Laser amplification medium and method of manufacturing the same

Abstract

To provide a laser amplification medium which can be easily manufactured, and to provide a manufacturing method of the laser amplification medium which can be easily realized.SOLUTION: A laser amplification medium comprises: a clad part; a first core part and a second core part; and virtual first, second, and third layers. The first core part and the second core part are extended in parallel to an axial direction, and a side surface is covered with the clad part. The first layer contains the first core part and the second core part of one part of the clad part. The second layer and the third layer contain one part of the clad part. The first layer is laminated and bonded in a lamination direction orthogonal to the axial direction between the second layer and the third layer. The side surfaces in each of the first core part and the second core part, comprise a first plane part and a second plane part. The first plane part is contained in a first front surface as a virtual bonding surface of the first layer and the second layer. The second plane part is contained in a second front surface that is the virtual bonding surface of the first layer and the third layer.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a laser amplification medium and a method for manufacturing the laser amplification medium. [Background technology]

[0002] High-quality, high-power lasers are needed in fields such as laser processing, scientific research, nuclear fusion, space debris removal, safety compensation, etc. Solid-state lasers and fiber lasers are often considered as a way to realize such lasers.

[0003] Among these, fiber lasers have a relatively small waveguide area, which means that the power density inside the waveguide tends to be relatively large. This is particularly noticeable in pulsed lasers. As a result, problems such as damage to materials such as optical fibers and degradation of characteristics due to nonlinear optical effects are known.

[0004] Therefore, a technique has been proposed in which a large output power is obtained by combining a large number of fiber lasers each having a small output power.

[0005] In relation to the above, Non-Patent Document 1 (R. Soulard et al., "ICAN: A novel laser architecture for space debris removal," Acta Astronautica 105, 2014, pp. 192-200) and Non-Patent Document 2 (T. Ebisuzaki et al., "Demonstration designs for the remediation of space debris from the International Space Station," Acta Astronautica 112, 2015, pp. 102-113) propose combining a large number (e.g., 10,000) of fiber lasers, called a CAN (Coherent Amplification Network).

[0006] Furthermore, Patent Document 1 (JP 2013-148769 A) discloses a multiple beam combining device. This multiple beam combining device includes a phase shift unit, a superimposing unit, an observation unit, and a phase control unit. The phase shift unit generates multiple phase-shifted laser beams by shifting the phase of each of multiple laser beams. The superimposing unit generates multiple superimposed laser beams by superimposing each of the multiple phase-shifted laser beams with a reference beam. The observation unit generates interference pattern information regarding a spatial interference pattern that appears when each of the multiple superimposed laser beams is observed. The phase control unit feedback-controls the phase shift by the phase shift unit based on the interference pattern information obtained for each of the multiple superimposed laser beams, thereby setting the multiple phase-shifted laser beams to a desired state. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-148769 [Non-patent literature]

[0008] [Non-Patent Document 1] R. Soulard et al., “ICAN: A novel laser architecture for space debris removal”, Acta Astronautica 105, published 2014, pp. 192-200 [Non-patent document 2] T. Ebisuzaki et al., "Demonstration designs for the remediation of space debris from the International Space Station," Acta Astronautica 112, 2015, pp. 102-113 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention provides a laser amplifying medium that is easy to manufacture and a method for manufacturing the laser amplifying medium that is easy to realize. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0010] The following describes the means for solving the problems using the numbers used in the (Mode for Carrying Out the Invention). These numbers are added to clarify the correspondence between the statements in the (Claims) and the (Mode for Carrying Out the Invention). However, these numbers should not be used to interpret the technical scope of the invention described in the (Claims).

[0011] According to one embodiment, the laser amplification medium (1) includes a cladding portion (2), a first core portion (3), a second core portion (3), a virtual first layer (12), a virtual second layer (11), and a virtual third layer (11). The cladding portion (2) has a predetermined first refractive index. The first core portion (3) and the second core portion (3) each have a second refractive index higher than the first refractive index, extend parallel to a predetermined axial direction (X), and are covered at their respective side surfaces (32) by the cladding portion (2). The virtual first layer (12) includes a portion of the cladding portion (2) and the first and second core portions (3). The virtual second layer (11) and the virtual third layer (11) each include another portion of the cladding portion (2). The first layer (12) is stacked and joined between the second layer (11) and the third layer (11) in a predetermined stacking direction (Z) perpendicular to the axial direction (X). In each of the first core portion (3) and the second core portion (3), the side surface (32) has a first flat portion and a second flat portion. The first flat portion is an imaginary joint surface of the first layer (12) with the second layer (11) and is included in an imaginary first surface perpendicular to the stacking direction (Z). The second flat portion is an imaginary joint surface of the first layer (12) with the third layer (11) and is included in an imaginary second surface perpendicular to the stacking direction (Z), and faces the first flat portion.

[0012] According to one embodiment, a method for manufacturing a laser amplification medium (1) includes generating (S2) a first layer (12) including a plurality of first regions (20) having a predetermined first refractive index and a plurality of second regions (30) having a second refractive index greater than the first refractive index, generating (S1) a second layer (11) and a third layer (11) having the first refractive index, and stacking (S3) the second layer (11), the first layer (12), and the third layer (11) in this order in a predetermined stacking direction (Z). The stacking (S3) includes bonding the second layer (11) to a first surface of the first layer (12) perpendicular to the stacking direction (Z) so as to bond the plurality of first regions (20) and the second layer (11), and bonding the third layer (11) to a second surface of the first layer (12) opposite the first surface so as to bond the plurality of first regions (20) and the third layer (11). The plurality of second regions (30) each extend parallel to a predetermined axial direction (X) parallel to the first surface, and comprise a first core portion (3) and a second core portion (3) each having a side surface including a first flat portion included in the first surface and a second flat portion included in the second surface. The integrated plurality of first regions (20), second layer (11), and third layer (11) function as a cladding portion (2) that covers the side surface of each of the first core portion (3) and second core portion (3). [Effects of the Invention]

[0013] According to the embodiment, it is possible to provide a laser amplifying medium that is easy to manufacture and a method for manufacturing the laser amplifying medium that is easy to realize. [Brief explanation of the drawings]

