Single-mode annular light spot transmission optical fiber
By optimizing the design of the fiber core and cladding, efficient single-mode conversion from Gaussian beam to annular spot was achieved, solving the single-mode and insertion loss problems of annular spot in the prior art, and improving the transmission efficiency and reliability of optical fiber.
Patent Information
- Application Number
- CN202511869614.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-11
- Publication Date
- 2026-01-20
AI Technical Summary
In existing technologies, annular light spots are difficult to achieve single-mode performance, have complex structures, and high insertion loss, resulting in insufficient applicability and reliability in special application fields such as 3D printing.
A single-mode annular spot transmission fiber was designed. By optimizing the geometry and refractive index distribution of the core and cladding, the efficient conversion of Gaussian beams to annular spots is achieved, reducing fusion splicing loss and ensuring single-mode output.
It achieves efficient single-mode conversion of the beam, reduces the risk of fiber failure, simplifies the structure and improves transmission efficiency, and meets the needs of special applications such as 3D printing.
Smart Images
Figure CN121364526A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of optical fiber technology, in particular to a single-mode annular spot transmission optical fiber. BACKGROUND
[0002] The annular spot is different from the conventional Gaussian spot, especially the single-mode annular spot, which takes into account both the annular shape and the single-mode property of the spot, and has broad application prospects in special application fields such as laser 3D printing and laser welding, and is a key research direction of laser beam shaping.
[0003] The annular spot of the prior art mainly has the following defects: (1) Single-mode property is difficult to achieve: in the prior art, the annular spot is mainly achieved by multi-laser beam combining, injection into the annular region of the transmission optical fiber, and in order to reduce the fusion loss, the width of the annular region is relatively wide, and the numerical aperture (Numerical Aperture; abbreviated as: NA) is not specially designed, and the output light is usually in a multi-mode form, which is not suitable for special application fields such as 3D printing; (2) Complex structure: multi-laser beam combining is required, and then the subsequent point-ring transmission optical fiber is fused by means of tapering, which has many devices and is not easy to integrate, and the engineering implementation and mass application are difficult; (3) High insertion loss: the annular optical fiber is directly fused with the Gaussian-type input optical fiber, and the loss caused by mode matching at the fusion point is large, which easily causes heating and even ablation at the fusion point, resulting in failure of the optical fiber. SUMMARY
[0004] The present application provides a single-mode annular spot transmission optical fiber to solve the defects of the prior art, such as the difficulty in achieving single-mode property, complex structure, and high insertion loss.
[0005] The present application provides a single-mode annular spot transmission optical fiber, comprising: a core with a radius R1 and a refractive index n1, wherein 3pm≤R1≤5pm; a first cladding with a radius R2 and a refractive index n2, wherein 10pm≤R2≤15pm; a second cladding with a radius R3 and a refractive index n3, wherein 20pm≤R3≤40pm; a third cladding with a refractive index n4; an inner coating layer with a refractive index n5; an outer coating layer with a refractive index n6; The core, the first cladding, the second cladding, the third cladding, the inner coating layer and the outer coating layer are sequentially nested from inside to outside, and n5 n3 n1 n4 n2 n6.
[0006] The single-mode annular light spot transmission optical fiber provided by the application is characterized in that the fiber core, the first cladding layer, the second cladding layer, the third cladding layer, the inner coating layer and the outer coating layer are sequentially nested with the same circular center.
[0007] The single-mode annular light spot transmission optical fiber provided by the application is characterized in that the fiber core, the second cladding layer and the third cladding layer are all fluorine-doped silica glass.
[0008] The single-mode annular light spot transmission optical fiber provided by the application is characterized in that the fluorine content in the fiber core is in the range of 1.12mol% to 1.53mol%; the fluorine content in the second cladding layer is in the range of 1.53mol% to 2.0mol%; and the fluorine content in the third cladding layer is in the range of 0.78mol% to 1.12mol%.
[0009] The single-mode annular light spot transmission optical fiber provided by the application is characterized in that the first cladding layer is pure silica glass.
[0010] The single-mode annular light spot transmission optical fiber provided by the application is characterized in that the inner coating layer and the outer coating layer are both polyacrylic resin.
[0011] The single-mode annular light spot transmission optical fiber provided by the application is characterized in that the refractive indexes of the fiber core and the first cladding layer satisfy the following relationship: 0.06≤ ≤0.07 The single-mode annular light spot transmission optical fiber provided by the application is characterized in that the refractive indexes of the first cladding layer and the second cladding layer satisfy the following relationship: 0.07≤ ≤0.08.
