Optical amplifier and laser processing apparatus

Abstract

The utility model discloses an optical amplifier and a laser processing apparatus. The optical amplifier includes: a gain medium having a first surface on which a seed beam is incident, a second surface on an opposite side to the first surface, and a side surface connecting the first surface and the second surface, the incident seed beam being amplified while moving to the second surface and being emitted through the second surface; and a pump source providing a pump beam via at least one of the first face or the second face, in one region of the side face of the gain medium being equipped with a pump beam removal region that is surface-treated such that at least a portion of the pump beam present inside the gain medium is released to the outside of the gain medium, and the pump beam removal region is positioned closer to the first face than a region in which the pump beam is first reflected at the side face of the gain medium. The utility model provides an optical amplifier which can remove unwanted pump beams which may hinder amplification efficiency or safety of the optical amplifier.

Description

Technical Field

[0001] The present disclosure relates to an optical amplifier and a laser processing device. Background Art

[0002] A laser processing device refers to a device that uses a focusing lens to focus a laser beam into a focal shape and irradiates the focal point onto the surface or inside of a processing object to perform processing.

[0003] The laser processing apparatus may include a laser oscillator for generating a seed beam and an optical amplifier for amplifying the seed beam.

[0004] The optical amplifier may include a gain medium that can amplify a seed beam, and a pump source that provides a pump beam to the gain medium to induce a density inversion inside the gain medium.

[0005] In order to improve the amplification efficiency of the optical amplifier, it is important not to let the pump beam incident into the gain medium accidentally escape to the outside of the gain medium. However, since the unwanted pump beam may reduce the amplification efficiency of the optical amplifier or damage the laser oscillator, it is necessary to remove it to the outside of the gain medium. The unwanted pump beam may include a pump beam with an unexpected incident direction and property, or a pump beam incident from the outside. For example, a "backward signal" traveling in the opposite direction of the emission direction of the seed beam inside or on the surface of the gain medium corresponds to this situation.

[0006] "Backward signal" refers to a pump beam that travels in the opposite direction of the emission direction of the seed beam inside or on the surface of the gain medium. The backward signal can be emitted to the outside of the gain medium through the incident surface of the gain medium into which the seed beam is input. In particular, in a multi-stage amplification system, when the backward signal enters the gain medium of the previous stage, the amplification efficiency of the multi-stage amplification system may be reduced, thereby reducing the output of the seed beam or reducing the laser quality. In addition, the backward signal may be amplified and flow back to the laser oscillator that generates the seed beam, thereby damaging the laser oscillator.

[0007] Therefore, a technique for reducing the reverse signal is needed. Utility Model Content

[0008] [Problems to be Solved by the Utility Model]

[0009] A technical problem to be solved by the utility model is to provide an optical amplifier capable of removing unnecessary pump light beams which may hinder the amplification efficiency or safety of the optical amplifier.

[0010] Another technical problem to be solved by the utility model is to provide an optical amplifier which reduces the generation of reverse signals inside a gain medium.

[0011] Another technical problem to be solved by the utility model is to provide an optical amplifier which amplifies a reverse signal entering into a gain medium without sending it to a previous step and weakens the reverse signal.

[0012] The technical issues of the present invention are not limited to the above-mentioned technical issues, and other technical issues not mentioned can be clearly understood by ordinary technicians in the technical field of the present invention according to the following description.

[0013] [Technical means to solve the problem]

[0014] According to one embodiment of the present disclosure, an optical amplifier can be provided, comprising: a gain medium, having a first surface for incident seed beam, a second surface located on the opposite side of the first surface, and a side surface connecting the first surface and the second surface, wherein the incident seed beam is amplified during movement to the second surface and is emitted through the second surface; and a pump source, providing a pump beam through at least one of the first surface or the second surface, wherein in an area of ​​the side surface of the gain medium, a pump beam removal area is provided which is surface-treated so that at least a portion of the pump beam existing inside the gain medium is released to the outside of the gain medium, and the pump beam removal area is positioned closer to the first surface than the area where the pump beam is first reflected on the side surface of the gain medium.

[0015] The surface treatment includes at least one of sanding, etching or wire processing, and the gain medium may have a non-flat surface with a non-uniform depth in the pump beam removal region.

[0016] The gain medium further includes: an additional pump beam removal region located at the side surface adjacent to the second surface, and a length of the additional pump beam removal region may be greater than a length of the pump beam removal region.