[0014] [Figure 1A] FIG. 1A is a perspective view showing an example of a configuration of a laser amplification medium according to an embodiment. [Figure 1B] FIG. 1B is a perspective view showing an example of the configuration of a virtual unit laser amplifying medium obtained by extracting a part of the laser amplifying medium of FIG. 1A. [Figure 2] FIG. 2 is a cross-sectional view of the unit laser amplifying medium of FIG. 1B taken along an arbitrary cross section passing through the optical axis of the core portion. [Figure 3A] FIG. 3A is a perspective view showing an example of a method for making pumping light incident on an end face of each core portion of the laser amplification medium of FIG. 1A. [Figure 3B] FIG. 3B is a perspective view showing an example of a method for making pumping light incident on the side surface of each core portion of the laser amplification medium of FIG. 1A. [Figure 3C] FIG. 3C is a perspective view showing the configuration of a modified example of the laser amplifying medium of FIG. 1A and an example of a method for making pumping light incident on the laser amplifying medium according to this modified example. [Figure 4A] FIG. 4A is a transmission overhead view showing the configuration of another modified example of the laser amplification medium of FIG. 1A and an example of a method for making pumping light incident on the laser amplification medium of this modified example. [Figure 4B] FIG. 4B is a bird's-eye view showing an example of how excitation light incident from the end of the excitation light optical path in FIG. 4A leaks out from the side surface of the excitation light optical path. [Figure 5] FIG. 5 is a flowchart showing an example of a configuration of a method for manufacturing a laser amplification medium according to an embodiment. [Figure 6A] FIG. 6A is a cross-sectional view showing that the laser amplification medium of FIG. 1A can be manufactured by laminating a first substrate and a second substrate. [Figure 6B] FIG. 6B is a cross-sectional view showing an example of a state of the laser amplification medium during its manufacture. [Figure 6C] FIG. 6C is a cross-sectional view showing an example of a state of the laser amplification medium during its manufacture. [Figure 6D] FIG. 6D is a cross-sectional view showing an example of a state of the laser amplification medium during its manufacture. [Figure 6E] FIG. 6E is a cross-sectional view showing an example of a state of the laser amplification medium during its manufacture. [Figure 6F] FIG. 6F is a cross-sectional view showing an example of a state of the laser amplification medium during its manufacture. [Figure 6G] FIG. 6G is a cross-sectional view showing an example of a state of the laser amplification medium during its manufacture. [Figure 6H] FIG. 6H is a cross-sectional view showing an example of a state during the manufacturing of the laser amplification medium. [Figure 7] FIG. 7 is a cross-sectional view of an example of a configuration of a laser amplification medium according to an embodiment. [Figure 8] FIG. 8 is a perspective view showing an example of the configuration of a laser amplification medium according to an embodiment. [Figure 9] FIG. 9 is a graph for explaining an example of a method for controlling the temperature of a laser amplification medium by flowing a predetermined fluid through the laser amplification medium using the flow path according to one embodiment. [Figure 10A] FIG. 10A is a cross-sectional view showing an example of a configuration of a laser amplification medium according to an embodiment. [Figure 10B] FIG. 10B is a cross-sectional view showing another configuration example of the laser amplification medium according to one embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing yet another example of the configuration of the laser amplification medium according to an embodiment. [Figure 12] FIG. 12 is a cross-sectional view showing an example of the configuration of a laser amplification medium according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] With reference to the accompanying drawings, a laser amplification medium and a laser amplifier according to the present invention will be described. medium An embodiment for carrying out the manufacturing method will be described below.

[0016] (First embodiment) An example of the configuration of a laser amplification medium 1 according to this embodiment will be described with reference to Fig. 1A. Fig. 1A is a perspective overhead view showing an example of the configuration of a laser amplification medium 1 according to an embodiment.

[0017] The components of the laser amplifying medium 1 in Fig. 1A will be described. The laser amplifying medium 1 in Fig. 1A includes a cladding portion 2 and a plurality of core portions 3. In the example of Fig. 1A, the total number of core portions 3 is 16, but this is merely an example and does not limit the present embodiment. On the other hand, it is preferable that there is only one cladding portion 2.

[0018] The core portions 3 extend in one direction and are formed in a shape having flat surfaces on opposing side surfaces. For example, in the example of FIG. 1A, each core portion 3 has the same rectangular parallelepiped shape. The cladding portions 2 also have a rectangular parallelepiped shape, but their dimensions are different from those of the core portions 3. However, these are merely examples and do not limit this embodiment. For example, the core portions 3 may have the shape of a hexagonal prism, the cross section of which perpendicular to the extension direction is hexagonal.

[0019] The positional relationship of the components of the laser gain medium 1 in Figure 1A will be explained. In the example of Figure 1A, a total of 16 core portions 3 extend in the same direction. This extension direction is called the X-axis direction. The cladding portions 2 also extend in the same X-axis direction. The core portions 3 are doped with a laser gain medium, and by inputting pumping light and seed light, it is possible to emit amplified light obtained by amplifying the seed light, as will be described later.

[0020] Here, consider a cross section of the laser amplification medium 1 taken along a virtual plane perpendicular to the X-axis direction. The configuration of this cross section is the same as the configuration of both end faces of the laser amplification medium 1. In other words, in the X-axis direction, the length of the cladding portion 2 and the length of each core portion 3 are the same. In other words, in the X-axis direction, each end face of each core portion 3 is exposed flush with each end face of the cladding portion 2. However, this configuration is an example for explaining the embodiment, and the end faces of the core portions 3 do not necessarily have to be perpendicular to the X-axis. This may make it possible to adjust the output direction and prevent return light. In addition, a coating such as an anti-reflective coating may be added to the end faces of the core portions 3.

[0021] The side surfaces of the core portions 3 are formed in a shape having opposing flat surfaces extending parallel to the X-axis direction. For example, in the example of FIG. 1A, the side surfaces of each core portion 3 are rectangular in shape in the cross section or end surface. In the example of FIG. 1A, the side surfaces of the core portions 3 refer to four of the six faces of a rectangular parallelepiped that are parallel to the X-axis direction. Furthermore, in the cross section or end surface, the side surfaces of the total of 16 core portions 3 are arranged in a 4x4 two-dimensional array. The two directions relating to this two-dimensional array are referred to as the Y-axis direction and the Z-axis direction, respectively. Furthermore, it is preferable that the side surfaces of each core portion 3 are parallel to the Y-axis direction or the Z-axis direction.

[0022] The laser amplification medium 1 in FIG. 1A has a structure in which core portions 3 extending parallel to the X-axis direction are arranged inside a cladding portion extending parallel to the X-axis direction, and the side surfaces of the core portions 3 are formed to have opposing flat surfaces extending parallel to the X-axis direction. For example, the core portions 3 according to this embodiment have the shape of a quadrangular prism or a rectangular parallelepiped. Furthermore, in this embodiment, it is preferable that the dimension in the width direction of each core portion 3 is about 5 to 10 times the diameter of the core of a general optical fiber. In other words, the cross-sectional area of ​​the core portions 3 according to this embodiment is about 5 to 10 times the diameter of the core of a general optical fiber. cross-sectional area It is preferable that the value is about 25 to 100 times the value of the reference value. However, these values ​​are merely examples and do not limit the present embodiment.

