Optical combiner and laser device
By designing a structure in the optical combiner where the outer cladding layer of the output fiber is smaller than that of the input fiber cladding layer, the problem of fiber fusion splicing is solved, enabling easy fiber fusion splicing and efficient beam coupling.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FUJIKURA LTD
- Filing Date
- 2021-02-19
- Publication Date
- 2026-06-05
AI Technical Summary
Existing optical combiners suffer from uneven fiber softening when splicing input and output fibers, making splicing difficult, especially when there are gaps between the input fibers.
An optical combiner was designed in which the outer diameter of the outer cladding layer of the output fiber is smaller than the cladding diameter of the input fiber, and they are connected by optical coupling to reduce the heating requirement of the output fiber and simplify the fusion splicing process.
This technology facilitates easy fusion splicing of optical fibers, reduces heat requirements during splicing, minimizes the risk of beam quality degradation, and improves splicing efficiency and beam coupling efficiency.
Smart Images
Figure CN115698794B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to optical combiners and laser devices, and more particularly to optical combiners that couple and output optical signals propagating in multiple optical fibers. Background Technology
[0002] Optical combiners are widely used to couple lasers from multiple light sources to obtain high-power lasers. One known optical combiner is one that combines multiple fiber bundles on the input side with a large-diameter fiber fused to the output side (see, for example, Patent Document 1). In this optical combiner, to ensure efficient propagation of light from the input fiber to the output fiber, the outer diameter of the output fiber is typically larger than the diameter of the input fiber bundle.
[0003] For such optical combiners, there is a tendency that when splicing the input-side fiber bundle and the output-side fiber, if both are heated under the same conditions, the input-side fiber will soften and melt before the output-side fiber. This tendency is further amplified when gaps exist between the input-side fibers before the splicing process. Therefore, when splicing these fibers, measures such as heating the output-side fiber more intensely than the input-side fiber are required, making fiber splicing difficult.
[0004] Existing technical documents
[0005] Patent documents
[0006] Patent Document 1: US Patent No. 9,620,925 Summary of the Invention
[0007] (a) Technical problems to be solved
[0008] The present invention addresses the problems of the prior art and aims to provide an optical combiner capable of easily performing the fusion process of an input-side optical component and an output-side optical component, as well as a laser device comprising such an optical combiner.
[0009] (II) Technical Solution
[0010] According to a first aspect of the present invention, an optical combiner is provided that enables easy fusion of optical components on the input side and optical components on the output side. The optical combiner includes: a plurality of first optical input sections, each having a first input optical waveguide; and an optical output section connected to the plurality of first optical input sections. The optical output section includes: at least one fiber core for propagating light, and an outermost cladding layer having a refractive index lower than that of the at least one fiber core and located outside the at least one fiber core. The plurality of first optical input sections are optically coupled to a connection end face of the optical output section via the first input optical waveguide of at least one of the plurality of first optical input sections and the at least one fiber core of the optical output section. The outer diameter of the outermost cladding layer on the connection end face of the optical output section is smaller than the diameter of the smallest encompassing circle covering all the plurality of first optical input sections on the connection end face of the optical output section. In this specification, the circle circumscribed to one or more elements X and the smallest containing circle that includes all of the elements X have the same meaning, referring to the circle with the smallest diameter among the circles that completely encompass the region of one or more elements X.
[0011] According to a second aspect of the present invention, a laser device is provided that enables easy fusion processing of an input-side optical component and an output-side optical component. The laser device includes: a plurality of laser sources for generating laser light, and the aforementioned optical combiner. The first input waveguides of the plurality of first optical input sections of the optical combiner are optically coupled to the plurality of laser sources. Attached Figure Description
[0012] Figure 1 This is a block diagram illustrating the structure of a laser device according to the first embodiment of the present invention.
[0013] Figure 2 It is Figure 1 The figure shows the cross-section of the output fiber of the laser device and its refractive index distribution along the radial direction.
[0014] Figure 3 It means Figure 1 A three-dimensional view of the optical combiner of the laser device shown.
[0015] Figure 4 yes Figure 3 An exploded 3D view of the optical combiner shown.
[0016] Figure 5 It means Figure 3 A cross-sectional view of the downstream end of the optical input section of the optical combiner shown.
[0017] Figure 6 It is a schematic representation Figure 3The diagram shows the connection relationship between the connection end of the optical input section and the connection end face of the optical output section of the optical combiner.
[0018] Figure 7 It is a schematic representation Figure 5 The diagram shows the optical input section.
[0019] Figure 8 This is a perspective view showing the optical combiner according to the second embodiment of the present invention.
[0020] Figure 9 yes Figure 8 An exploded 3D view of the optical combiner shown.
[0021] Figure 10 This is a block diagram illustrating the structure of a laser device according to a third embodiment of the present invention.
[0022] Figure 11 It means Figure 10 A three-dimensional view of the optical combiner of the laser device shown.
[0023] Figure 12 yes Figure 11 An exploded 3D view of the optical combiner shown. Detailed Implementation
[0024] The following is for reference Figures 1 to 12 Embodiments of a laser device incorporating the optical combiner of the present invention will be described in detail. Figures 1 to 12 In this context, identical or equivalent constituent elements are given the same reference numerals, and redundant descriptions are omitted. Additionally, Figures 1 to 12 There are instances where the scale or dimensions of each component are exaggerated, and instances where some components are omitted. In the following description, unless otherwise specified, terms such as "first" and "second" are used only to distinguish the components from each other, and do not indicate a specific order or sequence.
[0025] Figure 1 This is a block diagram schematically illustrating the structure of the laser device 1 according to the first embodiment of the present invention. For example... Figure 1As shown, the laser apparatus 1 of this embodiment includes: a laser source 2 for generating laser light; an optical fiber 10 connected to the laser source 2; multiple laser sources 3 for generating laser light; an optical fiber 20 connected to the laser source 3; an output optical fiber 30 connecting the optical fibers 10 and 20; an optical combiner 40 that couples the laser light propagating in the optical fibers 10 and 20 and guides it into the output optical fiber 30; a laser emission section 4 provided at the end of the output optical fiber 30; a control section 5 for controlling the laser sources 2 and 3; and a stage 6 for holding the workpiece W. For example, fiber lasers and semiconductor lasers can be used as the laser sources 2 and 3. Furthermore, in the following embodiments, unless otherwise specified, the direction from the laser sources 2 and 3 toward the laser emission section 4 is referred to as the "downstream side," and the opposite direction is referred to as the "upstream side."