[0017] The optical amplifier further includes: a heat dissipation structure surrounding at least a portion of the side surface of the gain medium; and a filling layer disposed between the gain medium and the heat dissipation structure, wherein the filling layer may have a flat surface.

[0018] The optical amplifier further includes: a metal layer surrounding the side surface of the gain medium, the metal layer including: a first surface in contact with the gain medium and a second surface opposite to the first surface, the first surface being non-flat along the contour of the non-flat surface of the gain medium in a first region corresponding to the pump beam removal region, and being flat in a second region not corresponding to the pump beam removal region. The second surface may be flat in the first region and the second region.

[0019] The pump beam may be released to the outside of the gain medium based on a refractive index difference between the gain medium and the metal layer.

[0020] The second surface may have a shape inclined at a preset first angle based on the first axis.

[0021] The first surface may have a shape inclined at a preset second angle with respect to a second axis perpendicular to the first axis.

[0022] The preset first angle and the preset second angle may be the same.

[0023] The gain medium may include: yttrium aluminum garnet (YAG) crystal added to a rare earth metal.

[0024] According to another embodiment of the present disclosure, a laser processing device can be provided, which includes: a laser oscillator, which generates a seed beam; and an optical amplifier, which amplifies the seed beam generated from the laser oscillator, and the optical amplifier includes: a gain medium, which has a first surface for the seed beam to be incident, a second surface located on the opposite side of the first surface, and a side surface connecting the first surface and the second surface, and the incident seed beam is amplified during movement to the second surface and is emitted through the second surface; and a pump source, which provides a pump beam through at least one of the first surface or the second surface, and in an area of ​​the side surface of the gain medium, there is provided a pump beam removal area that has been surface-treated so that at least a portion of the pump beam existing inside the gain medium is released to the outside of the gain medium, and the pump beam removal area is positioned closer to the first surface than the area where the pump beam is first reflected on the side surface of the gain medium.

[0025] The above exemplary embodiments and other exemplary embodiments will be described in detail below to illustrate or clarify the exemplary embodiments related to and read from the accompanying drawings.

[0026] [Effects of the utility model]

[0027] The disclosed technology may have the following effects. However, since a specific embodiment does not necessarily mean that all of the following effects or only the following effects are included, the scope of rights of the disclosed technology should not be understood as being limited by the embodiments.

[0028] According to an embodiment of the present disclosure, the amplification efficiency, safety, and laser quality of the optical amplifier can be improved by removing unnecessary pump light beams remaining in the gain medium.

[0029] According to another embodiment of the present disclosure, the generation of reverse signals inside the gain medium can be reduced, thereby improving the amplification efficiency, safety, and laser quality of the optical amplifier.

[0030] According to yet another embodiment of the present disclosure, the safety of an optical amplifier can be improved by weakening a reverse signal entering a gain medium.

[0031] The above utility model does not include a complete catalog of all aspects of the utility model. The utility model should be understood to include not only the matters summarized above, but also all methods, instruments and systems that can be implemented according to all appropriate combinations of various aspects disclosed in the following detailed description and claims. In addition, the effects that may be obtained or predicted by the embodiments of the present disclosure should be disclosed directly or implicitly in the detailed description of the embodiments of the present disclosure. For example, various effects predicted according to the embodiments of the present disclosure will be disclosed in the detailed description described later. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The aspects, features and advantages of specific embodiments of the present disclosure will become more apparent from the following description with reference to the accompanying drawings.

[0033] Figure 1 FIG. 1 is a schematic diagram showing an optical amplifier 100 according to an embodiment of the present disclosure.

[0034] Figure 2 FIG. 1 is a diagram showing a cross section of an optical amplifier 100 according to an embodiment of the present disclosure.

[0035] Figure 3 2 is a cross-sectional view for explaining the operation of the optical amplifier 100 according to an embodiment of the present disclosure.

[0036] Figure 4 FIG. 1 is a diagram showing a cross section of an optical amplifier 100 according to an embodiment of the present disclosure.

[0037] Figure 5 FIG. 1 is a diagram showing a cross section of an optical amplifier 100 according to another embodiment of the present disclosure.

[0038] Figure 6 FIG. 1 is a diagram showing a cross section of an optical amplifier 100 according to an embodiment of the present disclosure.

[0039] Figure 7 FIG. 1 is a diagram showing a cross section of an optical amplifier 100 according to another embodiment of the present disclosure.

[0040] Figure 8 is a block diagram conceptually showing a laser processing apparatus according to an embodiment of the present disclosure.

