WAVEL BEAM COMBINATION DEVICE, DIRECT DIODE LASER DEVICE, AND LASER PROCESSING MACHINE

Abstract

A wavelength beam combining device for combining laser beams having different peak wavelengths comprises: a first optical component that separates the laser beams into first polarization beams, which are linearly polarized in a first polarization direction, and second polarization beams, which are linearly polarized in a second polarization direction orthogonal to the first polarization direction; a first polarization conversion element that converts the second polarization beams into third polarization beams, which are linearly polarized in the first polarization direction; a first and a second mirror that reflect the first and second polarization beams, respectively.third polarization rays reflect; a first diffraction element that receives the first polarization rays and diffractes them to form a first wavelength-combined ray that is coaxially combined; a second diffraction element that receives the third polarization rays and diffractes them to form a second wavelength-combined ray in which the third polarization rays are coaxially combined; and a second optical component onto which the first and second wavelength-combined rays are incident.

Description

CROSS-REFERENCE TO RELATED REGISTRATIONS

[0001] This application claims priority over Japanese patent application No. 2024-111003, filed on July 10, 2024, the entire contents of which are hereby incorporated by reference. BACKGROUND Technical area

[0002] The present disclosure relates to a wavelength beam combination device, a direct diode laser device and a laser processing machine. State of the art

[0003] High-power, high-brightness laser beams are used to perform machining operations, such as cutting, drilling, and marking, on various types of materials or weldable metals. Some carbon dioxide gas laser machining machines and some YAG solid-state laser machining machines, previously used for such laser processing, are being replaced by fiber laser machining machines, which offer high energy conversion efficiency. A laser diode (hereinafter referred to simply as LD) is used as the pump light source of a fiber laser machining machine. In recent years, with the increasing availability of LDs, technology has been developed to use the LD not as a pump light source, but as the light source of a laser beam that directly irradiates and processes a material. This technology is called direct diode laser (DDL) technology.

[0004] US Patent No. 6192062 discloses an example of a light source device that increases light output by combining a plurality of laser beams having different peak wavelengths and emitted by a plurality of laser lights. Coaxially combining a plurality of laser beams with different wavelengths is referred to as "wavelength beam combining (WBC)" or "spectral beam combining (SBC)" and can be used, for example, to increase the light output and brightness of a DDL device.

[0005] Japanese patent application No. 2023-088438 A discloses a wavelength beam combination device in which a plurality of diffraction gratings are arranged in series on an optical path. OVERVIEW

[0006] There is a need for a wavelength beam combination device that can combine a plurality of laser beams having different peak wavelengths with low loss.

[0007] A wavelength beam combining device according to certain embodiments of the present disclosure is a wavelength beam combining device configured to combine a plurality of laser beams having different peak wavelengths, wherein the wavelength beam combining device comprises: a first optical component configured to separate the plurality of laser beams into a plurality of first polarization beams linearly polarized in a first polarization direction and a plurality of second polarization beams linearly polarized in a second polarization direction orthogonal to the first polarization direction; a first polarization conversion element configured to convert the plurality of second polarization beams into a plurality of third polarization beams linearly polarized in the first polarization direction;a plurality of first mirrors, each configured to reflect one of the plurality of first polarization rays towards a first diffraction position; a plurality of second mirrors, each configured to reflect one of the plurality of third polarization rays towards a second diffraction position; a first diffraction element configured at the first diffraction position to receive the plurality of first polarization rays reflected by the plurality of first mirrors and to diffract the plurality of first polarization rays to form a first wavelength-combined beam in which the plurality of first polarization rays are coaxially combined;a second diffraction element configured to receive, at the second diffraction position, the majority of third polarization rays reflected by the majority of second mirrors, and to diffract the majority of third polarization rays to form a second wavelength-combined beam in which the majority of third polarization rays are coaxially combined; and a second optical component onto which the first wavelength-combined beam and the second wavelength-combined beam are incident.

[0008] A direct diode laser device according to the present disclosure includes the wavelength beam combination device and a laser light source configured to emit a plurality of laser beams that are parallel to each other.

[0009] A laser processing machine according to the present disclosure comprises at least one direct diode laser device, which is the direct diode laser device described above; an optical transmission fiber to be coupled to a laser beam emitted by the at least one direct diode laser device; and a processing head connected to the optical transmission fiber.

[0010] According to one embodiment of the present disclosure, it is possible to provide a wavelength beam combination device that can combine a plurality of laser beams having different peak wavelengths with low loss. BRIEF DESCRIPTION OF DRAWINGS Fig. Figure 1 is a diagram schematically representing a configuration of a wavelength beam combination device according to an exemplary embodiment of the present disclosure. Fig. Figure 2 is a perspective view that schematically illustrates a configuration example and function of a polarization beam splitter. Fig. Figure 3A is a perspective view that schematically illustrates a configuration example for a diffraction grating. Fig. 3B is a cross-sectional view that schematically illustrates a configuration example for the diffraction grating. Fig. 4 is a diagram that is a modified example of the one in Fig. Figure 1 schematically represents the wavelength beam combination device shown. Fig. Figure 5 is a diagram that schematically illustrates another configuration of the wavelength beam combination device according to the exemplary embodiment of the present disclosure. Fig. Figure 6 is a diagram that schematically illustrates yet another configuration of the wavelength beam combination device according to the exemplary embodiment of the present disclosure. Fig. Figure 7 is a diagram that schematically illustrates yet another configuration of the wavelength beam combination device according to the exemplary embodiment of the present disclosure. Fig. Figure 8 is a diagram showing a diffraction region in the wavelength beam combination device of Fig. 7 schematically represents. Fig. Figure 9 is a diagram that schematically illustrates yet another configuration of the wavelength beam combination device according to the exemplary embodiment of the present disclosure. Fig. Figure 10 is a diagram showing a diffraction region in the wavelength beam combination device of Fig. 9 schematically represents. Fig. Figure 11 is a schematic diagram representing a configuration of a direct diode laser device according to an exemplary embodiment of the present disclosure. Fig. Figure 12 is a schematic diagram representing a configuration of a laser processing machine according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0011] A wavelength beam combination device, a direct diode laser device, and a laser processing machine according to certain embodiments of the present disclosure are described below with reference to the drawings. Parts that have the same reference numerals in the majority of the drawings indicate identical or equivalent parts.

[0012] The embodiments described below are examples that illustrate the technical ideas of the present invention, but the present invention is not limited to the described embodiments. The descriptions of dimensions, materials, shapes, relative arrangements, and the like of components are not intended to limit the scope of the present invention but serve only for illustration. The sizes and positional relationships of components shown in the drawings may be exaggerated for clarity.

[0013] In the present description and within the scope of the claims, a polygon refers to a polygonal shape, such as a triangle or a quadrilateral, including a shape in which one corner of the polygon is rounded, chamfered, beveled, or grooved. A polygon includes not only a polygonal shape with such a modification at its corner (an end of a side), but also a polygonal shape with a modification at an intermediate part of a side. In other words, a polygon-based shape with partial modification is included in the interpretation of "polygon" as described in the present description and within the scope of the claims. Embodiments of Wavelength Beam Combination Device: First Embodiment

[0014] First, a configuration example of a wavelength beam combination device according to a first embodiment of the present disclosure is presented with reference to Fig. 1 described.

[0015] Fig. Figure 1 is a diagram schematically illustrating a configuration example for a wavelength beam combination device 100 according to the present embodiment. In each drawing, including Fig. Figure 1 shows a schematic representation of an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other. The direction of an arrow on the X-axis is called the +X direction, and the opposite direction is called the -X direction. If the ±X directions are not distinguished from each other, they are simply referred to as X directions. The same applies to a Y direction and a Z direction. This does not limit the orientation of the wavelength beam combination device 100 in use, and the wavelength beam combination device 100 can be used in any suitable orientation.

[0016] First, a schematic configuration of the wavelength beam combination device 100 is shown in the example of Fig. 1 described.