[0026] Figure 2 This is a diagram that shows the cross-section of the output fiber 30 together with its refractive index distribution along the radial direction. For example... Figure 2 As shown, the output optical fiber 30 has: a central core 31 (first core); an inner cladding 32 (first cladding) covering the periphery of the central core 31; an annular core 33 (second core) covering the periphery of the inner cladding 32; and an outer cladding 34 (second cladding) covering the periphery of the annular core 33.
[0027] The refractive index of the inner cladding 32 is lower than that of the central fiber core 31 and the annular fiber core 33, and the refractive index of the outer cladding 34 is lower than that of the annular fiber core 33. Thus, optical waveguides for propagating light are formed inside the central fiber core 31 and the annular fiber core 33, respectively. Therefore, in this embodiment, the independent optical waveguides, namely the central fiber core 31 and the annular fiber core 33, are concentrically arranged inside the output optical fiber 30. For example, the central fiber core 31 and the annular fiber core 33 can be formed using quartz glass (SiO2), and the inner cladding 32 and the outer cladding 34 can be formed by adding dopants (e.g., fluorine (F) or boron (B)) that have properties that lower the refractive index. Alternatively, the inner cladding 32 and the outer cladding 34 can also be formed using quartz glass (SiO2), and the central fiber core 31 and the annular fiber core 33 can be formed by adding dopants (e.g., germanium (Ge)) that have properties that increase the refractive index.
[0028] In this embodiment, the inner cladding 32 is located radially inside the outer cladding 34, which is the outermost cladding layer in the output optical fiber 30. Furthermore, the annular core 33, serving as the outermost fiber core, is adjacent to the inner side of the outer cladding 34. Additionally, the outer cladding 34 is surrounded by a coating, for example, made of resin. Figure 3 The attached figure (35) is covered, in Figure 2 The illustration of the skin covering is omitted in the text.
[0029] The outer diameters of the central core 31, inner cladding 32, annular core 33, and outer cladding 34 of the output fiber 30 are important factors determining the intensity distribution of the laser L emitted from the laser emission section 4, and can be appropriately set according to the application and output specifications of the laser device 1. In particular, in this embodiment, as explained later, the outer diameter of the outer cladding 34 is designed to facilitate the splicing of the fibers 10, 20, and output fiber 30. For example, the outer diameter of the central core 31 is 100 μm, the outer diameter of the inner cladding 32 (the inner diameter of the annular core 33) is 150 μm, the outer diameter of the annular core 33 is 300 μm, and the outer diameter of the outer cladding 34 is 330 μm. Furthermore, the refractive index of the inner cladding 32 and the refractive index of the outer cladding 34 can be the same or different.
[0030] Figure 3 This is a 3D diagram showing the optical combiner 40. Figure 4 It is an exploded 3D diagram. For example... Figure 3 and Figure 4 As shown, the optical combiner 40 of this embodiment includes: an optical input section 110 (first optical input section) which is composed of the downstream end of an optical fiber 10 extending from the laser source 2; a plurality of optical input sections 120 (first optical input sections) which are each composed of the downstream end of an optical fiber 20 extending from the laser source 3; and an optical output section 130 which is composed of the upstream end of an output optical fiber 30.
[0031] like Figure 3 and Figure 4 As shown, the optical fiber 10 constituting the optical input section 110 has a core 11 and a cladding 12 covering the core 11, the refractive index of which is lower than that of the core 11. For example, the core 11 can be formed using quartz glass (SiO2), and the cladding 12 can be formed by adding dopants (e.g., fluorine (F) or boron (B)) that have properties that lower the refractive index to the quartz glass. Alternatively, the cladding 12 can be formed using quartz glass (SiO2), and the core 11 can be formed by adding dopants (e.g., germanium (Ge)) that have properties that increase the refractive index. Thus, an optical waveguide (first input optical waveguide) for propagating light is formed inside the core 11 of the optical fiber 10. Therefore, the laser generated by the laser source 2 propagates inside the core 11 of the optical fiber 10. As an example, the outer diameter of the core 11 of the optical fiber 10 is 30 μm, and the outer diameter of the cladding 12 is 125 μm. Furthermore, for in Figure 3 and Figure 4 As shown in the part not shown, the cladding 12 of the optical fiber 10 is covered by a coating (not shown) made of, for example, resin.
[0032] Furthermore, the optical fiber 20 constituting the optical input section 120 has a core 21 and a cladding 22 covering the core 21, the refractive index of which is lower than that of the core 21. For example, the core 21 can be formed using quartz glass (SiO2), and the cladding 22 can be formed by adding dopants (e.g., fluorine (F) or boron (B)) that have properties that lower the refractive index to the quartz glass. Alternatively, the cladding 22 can be formed using quartz glass (SiO2), and the core 21 can be formed by adding dopants (e.g., germanium (Ge)) that have properties that increase the refractive index. Thus, an optical waveguide (first input optical waveguide) for propagating light is formed inside the core 21 of the optical fiber 20. Therefore, the laser generated by the laser source 3 propagates inside the core 21 of the optical fiber 20. As an example, the outer diameter of the core 21 of the optical fiber 20 is 30 μm, and the outer diameter of the cladding 22 is 125 μm. Furthermore, for in Figure 3 and Figure 4 As not shown, the cladding 22 of the optical fiber 20 is surrounded by a coating (not shown) made of, for example, resin. Furthermore, in this embodiment, optical fibers 10 and 20 are made of optical fibers with the same structure and size, but optical fibers 10 and 20 may also be made of different optical fibers.