[0023] 1A, the side surfaces of each core portion 3 are covered with a cladding portion 2. In other words, a cladding portion 2 exists between two adjacent core portions 3.

[0024] With reference to Fig. 1B, it will be explained that each core portion 3 in Fig. 1A and the cladding portion 2 covering the side surface thereof can also function as an optical waveguide. Fig. 1B is a perspective view showing an example of the configuration of a virtual unit laser amplifying medium 10 obtained when a part of the laser amplifying medium 1 in Fig. 1A is extracted.

[0025] 1B includes one core portion 3 and a cladding portion 2 covering the side surface of the core portion 3. The refractive index of the core portion 3 is higher than the refractive index of the cladding portion 2. It is expected that the laser light incident on one end face of the core portion 3 will not leak from the core portion 3 to the cladding portion 2 if the incident angle satisfies a predetermined condition.

[0026] It can also be said that the laser amplifying medium 1 of FIG. 1A can be obtained by preparing a total of 16 unit laser amplifying media 10 of FIG. 1B, arranging them in a two-dimensional 4×4 array, joining them, and optically integrating all the cladding portions 2.

[0027] 2, 3A, 3B, 3C, 4A and 4B, a description will be given of several methods for irradiating pumping light 4A, 4B, 4C and 4D to the laser amplification medium 1 according to this embodiment. FIG. 2 is a cross-sectional view of an arbitrary cross section passing through the optical axis 31 of the core portion 3 of the unit laser amplification medium 10 of FIG. 1B. Disclosure In all the figures, the optical axis direction is the same as the X-axis direction.

[0028] In the example of FIG. 2, the pumping light 4A and 4B are incident on the unit laser amplification medium 10 by roughly two methods. In the first method, the pumping light 4A is incident on the end face of the core portion 3. However, the pumping light 4A does not necessarily have to be incident parallel to the optical axis 31 of the core portion 3, and it does not necessarily have to be incident on both end faces. In the second method, the pumping light 4B is incident on the side face 32 of the core portion 3. Here, the pumping light 4B does not necessarily have to be incident perpendicular to the side face 32 of the core portion 3, and it does not necessarily have to be incident from multiple directions. Note that these two methods can be combined to make the pumping light 4A and 4B incident on both the end face and the side face 32 of the core portion 3. In either case, it is preferable that the seed light amplified by the energy of the pumping light 4A and 4B be incident on the end face of the core portion 3.

[0029] Fig. 3A is a transmission overhead view showing an example of a method for making pumping light 4A incident from the end face of each core portion 3 of the laser amplification medium 1 of Fig. 1A. The pumping light 4A shown in Fig. 3A corresponds to the pumping light 4A in Fig. 2. For ease of viewing, Fig. 3A omits the incident positions of the pumping light 4A for some core portions 3, but in practice it is preferable to make the pumping light 4A incident on all core portions 3.

[0030] FIG. 3B is a transmission overhead view showing an example of a method for introducing pumping light 4B from the side surface 32 of each core portion 3 of the laser amplification medium 1 of FIG. 1A. The pumping light 4B shown in FIG. 3B corresponds to the pumping light 4B in FIG. 2. In FIG. 3B, by introducing pumping light 4B from the side surface of the cladding portion 2, the pumping light 4B also enters the inside of the core portion 3 from the side surface 32 of the core portion 3. Therefore, in the case of FIG. 3B, unlike the case of FIG. 3A, seed light present in all core portions 3 can be amplified by simply introducing pumping light 4B from the side surface of the cladding portion 2 at once. Note that although some core portions 3 may be geometrically shaded by other core portions 3, it is possible to adopt a configuration in which the unabsorbed pumping light 4B is absorbed by the shaded core portions 3 because the distance between the core portions 3 in the direction of the pumping light 4B is short.

[0031] 3C is a transmission overhead view showing the configuration of a modified example of the laser amplifying medium 1 of FIG. 1A and an example of a method for inputting pumping light 4C into the laser amplifying medium 1 of this modified example. The laser amplifying medium 1 of the modified example of FIG. 3C can be obtained by applying a double clad structure to the laser amplifying medium 1 of FIG. 1A. In other words, the laser amplifying medium 1 of FIG. 3C can be obtained by replacing the clad portion 2 of the laser amplifying medium 1 of FIG. 1A with an inner clad portion 2A and an outer clad portion 2B. Alternatively, the laser amplifying medium 1 of FIG. 3C can be obtained by renaming the clad portion 2 of the laser amplifying medium 1 of FIG. 1A to an inner clad portion 2A and adding an outer clad portion 2B to the outside of its side surface.

[0032] In the case of Fig. 3C, for example, by making pumping light 4C incident on the end face of the inner cladding 2A at an appropriate incident angle, the pumping light 4C is repeatedly totally reflected at the boundary surface between the inner cladding 2A and the outer cladding 2B, and during this time, the pumping light 4C also enters the inside of the core 3 from the side surface 32 of the core 3. In this case, the refractive index of the outer cladding 2B may be smaller than the refractive index of the inner cladding 2A. In the case of Fig. 3C, unlike the case of Fig. 3A, the seed light present in all of the cores 3 can be amplified by simply making the pumping light 4C incident on the end face of the inner cladding 2A at once.

[0033] Fig. 4A is a transmission overhead view showing the configuration of another modified example of the laser amplifying medium 1 of Fig. 1A and an example of a method for inputting pumping light 4D into this modified laser amplifying medium 1. The modified laser amplifying medium 1 of Fig. 4A can be obtained by replacing a part of the core portion 3 of the laser amplifying medium 1 of Fig. 1A with an optical path 6 for pumping light in which the laser gain medium is not doped.

[0034] FIG. 4B is a bird's-eye view showing an example of how the excitation light 4D incident from the end of the excitation light optical path 6 in FIG. 4A leaks out from the side of the excitation light optical path 6. In the example of FIG. 4B, the excitation light optical path 6 has a function of leaking the incident light out of the excitation light optical path 6. For example, the excitation light optical path 6 includes a scattering source that scatters the incident light or a diffuse reflection source that diffuses the incident light. As a result, the excitation light 4D incident from the end of the excitation light optical path 6 leaks in all directions from the side of the excitation light optical path 6. The excitation light 4D leaking from the side of the excitation light optical path 6 enters all of the core sections 3 from the side surfaces 32 of the core sections 3. Here, the side surfaces of the excitation light optical path 6 may be appropriately processed to facilitate leakage of the excitation light 4D toward the cladding section 2 covering these side surfaces.