[0017] The wavelength beam combination device 100 is a device that combines a plurality of laser beams L with mutually different peak wavelengths and includes a first optical component 10 and a second optical component 12, each of which separates or combines light, a first polarization conversion element 20 and a second polarization conversion element 22 that change a polarization state of incident light and emit the light, a plurality of first mirrors 30A and a plurality of second mirrors 30B that change a direction of propagation of the incident light and reflect the light, and a first diffraction element 40A and a second diffraction element 40B that act as diffraction gratings.

[0018] The first optical component 10 separates the plurality of laser beams L into a plurality of first polarization beams L1, which are linearly polarized in a first polarization direction (Y-direction), and a plurality of second polarization beams L2, which are linearly polarized in a second polarization direction (X-direction) orthogonal to the first polarization direction (Y-direction). The first optical component 10 in the example of Fig. 1 is formed by a polarization beam splitter BS. As described below, the first optical component 10 is not limited to a single component and can include other optical elements in addition to the polarization beam splitter BS, such as a component that forms a reflection surface and a component that offsets an optical path.

[0019] The first polarization conversion element 20 converts the majority of the second polarization rays L2 into a majority of third polarization rays L3, which are linearly polarized in the first polarization direction (Y direction).

[0020] The majority of first mirrors 30A are arranged such that they reflect each of the majority of first polarization rays L1 in the direction of the first diffraction position P1.

[0021] The majority of the second mirrors 30B are arranged such that they reflect each of the majority of third polarization rays L3 in the direction of the second diffraction position P2.

[0022] The first diffraction element 40A receives the majority of first polarization rays L1, which are reflected by the majority of first mirrors 30A, at the first diffraction position P1 and diffractes the majority of first polarization rays L1 to form a first wavelength-combined beam CL1 in which the majority of first polarization rays L1 are coaxially combined.

[0023] The second diffraction element 40B receives the majority of third polarization rays L3 reflected by the majority of second mirrors 30B at the second diffraction position P2 and diffracts the majority of third polarization rays L3 to form a second wavelength-combined beam CL2 in which the majority of third polarization rays L3 are coaxially combined.

[0024] The second polarization conversion element 22 converts in the Fig. In the example shown, the polarization direction of the second wavelength-combined beam CL2 changes from the first polarization direction (Y-direction) to the second polarization direction (X-direction) in the Fig. (Example 1) orthogonal to the first polarization direction. The second polarization conversion element 22 can be arranged such that it changes the polarization direction of the first wavelength-converted beam CL1 from the first polarization direction (Y-direction) to a direction (Z-direction in which in Fig. (Example 1) converts the polarization direction orthogonally to the first polarization direction. Importantly, the second polarization conversion element 22 causes the polarization direction of the first wavelength-combined beam CL1 and the polarization direction of the second wavelength-combined beam CL2 to be orthogonal to each other, which allows polarization combining (multiplexing) by the second optical component 12.

[0025] The second optical component 12 is arranged such that the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are incident on the second optical component 12. In the Fig. In the example shown, the second optical component 12 includes a polarizing beam splitter BS, which coaxially combines the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 and emits the combined beam as a third wavelength-combined beam CL3. In a case where the second optical component 12 does not perform polarization combination by means of the polarizing beam splitter BS, the second optical component 12 can be formed by a condenser lens 50 without including the polarizing beam splitter BS. Such an example is described below.

[0026] In the example of Fig. 1 The third wavelength-combined beam CL3, condensed by the condenser lens 50, enters a core of an optical fiber 60 (is optically coupled to it).

[0027] In the wavelength beam combination device 100 according to the present embodiment, a single diffraction grating is placed on the optical path of each of the polarization beams (L1 and L3) instead of a plurality of diffraction gratings. Therefore, optical loss due to diffraction is reduced.

[0028] Furthermore, in the present embodiment, a plurality of laser beams L can be incident parallel to one another onto the first optical component 10. The polarization separation characteristic of the first optical component 10 depends on an angle of incidence, and thus the polarization separation of the laser beams L can be efficiently carried out by causing the laser beams L to be incident parallel to one another onto the first optical component 10. Each of the plurality of light beams separated by the first optical component 10 can be incident at a predetermined angle onto the first target diffraction element 40A or the second target diffraction element 40B through a corresponding plurality of first mirrors 30A or a corresponding plurality of second mirrors 30B.

[0029] The laser beam L and the components of the wavelength beam combination device 100 are described in detail below. Laser beam L

[0030] The majority of laser beams L exhibit different peak wavelengths, for example, within a predetermined wavelength range of 50 nm or less. This predetermined wavelength range corresponds to at least a portion of a wavelength range where the light absorption of the material being processed is high. If, for example, the absolute value of the difference between a maximum and a minimum value of the peak wavelengths is equal to or less than 50 nm, optical system elements exhibiting wavelength-dependent optical characteristics, such as the polarizing beam splitter BS, the polarizing conversion elements 20 and 22, and the condenser lens 50, can typically be used for a majority of light beams exhibiting different peak wavelengths, regardless of the wavelengths of the light beams.In a case where the material to be processed is made of copper, the predetermined wavelength range can be, for example, between 430 nm and 480 nm.

[0031] In Fig. Figure 1 shows three laser beams L with different peak wavelengths λ1, λ2, and λ3. The number of laser beams L is not limited to this example and can be two, four, or more. With a larger number, e.g., 10 or more, of laser beams L, the output and energy density of the wavelength-combined beam CL3, obtained by combining the majority of laser beams L, can be increased. If the interval between the peak wavelengths of the majority of laser beams L becomes narrower, the number of laser beams L within a predetermined wavelength range can be increased.

[0032] In the following, the peak wavelength of the plurality of laser beams L to be combined is also denoted by λn. Here, "n" is an integer of 1 or more and is used as a numerical value to distinguish it from the plurality of laser beams L. In the Fig. In the example shown, a relationship of λ1 < λ2 < λ3 is established.

[0033] In Fig. In 1, every laser beam L is represented by a simple straight line. An actual laser beam L is a light beam that has an intensity distribution in a plane orthogonal to the direction of propagation. The intensity distribution can be approximated by a distribution function, such as a Gaussian distribution, in a plane orthogonal to the direction of propagation of the light beam. The diameter of the light beam is defined, for example, by the size of a cross-sectional area that has an intensity equal to 1 / e 2-fold or more of the intensity at the center of the beam. e is the base of a natural logarithm. In the present disclosure, the laser beam L is collimated by an optical system, such as a collimating lens. In the drawings, a central axis of the light beam is represented by a straight line to schematically illustrate the direction of propagation of a collimated light beam, such as the laser beam L. These straight lines can be taken into account to indicate light rays passing through the center of the respective light beam.

[0034] The polarization state of the laser beam L can vary depending on, for example, a gain medium, a resonator, and the oscillation scheme of the laser light source. Furthermore, the polarization state of the laser beam L, which is in a specific polarization state at the stage where it is emitted by the semiconductor laser device, can be changed or depolarized, for example, as it passes through a transmission medium such as an optical fiber.

[0035] Each laser beam L is, for example, in a non-polarized state. For example, as described above, each laser beam L is obtained by emitting each laser beam L from the semiconductor laser device via the optical fiber.

[0036] In the present disclosure, “non-polarized light” means light that is not linearly polarized in a predetermined direction. As described above, “non-polarized light” in a broader sense can include circularly polarized light and elliptically polarized light. Furthermore, “non-polarized light” also includes a mixed state of linearly polarized light in which the polarization direction changes randomly or regularly depending on time or location. First optical component

[0037] The first optical component 10 in the example of Fig. 1 is the polarization beam splitter BS. The polarization beam splitter BS is made, for example, of quartz or synthetic quartz. The first optical component 10 has a polarization surface 10R for separating each incident laser beam L into light beams with different polarization states. The transmittance and reflectance of the polarization surface 10R differ depending on the polarization state of the laser beam L. The polarization surface 10R of the first optical component 10 can selectively reflect a polarization component linearly polarized in a predetermined direction and transmit a polarization component linearly polarized in a direction orthogonal to the predetermined direction. The polarization surface 10R is, for example, provided with a dielectric multilayer film that exhibits a dependence on polarized light.