[0033] like Figure 3 and Figure 4 As shown, in the optical output section 130, the upstream end of the cladding 35 surrounding the outer cladding 34 of the output optical fiber 30 is removed, exposing the outer cladding 34 to the outside. The aforementioned optical input sections 110 and 120 are fused to the exposed portion of the outer cladding 34. Specifically, the downstream end of the optical input section 110 (optical fiber 10) and the downstream end of the optical input section 120 (optical fiber 20) are fused to the upstream end face (connection end face) 135 of the optical output section 130, respectively.
[0034] Figure 5 This is a cross-sectional view showing the downstream end (connection end) of the light input sections 110 and 120 connected to the connection end face 135 of the light output section 130. (Example) Figure 5 As shown, at the connection ends of the optical input sections 110 and 120, six optical input sections 120 (fiber 20) are arranged outside one optical input section 110 (fiber 10) with equal distances from the center O2 of the fiber 10, and adjacent fibers 10 and 20 are in the closest possible contact state. Here, the connection ends of the optical input sections 110 and 120 are fused to the connection end face 135 of the optical output section 130 in the following manner: the center O2 of the centrally located fiber 10 is fused to the center O1 of the output fiber 30 (see reference). Figure 2 Consistent.
[0035] Figure 6This diagram schematically illustrates the connection relationship between the connection ends of the light input sections 110 and 120 and the connection end face 135 of the light output section 130. (See diagram below.) Figure 6 As shown, the region S1 (inner shaded area) of the central fiber core 31 of the light output section 130 is large enough to include the fiber core 11 of the centrally located light input section 110. Furthermore, the region S2 (outer shaded area) of the annular fiber core 33 of the light output section 130 is large enough to include all the fiber cores 21 of the six light input sections 120. The light input sections 110 and 120 are fused to the light output section 130 in such a way that the fiber core 11 of the light input section 110 is located within the region of the central fiber core 31 of the light output section 130, and all the fiber cores 21 of the light input sections 120 are located within the region of the annular fiber core 33 of the light output section 130.
[0036] According to this structure, the laser generated by the laser source 2 propagates inside the core 11 of the optical fiber 10, reaches the optical input section 110 of the optical combiner 40, and is incident on the central core 31 of the optical output section 130. The laser incident on the central core 31 of the optical output section 130 propagates inside the central core 31 of the output optical fiber 30 and, as part of the laser L, irradiates the workpiece W on the stage 6 from the laser emission section 4 (see reference). Figure 1 ).
[0037] Furthermore, the laser generated by the laser source 3 propagates inside the core 21 of the optical fiber 20, reaches the optical input section 120 of the optical combiner 40, and is incident on the annular core 33 of the optical output section 130. The laser incident on the annular core 33 of the optical output section 130 propagates inside the annular core 33 of the output optical fiber 30 and, as part of the laser L, irradiates the workpiece W on the stage 6 from the laser emission section 4 (see reference). Figure 1 ).
[0038] Thus, in the laser device 1 of this embodiment, laser L is irradiated from the laser emission section 4 toward the workpiece W on the stage 6. The laser L contains laser generated by laser source 2 on its central side and laser generated by laser source 3 on its outer side.
[0039] Here, as Figure 1As shown, a light removal section 7 is provided on the output optical fiber 30 between the optical combiner 40 and the laser emission section 4. The light removal section 7 is used to remove excess light (cladding mode light) leaking from the central core 31 or the ring core 33 of the output optical fiber 30 to the outer cladding 34. A known structure (cladding mode remover) can be used for this light removal section 7, so a detailed description is omitted. Since the unwanted light leaking from the central core 31 or the ring core 33 of the output optical fiber 30 to the outer cladding 34 can be removed using this light removal section 7, it is possible to suppress the adverse effects of this light on the laser L emitted from the laser emission section 4.
[0040] The control unit 5 can control the laser sources 2 and 3, for example, by controlling the current supplied to them. By controlling the laser sources 2 and 3 using the control unit 5, the power of the laser generated by the laser source 2 and the power of the laser generated by the laser source 3 can be changed. As a result, the power of the laser L output from the laser emission unit 4 of the laser device 1 at its center and at its outer edges can be adjusted, and the contour of the laser L can be easily changed.
[0041] Here, in the above example, the outer diameter D1 of the outer cladding 34 on the connection end face 135 of the light output section 130 (refer to...) Figure 2 The diameter is 330 μm, which is larger than the circle C1 (refer to) circumscribed in the cladding 22 of the light input section 120. Figure 7 The diameter of the outer cladding 34 (125μm × 3 = 375μm) is small. Thus, in the optical combiner 40 of this embodiment, the outer diameter D1 of the outer cladding 34 on the connection end face 135 of the light output section 130 (refer to...) is small. Figure 2 The smallest inclusion circle C1 of the cladding 22 that includes the entire optical input section 120 on the connection end face 135 of the optical output section 130 (refer to) Figure 7 The diameter of the light output section 130 is small. Therefore, the amount of heating required for the light output section 130 during the fusion bonding of the light input sections 110, 120 and the light output section 130 can be reduced. As a result, the necessity for measures such as heating the light output section 130 more vigorously than the light input sections 110, 120 and the light output section 130 is reduced, and the fusion bonding process of the light input sections 110, 120 and the light output section 130 is easier to perform.
[0042] Furthermore, in the event of overheating of the light input sections 110 and 120, the following situation needs to be considered: the refractive index distribution of the light input sections 110 and 120 near the fusion joint changes due to the diffusion of the dopant, resulting in changes in the beam quality of the laser output from the optical combiner 40 (e.g., the laser divergence angle, M). 2Beam quality degradation can occur due to factors such as beam ratio (BPP). In particular, the diameters of the fiber cores 11 and 21 of the optical input sections 110 and 120 are smaller than the diameters of the central fiber core 31 and the annular fiber core 33 of the optical output section 130. Therefore, the change in refractive index distribution caused by dopant diffusion due to heating is greater, easily leading to beam quality degradation. In this embodiment, since the outer diameter D1 of the outer cladding 34 of the optical output section 130 is smaller than the diameter of the circle C1 tangent to the cladding 22 of the optical input section 120, excessive heating of the optical input sections 110 and 120 is less likely, thus suppressing beam quality degradation of the laser beam output from the optical combiner 40.