[0035] The pumping lights 4A, 4B, 4C, and 4D described above may be, for example, semiconductor laser lights having an absorption wavelength of the laser gain medium.

[0036] 4A and 4B, by injecting the pumping light 4D into the pumping light optical path 6 from its end face, it is possible to amplify the seed light present inside all of the core portions 3. Therefore, in the cases of FIGS. 4A and 4B, unlike the case of FIG. 3A, it is possible to amplify the seed light present inside all of the core portions 3 simply by injecting the pumping light 4D into the pumping light optical path 6 from its end face at once.

[0037] As described above, the laser amplification medium 1 according to this embodiment can amplify the seed light present inside all of the core portions 3 by simultaneously inputting the pumping light 4B, 4C, or 4D.

[0038] An example of a method for easily manufacturing the laser amplifying medium 1 shown in FIG. 1A, that is, a method for manufacturing the laser amplifying medium 1 according to this embodiment, will be described with reference to FIG. 5 and FIGS. 6A to 6H. FIG. 5 is a flowchart showing an example of a configuration of a method for manufacturing the laser amplifying medium 1 according to an embodiment. FIG. 6A is a cross-sectional view showing that the laser amplifying medium 1 of FIG. 1A can be manufactured by laminating a first substrate 11 and a second substrate 12. FIGS. 6B to 6H are cross-sectional views showing an example of a state during the manufacturing of the laser amplifying medium 1. In addition, in this Disclosure In all the figures, the stacking direction is the Z-axis direction.

[0039] The flowchart of Fig. 5 includes a total of four steps, from a first step S1 to a fourth step S4. When the flowchart of Fig. 5 starts, the first step S1 is executed.

[0040] In the first step S1, a first substrate 11 is produced. Here, the first substrate 11 includes a first portion 20. The first substrate 11 may be composed of only the first portion 20. The first portion 20 is made of a first material that constitutes the cladding portion 2 of the laser amplification medium 1. This first material may be, for example, glass having predetermined properties, YAG (Yttrium Aluminum Garnet) crystal, or YAG ceramics. The first material has the same refractive index as the cladding portion 2.

[0041] 6B shows a cross section of first substrate 110 that is thicker than the desired thickness. In the first step S1, first, first substrate 110 that is thicker than the desired thickness may be produced, and then a portion of first substrate 110 may be removed from one or both sides of first substrate 110 to produce first substrate 11 of the desired thickness. Known methods for removing first substrate 110 include, for example, chemical mechanical polishing (CMP), which is used in semiconductor manufacturing methods.

[0042] This scraping step may be performed as part of the first step S1, or may be performed as a separate step from the first step S1, in which case the first step S1 may produce a thicker first substrate 110 instead of producing a first substrate 11 having the desired thickness.

[0043] In the first step S1, the required number of first substrates 11, 110 may be produced all at once. Alternatively, the required number of first substrates 11, 110 may be produced little by little by executing the first step S1 multiple times before and after other steps.

[0044] Following the first step S1, a second step S2 is performed. In the second step S2, a second substrate 12 is produced. Here, the second substrate 12 includes a first portion 20 and a second portion 30. The second substrate 12 may be composed of only the first portion 20 and the second portion 30. The second portion 30 may be composed of a second material. The second material is the material that constitutes the core portion 3 of the laser gain medium 1, and is obtained, for example, by doping glass, YAG crystal, or YAG ceramic with ions of an appropriate active element as a laser gain medium. This active element may be, for example, neodymium, ytterbium, erbium, or the like.

[0045] The second material preferably has the same refractive index as the core portion 3. However, the refractive index of the core portion 3 may be uniform throughout its entire area, or may vary continuously depending on the distance from the optical axis 31 in the radial direction.

[0046] The multiple second portions 30 formed by ion doping do not necessarily have an ideal shape due to factors such as manufacturing errors. Here, the ideal shape is a rectangular parallelepiped extending in the same direction, like the core portion 3 in FIG. 1A. However, in this embodiment, even if realistic manufacturing errors are included, as long as the core portion 3 has a shape with sufficient precision for practical use, it is simply called a "rectangular parallelepiped." The same applies to other geometric definitions.

[0047] 6C shows a cross section of second substrate 120 that is thicker than the desired thickness. In second step S2, similar to first step S1, second substrate 120 that is thicker than the desired thickness may first be produced, and then one or both sides of second substrate 120 may be scraped away to produce second substrate 12 of the desired thickness. This scraping step may be performed as part of second step S2 or may be performed as a step separate from second step S2. In this regard, second portion 30 may be exposed on one surface of second substrate 120, but may not necessarily extend to the other surface.

[0048] In the second step S2, the required number of second substrates 12, 120 may be produced all at once. Alternatively, the required number of second substrates 12, 120 may be produced little by little by executing the second step S2 multiple times before and after other steps.

[0049] After the second step S2, the third step S3 is performed. In the third step S3, the first substrates 11, 110 and the second substrates 12, 120 are stacked. At this time, one surface of the second substrates 12, 120 is bonded to one surface of the first substrates 11, 110. This bonding preferably involves bonding both first portions 20 so that they are optically integrated. Here, bonding that results in optical integration means, for example, bonding that does not cause undesired phenomena such as refraction, reflection, diffraction, or scattering when light passes through the bonding surface, or even if such phenomena occur, they are negligible in practical terms. The first substrates 11, 110 and the second substrates 12, 120 after optical integration may each be referred to as a virtual substrate, a virtual layer, or the like. Furthermore, the bonding surface after optical integration may also be referred to as a virtual surface, a virtual plane, a virtual bonding surface, or the like.

[0050] Known methods for achieving such bonding include room temperature bonding. In either case, it is preferable to process the surfaces to be bonded by polishing or other methods before bonding.

[0051] In FIG. 6D, the surface of the second substrate 120 where the second portion 30 is exposed is bonded to the surface of the first substrate 110. After this, a scraped-off portion 121 is removed down to a predetermined thickness from the unbonded surface of the second substrate 120, thereby producing a second substrate 12 having a desired thickness. FIG. 6E shows the bonded body of the first substrate 110 and the second substrate 12 after the scraped-off portion 121 of FIG. 6D has been removed. In the state shown in FIG. 6E, the side surface of the second portion 30 to be used as the future core portion 3 preferably includes at least a planar portion in the +Z-axis direction and a planar portion in the -Z-axis direction, both of which are parallel to the XY plane, i.e., parallel to each other. In other words, the side surface 32 of each core portion 3 of the laser amplification medium 1 according to this embodiment preferably includes at least two planar portions facing each other in the Z-axis direction at the virtual bonding surface of the first substrate 11 and the second substrate 12.