[0038] In the Fig. In the example shown, the polarization surface 10R of the first optical component 10 is orthogonal to the XZ plane, and the normal to the polarization surface 10R lies in a plane parallel to the XZ plane. The propagation direction of the laser beam L is parallel to the XZ plane. In this description, light that is linearly polarized in the Y direction, which is a direction orthogonal to the XZ plane, is referred to as "S-polarized light," and light that is linearly polarized in a direction parallel to the XZ plane is referred to as "P-polarized light." In this description, the polarization direction of the S-polarized light is also referred to as the "first polarization direction," and the polarization direction of the P-polarized light is also referred to as the "second polarization direction." The second polarization direction is orthogonal to the first polarization direction.

[0039] In the accompanying drawings, a symbol with a cross surrounded by a small circle represents, in principle, "S-polarized light," and a symbol with a double-headed arrow represents "P-polarized light." Since the polarization direction of "P-polarized light" is parallel to the XZ plane and orthogonal to the direction of light propagation, if the direction of light propagation is rotated by reflection or diffraction while remaining parallel to the XZ plane, the polarization direction of "P-polarized light" will also be rotated into a plane parallel to the XZ plane. Therefore, in this description, the "second polarization direction" is defined as a direction that is orthogonal to the direction of light propagation and orthogonal to the first polarization direction.

[0040] Fig. Figure 2 is a perspective view that schematically illustrates a configuration example and function of the polarization beam splitter BS, which acts as the first optical component 10. Since it is Fig. Since figure 2 is a perspective view, the orientation of the "S-polarized light" is also indicated by a double arrow. In the example of Fig. 2. The laser beam L, which contains the S-polarized light and the P-polarized light, moves in the positive direction of the Z-axis and enters the polarization beam splitter BS. As in Fig. As shown in Figure 2, the polarization surface 10R of the polarization beam splitter BS reflects an S-polarization component from each of the laser beams L and transmits a P-polarization component from each of the laser beams L. Therefore, the polarization surface 10R of the polarization beam splitter BS separates the majority of laser beams L into a majority of first polarization beams L1, corresponding to S-polarized light, and a majority of second polarization beams L2, corresponding to P-polarized light. The majority of first polarization beams L1 (S-polarized) reflected by the polarization surface 10R of the polarization beam splitter BS propagate in the -X direction, and the majority of second polarization beams L2 (P-polarized) transmitted by the polarization surface 10R of the polarization beam splitter BS propagate in the +Z direction.

[0041] Each laser beam L can be incident on the polarization surface 10R at an angle of incidence in a range of, for example, 40° to 50°, preferably in a range of 42° to 48°. The closer the angle of incidence is to 45°, the higher the separation efficiency in separating the corresponding first polarization beam L1 and the second polarization beam L2 from each laser beam L.

[0042] If the majority of laser beams L incident on the polarization beam splitter BS are "unpolarized," the laser beams L are separated into a first polarization beam (S-polarized) L1 and a second polarization beam (P-polarized) L2. However, even if the laser beam L is linearly polarized light in which S-polarized and P-polarized light are combined, such a laser beam L is separated into the first polarization beam (S-polarized) L1 and the second polarization beam (P-polarized) L2, unless the polarization direction of the linearly polarized light is parallel to one of the X and Y directions.Furthermore, even if the majority of laser beams L incident on the polarization beam splitter BS are linearly polarized in different directions, the majority of laser beams L can be separated into the majority of first polarization beams (S-polarized) L1 and the majority of second polarization beams (P-polarized) L2 as a whole. Provided that not all of the majority of laser beams L incident on the polarization beam splitter BS are linearly polarized in the same direction from the X-direction and the Y-direction, polarization separation can be achieved by the polarization beam splitter BS, and thus such a majority of laser beams L are considered as a whole to be "non-polarized".

[0043] In the Fig. In the example shown, the first optical component 10 is a cube-shaped polarizing beam splitter BS, but this is not limited to this example. The first optical component 10 can be the polarizing beam splitter BS of the plate type or another type. In addition to the polarizing beam splitter, the first optical component 10 can include an optical element, such as a reflective prism-type component. The first optical component 10 can include an antireflection film applied to the polarizing beam splitter BS and other optical elements.

[0044] The second optical component 12 in the example of Fig. 1 also includes a polarization beam splitter BS similar to the polarization beam splitter BS of the first optical component 10. First polarization conversion element

[0045] As in Fig. As shown in Figure 1, the first polarization conversion element 20 converts the majority of second polarization rays L2, corresponding to P-polarized light, into the majority of third polarization rays L3, corresponding to S-polarized light. The majority of third polarization rays (S-polarized) L3 propagate in the +Z direction.

[0046] The first polarization conversion element 20 is made, for example, of quartz or synthetic quartz and can be a 1 / 2-wavelength plate. The 1 / 2-wavelength plate exhibits birefringence and changes the phase difference between two orthogonal components of an electromagnetic wave propagating in a thickness direction. By orienting a slow axis or a fast axis of the 1 / 2-wavelength plate so that it forms an angle of 45° relative to the polarization direction of the P-polarized light, the 1 / 2-wavelength plate can convert P-polarized light into S-polarized light.

[0047] In this way, using the first optical component 10 and the first polarization conversion element 20, for example, the plurality of first polarization beams L1 and the plurality of third polarization beams L3, which are linearly polarized in the same specific direction, can be obtained from the plurality of laser beams L, which are all unpolarized. At this stage, the plurality of first polarization beams (S-polarized) L1 consists of a plurality of laser beams that have different peak wavelengths and are not combined coaxially. The same applies to the plurality of polarization beams (S-polarized) L3.

[0048] Unlike in the Fig. In the example shown, the polarization surface 10R of the first optical component 10 can reflect the P-polarization components of the laser beams L and transmit the S-polarization components of the laser beams L. In this case, the majority of second polarization beams (P-polarized) L2, reflected by the polarization surface 10R of the first optical component 10, travel in the -X direction, and the majority of first polarization beams (S-polarized) L1, transmitted through the polarization surface 10R of the first optical component 10, travel in the +Z direction. The first polarization conversion element 20 is positioned where the majority of second polarization beams (P-polarized) L2 pass through and converts the majority of second polarization beams (P-polarized) L2 into the majority of third polarization beams L3.

[0049] The phase difference formed by the 1 / 2-wavelength plate depends on the wavelength of the incident light. Therefore, when the three second polarization beams L2, exhibiting peak wavelengths λ1, λ2, and λ3, pass through the 1 / 2-wavelength plate, phase differences of exactly 1 / 2 wavelength are not formed at all peak wavelengths, and the P-polarization components remain in the S-polarized light that has been converted from the P-polarized light. Consequently, the P-polarization components remain in the majority of the third polarization beams L3 emitted by the first polarization conversion element 20, and in particular, elliptically polarized light may be present.

[0050] However, if all of the majority of peak wavelengths λn are contained within a relatively narrow range, for example, within a range of 50 nm or less (preferably 10 nm or less), the difference in phase (chromatic dispersion) due to the 1 / 2-wavelength plate is sufficiently small. Therefore, the second polarization beam L2 can mainly contain the S-polarization component and may partially contain the P-polarization component.

[0051] The second polarization conversion element 22 can also have a similar configuration to the first polarization conversion element 20. First mirror and second mirror

[0052] Each of the plurality of first mirrors 30A is arranged such that it reflects one of the plurality of first polarization rays L1 in the direction of the first diffraction position P1, as shown in Fig. Figure 1 illustrates this. A first diffraction grating 40, acting as the first diffraction element 40A, is positioned at the first diffraction position P1. The plurality of first polarization rays L1, reflected by the plurality of first mirrors 30A, propagate parallel to the XZ plane and incident on the predetermined region (first diffraction position P1) of the first diffraction element 40A. Similarly, each of the plurality of second mirrors 30B is positioned to reflect one of the plurality of third polarization rays L3 toward the second diffraction position P2. A second diffraction grating 40, acting as the second diffraction element 40B, is positioned at the second diffraction position P2.The majority of third polarization rays L3, which are reflected by the majority of second mirrors 30B, travel parallel to the XZ plane and fall on the predetermined region (second diffraction position P2) of the second diffraction element 40B.