[0043] Furthermore, since it is necessary to connect the fiber core 21 of the light input section 120 with the annular fiber core 33 of the light output section 130 in region S2 (refer to...) Figure 6 For optical coupling, the outer diameter of the annular fiber core 33 is larger than the diameter of the circle tangent to at least one of the fiber cores 21 of the light input section 120. Furthermore, the outer diameter D1 of the outer cladding 34 located outside the annular fiber core 33 is also larger than the diameter of the circle tangent to at least one of the fiber cores 21 of the light input section 120. In this embodiment, to improve optical coupling efficiency, the outer diameter of the annular fiber core 33 and the outer diameter D1 of the outer cladding 34 are larger than the smallest encompassing circle C2 (refer to) that includes all the fiber cores 11 and 21 of the light input sections 110 and 120 on the connection end face 135 of the light output section 130. Figure 7 The diameter of the ) is large (280 μm in the example above).
[0044] Here, since there is a gap between the optical input sections 110 and 120 before the fusion splicing process, and the sum of the surface areas of the cladding layers 12 and 22 of the heated optical input sections 110 and 120 is larger than the surface area of the outer cladding layer 34 of the optical output section 130, the optical input sections 110 and 120 have higher heating efficiency than the optical output section 130. This results in the optical output section 130 requiring more intense heating compared to the optical input sections 110 and 120. Considering this, to further reduce the amount of heating required for the optical output section 130 during the fusion splicing of the optical input sections 110 and 120 and the optical output section 130, it is preferable that the cross-sectional area of the connection end face 135 of the optical output section 130 (output fiber 30) is equal to or less than the sum of the cross-sectional areas of the optical input sections 110 and 120 (fibers 10 and 20) on the connection end face 135. In the above example, the cross-sectional area of the optical input sections 110 and 120 on the connection end face 135 is 85903 μm. 2 The cross-sectional area of the light output section 130 is 85530μm. 2 Furthermore, in this specification, when the cross-sectional area of the light output section on the connection end face is equal to a certain value, it indicates that the manufacturing error is within ±20% of that value.
[0045] In the above example, since the fiber core 21 and cladding 22 of all the optical input sections 120 have the same diameter, and these optical input sections 120 are located at equal distances from the center O1 of the output optical fiber 30 (the center O2 of the optical fiber 10), the circle C1 circumscribed to the cladding 22 of the optical input section 120 is tangent to the cladding 22 of all the optical input sections 120, and the circle C2 circumscribed to the fiber core 21 of the optical input section 120 is tangent to the fiber core 21 of all the optical input sections 120. However, the present invention can also be applied to other situations. That is, even if the diameters of the fiber core 21 and cladding 22 of the optical input section 120, and the distance from the center O1 of the output fiber 30, vary depending on the optical input section 120, it is sufficient that the outer diameter D1 of the outer cladding 34 on the connection end face 135 of the optical output section 130 is smaller than the diameter of the smallest encompassing circle of the cladding 22 of all the optical input sections 120, and larger than the diameter of the circle circumscribed to any one of the fiber cores 21 of all the optical input sections 120 (for example, the fiber core 21 located at the outermost position from the center O1 of the output fiber 30). Furthermore, it is sufficient that the outer diameter of the annular fiber core 33 on the connection end face 135 of the optical output section 130 is larger than the diameter of the smallest encompassing circle of the fiber cores 21 of all the optical input sections 120.
[0046] Figure 8 This is a perspective view showing the optical combiner 240 according to the second embodiment of the present invention. Figure 9 It is an exploded 3D diagram. For example... Figure 8 and Figure 9 As shown, the optical combiner 240 of this embodiment includes: an optical input section 110 (first optical input section), which is composed of the downstream end of the optical fiber 10; an optical input section 320 (first optical input section), which is composed of the downstream end of the optical fiber 20 and an optical adjustment member 220; and an optical output section 130, which is composed of the upstream end of the output optical fiber 30. The upstream end face of the optical adjustment member 220 of the optical input section 320 is fused to the downstream end of the optical fiber 20, and the downstream end face of the optical adjustment member 220 is fused to the connection end face 135 of the optical output section 130.
[0047] The optical adjustment component 220 is a cylindrical component that changes the emission angle of the laser propagating in the core 21 of the optical fiber 20 and guides it into the annular core 33 of the output optical fiber 30. A region with a predetermined radius from the central axis of this component serves as the laser's optical waveguide (first input optical waveguide). In this embodiment, the region of the optical adjustment component 220 that serves as the optical waveguide corresponds to the region of the core 21 of the optical input section 120 described in the first embodiment. By changing the emission angle of the laser propagating in the core 21 of the optical fiber 20 and guiding it into the annular core 33 of the output optical fiber 30, the beam profile of the laser L emitted from the laser emission section 4 can be adjusted to a desired shape. As an example, the outer diameter of the optical adjustment component 220 is 125 μm.
[0048] When the exit angle of light propagating in the core 21 of optical fiber 20 is reduced, for example, as a light adjustment component 220, a GRIN (Graded Index or Gradient Index) lens component whose refractive index gradually decreases from the central axis toward the radial direction can be used. Such a GRIN lens component can be formed, for example, by adding a high concentration of dopants such as germanium (Ge) to the center of a cylindrical glass made of quartz. In this case, the portion of the light adjustment component 220 where the refractive index decreases parabolically from the central axis toward the radial direction serves as the laser waveguide.
[0049] Furthermore, when increasing the exit angle of light propagating in the core 21 of the optical fiber 20, for example, as a light adjustment component 220, a lens component whose refractive index gradually increases from the central axis toward the radial direction can be used. Such a lens component can be formed, for example, by adding a high concentration of dopants such as germanium (Ge) to the periphery of a cylindrical glass made of quartz. In this case, the portion of the light adjustment component 220 where the refractive index increases parabolically from the central axis toward the radial direction serves as a laser waveguide.