[0052] The third step S3 may be repeated as many times as necessary, or may be repeated little by little in accordance with the timing of performing the first step S1 for producing the first substrates 11, 110 and the second step S2 for producing the second substrates 12, 120.

[0053] In Figure 6F, a new first substrate 110 is further laminated on the surface of second substrate 12 laminated on first substrate 110. Thereafter, a shaved-off portion 111 down to a predetermined thickness is scraped off from the surface of the new first substrate 110 that is not bonded, thereby generating a first substrate 11 having a desired thickness. Figure 6G shows the bonded body of first substrate 110, second substrate 12, and new first substrate 11 after scraping off shaved-off portion 111 of Figure 6F.

[0054] 6H shows a laminate in which the first substrates 11, 110 and the second substrate 12 are laminated the number of times required to produce the laser amplification medium 1 of FIG. 1A. After this, the scraped-off portions 111 are scraped off from each of the bottom and top first substrates 110, thereby forming the bottom and A first substrate 11 having a desired thickness for each of the uppermost layers is produced, and the laser amplifying medium 1 of FIG. 6A is produced, that is, the laser amplifying medium 1 of FIG. 1A is produced.

[0055] After the third step S3, a fourth step S4 is performed. In the fourth step S4, finishing is performed. For example, the finishing performed here may involve polishing or other processing on the end faces in the X-axis direction and / or the Y-axis direction of the laser amplification medium 1 in FIG. 6A.

[0056] In particular, it is preferable that one end face in the X-axis direction of the laser amplification medium 1 is processed to a state suitable for optically connecting a front-end device for inputting seed light to be amplified into each core portion 3. It is also preferable that the other end face in the X-axis direction of the laser amplification medium 1 is processed to a state suitable for externally emitting laser light amplified in each core portion 3. Alternatively, it is preferable that the other end face in the X-axis direction of the laser amplification medium 1 is processed to a state suitable for optically connecting a rear-end device for combining multiple laser light beams amplified in the multiple core portions 3 into one high-power laser light.

[0057] When the fourth step S4 is completed, the flowchart of FIG. 5 also ends.

[0058] In the manufacturing method of the laser amplification medium 1 according to this embodiment, various modifications can be made to the flowchart of Fig. 5 described above. For example, in the second step S2, the first portion 20 and the second portion 30 may be separately generated, processed into a desired shape, and then alternately bonded to generate the second substrate 12. In this case, it is expected that the shape of the core portion 3 can be made closer to an ideal rectangular parallelepiped.

[0059] A modified example of lamination of the laser amplifying medium 1 according to this embodiment will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view of an example of a configuration of the laser amplifying medium 1 according to one embodiment.

[0060] In the modification of Fig. 7, a plurality of first substrates 11 and a plurality of second substrates 12 are alternately stacked in the Z-axis direction. However, among the plurality of stacked second substrates 12, in any combination of two second substrates 12 that are closest to each other with one first substrate 11 sandwiched therebetween, the arrangement of the plurality of core portions 3 in the Y-axis direction is staggered. In other words, two first substrates 11 and one second substrate 12 are sandwiched between any core portion 3 and the core portion 3 that is closest to this any core portion 3 in the +Z-axis direction or the -Z-axis direction. In further other words, in the modification of Fig. 7, in a cross section of the laser amplification medium 1 taken along a virtual plane orthogonal to the X-axis direction, the plurality of core portions 3 are arranged in a so-called staggered array.

[0061] As described above, the laser amplification medium 1 according to this embodiment can be manufactured by alternately stacking the first substrate 11 and the second substrate 12, and therefore, it is possible to easily adopt a modified example such as that shown in Fig. 7. Such a modified example is expected to be advantageous for making the pumping light 4B more uniformly incident on all of the core portions 3 when the pumping light 4B is incident from the side surface of the cladding portion 2, for example, as shown in Fig. 3B.

[0062] (Second embodiment) An example of the configuration of the laser amplification medium 1 according to another embodiment will be described with reference to Fig. 8. Fig. 8 is a perspective overhead view showing an example of a partial configuration of the laser amplification medium 1 according to an embodiment.

[0063] The laser amplification medium 1 in Fig. 8 includes a cladding portion 2, a core portion 3, and a plurality of flow paths 5. In the example of Fig. 8, the total number of flow paths 5 is 8 and the total number of core portions 3 is 1, but these numerical values ​​are merely an example and do not limit the present embodiment. On the other hand, it is preferable that the cladding portion 2 is a single portion.

[0064] The flow path 5 is a cavity provided inside the cladding portion 2 and extends in the same X-axis direction as the core portion 3. The flow path 5 penetrates the cladding portion 2 in the X-axis direction. The flow path 5 may be defined as a side surface parallel to the X-axis direction.

[0065] In the example of FIG. 8, the cross section of the flow channel 5 taken along a virtual plane perpendicular to the X-axis direction is rectangular. The rectangular shape of the flow channel 5 may be a different rectangle from the rectangular shape of the cross section of the core portion 3 taken along the same plane. In the example of FIG. 8, the rectangular shape of the flow channel 5 has a larger area than the rectangular shape of the core portion 3. Here, the cross-sectional shape and cross-sectional area of ​​the flow channel 5 are merely examples, and the cross section of the flow channel 5 may have a shape other than a rectangle, and may not necessarily be larger than the cross-sectional area of ​​the core portion 3.

[0066] An example of a method for manufacturing the flow channel 5 will be described. The flow channel 5 may be generated, for example, by forming a cavity inside the cladding portion 2 of the laser amplification medium 1 according to the first embodiment. Known specific methods for this include microfabrication techniques such as ablation using a femtosecond laser.

[0067] An example of a method for using the flow path 5 according to this embodiment will be described with reference to Fig. 9. Fig. 9 is a graph for explaining an example of a method for controlling the temperature of the laser amplification medium 1 by flowing a predetermined fluid through the laser amplification medium 1 using the flow path 5 according to one embodiment.