[0053] The positions and angles of the majority of first mirrors 30A and the majority of second mirrors 30B are determined such that the first wavelength-combined beam CL1, which is diffracted by the first diffraction element 40A at the first diffraction position P1, and the second wavelength-combined beam CL2, which is diffracted by the second diffraction element 40B at the second diffraction position P2, are orthogonal to each other in the second optical component 12.

[0054] Reflection by the majority of first mirrors 30A and the majority of second mirrors 30B does not change the polarization direction of the majority of first polarization rays L1 or third polarization rays L3.

[0055] The first mirrors 30A and the second mirrors 30B can be formed, for example, by applying a dielectric multilayer film with low optical loss to heat-resistant glass. The dielectric multilayer film exhibits a reflectance of nearly 100% in a wavelength range known as the stop band.

[0056] If all peak wavelengths λn are contained within the stopband, the majority of first mirrors 30A and the majority of second mirrors 30B can be formed from the same dielectric multilayer film. If optical loss is disregarded, the majority of first mirrors 30A and the majority of second mirrors 30B can be formed from a metallic material. Diffraction element

[0057] In this embodiment, the first diffraction element 40A and the second diffraction element 40B have the same structure. In particular, the first diffraction element 40A and the second diffraction element 40B consist of diffraction gratings 40 that have the same structure. The diffraction grating 40 is, for example, made of quartz or synthetic quartz. Hereinafter, the diffraction grating 40 that includes the first diffraction element 40A can be referred to as the "first diffraction grating," and the diffraction grating 40 that includes the second diffraction element 40B can be referred to as the "second diffraction grating" for the sake of distinction.

[0058] Fig. Figure 3A is a perspective view schematically depicting a state in which an incident ray 14A, having a peak wavelength λn, enters the diffraction grating 40 and is diffracted to form a diffracted ray 14B. The number of diffracted rays 14B that can be formed is not limited to one. For simplicity, in Fig. 3A represents only one of the plurality of diffracted rays 14B. The incident ray 14A represents a ray contained in each of the plurality of first polarizing rays L1, or a ray contained in each of the plurality of third polarizing rays L3.

[0059] The angle of incidence of the incident beam 14A is αn. The 'n' of the angle of incidence αn is the same integer as the 'n' of the peak wavelength λn. The angle of incidence αn is an angle formed by the normal direction H perpendicular to the diffraction surface of the diffraction grating 40 and the incident beam 14A with peak wavelength λn. A large number of diffraction grooves extending in the Y direction are formed in a surface of the diffraction grating 40.

[0060] A plane 44, which is parallel to the XZ plane, is in Fig. Figure 3A shows the plane 44. The plane contains the incident ray 14A and the diffracted ray 14B and is orthogonal to the diffraction grooves. Diffractions are phenomena (dispersions) in which the angle between the incident ray 14A and the diffracted ray 14B in plane 44 varies according to the wavelengths.

[0061] If the diffraction angle of the diffracted beam is 14B β, the following expression 1 results in a relationship. sin(αn)+sin(β)=N⋅m⋅λn

[0062] Here, N is the number of diffraction grooves per 1 mm of the diffraction grating 40, and m is the diffraction order. N can, for example, be in a range from 1000 / mm to 5000 / mm.

[0063] If the diffraction order m is, for example, 1 and the diffraction angle β is 45.0 degrees, the angle of incidence αn is 24.7 degrees when N = 2500 and the wavelength λn is 450 nm. If a plurality of laser beams having different peak wavelengths λn are incident on the same position of the diffraction grating 40, the plurality of laser beams having different peak wavelengths λn can be diffracted in the direction of the same diffraction angle β by selecting the wavelength λn and the angle of incidence αn accordingly.

[0064] As described above, in the present embodiment the relationship λ1 < λ2 < λ3 is established. In a case where the majority of laser beams L, having peak wavelengths λ1, λ2 and λ3, are incident on the diffraction grating 40, when the diffracted light is formed at the same diffraction angle β, the relationship α1 < α2 < α3 is established for the angle of incidence αn.

[0065] Fig. Figure 3B is a cross-sectional view schematically representing the principal diffraction rays formed when ray I is incident on the transmitting diffraction grating 40. Fig. Figure 3B shows a reflected zero-order diffracted beam R-0, a reflected first-order diffracted beam R-1, a transmitted zero-order diffracted beam T-0, and a transmitted first-order diffracted beam T-1, all formed by the diffraction grating 40. Although the diffraction grating 40 is a transmitting diffraction grating in this embodiment, it is configured such that the reflected first-order diffracted beam R-1 is selectively generated with high intensity. Therefore, the reflected zero-order diffracted beam R-0, the transmitted zero-order diffracted beam T-0, and the transmitted first-order diffracted beam T-1 generated by the transmitting diffraction grating 40 can be ignored.As a result, most of the laser beam incident on the diffraction grating is not absorbed by the material forming the diffraction grating 40, and light loss is reduced. In contrast to a transmitting diffraction grating, a reflective diffraction grating includes a reflective component, such as a dielectric multilayer film or a mirror, and light absorption by this component cannot be neglected. Therefore, with a reflective diffraction grating, there is a possibility that heat generation due to light absorption will degrade the grating's performance when the intensity of the incident laser beam becomes high. The base material of the diffraction grating 40 can be made of a material exhibiting low absorption at the peak wavelength of the laser beam, such as quartz or synthetic quartz. The cross-sectional shape of the grating is, for example, rectangular or trapezoidal.

[0066] A light-absorbing component can be provided on an inner lateral surface of a housing that accommodates the components of the wavelength beam combination device 100. The light-absorbing component absorbs diffracted rays that are different from the reflected first-order diffracted beam R-1 and reduces the occurrence of scattered light.

[0067] As described above, by appropriately selecting the wavelengths λn and the angles of incidence αn, a plurality of first polarization rays L1, which have different peak wavelengths λn, can be diffracted in the direction of the same diffraction angle β. The same applies to the plurality of third polarization rays L3, which have different peak wavelengths λn.

[0068] In the present embodiment, the S-polarized polarization beam L1 or the S-polarized polarization beam L3 is incident on the diffraction grating 40. If the diffraction grating 40 is dependent on polarized light, the diffraction efficiency can decrease depending on the polarization component when a non-polarized laser beam enters the diffraction grating 40. In the diffraction grating 40, which has a plurality of diffraction grooves parallel to the Y direction (the first polarization direction), the diffraction efficiency of the S-polarized light is higher than that of the P-polarized light. Therefore, the diffraction grating 40 can effectively diffract the S-polarized polarization beams L1 and L3.

[0069] In a case where the laser beam L has a spectral width of Δλn with a peak wavelength λn as its essential center, the spectral width Δλn is preferably as small as possible. When the spectral width Δλn is broadened, the diffraction angle β has a large range, which increases the region in the propagation direction of the combined wavelength beams CL1 and CL2. The spectral width Δλn is, for example, set to 0.3 nm or less. By combining a plurality of laser beams L, which have narrow spectral widths Δλn, combined wavelength beams CL1 and CL2 can be formed that contain a plurality of peak wavelengths within a predetermined wavelength range, and their output and luminous intensity can be effectively increased.

[0070] In the example of Fig. 1. The diffraction element 40A or 40B, consisting of a single diffraction grating 40, is arranged on the same optical path. Since the diffraction of the diffraction grating 40 generates an unnecessary diffraction beam, the optical loss can be reduced more in the case where one diffraction grating is arranged on the same optical path than in the case where two diffraction gratings are arranged on the same optical path.

[0071] In the example of Fig. In Figure 1, the first diffraction element 40A is arranged such that it emits the first wavelength-combined beam CL1 from the first diffraction position P1 in the -X direction. In contrast, the second diffraction element 40B is arranged such that it emits the second wavelength-combined beam CL2 from the second diffraction position P2 in the +Z direction. Specifically, the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are on the same plane parallel to the XZ plane and are orthogonal to each other. The positions and orientations of the first diffraction element 40A and the second diffraction element 40B are determined such that the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are incident at an angle of 45° on the polarization surface 12R of the second optical component 12 (polarization beam splitter BS).