[0050] Furthermore, when increasing the exit angle of light propagating in the core 21 of optical fiber 20, an optical fiber with a reduced diameter toward the output optical fiber 30 can be used as the optical adjustment component 220. For example, an optical fiber identical to optical fiber 20 can be extended such that its outer diameter decreases toward the output optical fiber 30. In this case, the core portion of the optical fiber used as the optical adjustment component 220 is a laser waveguide.
[0051] In this embodiment, the outer diameter D1 of the outer cladding 34 on the connection end face 135 of the light output section 130 (refer to...) Figure 2The outer diameter D1 of the outer cladding 34 on the connection end face 135 of the light output section 130 is smaller than the diameter of the smallest enclosing circle that encompasses all of the light input sections 320 (light adjustment members 220) on the connection end face 135 of the light output section 130. Therefore, the amount of heating required for the light output section 130 during the fusion welding connection of the light input sections 110, 320, and the light output section 130 can be reduced. This reduces the need for measures such as stronger heating of the light output section 130 compared to the light input sections 110, 320, and the light output section 130, making the fusion welding process of the light input sections 110, 320, and the light output section 130 easier.
[0052] In this embodiment, each light input unit 320 includes a light adjustment component 220, but it is also possible that only a part of the light input unit 320 includes a light adjustment component 220. In addition, the light input unit 110 may also include the same light adjustment component as the light adjustment component 220.
[0053] Figure 10 This is a schematic block diagram illustrating the structure of the laser device 401 according to the third embodiment of the present invention. Figure 10 As shown, the laser device 401 of this embodiment includes: a plurality of laser light sources 3 for generating laser light, an optical fiber 20 connected to the laser light sources 3, a plurality of laser light sources 402 for generating laser light, an optical fiber 410 connected to the laser light sources 402, an optical combiner 440 for coupling the laser light propagating in the optical fibers 20 and 410 and guiding it into the output optical fiber 30; and a control unit 405 for controlling the laser light sources 3 and 402. For example, a fiber laser or a semiconductor laser can be used as the laser light source 402.
[0054] Figure 11 This is a 3D diagram showing the optical combiner 440. Figure 12 It is an exploded 3D diagram. For example... Figure 11 and Figure 12 As shown, the optical combiner 440 of this embodiment includes: a plurality of optical input sections 120 (first optical input sections), each of which is composed of the downstream end of an optical fiber 20 extending from the laser source 3; a plurality of optical input sections 510 (second optical input sections), each of which is composed of the downstream end of an optical fiber 410 extending from the laser source 402; a bridging optical fiber 450 connected to these optical input sections 510; an optical input section 520 (first optical input section), which is composed of an intermediate optical fiber 420 connected to the downstream side of the bridging optical fiber 450; and an optical output section 130, which is composed of the upstream end of an output optical fiber 30.
[0055] As described in the first embodiment, an optical waveguide (first input optical waveguide) for propagating light is formed inside the core 21 of the optical fiber 20 constituting the optical input section 120. The laser generated by the laser source 3 propagates in the core 21 of the optical fiber 20 and reaches the optical input section 120 of the optical combiner 440.
[0056] like Figure 11 and Figure 12 As shown, the optical fiber 410 constituting the optical input section 510 has a core 411 and a cladding 412 surrounding the core 411, the refractive index of the cladding 412 being lower than that of the core 411. For example, the core 411 can be formed using quartz glass (SiO2), and the cladding 412 can be formed by adding dopants (e.g., fluorine (F) or boron (B)) that have properties that lower the refractive index to the quartz glass. Alternatively, the cladding 412 can also be formed using quartz glass (SiO2), and the core 411 can be formed by adding dopants (e.g., germanium (Ge)) that have properties that increase the refractive index. Thus, an optical waveguide (second input optical waveguide) for propagating light is formed inside the core 411 of the optical fiber 410. Therefore, the laser generated by the laser source 402 propagates in the core 411 of the optical fiber 410 and reaches the optical input section 510 of the optical combiner 440. As an example, the outer diameter of the core 411 of optical fiber 410 is 30 μm, and the outer diameter of the cladding 412 is 125 μm. Furthermore, for in... Figure 11 and Figure 12 As not shown, the cladding 412 of the optical fiber 410 is surrounded by a coating (not shown) made of, for example, resin. Furthermore, in this embodiment, optical fibers 410 and 20 are made of optical fibers with the same structure and dimensions, but optical fibers 410 and 20 may also be made of different optical fibers.
[0057] like Figure 12 As shown, the intermediate optical fiber 420 constituting the optical input section 520 has a core 421 and a cladding 422 surrounding the core 421, the refractive index of the cladding 422 being lower than that of the core 421. Thus, an optical waveguide (first input optical waveguide) for propagating light is formed inside the core 421 of the intermediate optical fiber 420.
[0058] The bridging fiber 450 has a core 451 and a cladding 452 covering the core 451. The refractive index of the cladding 452 is lower than that of the core 451, forming an optical waveguide for light propagation inside the core 451. The bridging fiber 450 having such a core-cladding structure includes: a first cylindrical portion 461 extending along the optical axis with a constant outer diameter; a tapered portion 462 gradually decreasing in outer diameter along the optical axis from the first cylindrical portion 461; and a second cylindrical portion 463 extending along the optical axis with a constant outer diameter from the tapered portion 462.
[0059] The end face of the first cylindrical portion 461 becomes a bridging access surface 465 for fusion-connecting the downstream ends of each optical input portion 510. In this embodiment, the three optical input portions 510 are connected to the bridging access surface 465 of the bridging fiber 450 in a state of mutual contact. The size of the fiber core 451 in the bridging access surface 465 of the bridging fiber 450 is such that it can contain all the fiber cores 411 of the optical input portions 510. The optical input portions 510 and the bridging fiber 450 are fused together in such a way that all the fiber cores 411 of the three optical input portions 510 are located within the area of the fiber cores 451 on the bridging access surface 465 of the bridging fiber 450.