[0012] The single-mode annular light spot transmission optical fiber provided by the application is characterized in that the refractive indexes of the first cladding layer and the third cladding layer satisfy the following relationship: 0.05≤ ≤0.06.
[0013] The single-mode annular light spot transmission optical fiber provided by the application is characterized in that the input light spot pattern of the single-mode annular light spot transmission optical fiber is Gaussian distribution, and the output light spot is an annular light spot.
[0014] This invention provides a single-mode annular spot transmission optical fiber, comprising: a fiber core, a first cladding, a second cladding, a third cladding, an inner coating, and an outer coating. The fiber core has a radius of R1, where 3μm ≤ R1 ≤ 5μm, and a refractive index of n1; the first cladding has a radius of R2, where 10μm ≤ R2 ≤ 15μm, and a refractive index of n2; the second cladding has a radius of R3, where 20μm ≤ R3 ≤ 40μm, and a refractive index of n3; the third cladding has a refractive index of n4; the inner coating has a refractive index of n5; and the outer coating has a refractive index of n6. The fiber core, first cladding, second cladding, third cladding, inner coating, and outer coating are nested sequentially from the inside out, and n5 < n3 < n1 < n4 < n2 < n6. The single-mode ring spot transmission fiber provided by this invention has the following advantages: 1. Simple structure: Gaussian beam to ring spot conversion is achieved through a single transmission fiber; 2. High transmission efficiency: High coupling efficiency transmission of Gaussian beam to ring spot is achieved through the refractive index gradient design at the fiber core, reducing the risk of fiber failure; 3. Single-mode ring spot transmission is realized to meet the needs of different fields. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in this invention 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0016] Figure 1 This is an axial cross-sectional view of a single-mode annular spot transmission optical fiber provided in one embodiment of the present invention.
[0017] Figure 2 This is a refractive index distribution diagram of a single-mode annular spot transmission optical fiber provided in one embodiment of the present invention.
[0018] Figure 3 This is a simulated output light spot diagram provided in one embodiment of the present invention.
[0019] Figure label: 1. Core; 2. First cladding; 3. Second cladding; 4. Third cladding; 5. Inner coating; 6. Outer coating. Detailed Implementation
[0020] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below with reference to the drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based upon the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall into the scope of the present application.
[0021] In the description of the present embodiments, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present embodiments and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be understood as a limitation on the present embodiments.
[0022] In addition, the terms "first", "second" are only used for descriptive purposes, and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present embodiments, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.
[0023] In the present embodiments, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection", "connection", "fixation" and the like should be understood broadly, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present embodiments can be understood according to the specific circumstances.
[0024] In the embodiments of the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be "above", "over" and "on" the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only means that the first feature is higher in horizontal height than the second feature. The first feature can be "under", "below" and "under" the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only means that the first feature is lower in horizontal height than the second feature.
[0025] The prior art annular light spot mainly has the following defects: (1) Single mode is difficult to achieve: in the prior art, the annular light spot is mainly realized by multi-laser beam combining, injection into the annular region of the transmission optical fiber, and in order to reduce the fusion loss, the width of the annular region is relatively wide, and the numerical aperture (Numerical Aperture; abbreviated: NA) is not specially designed, and the output light is usually in a multi-mode form, which is not suitable for special application fields such as 3D printing; (2) Complex structure: multi-laser beam combining is needed, and then the subsequent point-ring transmission optical fiber is fused by means of tapering, etc., which has many devices and is not easy to integrate, and the engineering implementation difficulty and large-scale application difficulty are relatively large; (3) High insertion loss: the mode matching at the fusion point causes large loss, which easily causes the fusion point to heat and even ablate, resulting in optical fiber failure.
[0026] In view of the deficiencies of the prior art, the present application provides a single-mode annular light spot transmission optical fiber, which mainly uses the special design of the NA and geometric size of the core region and each cladding region to meet the direct end face fusion of the conventional transmission optical fiber and the annular light spot transmission optical fiber, reduce the fusion loss, improve the transmission efficiency, and reduce the risk of optical fiber failure. In addition, the output annular light spot is single-mode, has high beam quality, and meets the special application requirements of 3D printing.
[0027] The present application is described below in conjunction with Figure 1 and Figure 2 A single-mode annular light spot transmission optical fiber is described. The single-mode annular light spot transmission optical fiber comprises a core 1, a first cladding 2, a second cladding 3, a third cladding 4, an inner coating 5, and an outer coating 6.