[0072] In the present embodiment, the first diffraction element 40A and the second diffraction element 40B are arranged such that the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are orthogonal to each other, and the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are incident on the second optical component 12 from directions that are orthogonal to each other. Second polarization conversion element

[0073] In the Fig. In the example shown, the second polarization conversion element 22 converts the second wavelength-combined beam CL2, which is S-polarized light, into P-polarized light. As a result, the polarization direction of the first wavelength-combined beam CL1 and the polarization direction of the second wavelength-combined beam CL2 are orthogonal to each other. The configuration of the second polarization conversion element 22 can be similar to the configuration of the first polarization conversion element 20. Second optical component

[0074] The second optical component 12 in the example of Fig. 1 is formed by a polarization beam splitter BS, which has a polarization surface 12R. Similar to the polarization surface 10R, the polarization surface 12R reflects the S-polarized light and transmits the P-polarized light. The second optical component 12 performs a polarization combination of the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2. The second optical component 12 coaxially combines the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 and emits the combined beam in the +Z direction as a third wavelength-combined beam CL3.

[0075] The polarization surface 12R of the second optical component 12 can transmit S-polarized light and reflect P-polarized light. In this case, the second polarization conversion element 22 can be moved along the optical path of the second combined wavelength beam CL2 to the optical path of the first combined wavelength beam CL1. If the position of the second polarization conversion element 22 is not changed, the third combined wavelength beam CL3, emitted by the second optical component 12, propagates in the -X direction, and therefore the condenser lens 50 and the optical fiber 60 can be arranged along the optical path of the third combined wavelength beam CL3. Condenser lens and optical fiber

[0076] The condenser lens 50 is positioned where the third wavelength combined beam CL3 is received and condenses the third wavelength combined beam CL3 such that it is incident on the optical fiber 60. The optical axis of the condenser lens 50 is parallel to the direction of propagation of the third wavelength combined beam CL3. The focal point of the condenser lens 50 is located at the incident end surface of the optical fiber 60. The condenser lens 50 can be a single lens or a combination of several lenses. The condenser lens 50 is made, for example, of quartz or synthetic quartz.

[0077] Optical fiber 60 emits the third wavelength-combined beam CL3, which is incident on the emission end surfaces from the incident end surfaces. Optical fiber 60 has a suitable length and can be bent, and thus the third wavelength-combined beam CL3 can be emitted from the emission end surfaces of optical fiber 60 in a suitable direction. Modified example of the first embodiment

[0078] Fig. Figure 4 represents a configuration of a wavelength beam combination device 110, which is a modified example of the one described in Fig. The embodiment shown in 1 is the difference between the one in Fig. 4 shown configuration of the wavelength beam combination device 110 and the configuration of the in Fig. The wavelength beam combination device 100 shown in Figure 1 consists of the arrangement of laser beams L having peak wavelengths λ1, λ2 and λ3 (λ1 < λ2 < λ3). In the wavelength beam combination device 100 of Fig. 1. The laser beam L with the shortest peak wavelength λ1 is located on the upper side (side of the +X direction) of the drawing, and the laser beam L with the longest peak wavelength λ3 is located on the lower side (side of the -X direction) of the drawing. On the other hand, in the wavelength beam combination device 110 of Fig. 4 The laser beam L, which has the longest peak wavelength λ3, is located on the upper side (side of the +X direction) of the drawing, and the laser beam L, which has the shortest peak wavelength λ1, is located on the lower side (side of the -X direction) of the drawing.

[0079] In accordance with such a difference in the arrangement of the laser beams L, the majority of first mirrors 30A and the majority of second mirrors 30B are arranged such that α1 < α2 < α3 is satisfied for the angle of incidence α1 when the first polarization beam L1 is incident on the first diffraction element 40A, and for the angle of incidence α3 when the third polarization beam L3 is incident on the second diffraction element 40B.

[0080] According to the configuration of Fig. 4. The optical path length differences of the respective optical paths of the first polarization beam L1 and the third polarization beam L3 can be essentially the same, and the beam diameters at the first diffraction position P1 and the second diffraction position P2 can be essentially the same, such that the combination efficiency to the optical fiber 60 can be increased.

[0081] In each of the configuration examples of Fig. 1 and Fig. In Figure 4, the two diffraction gratings 40 are arranged such that the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are orthogonal to each other. The polarization surface 12R of the polarization beam splitter BS in the second optical component 12 is located at a position where the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 meet orthogonally. In this way, the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 incident on the second optical component 12 from mutually orthogonal directions and are subjected to polarization combination. However, the configuration for the polarization combination of the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 is not limited to the examples of Fig. 1 and Fig. 4 limited edition. Second embodiment

[0082] Fig. Figure 5 presents a configuration example of a wavelength beam combination device 120 according to another embodiment of the present disclosure. In the wavelength beam combination device 120, the two diffraction gratings 40 are arranged such that the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are parallel to each other, and the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are incident on the second optical component 12 from the same direction.

[0083] The following is a configuration of the wavelength beam combination device 120. Fig. 5 described. Components that correspond to the components of the wavelength beam combination device 100 are described in this section. Fig. 1. Common to each other, not described redundantly.

[0084] Similar to the ones in Fig. The wavelength beam combination device 100 shown in Figure 1 includes the one shown in Figure 1. Fig. 5 wavelength beam combination device 120 shown, comprising the first optical component 10 and the second optical component 12, each separating or combining light, the first polarization conversion element 20 and the second polarization conversion element 22, which change the polarization state of incident light and emit the light, the plurality of first mirrors 30A and the plurality of second mirrors 30B, which change the direction of propagation of the incident light and reflect the incident light, and the first diffraction element 40A and the second diffraction element 40B, which function as the diffraction grating 40.

[0085] The first optical component 10 has a reflective surface 10M that reflects one of the majority of first polarization rays L1 and the majority of second polarization rays L2, which are separated by the first polarization beam splitter BS. The reflective surface 10M causes the direction of propagation of the majority of first polarization rays L1 and the direction of propagation of the majority of second polarization rays L2 to be parallel to each other. In the example of Fig. In 5, the reflection surface 10M is part of an optical component integrated with the polarization surface 10R of the polarization beam splitter BS and is parallel to the polarization surface 10R. Specifically, the polarization surface 10R is localized on one inclined surface of the prism component, which has a parallelogram cross-section, and the reflection surface 10M is localized on the other inclined surface. Therefore, it is not necessary to perform an alignment to cause the first polarization beam L1 to be parallel to the majority of third polarization beams L3, which are converted from the majority of second polarization beams L2 transmitted through the polarization surface 10R. However, the configuration of the first optical component 10 is not limited to this example.The reflective surface 10M can be another optical component separated from the polarizing beam splitter BS. The reflective surface 10M does not necessarily have to be parallel to the polarizing surface 10R.

[0086] In the Fig. In the wavelength beam combination device 120 shown in Figure 5, the majority of first polarization beams L1 and the majority of third polarization beams L3, which have emerged from the first optical component 10, propagate in the +X direction and are reflected by the majority of first mirrors 30A and the majority of second mirrors 30B, respectively. The majority of first mirrors 30A are positioned and oriented such that they align the majority of first polarization beams L1 to the first diffraction position P1. Similarly, the majority of second mirrors 30B are positioned and oriented such that they align the majority of third polarization beams L3 to the second diffraction position P2. Furthermore, the first diffraction element 40A and the second diffraction element 40B are arranged such that they are oriented in the same direction.As a result, the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 move parallel to each other in the same direction (-X direction in the example of ) from the first diffraction position P1 and the second diffraction position P2, respectively. Fig. 5).

[0087] The direction of propagation of the first wavelength-combined beam CL1 from the first diffraction position P1 and the direction of propagation of the second wavelength-combined beam CL2 from the second diffraction position P2 need not necessarily be parallel to the -X direction, as long as they are parallel to each other. By changing the positions and orientations of the majority of first mirrors 30A and the first diffraction element 40A from the example shown, and by similarly changing the positions and orientations of the majority of second mirrors 30B and the second diffraction element 40B, it is possible for the direction of propagation of the first wavelength-combined beam CL1 and the direction of propagation of the second wavelength-combined beam CL2 from the second diffraction position P2 to remain parallel to each other while being inclined with respect to the X direction.