[0068] In the graph of FIG. 9, the horizontal axis represents time, and the vertical axis represents the temperature of the laser amplification medium 1. On the vertical axis, the target temperature at which the laser amplification medium 1 functions most efficiently is represented by "T0", and the minimum and maximum temperatures at which the laser amplification medium 1 functions properly are represented by "T min " and "T max " is expressed as

[0069] The temperature of the laser amplification medium 1 reaches the maximum temperature T max When the temperature of the laser amplification medium 1 exceeds the target temperature T0, the cooling C of the laser amplification medium 1 is performed by flowing a fluid whose temperature is equal to or lower than the target temperature T0 through the flow path 5, and the temperature of the laser amplification medium 1 can be brought closer to the target temperature T0. minWhen the temperature of the laser amplification medium 1 falls below the target temperature T0, a fluid having a temperature equal to or higher than the target temperature T0 is passed through the flow path 5 to heat the laser amplification medium 1 (H), thereby bringing the temperature of the laser amplification medium 1 closer to the target temperature T0. This fluid may be a liquid or a gas. One example of this fluid is helium gas. By using a fluid having a desired refractive index, scattering of the pumping light 4A, 4B, and 4C inside the laser amplification medium 1 may be suppressed, or conversely, scattering may be promoted. If scattering is suppressed, it is expected that the pumping light 4A, 4B, and 4C will be able to reach a core 3 that is further away. Conversely, if scattering is promoted, it is expected that the pumping light 4A, 4B, and 4C will be able to reach a core 3 that is hidden behind another core 3 more easily.

[0070] 10A and 10B, a description will be given of a configuration example of a laser amplifying medium 1 including a plurality of core portions 3 and a plurality of flow paths 5. Fig. 10A is a cross-sectional view showing a configuration example of a laser amplifying medium 1 according to an embodiment. Fig. 10B is a cross-sectional view showing another configuration example of a laser amplifying medium 1 according to an embodiment.

[0071] The laser amplification medium 1 of Figure 10A can be obtained, for example, by increasing the number of core portions 3 of the laser amplification medium 1 shown in Figure 8 to a total of 16 and arranging them in a 4 x 4 two-dimensional array as in the case of Figure 1A, and by increasing the number of flow paths 5 shown in Figure 8 to a total of 20 and arranging them around the 16 core portions 3.

[0072] The laser amplifying medium 1 of Fig. 10B can be obtained by, for example, changing the number of flow paths 5 of the laser amplifying medium 1 of Fig. 10A to 24 in total and the number of core portions 3 to 18 in total, and arranging these 42 flow paths 5 and core portions 3 in a 6 x 7 two-dimensional array in a cross section of an imaginary plane perpendicular to the X-axis direction. However, in this two-dimensional array, the flow paths 5 and core portions 3 are alternately arranged in the Z-axis direction, and six flow paths 5 and six core portions 3 are arranged in the Y-axis direction. In this case, when focusing on the core portions 3, they are arranged in a 6 x 3 two-dimensional array. Also, when focusing on the flow paths 5, they are arranged in a 6 x 4 two-dimensional array.

[0073] Consider the thermal resistance R1 between the core portion 3A and the flow path 5 and the thermal resistance R2 between the core portion 3B and the flow path 5 in FIG. 10A. The core portion 3A is located on the outside of the 4×4 two-dimensional array. Therefore, there are no other core portions 3 between the core portion 3A and the flow path 5A, which is the closest to the core portion 3A. On the other hand, the core portion 3B is located on the inside of the 4×4 two-dimensional array. Therefore, there are other core portions 3 between the core portion 3B and the flow path 5B, which is the closest to the core portion 3B. Therefore, the thermal resistance R2 is considered to be greater than the thermal resistance R1. In other words, when the same fluid is flowed through all the flow paths 5 under the same conditions, it is more difficult to control the temperature of the core portion 3B than the core portion 3A. In other words, it is more likely that a temperature difference will occur between the core portion 3A and the core portion 3B.

[0074] Similarly, in FIG. 10B, consider the thermal resistance R3 between the core portion 3C and the flow path 5 and the thermal resistance R4 between the core portion 3D and the flow path 5. The core portion 3C is located on the outside of the 6×3 two-dimensional array. On the other hand, the core portion 3D is located on the inside of the same two-dimensional array. Here, there are no other core portions 3 between the core portion 3C and the flow paths 5C and 5D, which are closest to the core portion 3C. Similarly, there are no other core portions 3 between the core portion 3D and the flow paths 5E and 5F, which are closest to the core portion 3D. Therefore, the thermal resistances R3 and R4 are considered to be the same. In other words, a temperature difference is unlikely to occur between the core portion 3C and the core portion 3D. In other words, it is considered easier to uniformly control the temperatures of multiple core portions 3 in the case of FIG. 10B compared to the case of FIG. 10A. This leads to the laser amplification medium 1 being able to output higher quality laser light.

[0075] Taking this idea a step further, the flow paths 5 and core portions 3 may be arranged as shown in Fig. 11. Fig. 11 is a cross-sectional view showing yet another configuration example of the laser amplification medium 1 according to an embodiment. In Fig. 11, the plurality of flow paths 5 and the plurality of core portions 3 are arranged in a so-called checker array. In other words, the flow paths 5 and the core portions 3 are arranged in a two-dimensional array in a cross section taken along an imaginary plane perpendicular to the X-axis direction, where the core portions 3 are adjacent to the flow paths 5 in the Y-axis and Z-axis directions, and the flow paths 5 are adjacent to the core portions 3 in the Y-axis and Z-axis directions.

[0076] (Third embodiment) The polarization-controllable laser amplification medium 1 will be described with reference to Fig. 12. Fig. 12 is a cross-sectional view showing an example of the configuration of the laser amplification medium 1 according to an embodiment.

[0077] The laser amplifying medium 1 of FIG. 12 can be obtained, for example, by increasing the number of core portions 3 of the laser amplifying medium 1 of FIG. 1A to a total of 25 and replacing 15 of them with stress-applying portions 7. Here, the remaining 10 core portions 3 and 15 stress-applying portions 7 each have a rectangular parallelepiped shape extending in the X-axis direction. In a cross section taken along a virtual plane perpendicular to the X-axis direction, the core portions 3 and the stress-applying portions 7 are arranged in a 5×5 two-dimensional array. Here, the stress-applying portions 7 and the core portions 3 are arranged alternately in the Y-axis direction. Furthermore, in the Z-axis direction, five of each of the stress-applying portions 7 and the core portions 3 are arranged in a row. In other words, in the laser amplifying medium 1 of FIG. 12, a stress-applying portion 7 is arranged on both sides in the Y-axis direction for each of the multiple core portions 3.