[0041] [Explanation of Symbols]

[0042] 10: Seed Beam

[0043] 20: Pump beam

[0044] 31. S1: First side

[0045] 32. S2: Second side

[0046] 33: Side

[0047] 41: Region

[0048] 61: First Angle

[0049] 71: Second Angle

[0050] 100: Optical amplifier

[0051] 110: Gain medium

[0052] 120: Metal layer

[0053] 130: Filling layer

[0054] 140: Heat dissipation structure

[0055] 200: Laser Oscillator

[0056] 1000: Laser processing equipment

[0057] A1, A2: Pump beam removal area / area

[0058] G: Groove

[0059] P1: First pump beam

[0060] P2: Second pump beam

[0061] X, Y, Z: Axis DETAILED DESCRIPTION

[0062] The terms used in this specification will be briefly explained, and the present disclosure will be explained specifically.

[0063] The terms used in the embodiments of the present disclosure are selected as far as possible from currently widely used general terms while considering the functions in the present disclosure, but this may vary according to the intentions of technicians engaged in the corresponding fields or precedents, the emergence of new technologies, etc. In addition, in certain cases, there are also terms arbitrarily selected by the applicant, and in this case, their meanings will be described in detail in the corresponding initial description section. Therefore, the terms used in the present disclosure are not simple term names, but should be defined based on the meanings of the terms and the overall content of the present disclosure.

[0064] The embodiments of the present disclosure may be subjected to various transformations and may have various embodiments, so specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the scope of specific implementations, but should be understood to include all transformations, equivalents and even substitutes included in the disclosed ideas and technical scope. When describing the embodiments, if it is considered that the specific description of the related known technology may obscure the gist, its detailed description will be omitted.

[0065] The terms "first", "second", etc. may be used to describe various components, but the components should not be limited by the terms. These terms are only used to distinguish one component from another.

[0066] Unless otherwise clearly indicated in the context, singular expressions include plural expressions. In this application, the terms "including" or "consisting of" are intended to specify the existence of features, numbers, steps, actions, constituent elements, parts or combinations thereof recorded in the specification, and should be understood as not excluding in advance the existence or additional possibility of one or more other features or numbers, steps, actions, constituent elements, parts or combinations thereof.

[0067] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings so that those skilled in the art to which the present disclosure belongs can easily implement it. However, the present disclosure can be implemented in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly illustrate the present disclosure in the accompanying drawings, parts not related to the description are omitted, and similar parts are given similar figure symbols throughout the specification.

[0068] Figure 1 FIG. 1 is a schematic diagram showing an optical amplifier 100 according to an embodiment of the present disclosure.

[0069] Reference Figure 1 , the optical amplifier 100 may include a gain medium 110 and a heat dissipation structure 140 .

[0070] The gain medium 110 may include active ions obtained from rare earth metals. Exemplary rare earth metals may include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), diopside (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), scandium (Sc), and yttrium (Y).

[0071] In addition, the gain medium 110 may also include active ions obtained from transition metal elements such as chromium (Cr) and titanium (Ti). For example, the gain medium 110 may be a Yttrium Aluminum Garnet (YAG) crystal to which active ions are added. As another embodiment, the gain medium 110 may include other types of single crystals other than YAG crystals.

[0072] The gain medium 110 may have a rod shape. The gain medium 110 may have a cylindrical shape. The gain medium 110 may include a first surface, a second surface on the opposite side of the first surface, and a side surface connecting the first surface and the second surface. The first surface may be an incident surface for the seed beam (or signal beam) to be incident. The second surface may be an exit surface for outputting the amplified seed beam. The pump beam may be incident through the first surface and / or the second surface. For example, the diameter of the cross section of the gain medium 110 may be 1 mm or 1.5 mm. However, this is an example, and the diameter of the cross section of the gain medium 110 is greater than 1 mm and less than 1.5 mm, or may be greater than 1.5 mm.

[0073] The heat dissipation structure 140 may surround at least a portion of the side surface of the gain medium 110. The heat dissipation structure 140 may include a groove (G) for receiving the gain medium 110. The groove (G) may be a U-shaped groove.

[0074] The heat dissipation structure 140 can dissipate the heat generated by the gain medium 110 to the outside. The heat dissipation structure 140 can have various shapes. For example, the heat dissipation structure 140 can be a heat sink.

[0075] The heat dissipation structure 140 may include a material having a greater thermal conductivity than the gain medium 110. For example, the material of the heat dissipation structure 140 may include copper.