[0060] Thus, the bridging fiber 450 is configured such that the laser emitted from the fiber core 411 of the optical input section 510 propagates inside its fiber core 451, and its beam diameter is reduced by the diameter reduction section 462. Furthermore, in order to suppress reflection when the laser light incident from the fiber core 411 of the optical input section 510 onto the fiber core 451 of the bridging fiber 450, it is preferable that the refractive index of the fiber core 451 of the bridging fiber 450 is approximately the same as the refractive index of the fiber core 411 of the optical input section 510.
[0061] The end face of the second cylindrical portion 463, located on the opposite side of the bridging input surface 465 in the optical axis direction, is the bridging output surface 466 for fusion splicing the intermediate optical fiber 420. Here, the size of the fiber core 421 of the intermediate optical fiber 420 is larger than the size of the fiber core 451 on the bridging output surface 466 of the bridging optical fiber 450. The bridging optical fiber 450 and the optical input portion 520 (intermediate optical fiber 420) are fused together in such a way that the fiber core 451 of the bridging optical fiber 450 on the bridging output surface 466 is located within the region of the fiber core 421 of the intermediate optical fiber 420.
[0062] Thus, the intermediate optical fiber 420 of the optical input section 520 is configured such that laser light propagating in the core 451 of the bridging optical fiber 450 propagates inside its core 421. Furthermore, to suppress reflection of laser light incident from the core 451 of the bridging optical fiber 450 to the core 421 of the intermediate optical fiber 420, it is preferable that the refractive index of the core 421 of the intermediate optical fiber 420 is approximately the same as the refractive index of the core 451 of the bridging optical fiber 450.
[0063] For the bridging fiber 450 of this embodiment, a cladding 452 is provided on the outside of the fiber core 451 as a low refractive index medium having a refractive index lower than that of the fiber core 451. Such a low refractive index medium is not limited to a cladding layer such as the cladding 452. For example, an air layer may be formed around the fiber core 451 and used as a low refractive index medium.
[0064] The following are fused together at the connection end face 135 of the optical output section 130: the downstream end of the optical input section 120 (fiber 20) and the downstream end of the optical input section 520 (intermediate fiber 420). At the downstream ends (connection ends) of the optical input sections 120 and 520, the six optical input sections 120 (fiber 20) are arranged outside the optical input section 520 (intermediate fiber 420) with equal distances from the center of the intermediate fiber 420, and adjacent fibers 20 and 420 are in the closest possible contact. Here, the connection ends of the optical input sections 120 and 520 are connected to the connection end face 135 of the optical output section 130 in such a way that the center of the centrally located intermediate fiber 420 is aligned with the center O1 of the output fiber 30 (refer to...). Figure 2 Consistent.
[0065] The central fiber core 31 of the light output section 130 is large enough to contain the fiber core 421 of the centrally located light input section 520. The annular fiber core 33 of the light output section 130 is large enough to contain all the fiber cores 21 of the six light input sections 120. Furthermore, the light input sections 120 and 520 are fused together with the light output section 130 such that the fiber core 421 of the light input section 520 is located within the central fiber core 31 of the light output section 130, and all the fiber cores 21 of the light input sections 120 are located within the annular fiber core 33 of the light output section 130.
[0066] According to this structure, for the laser generated by the laser source 402, the laser propagates inside the core 411 of the optical fiber 410 and is incident on the core 451 of the bridging optical fiber 450 from the bridging input surface 465. The laser incident on the core 451 of the bridging optical fiber 450 is reflected at the interface between the core 451 and the cladding 452 and propagates in the core 451 of the bridging optical fiber 450, and is incident on the core 421 of the intermediate optical fiber 420 from the bridging output surface 466 with its beam diameter reduced by the reduction portion 462. The laser introduced into the core 421 of the intermediate optical fiber 420 propagates inside the core 421 and is incident on the central core 31 of the light output section 130. The laser incident on the central core 31 of the light output section 130 propagates inside the central core 31 and, as part of the laser L, irradiates the workpiece W on the stage 6 from the laser output section 4 (see reference). Figure 10 ).
[0067] Furthermore, the laser generated by the laser source 3 propagates within the core 21 of the optical fiber 20 and is incident on the annular core 33 of the light output section 130. The laser incident on the annular core 33 of the light output section 130 propagates within the annular core 33 and, as part of the laser L, irradiates the workpiece W on the stage 6 from the laser emission section 4 (see reference). Figure 10 ).
[0068] Thus, in this embodiment, the lasers from multiple laser sources 402 can be coupled and introduced into the central core 31 of the optical output section 130 using the bridging fiber 450, thereby easily increasing the power of the laser propagating in the central core 31 of the output fiber 30.
[0069] The control unit 405 can control the laser sources 3 and 402, for example, by controlling the current supplied to them. By controlling the laser sources 3 and 402 using the control unit 405, the power of the laser generated by the laser source 3 and the laser generated by the laser source 402 can be changed. As a result, the power of the laser L output from the laser emission unit 4 of the laser device 401 at its center and at its outer edges can be adjusted, and the contour of the laser L can be easily changed.
[0070] In this embodiment, the outer diameter D1 of the outer cladding 34 on the connection end face 135 of the light output section 130 (refer to...) Figure 2 The diameter is smaller than the minimum encompassing circle of the cladding 22 that includes the entire light input section 120. Therefore, the amount of heating required for the light output section 130 during the fusion bonding of the light input sections 120, 520, and light output section 130 can be reduced. This reduces the need for measures such as more intense heating of the light output section 130 compared to the light input sections 120 and 520, making the fusion bonding process of the light input sections 120, 520, and light output section 130 easier.