[0078] The stress-applying portion 7 may be formed, for example, in the same manner as the core portion 3, or may be formed by opening a flow path 5 inside the cladding portion 2 and pouring and solidifying an appropriate material into the internal space. In either case, the core portion 3 is subjected to stress from both sides in the Y-axis direction, thereby controlling the polarization direction of light propagating inside the core portion 3 in the X-axis direction to approach the Z-axis direction. This enables the laser amplification medium 1 to output higher quality laser light. It may also be possible to use it in applications such as beam combining using linearly polarized light and harmonic generation using nonlinear optical phenomena.

[0079] The invention made by the inventor has been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from the spirit of the invention. Furthermore, the features described in the above embodiments can be freely combined within the scope of technical compatibility. [Explanation of symbols]

[0080] 1 Laser amplification medium 10 units laser amplification medium 11, 110 First board 111 Scraped-off part 12, 120 Second board 121 Scraped-off part 2 Cladding section 2A Inner cladding 2B Outer cladding part 20 Part 1 3, 3A, 3B, 3C, 3D core section 30 Part 2 31 Optical axis 32 Side 4A, 4B, 4C, 4D Excitation light 5, 5A, 5B, 5C, 5D, 5E, 5F flow path 6. Excitation light path 7 Stress applying section C cooling H heating R1, R2, R3, R4 thermal resistance T0 target temperature T min minimum temperature T max highest temperature

Claims

1. a cladding portion having a first predetermined refractive index; a first core portion and a second core portion each having a second refractive index higher than the first refractive index, extending parallel to a predetermined axial direction, and each having a side surface covered with the cladding portion; a virtual first layer including a part of the cladding portion, the first core portion, and the second core portion; a virtual second layer and a virtual third layer each including another part of the cladding portion; Equipped with the first layer is stacked and joined between the second layer and the third layer in a predetermined stacking direction perpendicular to the axial direction, In each of the first core portion and the second core portion, the side surface is a first planar portion of the first layer, the first planar portion being included in a virtual first surface that is a virtual joint surface with the second layer and is perpendicular to the stacking direction; a second flat surface portion of the first layer, which is a virtual joint surface with the third layer and is included in a virtual second surface perpendicular to the stacking direction, and which faces the first flat surface portion; Equipped with The cladding portion is A side surface configured to allow excitation light to enter from the outside Equipped with Laser amplification medium.

2. 2. The laser amplification medium according to claim 1, a third core portion and a fourth core portion each having the second refractive index, extending parallel to the axial direction, and each having a side surface covered by the cladding portion; a virtual fourth layer including a part of the cladding portion, the third core portion, and the fourth core portion; a virtual fifth layer including another part of the cladding portion; Furthermore, the fourth layer is stacked and joined between the third layer and the fifth layer in the stacking direction, In each of the third core portion and the fourth core portion, the side surface is a third planar portion of the fourth layer, the third planar portion being a virtual joint surface with the third layer and included in a virtual third surface perpendicular to the stacking direction; a fourth flat surface portion that is a virtual joint surface of the fourth layer with the fifth layer and is included in a virtual fourth surface perpendicular to the stacking direction, and that faces the third flat surface portion; Equipped with Laser amplification medium.

3. 3. The laser amplification medium according to claim 2, In a cross section taken along a virtual plane perpendicular to the axial direction, the first core portion, the second core portion, the third core portion, and the fourth core portion are arranged in a staggered arrangement. Laser amplification medium.

4. The laser amplification medium according to any one of claims 1 to 3, The cladding portion is An end face configured to allow excitation light to enter from the outside Equipped with a second cladding portion having a third refractive index lower than the first refractive index and covering the side surface of the cladding portion; Further equipped Laser amplification medium.

5. a cladding portion having a first predetermined refractive index; a first core portion and a second core portion each having a second refractive index higher than the first refractive index, extending parallel to a predetermined axial direction, and each having a side surface covered with the cladding portion; a virtual first layer including a part of the cladding portion, the first core portion, and the second core portion; a virtual second layer and a virtual third layer each including another part of the cladding portion; Equipped with the first layer is stacked and joined between the second layer and the third layer in a predetermined stacking direction perpendicular to the axial direction, In each of the first core portion and the second core portion, the side surface is a first planar portion of the first layer, the first planar portion being included in a virtual first surface that is a virtual joint surface with the second layer and is perpendicular to the stacking direction; a second planar portion that is included in a virtual second surface of the first layer, which is a virtual joint surface with the third layer and is perpendicular to the stacking direction, and faces the first planar portion; Equipped with an optical path for excitation light extending in the axial direction so that a side surface is covered by the cladding portion; Furthermore, The side surface of the optical path for pumping light is configured so that the pumping light incident from the end face of the optical path for pumping light leaks out to the cladding portion through the side surface. Laser amplification medium.

6. a cladding portion having a first predetermined refractive index; a first core portion and a second core portion each having a second refractive index higher than the first refractive index, extending parallel to a predetermined axial direction, and each having a side surface covered with the cladding portion; a virtual first layer including a part of the cladding portion, the first core portion, and the second core portion; a virtual second layer and a virtual third layer each including another part of the cladding portion; a third core portion and a fourth core portion each having the second refractive index, extending parallel to the axial direction, and each having a side surface covered by the cladding portion; a virtual fourth layer including a part of the cladding portion, the third core portion, and the fourth core portion; a virtual fifth layer including another part of the cladding portion; Equipped with the first layer is stacked and joined between the second layer and the third layer in a predetermined stacking direction perpendicular to the axial direction, In each of the first core portion and the second core portion, the side surface is a first planar portion of the first layer, the first planar portion being included in a virtual first surface that is a virtual joint surface with the second layer and is perpendicular to the stacking direction; a second planar portion that is included in a virtual second surface of the first layer, which is a virtual joint surface with the third layer and is perpendicular to the stacking direction, and faces the first planar portion; Equipped with the fourth layer is stacked and joined between the third layer and the fifth layer in the stacking direction, In each of the third core portion and the fourth core portion, the side surface is a third planar portion of the fourth layer, the third planar portion being a virtual joint surface with the third layer and included in a virtual third surface perpendicular to the stacking direction; a fourth planar portion that is a virtual joint surface of the fourth layer with the fifth layer and is included in a virtual fourth surface perpendicular to the stacking direction, and that faces the third planar portion; Equipped with a plurality of flow paths extending in the axial direction so that their sides are covered by the cladding portion, the flow paths being configured so that a predetermined fluid passes through the inside of the flow paths; Furthermore, In a cross section perpendicular to the axial direction, a cross-sectional area of ​​the flow path is larger than a cross-sectional area of ​​the first core portion and a cross-sectional area of ​​the second core portion, The first core portion, the second core portion, the third core portion, and the fourth core portion are arranged alternately with the plurality of flow paths in the stacking direction, or the first core portion, the second core portion, the third core portion, and the fourth core portion are arranged alternately adjacent to the plurality of flow paths in the stacking direction and a direction perpendicular to the stacking direction. Laser amplification medium.