[0028] Wherein, the core 1 is provided with a radius R1 and 3 μm≤R1≤5 μm, and a refractive index n1; the first cladding 2 is provided with a radius R2 and 10 μm≤R2≤15 μm, and a refractive index n2; the second cladding 3 is provided with a radius R3 and 20 μm≤R3≤40 μm, and a refractive index n3; the third cladding 4 is provided with a refractive index n4; the inner coating 5 is provided with a refractive index n5; and the outer coating 6 is provided with a refractive index n6.
[0029] Specifically, the core 1, the first cladding 2, the second cladding 3, the third cladding 4, the inner coating 5 and the outer coating 6 are sequentially nested from inside to outside, and n5
[0030] Generally, without special treatment such as beam shaping, the output spot of the fiber laser is Gaussian distribution, especially for single-mode fiber laser, the main feature of the Gaussian distribution spot is that the energy is basically concentrated in the middle area, that is, the light energy within the mode field diameter accounts for 80% or even higher of the total energy, while the main feature of the ring-shaped spot is that the energy is mainly concentrated in the ring-shaped area, and the central area has lower energy.
[0031] The implementation of beam shaping is generally to fuse the output fiber of the fiber laser (generally the output tail fiber of the cladding light stripper) with a beam shaping optical fiber, and the requirement of the present application is to fuse the ring-shaped spot output fiber, the angle of beam transmission, after fusing the ring-shaped spot transmission fiber, the beam enters the ring-shaped spot transmission fiber from the output fiber through the fusion point, and then is transmitted to the next optical device after passing through the ring-shaped spot output fiber.
[0032] In the above fusion point, that is, in the process of beam transmission from the output fiber of the laser to the ring-shaped spot, the coupling efficiency of energy is mainly reflected in the matching efficiency, and the matching mainly includes mode field matching and phase matching, wherein the mode field matching mainly investigates the size of the overlapping area of the mode field of the light mode on the left and right of the fusion point, and the phase matching mainly investigates the difference of the effective refractive index of each mode supported by the fiber.
[0033] The present application adopts the design of optimized refractive index to ensure Gaussian spot injection, and the single-mode ring-shaped spot transmission fiber of the present application outputs a ring-shaped spot, the refractive index of the core 1 region is slightly lower than that of the first cladding 2, so as to ensure that the coupling efficiency at the fusion point reaches a high state, greatly reduces the fusion loss caused by the matching of the two types of fibers, and then reduces the fusion point temperature, improves the fiber reliability, in addition, the difference between the refractive index of the first cladding 2 and the refractive index of the third cladding 4 meets certain requirements, and the single-mode ring-shaped spot output is realized.
[0034] The single-mode annular light spot transmission optical fiber provided by the application comprises a fiber core 1, a first cladding layer 2, a second cladding layer 3, a third cladding layer 4, an inner coating layer 5 and an outer coating layer 6. The fiber core 1 has a radius R1 and a refractive index n1, and 3 μm≤R1≤5 μm. The first cladding layer 2 has a radius R2 and a refractive index n2, and 10 μm≤R2≤15 μm. The second cladding layer 3 has a radius R3 and a refractive index n3, and 20 μm≤R3≤40 μm. The third cladding layer 4 has a refractive index n4. The inner coating layer 5 has a refractive index n5. The outer coating layer 6 has a refractive index n6. The fiber core 1, the first cladding layer 2, the second cladding layer 3, the third cladding layer 4, the inner coating layer 5 and the outer coating layer 6 are sequentially nested from inside to outside, and n5
[0035] In one of the embodiments of the application, the fiber core 1, the first cladding layer 2, the second cladding layer 3, the third cladding layer 4, the inner coating layer 5 and the outer coating layer 6 are sequentially nested with the same circle as the center, that is, the fiber core 1, the first cladding layer 2, the second cladding layer 3, the third cladding layer 4, the inner coating layer 5 and the outer coating layer 6 are sequentially nested from inside to outside in the form of concentric circles.
[0036] In one of the embodiments of the application, the fiber core 1, the second cladding layer 3 and the third cladding layer 4 are all fluorine-doped silica glass.
[0037] In one of the embodiments of the application, the fluorine content in the fiber core 1 is in the range of 1.12 mol% to 1.53 mol%, the fluorine content in the second cladding layer 3 is in the range of 1.53 mol% to 2.0 mol%, and the fluorine content in the third cladding layer 4 is in the range of 0.78 mol% to 1.12 mol%.
[0038] In one of the embodiments of the application, the first cladding layer 2 is pure silica glass.