[0071] Here, since it is necessary to achieve regional optical coupling between the fiber core 21 of the light input section 120 and the annular fiber core 33 of the light output section 130, the outer diameter of the annular fiber core 33 is larger than the diameter of the circle circumscribed to at least one of the fiber cores 21 of the light input section 120. Furthermore, the outer diameter D1 of the outer cladding 34 located outside the annular fiber core 33 is also larger than the diameter of the circle circumscribed to at least one of the fiber cores 21 of the light input section 120. In this embodiment, to improve optical coupling efficiency, the outer diameter of the annular fiber core 33 and the outer diameter D1 of the outer cladding 34 are larger than the diameter of the smallest encompassing circle that includes all the fiber cores 11 and 421 of the light input sections 110 and 520 on the connection end face 135 of the light output section 130. In addition, in order to further reduce the amount of heating required for the optical output section 130 when splicing the optical input sections 120, 520 and the optical output section 130, it is preferable that the cross-sectional area of the connection end face 135 of the optical output section 130 (output optical fiber 30) is equal to or less than the sum of the cross-sectional areas of the optical input sections 120, 520 (optical fibers 20, 420) on the connection end face 135.
[0072] In this embodiment, at least one of the light input units 120 and 520 may include a light adjustment member as described in the second embodiment. Using such a light adjustment member, the beam profile of the laser L emitted from the laser emission unit 4 can be adjusted to a desired shape.
[0073] In the above embodiment, the output optical fiber 30 (optical output section 130) has two optical waveguides consisting of a central fiber core 31 and a ring fiber core 33. However, the output optical fiber 30 may also have a single optical waveguide or three or more optical waveguides. In addition, the cross-sectional shape of the fiber core (optical waveguide) included in the output optical fiber 30 is not limited to the circular shape or the ring shape shown in the figure.
[0074] Furthermore, although in the above embodiment the output optical fiber 30 (optical output section 130) has two cladding layers 32 and 34, the output optical fiber 30 may also have a single cladding layer or three or more cladding layers. In this case, the effects of the present invention can be obtained by reducing the outer diameter of the outermost cladding layer in the optical output section 130 as described above.
[0075] In the above embodiments, the structures of laser source 2, laser source 3, and laser source 402 can be the same or different. Furthermore, the wavelengths of the laser generated by laser source 2, laser source 3, and laser source 402 can be the same or different.
[0076] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments and can be implemented in various different ways within the scope of its technical concept.
[0077] As described above, according to a first aspect of the present invention, an optical combiner is provided that enables easy fusion of input-side optical components and output-side optical components. The optical combiner includes: a plurality of first optical input sections, each having a first input optical waveguide; and an optical output section connected to the plurality of first optical input sections. The optical output section includes: at least one fiber core for propagating light, and an outermost cladding layer having a refractive index lower than that of the at least one fiber core and located outside the at least one fiber core. The plurality of first optical input sections are optically coupled to the connection end face of the optical output section via the first input optical waveguide of at least one of the plurality of first optical input sections and the at least one fiber core of the optical output section. The outer diameter of the outermost cladding layer on the connection end face of the optical output section is smaller than the diameter of the smallest encompassing circle on the connection end face of the optical output section that includes all the plurality of first optical input sections.
[0078] With this structure, the outer diameter of the outermost cladding layer of the light output section is smaller than the diameter of the smallest encompassing circle containing all the multiple first light input sections. Therefore, the amount of heating required for the light output section during the fusion splicing of the multiple first light input sections and the light output section can be reduced. This reduces the need for measures such as stronger heating of the light output section compared to the first light input sections, and facilitates the fusion splicing process of the multiple first light input sections and the light output section.
[0079] In order to optically couple the first input waveguide of the first optical input section with at least one fiber core of the optical output section, preferably, the outer diameter of the outermost cladding layer on the connection end face of the optical output section is larger than the diameter of the circle circumscribed to at least one of the first input waveguides of the plurality of first optical input sections on the connection end face of the optical output section.
[0080] Alternatively, at least one fiber core may be included within the outermost fiber core adjacent to the inner side of the outermost cladding layer. In this case, preferably, the outer diameter of the outermost fiber core on the connection end face of the optical output section is larger than the diameter of the circle circumscribed on the connection end face of the optical output section and externally tangent to at least one of the first input optical waveguides of the plurality of first optical input sections.
[0081] For example, the circle circumscribed to at least one of the first input optical waveguides may be the smallest enclosing circle that includes all of the first input optical waveguides of the plurality of first optical input portions on the connection end face of the optical output portion.
[0082] In order to further reduce the amount of heating required for the light output section when welding multiple first light input sections and light output sections together, it is preferable that the cross-sectional area of the light output section on the connection end face is equal to or less than the sum of the cross-sectional areas of the multiple first light input sections on the connection end face of the light output section.
[0083] It is possible that at least one of the aforementioned plurality of first optical input sections comprises: an optical fiber including a core serving as a first input optical waveguide, and a cladding having a refractive index lower than that of the core and covering the periphery of the core; and an optical adjustment component that alters the exit angle of light propagating in the core of the optical fiber. Using such an optical adjustment component allows the characteristics of light introduced from the core of the first optical input section to the optical output section to be altered to a desired shape.
[0084] Alternatively, the aforementioned optical combiner may further include: a plurality of second optical input sections, each having a second input optical waveguide; and a bridging fiber. The bridging fiber has: a bridging input surface connecting the second input optical waveguides of the plurality of second optical input sections; a reduced diameter section whose diameter gradually decreases as it moves away from the bridging input surface along the optical axis; and a bridging output surface located on the opposite side of the bridging input surface in the optical axis direction. One of the plurality of first optical input sections includes an intermediate fiber containing a core connected to the bridging output surface of the bridging fiber. With this structure, light from the plurality of second optical input sections can be coupled and guided into the core of the optical output section using the bridging fiber, thus easily increasing the power of the light propagating in the core of the optical output section.
[0085] Alternatively, the light output section may comprise at least one fiber core, which may include multiple fiber cores. In this case, the light output section may include: a first fiber core, serving as the at least one fiber core; a first cladding layer having a refractive index lower than that of the first fiber core and covering the periphery of the first fiber core; a second fiber core, serving as the at least one fiber core; and a second cladding layer, serving as the outermost cladding layer, having a refractive index lower than that of the second fiber core and covering the periphery of the second fiber core. The second fiber core may have a refractive index higher than that of the first cladding layer and cover the periphery of the first cladding layer.