[0088] In the example of Fig. The second optical component 12, similar to the first optical component 10, has a polarization surface 12R that transmits P-polarized light and reflects S-polarized light, and a reflection surface 12M parallel to the polarization surface 12R. The polarization direction of the second combined wavelength beam CL2, emitted from the second diffraction position P2, is converted from the Y-direction to the Z-direction (S-polarized light to P-polarized light) by the second polarization conversion element 22. The reflection surface 12M reflects the second combined wavelength beam CL2, whose polarization direction has thus been converted, in the +Z direction. The second combined wavelength beam CL2 is transmitted through the polarization surface 12R, which transmits P-polarized light.On the other hand, the first wavelength-combined beam CL1 is reflected by the polarizing surface 12R, and the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are coaxially combined to form a third wavelength-combined beam. The third wavelength-combined beam CL3 is condensed by the condenser lens 50 and optically coupled to the optical fiber 60.

[0089] The configurations of the first optical component 10 and the second optical component 12 are not based on the example of Fig. 5 limited. The first optical component 10 and the second optical component 12 can also have different configurations.

[0090] In the present embodiment, the first diffraction element 40A and the second diffraction element 40B are contained in different diffraction gratings 40, but two different regions of the same diffraction grating 40 can function as the first diffraction element 40A and the second diffraction element 40B.

[0091] In the present embodiment, the majority of laser beams L can also be incident parallel to one another on the first optical component 10, such that the polarization separation of the laser beams L can be carried out efficiently. Furthermore, the individual diffraction grating is placed on the optical path of each of the polarization beams (L1, L3) such that the optical loss due to diffraction can be reduced. Third embodiment

[0092] Fig. Figure 6 presents a configuration example of a wavelength beam combination device 130 according to another embodiment of the present disclosure. In the wavelength beam combination device 130, the two diffraction gratings 40 are arranged such that the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are parallel to each other and facing each other (arranged antiparallel), and the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are incident on the second optical component 12 from opposite directions.

[0093] The first optical component 10 in the wavelength beam combination device 130 of Fig. 6 does not have the reflection surface 10M. In the wavelength beam combination device 130, the distance between the first diffraction position P1 and the second diffraction position P2 is increased by adjusting the positions and orientations of the plurality of first mirrors 30A and the plurality of second mirrors 30B, and the second optical component 12 is arranged between the first diffraction position P1 and the second diffraction position P2.

[0094] The configuration of the second optical component 12 in the wavelength beam combination device 130 differs from the configuration of the second optical component 12 in the wavelength beam combination device 120, and the polarization surface 12R is orthogonal to the reflection surface 12M. Since in the wavelength beam combination device 130 the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 incident on the second optical component 12 from the same direction such that they are parallel to and facing each other, the polarization surface 12R and the reflection surface 12M are arranged parallel to each other.These second optical components 12 can be produced by combining a cube-shaped polarizing beam splitter BS and a prism having a right-angled isosceles triangular cross-section, while changing the orientations of the polarizing beam splitter BS and the prism.

[0095] Since, in the present embodiment, the majority of laser beams L can be incident parallel to one another on the first optical component 10, the polarization separation of the laser beams L can be carried out efficiently. Furthermore, since the individual diffraction grating is placed on the optical path of each of the polarization beams (L1, L3), the optical losses due to diffraction can be reduced.

[0096] In each of the embodiments described above, the first optical component 10 includes the polarization beam splitter BS (first polarization beam splitter), which separates the plurality of laser beams L into the plurality of first polarization beams L1 and the plurality of second polarization beams L2, and the second optical component 12 includes the polarization beam splitter BS (second polarization beam splitter), which combines the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2. However, as described above, the second optical component 12 need not include the polarization beam splitter BS. Fourth embodiment

[0097] Fig. Figure 7 presents a configuration example of a wavelength beam combination device 140 according to another embodiment of the present disclosure. The wavelength beam combination device 140 includes a single diffraction grating 42, which contains the first diffraction element 40A and the second diffraction element 40B. The diffraction grating 42 emits the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 in the same direction. The second optical component in the present embodiment includes a lens 50, which receives and condenses the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 that have emerged from the diffraction gratings 42.

[0098] The first optical component 10 includes the polarization beam splitter BS, which splits the majority of laser beams L into the majority of first polarization beams L1 and the majority of second polarization beams L2. The first optical component 10 has the reflective surface 10M, which reflects one of the majority of first polarization beams L1 and the majority of second polarization beams L2 separated by the polarization beam splitter BS. The reflective surface 10M makes the direction of propagation of the majority of first polarization beams L1 and the direction of propagation of the majority of second polarization beams L2 parallel to each other.

[0099] The wavelength beam combination device 140 further includes a third optical component 18, which shifts the positions in the Y-direction of the majority of first polarization beams L1 reflected from the reflection surface 10M of the first optical component 10. The third optical component 18 is, for example, a rhomboid prism. The function of the third optical component 18 is described below.

[0100] Fig. Figure 8 is a schematic diagram explaining the function of the third optical component 18. The right side of Fig. Figure 8 schematically represents the optical path of the laser beam L, which has peak wavelength λ3, as seen from the -Z direction. Specifically, the optical path of the first polarization beam L1, which was separated from the laser beam L with peak wavelength λ3 by the first optical component 10, is shifted in the +Y direction by the third optical component 18. The third optical component 18 in the example of Fig. Figure 8 is a rhomboid prism that has a pair of parallel reflection surfaces R1 and R2 at its end surfaces. The rhomboid prism has a prism shape in which a cross-section parallel to the XY plane is a parallelogram. The third optical component 18 can be two mirrors whose reflection surfaces are parallel to each other. On the other hand, the left side of Fig. Figure 8 shows that the second polarization beam L2, which is separated from the laser beam L, which has peak wavelength λ3, by the first optical component 10, and the third polarization beam L3, which passes through the first polarization conversion element 20, propagate in the +X direction without being affected by the displacement effect of the third optical component 18. With such a function of the third optical component 18, the first polarization beam L1 can be displaced in the Y direction with respect to the third polarization beam L3.

[0101] With reference to Fig. 7. The optical path of the first polarization ray L1, reflected by the plurality of first mirrors 30A, and the optical path of the third polarization ray L3, reflected by the plurality of second mirrors 30B, appear to overlap. In reality, however, the position of the optical path of the first polarization ray L1, reflected by the plurality of first mirrors 30A, is offset in the +Y direction with respect to the position of the optical path of the third polarization ray L3, reflected by the plurality of second mirrors 30B.

[0102] A displacement magnitude in the Y-direction by the third optical component 18 is determined such that the majority of first mirrors 30A do not interfere with the propagation of the third polarizing beam L3. That is, this displacement magnitude is greater than the magnitude of each of the majority of first mirrors 30A in the Y-direction (for example, in a range of 5 mm to 20 mm).

[0103] In the Fig. In the example shown in Figure 8, the reflective surface R1 of the third optical component 18 reflects the first polarization ray L1 in the +Y direction. However, the direction in which the reflective surface R1 reflects the first polarization ray L1 can be rotated away from the +Y direction by rotating the orientation of the reflective surface R1 of the third optical component 18. Importantly, this increases the distance in the Y direction between the optical path of the first polarization ray L1 and the third polarization ray L3. The majority of first mirrors 30A and the majority of second mirrors 30B in Fig. 7 are arranged such that the first diffraction position P1 and the second diffraction position P2 are aligned in a direction parallel to the diffraction grooves of the diffraction grating 42.

[0104] The upper part of Fig. Figure 8 schematically shows the positions of the first diffraction element 40A and the second diffraction element 40B in the diffraction grating 42. The diffraction grating 42 is provided with diffraction grooves extending in the Y direction. As shown in Fig. As shown in Figure 8, the first diffraction position P1 is located on the first diffraction element 40A and the second diffraction position P2 on the second diffraction element 40B. According to the present embodiment, different regions of the individual diffraction grating 42 can be used as the first diffraction element 40A and the second diffraction element 40B. Therefore, the number of diffraction gratings can be reduced.