[0039] In one of the embodiments of the application, the inner coating layer 5 and the outer coating layer 6 are both polyacrylic acid resin.
[0040] In one of the embodiments of the application, the refractive indices of the fiber core 1 and the first cladding layer 2 satisfy the following relationship: 0.06≤ ≤0.07 In one of the embodiments of the application, the refractive indices of the first cladding layer 2 and the second cladding layer 3 satisfy the following relationship: 0.07≤ ≤0.08.
[0041] In one embodiment of the present application, the refractive indexes of the first cladding 2 and the third cladding 4 satisfy the following relationship: 0.05≤ ≤0.06.
[0042] In one embodiment of the present application, the input spot of the single-mode annular spot transmission fiber is Gaussian distribution, and the output spot is annular spot. According to the waveguide theory, the main energy of the annular spot is concentrated in the annular region between the radii R1 and R2, realizing annular spot transmission and single mode.
[0043] The present application provides one embodiment, the size and refractive index of which are as follows: The core 1, the second cladding 3 and the third cladding 4 all use fluorine-doped silica glass; wherein the fluorine content of the core 1 is 1.25mol%, the fluorine content of the second cladding 3 is 1.85mol%, and the fluorine content of the third cladding 4 is 0.95mol%. The first cladding 2 uses pure silica glass. The inner coating 5 and the outer coating 6 both use polyacrylic resin.
[0044] R1=4μm, R2=12μm, R3=30μm, R4=200μm, R5=250μm, R6=275μm; n1=1.4487, n2=1.4497, n3=1.4479, n4=1.4488, n5=1.3605, n6=1.5301.
[0045] According to the above parameter setting, fiber simulation is carried out, and under the condition of Gaussian light at the input end, the output spot is as shown in the figure Figure 3 The spot energy is mainly concentrated in the annular region with a radius of 4μm~12μm, realizing annular spot output.
[0046] The apparatus embodiments described above are only schematic, wherein the units shown as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. can be located in one place or distributed on multiple units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment scheme. Those skilled in the art can understand and implement without creative labor.
[0047] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. A single mode ring shaped spot transmission optical fiber, characterized in that, It comprises: a fiber core (1) with a radius R1 and 3 μm≤R1≤5 μm and a refractive index n1; a first cladding layer (2) with a radius R2 and 10 μm≤R2≤15 μm and a refractive index n2; a second cladding layer (3) with a radius R3 and 20 μm≤R3≤40 μm and a refractive index n3; a third cladding layer (4) with a refractive index n4; an inner coating layer (5) with a refractive index n5; an outer coating layer (6) with a refractive index n6; The fiber core (1), the first cladding layer (2), the second cladding layer (3), the third cladding layer (4), the inner coating layer (5) and the outer coating layer (6) are sequentially nested from inside to outside, and n5<n3<n1<n4<n2<n6.
2. The single-mode ring-fiber of claim 1, wherein, The fiber core (1), the first cladding layer (2), the second cladding layer (3), the third cladding layer (4), the inner coating layer (5) and the outer coating layer (6) are sequentially nested with the same circular center.
3. The single-mode ring-fiber of claim 1, wherein, The fiber core (1), the second cladding layer (3) and the third cladding layer (4) are all fluorine-doped silica glass.
4. The single-mode ring-fiber of claim 2, wherein, The fluorine content in the fiber core (1) is in the range of 1.12 mol% to 1.53 mol%, the fluorine content in the second cladding layer (3) is in the range of 1.53 mol% to 2.0 mol%, and the fluorine content in the third cladding layer (4) is in the range of 0.78 mol% to 1.12 mol%.
5. The single-mode ring-fiber of claim 1 wherein, The first cladding layer (2) is silica glass.
6. The single-mode ring-fiber of claim 1 wherein, The inner coating layer (5) and the outer coating layer (6) are both polyacrylic resin.
7. The single-mode ring-fiber of claim 1 wherein, The refractive indices of the fiber core (1) and the first cladding layer (2) satisfy the following relationship: 0.06≤ ≤0.07。 8. The single-mode ring-fiber of claim 1 wherein, The refractive indices of the first cladding layer (2) and the second cladding layer (3) satisfy the following relationship: 0.07≤ ≤0.08。 9. The single-mode ring-fiber of claim 1 wherein, The refractive indices of the first cladding layer (2) and the third cladding layer (4) satisfy the following relationship: 0.05≤ ≤0.06。 10. The single-mode ring-fiber of any of claims 1 to 9, wherein, The input spot pattern of the single-mode annular spot transmission optical fiber is Gaussian distribution, and the output spot is annular spot.