[0086] According to a second aspect of the present invention, a laser device is provided that enables easy fusion processing of an input-side optical component and an output-side optical component. The laser device includes: a plurality of laser sources for generating laser light, and the aforementioned optical combiner. The first input waveguides of the plurality of first optical input sections of the optical combiner are optically coupled to the plurality of laser sources.
[0087] In this manner, as described above, the amount of heating required for the optical output section during the fusion connection of multiple first optical input sections and optical output sections of the optical combiner can be reduced. Therefore, the necessity for measures such as heating the optical output section more strongly than the first optical input section is reduced, and the fusion processing of multiple first optical input sections and optical output sections can be easily performed.
[0088] Alternatively, the laser device may further include a light removal unit that removes light leaking into the outermost cladding layer of the light output section of the optical combiner. Such a light removal unit can remove unwanted light leaking into the outermost cladding layer of the light output section of the optical combiner.
[0089] Alternatively, the aforementioned laser device may also include a control unit that controls the plurality of laser light sources, thereby adjusting the output of the laser generated by the plurality of laser light sources. Using such a control unit, the power of the laser output from the laser device can be adjusted, and the laser profile can be easily varied.
[0090] This application claims priority to Japanese Patent Application No. 2020-091710, filed on May 26, 2020. The entire disclosure of that application is incorporated herein by reference.
[0091] Industrial applicability
[0092] This invention is applicable to optical combiners that couple and output light propagating in multiple optical fibers.
[0093] Explanation of reference numerals in the attached figures
[0094] 1-Laser device; 2, 3, 402-Laser source; 4-Laser emission section; 5-Control section; 6-Placement stage; 7-Light removal section; 10, 20-Fiber optic cable; 30-Output fiber optic cable; 31-Central core (first core); 32-Inner cladding (first cladding); 33-Annular core (second core); 34-Outer cladding (second cladding); 40, 240, 440-Optical combiner; 110, 120-(First) optical input section; 13 0 - Optical output section; 135 - Connecting end face; 220 - Optical adjustment component; 320 - (First) optical input section; 401 - Laser device; 405 - Control section; 410 - Optical fiber; 420 - Intermediate optical fiber; 450 - Bridging optical fiber; 461 - First cylindrical section; 462 - Reduced diameter section; 463 - Second cylindrical section; 465 - Bridging input emission surface; 466 - Bridging output surface; 510 - (Second) optical input section; 520 - (First) optical input section.
Claims
1. An optical combiner, comprising: Multiple first optical input sections, each having a first input optical waveguide; and The light output section is connected to the plurality of first light input sections. The light output section includes: multiple fiber cores for propagating light, and an outermost cladding layer. The outermost cladding layer has a lower refractive index than the plurality of fiber cores and is located outside the plurality of fiber cores. With gaps between them, the plurality of first optical input sections are fused to the connection end face of the optical output section by means of optical coupling between the first input waveguide of at least one of the plurality of first optical input sections and any one of the plurality of fiber cores of the optical output section. The outer diameter of the outermost cladding layer on the connection end face of the optical output section is smaller than the diameter of the smallest enclosing circle that includes all of the plurality of first optical input sections on the connection end face of the optical output section. The cross-sectional area of the light output portion on the connection end face is equal to or less than the sum of the cross-sectional areas of the plurality of first light input portions on the connection end face of the light output portion.
2. The optical combiner according to claim 1, characterized in that, The outer diameter of the outermost cladding layer on the connection end face of the optical output section is larger than the diameter of the circle circumscribed on the connection end face of the optical output section and externally tangent to at least one of the first input optical waveguides of the plurality of first optical input sections.
3. The optical combiner according to claim 1 or 2, characterized in that, The plurality of fiber cores are contained within the outermost adjacent fiber cores on the inner side of the outermost cladding layer. The outer diameter of the outermost fiber core on the connection end face of the optical output section is larger than the diameter of the circle tangent to at least one of the first input optical waveguides of the plurality of first optical input sections on the connection end face of the optical output section.
4. The optical combiner according to claim 2, characterized in that, The circle circumscribed in the at least one first input optical waveguide is the smallest enclosing circle that includes all the first input optical waveguides of the plurality of first optical input portions on the connection end face of the optical output portion.
5. The optical combiner according to claim 1 or 2, characterized in that, At least one of the plurality of first optical input units includes: An optical fiber comprising a core serving as a first input optical waveguide, and a cladding having a refractive index lower than that of the core and covering the periphery of the core; and An optical adjustment component that changes the exit angle of light propagating in the core of the optical fiber.
6. The optical combiner according to claim 1 or 2, characterized in that, It also features: multiple second optical input sections, each having a second input optical waveguide; And bridging fiber optic cables, The bridging optical fiber has: a bridging input surface that connects the second input optical waveguides of the plurality of second optical input sections; The diameter-reducing portion gradually decreases in diameter as it moves away from the bridging injection surface along the optical axis; and the bridging emission surface is located on the opposite side of the bridging injection surface in the optical axis direction. One of the plurality of first optical input sections includes an intermediate optical fiber, the intermediate optical fiber including a core connected to the bridging exit surface of the bridging optical fiber.
7. The optical combiner according to claim 1, characterized in that, The light output unit includes: The first fiber core serves as one of the plurality of fiber cores; A first cladding layer has a refractive index lower than that of the first fiber core and covers the periphery of the first fiber core. The second fiber core, which is one of the plurality of fiber cores, has a higher refractive index than the first cladding and covers the periphery of the first cladding; as well as The second cladding, which serves as the outermost cladding layer, has a lower refractive index than the second core and covers the area surrounding the second core.
8. A laser device comprising: Multiple laser sources that generate laser light; and The optical combiner according to any one of claims 1 to 7, The first input waveguide of the plurality of first optical input sections of the optical combiner is optically coupled to the plurality of laser light sources.
9. The laser device according to claim 8, characterized in that, It also includes a light removal unit that removes light leaking into the outermost cladding layer of the light output section of the light combiner.
10. The laser device according to claim 8 or 9, characterized in that, It also includes a control unit that controls the plurality of laser light sources to adjust the output of the laser generated by the plurality of laser light sources.