[0105] According to the present embodiment, the first wavelength-combined beam CL1, emitted from the first diffraction position P1, and the second wavelength-combined beam CL2, emitted from the second diffraction position P2, are not strictly on the same axis. Therefore, the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are spatially combined by the condenser lens 50 of the second optical component 12 and incident on the optical fiber 60. To increase the light combination ratio with respect to the optical fiber 60, it is preferred that the center-to-center distance between the first diffraction position P1 and the second diffraction position P2 on the diffraction grating 42 be short.

[0106] In this embodiment, the third optical component 18 displaces the optical path of the first polarization beam L1 in the Y direction, but the same effect can be obtained even if the optical path of the second polarization beam L2 or the third polarization beam L3 is displaced in the Y direction.

[0107] Since, in the present embodiment, the majority of laser beams L can be incident parallel to one another on the first optical component 10, the polarization separation of the laser beams L can also be carried out efficiently. Furthermore, since the single diffraction grating 42 is placed on the optical path of the polarization beams (L1, L3), it is possible to reduce the optical loss due to diffraction.

[0108] In the present embodiment, the laser beams incident on the optical fiber 60 are not obtained by polarization combination of the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2. Therefore, the laser beam incident on the optical fiber 60 is linearly polarized in a specific direction (Y-direction). However, the polarization state of the laser beam incident on the optical fiber 60 can change during propagation through the optical fiber 60. If the optical fiber 60 is sufficiently long, the polarization of the laser beam, which is optically coupled to the incident end surface, is refracted, and the laser beam can, for example, be in a non-polarized state at the emission end surface. The same applies to the embodiments described below. Fifth embodiment

[0109] Fig. Figure 9 presents a configuration example of a wavelength beam combination device 150 according to another embodiment of the present disclosure. Unlike the wavelength beam combination device 140 of Fig. 7 does not include the wavelength beam combination device 150, the third optical component 18, which offsets the optical path.

[0110] The right side of Fig. Figure 10 schematically illustrates that the first polarization beam L1, separated from the laser beam L, which has peak wavelength λ3, by the first optical component 10, is reflected from the reflection surface 10M and then propagates in the +X direction when viewed from the -Z direction. On the other hand, the left side of Fig. Figure 10 schematically shows that the second polarization beam L2, which is separated from the laser beam L, which has the peak wavelength λ3, by the first optical component 10, and the third polarization beam L3, which passes through the first polarization conversion element 20, move in the +X direction.

[0111] As in Fig. As shown in Figure 9, in the present embodiment the plurality of first mirrors 30A are arranged such that they do not interfere with the third polarization rays L3, which are reflected by the plurality of second mirrors 30B. Furthermore, the plurality of first mirrors 30A and the plurality of second mirrors 30B are arranged such that the first diffraction position P1 and the second diffraction position P2 are aligned in a direction that intersects the diffraction grooves of the diffraction grating 42.

[0112] The upper part of Fig. Figure 10 schematically illustrates the positions of the first diffraction element 40A and the second diffraction element 40B in the diffraction grating 42. Similar to the embodiment described above, the diffraction grating 42 is provided with diffraction grooves extending in the Y direction. As in Fig. As shown in Figure 10, the first diffraction position P1 is located on the first diffraction element 40A and the second diffraction position P2 is located on the second diffraction element 40B. The first diffraction element 40A and the second diffraction element 40B can overlap on the diffraction grating 42.

[0113] This embodiment also allows different regions of a single diffraction grating 42 to be used as the first diffraction elements 40A and the second diffraction element 40B. Therefore, the number of diffraction gratings can be reduced.

[0114] In the present embodiment, the first wavelength-combined beam CL1, emitted from the first diffraction position P1, and the second wavelength-combined beam CL2, emitted from the second diffraction position P2, are not strictly on the same axis. Therefore, the first wavelength-combined beam CL1 and the second wavelength-combined beam CL2 are spatially combined by the condenser lens 50 of the second optical component 12 and incident on the optical fiber 60. To increase the light combination ratio with respect to the optical fiber 60, it is preferred that the center-to-center distance between the first diffraction position P1 and the second diffraction position P2 on the diffraction grating 42 be short.

[0115] As from Fig. As can be seen in Figure 9, there is a case in which a significant difference occurs between the angle at which the majority of first polarization rays L1, directed by the majority of first mirrors 30A towards the first diffraction position P1, incident on the diffraction grating 42, and the angle at which the majority of third polarization rays L3, directed by the majority of second mirrors 30B towards the second diffraction position P2, incident on the diffraction grating 42. It is also possible to direct a pair of rays, consisting of the first polarization rays and the third polarization rays L3, with the same wavelengths, parallel to each other and incident on the diffraction grating 42 at the same angle by adjusting the positions and orientations of the majority of first mirrors 30A and the majority of second mirrors 30B.On the other hand, it is preferable that the difference between the diffraction angle of the first wavelength-combined beam CL1, which propagates from the first diffraction position P1 towards the condenser lens 50, and the diffraction angle of the second wavelength-combined beam CL2, which propagates from the second diffraction position P2 towards the condenser lens 50, be as small as possible. Since the angle of incidence (αn) and the diffraction angle (β) exhibit the relationship described above in expression (1), the first diffraction position P1 and the second diffraction position P2 cannot coincide. By increasing the distances from the majority of first mirrors 30A and the majority of second mirrors 30B to the diffraction gratings 42, it is possible to reduce the difference in the angle of incidence (αn) and to shorten the center-to-center distance between the first diffraction position P1 and the second diffraction position P2.

[0116] Since, in the present embodiment, the majority of laser beams L can be incident parallel to each other on the first optical component 10, the polarization separation of the laser beams L can also be carried out efficiently. Furthermore, since the single diffraction grating is placed on the optical path of the polarization beams (L1, L3), it is possible to reduce the optical loss due to diffraction. Direct diode laser device

[0117] The following is a configuration example of a DDL device according to an embodiment of the present disclosure with reference to Fig. 11 described. Fig. Figure 11 is a diagram schematically representing a configuration of a DDL device according to an exemplary embodiment of the present disclosure. A Fig. The DDL device 1000 shown in Figure 11 includes the [details omitted]. Fig. 1 Wavelength beam combination device 100 shown, a plurality of semiconductor laser devices 72, each of which emits laser light corresponding to one of the plurality of laser beams L, and an optical fiber array device 70 configured to form the one of the plurality of laser beams L from the laser light emitted by each of the semiconductor laser devices 72.

[0118] In the Fig. In the example shown in Figure 11, the number of semiconductor laser devices 72 is three, but this is not limited to this example. The number of semiconductor laser devices 72 is determined according to the required light output or irradiance. The wavelength of the laser light emitted by the semiconductor laser device 72 can also be selected according to the material to be processed.

[0119] The laser light emitted by each semiconductor laser device 72 is optically coupled to the corresponding optical fiber 74 of the optical fiber array device 70. The majority of semiconductor laser devices 72 are configured to oscillate laser light beams with different peak wavelengths. Even if the laser light emitted by each semiconductor laser device 72 is linearly polarized light, the polarization state of the laser light changes during the process of passing through the optical fiber 74 if the optical fiber 74 is not a polarization-preserving fiber. Therefore, the majority of laser beams L formed by the optical fiber array device 70 are not polarized.

[0120] Examples of the semiconductor laser device 72 include an external cavity laser device (ECL), a distributed feedback laser device (DFB), and a distributed Bragg reflector laser device (DBR).

[0121] The optical fibers 74 can be aligned by the optical fiber array device 70, and the emission angle of the laser beam L can be easily adjusted. This enables the optical fiber array device 70 to emit multiple laser beams L parallel to each other with high precision. An optical fiber extending from the semiconductor laser device 72 can be fused and connected to the optical fiber 74 of the optical fiber array device 70. The optical fiber array device 70 includes a lens system that collimates the laser light emitted from the distal end of each optical fiber 74.

[0122] In the DDL device 1000 according to the present embodiment, the wavelength-combined beam CL3 can be formed from the plurality of non-polarized laser beams L by the wavelength beam combination device 100, even if the laser light emitted by the plurality of semiconductor laser devices 72 is non-polarized by the optical fiber array device 70.

