third segment and the first segment, and the diameter of the first segment being larger than the diameter of the third segment.

6. The power transmission optical fiber as described in claim 5, characterized in that, The diameter of the third segment is greater than or equal to 20 μm.

7. The power transmission optical fiber as described in claim 1, characterized in that, The power transmission optical fiber also includes a double cladding, with both the main fiber core and the side fiber core disposed within the double cladding.

8. The power transmission optical fiber as described in claim 7, characterized in that, The ratio of the diameter of the double cladding layer at the periphery of the first segment to the diameter of the double cladding layer at the periphery of the second segment is the same as the ratio of the diameter of the first segment to the diameter of the second segment.

9. A laser, characterized in that, Including the power transmission optical fiber as described in any one of claims 1 to 8.

10. A processing device, characterized in that, Including the laser as described in claim 9.

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