7. 7. The laser amplification medium according to claim 1, a stress-applying portion that applies stress from both sides toward the first core portion in a direction orthogonal to both the axial direction and the stacking direction, thereby controlling polarization of light propagating through the first core portion; Further equipped Laser amplification medium.

8. creating a first layer including a plurality of first regions having a first predetermined refractive index and a plurality of second regions having a second refractive index greater than the first refractive index; creating a second layer and a third layer having the first refractive index; stacking the second layer, the first layer, and the third layer in this order in a predetermined stacking direction; Including, The laminating step comprises: bonding the second layer to a first surface of the first layer, the first surface being perpendicular to the stacking direction, so as to bond the plurality of first regions and the second layer; bonding the third layer to a second surface of the first layer opposite the first surface so as to bond the plurality of first regions and the third layer; Including, The plurality of second regions are a first core portion and a second core portion each having a side surface that extends parallel to a predetermined axial direction parallel to the first surface and includes a first flat portion included in the first surface and a second flat portion included in the second surface; Equipped with the integrated first regions, the second layer, and the third layer function as clad portions that cover the side surfaces of the first core portion and the second core portion, respectively; The cladding portion is A side surface configured to allow excitation light to enter from the outside Equipped with A method for manufacturing a laser amplification medium.

9. 9. The method for manufacturing a laser amplification medium according to claim 8, creating a fourth layer including a plurality of third regions having the first refractive index and a plurality of fourth regions having the second refractive index; creating a fifth layer having the first refractive index; the third layer, the fourth layer, and the fifth layer are stacked in this order in the stacking direction; further comprising The laminating of the third layer, the fourth layer, and the fifth layer includes: bonding the third layer to a third surface of the fourth layer that is perpendicular to the stacking direction, thereby optically integrating the third regions and the third layer; bonding the fifth layer to a fourth surface of the fourth layer opposite to the third surface, thereby optically integrating the plurality of third regions and the fifth layer; Including, The plurality of fourth regions are a third core portion and a fourth core portion each having a side surface that extends in the axial direction and includes a third flat surface portion included in the third surface and a fourth flat surface portion included in the fourth surface; Equipped with The integrated third regions, the third layer, and the fifth layer function as cladding portions that cover the side surfaces of the third core portion and the fourth core portion, respectively. A method for manufacturing a laser amplification medium.

10. creating a first layer including a plurality of first regions having a first predetermined refractive index and a plurality of second regions having a second refractive index greater than the first refractive index; creating a second layer and a third layer having the first refractive index; stacking the second layer, the first layer, and the third layer in this order in a predetermined stacking direction; Including, The laminating step comprises: bonding the second layer to a first surface of the first layer, the first surface being perpendicular to the stacking direction, so as to bond the plurality of first regions and the second layer; bonding the third layer to a second surface of the first layer opposite the first surface so as to bond the plurality of first regions and the third layer; Including, The plurality of second regions are a first core portion and a second core portion each having a side surface that extends parallel to a predetermined axial direction parallel to the first surface and includes a first flat portion included in the first surface and a second flat portion included in the second surface; Equipped with The integrated first regions, the second layer, and the third layer function as cladding portions that cover the side surfaces of the first core portion and the second core portion, respectively. A method for manufacturing a laser amplification medium, comprising: an optical path for excitation light extending in the axial direction so that a side surface thereof is covered with the cladding portion; The side surface of the optical path for pumping light is configured so that pumping light incident from an end face of the optical path for pumping light leaks out to the cladding portion through the side surface. A method for manufacturing a laser amplification medium.

11. creating a first layer including a plurality of first regions having a first predetermined refractive index and a plurality of second regions having a second refractive index greater than the first refractive index; creating a second layer and a third layer having the first refractive index; stacking the second layer, the first layer, and the third layer in this order in a predetermined stacking direction; Including, The laminating step comprises: bonding the second layer to a first surface of the first layer, the first surface being perpendicular to the stacking direction, so as to bond the plurality of first regions and the second layer; bonding the third layer to a second surface of the first layer opposite the first surface so as to bond the plurality of first regions and the third layer; Including, The plurality of second regions are a first core portion and a second core portion each having a side surface that extends parallel to a predetermined axial direction parallel to the first surface and includes a first flat portion included in the first surface and a second flat portion included in the second surface; Equipped with the integrated first regions, the second layer, and the third layer function as clad portions that cover the side surfaces of the first core portion and the second core portion, respectively; creating a fourth layer including a plurality of third regions having the first refractive index and a plurality of fourth regions having the second refractive index; creating a fifth layer having the first refractive index; the third layer, the fourth layer, and the fifth layer are stacked in this order in the stacking direction; further comprising The laminating of the third layer, the fourth layer, and the fifth layer includes: bonding the third layer to a third surface of the fourth layer that is perpendicular to the stacking direction, thereby optically integrating the third regions and the third layer; bonding the fifth layer to a fourth surface of the fourth layer opposite to the third surface, thereby optically integrating the plurality of third regions and the fifth layer; Including, The plurality of fourth regions are a third core portion and a fourth core portion each having a side surface that extends in the axial direction and includes a third flat surface portion included in the third surface and a fourth flat surface portion included in the fourth surface; Equipped with The integrated third regions, the third layer, and the fifth layer function as cladding portions that cover the side surfaces of the third core portion and the fourth core portion, respectively. A method for manufacturing a laser amplification medium, comprising: a plurality of flow paths extending in the axial direction so that a side surface thereof is covered by the cladding portion, the flow paths being configured so that a predetermined fluid passes through the inside of the flow paths; In a cross section perpendicular to the axial direction, a cross-sectional area of ​​the flow path is larger than a cross-sectional area of ​​the first core portion and a cross-sectional area of ​​the second core portion, The first core portion, the second core portion, the third core portion, and the fourth core portion are arranged alternately with the plurality of flow paths in the stacking direction, or the first core portion, the second core portion, the third core portion, and the fourth core portion are arranged alternately adjacent to the plurality of flow paths in the stacking direction and a direction perpendicular to the stacking direction. A method for manufacturing a laser amplification medium.

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