[0123] The DDL device 1000 can include other wavelength beam combination devices 110, 120, 130, 140 and 150 instead of the wavelength beam combination device 100. laser processing machine

[0124] The following is a configuration example of a laser processing machine according to an embodiment of the present disclosure with reference to Fig. 12 described. Fig. Figure 12 is a schematic diagram representing a configuration of a laser processing machine according to an exemplary embodiment of the present disclosure. Fig. The laser processing machine 2000 shown in Figure 12 includes a light source device 1100, i.e., the one in Fig. Figure 11 shows a DDL device 1000, an optical transmission fiber 90 extending from the light source device 1100 and coupled to a wavelength-combined beam CL3 emitted by the light source device 1100, and a processing head 1200 connected to the optical transmission fiber 90. The processing head 1200 irradiates an object 1300 with the wavelength-combined beam CL3 emitted by the optical transmission fiber 90.

[0125] In the Fig. In the example shown, the number of light source devices is 1100, but the number of light source devices is not limited to this example. The processing head 1200 can be connected to the majority of light source devices 1100 via the optical transmission fiber 90.

[0126] In the laser processing machine 2000 according to the present embodiment, it is possible to obtain a laser beam with high power density and excellent beam quality with high energy conversion efficiency, since a laser beam with high power density is generated by wavelength beam combination and efficiently combined with an optical fiber.

[0127] The laser beam emitted by the processing head 1200 may contain a different laser beam than the combined laser beam emitted by the Fig.The laser beams emitted by the semiconductor laser device 72 shown in Figure 11 are combined. The peak wavelengths of the laser beams emitted by the semiconductor laser devices 72 are, for example, contained in wavelengths in the range of 430 nm to 480 nm. Additionally, laser beams with near-infrared peak wavelengths can be combined. Depending on the material being processed, a laser beam with a wavelength at which the material exhibits high light absorption can be combined accordingly.

[0128] A wavelength beam combination device, a direct diode laser device and a laser processing machine of the present disclosure can be used extensively in applications requiring high output and high power density of laser light with high beam quality, such as cutting, drilling, local heat treatment, surface treatment of various materials, welding of metal, 3D printing and the like. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2024-111003

[0001] US 6192062

[0004] JP 2023-088438 A

[0005]

Claims

[1] Wavelength beam combination device for combining a plurality of laser beams having different peak wavelengths, the wavelength beam combination device comprising: a first optical component configured to separate the plurality of laser beams into a plurality of first polarization beams that are linearly polarized in a first polarization direction, and a plurality of second polarization beams that are linearly polarized in a second polarization direction orthogonal to the first polarization direction; a first polarization conversion element configured to convert the majority of second polarization rays into a majority of third polarization rays that are linearly polarized in the first polarization direction; a plurality of first mirrors, each configured to reflect one of the plurality of first polarization rays towards a first diffraction position; a plurality of second mirrors, each configured to reflect one of the plurality of third polarization rays towards a second diffraction position; a first diffraction element configured to receive at the first diffraction position the majority of first polarization rays reflected by the majority of first mirrors and to diffract the majority of first polarization rays to form a first wavelength-combined beam in which the majority of first polarization rays are coaxially combined; a second diffraction element configured to receive, at the second diffraction position, the majority of third polarization rays reflected by the majority of second mirrors, and to diffract the majority of third polarization rays to form a second wavelength-combined beam in which the majority of third polarization rays are coaxially combined; and a second optical component onto which the first wavelength-combined beam and the second wavelength-combined beam are incident. [2] Wavelength beam combination device according to one of the preceding claims, comprising: a first diffraction grating comprising the first diffraction element; a second diffraction grating that includes the second diffraction element; a second polarization conversion element configured to convert a polarization state of at least one of the first wavelength-combined beam or the second wavelength-combined beam such that the polarization directions of the first wavelength-combined beam and the second wavelength-combined beam are orthogonal to each other, wherein: the second optical component is configured to form and emit a third wavelength-combined beam in which the first wavelength-combined beam and the second wavelength-combined beam are coaxially combined. [3] Wavelength beam combination device according to claim 2, wherein: Each of the first diffraction grating and the second diffraction grating has a plurality of diffraction grooves extending in the first polarization direction. [4] Wavelength beam combination device according to claim 3, wherein: the first optical component comprises a first polarization beam splitter configured to separate the majority of laser beams into the majority of first polarization beams and the majority of second polarization beams, and the second optical component includes a second polarization beam splitter configured to combine the first wavelength-combined beam and the second wavelength-combined beam. [5] Wavelength beam combination device according to claim 4, wherein: the first diffraction grating and the second diffraction grating are arranged such that the first wavelength-combined beam and the second wavelength-combined beam are orthogonal to each other, wherein the first diffraction grating and the second diffraction grating are configured to cause the first wavelength-combined beam and the second wavelength-combined beam to incident on the second optical component from directions that are orthogonal to each other. [6] Wavelength beam combination device according to claim 2, comprising: a lens configured to condense the third wavelength-combined beam. [7] Wavelength beam combination device according to claim 4, wherein: the first optical component comprises a reflective surface configured to reflect one of the plurality of first polarization rays and the plurality of second polarization rays separated by the first polarization beam splitter, wherein the reflective surface is configured to cause one direction of propagation of the plurality of first polarization rays and one direction of propagation of the plurality of second polarization rays to be parallel to each other. [8] Wavelength beam combination device according to claim 7, wherein: the first diffraction grating and the second diffraction grating are arranged such that the first wavelength-combined beam and the second wavelength-combined beam are parallel, wherein the first diffraction grating and the second diffraction grating are configured to cause the first wavelength-combined beam and the second wavelength-combined beam to incident on the second optical component from the same direction. [9] Wavelength beam combination device according to claim 7, wherein: the first diffraction grating and the second diffraction grating are arranged such that the first wavelength-combined beam and the second wavelength-combined beam are antiparallel to each other, wherein the first diffraction grating and the second diffraction grating are configured to cause the first wavelength-combined beam and the second wavelength-combined beam to incident on the second optical component from directions opposite to each other. [10] Wavelength beam combination device according to any one of the preceding claims, comprising: a single diffraction grating comprising the first diffraction element and the second diffraction element, wherein: the diffraction grating is configured to cause the first wavelength-combined beam and the second wavelength-combined beam to emerge in the same direction, and the second optical component comprises a lens configured to receive and condense the first wavelength-combined beam and the second wavelength-combined beam that have emerged from the diffraction grating. [11] Wavelength beam combination device according to claim 10, wherein: the first optical component comprises a polarization beam splitter configured to separate the majority of laser beams into the majority of first polarization beams and the majority of second polarization beams, and the first optical component comprises a reflective surface configured to reflect one of the plurality of first polarization rays and the plurality of second polarization rays separated by the polarization beam splitter, wherein the reflective surface is configured to cause one direction of propagation of the plurality of first polarization rays and one direction of propagation of the plurality of second polarization rays to be parallel to each other. [12] Wavelength beam combination device according to claim 11, wherein: The diffraction grating has a plurality of diffraction grooves extending in the first polarization direction. [13] Wavelength beam combination device according to claim 12, further comprising: a third optical component configured to shift positions of the majority of first polarization rays reflected from the reflective surface of the first optical component in the first polarization direction, wherein: the majority of first mirrors and the majority of second mirrors are arranged such that the first diffraction position and the second diffraction position are aligned in a direction parallel to the majority of diffraction grooves of the diffraction grating. [14] Wavelength beam combination device according to claim 12, wherein: the majority of first mirrors and the majority of second mirrors are arranged such that the first diffraction position and the second diffraction position are aligned in a direction that crosses the majority of diffraction grooves of the diffraction grating. [15] Direct diode laser device comprising: the wavelength beam combination device according to one of the preceding claims; and a laser light source configured to emit a plurality of laser beams that are parallel to each other. [16] Direct diode laser device according to claim 15, wherein: The laser light source includes: a plurality of semiconductor laser elements, and a plurality of optical fibers, each coupled to a plurality of semiconductor laser elements. [17] Laser processing machine, comprising: at least one direct diode laser device, which is the direct diode laser device according to claim 15; an optical transmission fiber to be coupled with a laser beam emitted by the at least one direct diode laser device; and a processing head that is connected to the optical transmission fiber.

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