[0076] By improving the heat conduction and cooling efficiency of the gain medium 110 using the heat dissipation structure 140, the temperature difference about the Y-axis and the Z-axis in the gain medium 110 can be reduced. Therefore, the unexpected thermal lens phenomenon of the gain medium 110 and the degradation of the beam quality can be minimized.

[0077] Figure 2 FIG. 1 is a diagram showing a cross section of an optical amplifier 100 according to an embodiment of the present disclosure.

[0078] Reference Figure 2 , the optical amplifier 100 may include a gain medium 110, a metal layer 120, a filling layer 130, and a heat dissipation structure 140. The gain medium 110 performs the function of transmitting a laser beam. Inside the gain medium 110, a laser beam (e.g., a pump beam) may travel by total reflection. Total reflection may be achieved by a refractive index difference between the gain medium 110 and the metal layer 120. For example, the refractive index of the gain medium 110 may be 1.82. The refractive index of the metal layer 120 may be less than the refractive index of the gain medium 110. As an example, the refractive index of the metal layer 120 may be 0.2.

[0079] The metal layer 120 may guide the laser beam so that the laser beam travels inside the gain medium 110. The metal layer 120 may reflect the pump beam that is intended to escape to the outside of the gain medium 110 to the inside of the gain medium 110. For example, the metal layer 120 may reflect the pump beam at an angle greater than the critical angle of total reflection to the inside of the gain medium 110 again.

[0080] The metal layer 120 may surround the side of the gain medium 110 . Since the metal layer 120 is disposed at the periphery of the gain medium 110 , a portion of the pump light beam is blocked from escaping to the outside of the gain medium 110 and may be reflected to the inside of the gain medium 110 .

[0081] The material of the metal layer 120 may be determined in consideration of the wavelength of the pump beam and its reflectivity. The metal layer 120 may include a material having a reflectivity of 95% or more to the pump beam. For example, the metal layer 120 may include a material having a reflectivity of 95% or more to the pump beam incident into the gain medium 110 at a total reflection angle.

[0082] As an example, the material of the metal layer 120 may be silver. As another example, the material of the metal layer 120 may include at least one of copper (Cu), aluminum (Al), gold (Au), tungsten (W), and molybdenum (Mo).

[0083] The filling layer 130 may fix the gain medium 110 by bonding the gain medium 110 to the heat dissipation structure 140. The filling layer 130 may transfer heat generated in the gain medium 110 to the heat dissipation structure 140. For example, the filling layer 130 may include tin.

[0084] The pump light beam that is not totally reflected by the metal layer 120 may be absorbed by the metal layer 120 and converted into heat energy. The converted heat energy may be released to the outside through the filling layer 130 and the heat dissipation structure 140.

[0085] The heat dissipation structure 140 may dissipate heat generated in the gain medium 110. For example, the heat dissipation structure 140 may include copper.

[0086] Figure 3 2 is a cross-sectional view for explaining the operation of the optical amplifier 100 according to an embodiment of the present disclosure.

[0087] Reference Figure 3 , the gain medium 110 may include a first surface 31, a second surface 32 as an opposite surface of the first surface 31, and a side surface 33. Figure 3 In order to explain the amplification process of the seed beam 10, it is found that the illustration of the filling layer 130 is omitted for convenience. In addition, although the pump beam 20 is illustrated by only one light ray, this is for the convenience of explanation. Most of the light rays constituting the pump beam 20 are incident on the gain medium 110 and travel, and this is also the same below.

[0088] The gain medium 110 can receive the seed beam 10 and the pump beam 20 through the first surface 31. Since the gain medium 110 has a refractive index greater than that of the metal layer 120, the seed beam 10 and the pump beam 20 can be repeatedly totally reflected at the interface (i.e., the side surface 33) between the gain medium 110 and the metal layer 120, and can travel in the length direction (i.e., the -X axis direction) of the gain medium 110. When the pump beam 20 travels inside the gain medium 110, it is absorbed by the rare earth metal ions contained in the gain medium 110, thereby exciting the rare earth metal ions. Therefore, the seed beam 10 can be amplified.

[0089] On the other hand, there may be an unwanted pump beam inside the gain medium 110. The unwanted pump beam may include a pump beam with an unexpected incident direction and property, or a pump beam incident from the outside. For example, a pump beam with unplanned properties and direction that is not conducive to the amplification of the seed beam 10 in a preset direction and property may have an adverse effect on the characteristics of the seed beam 10. In addition, a portion of the pump beam 20 may return in the opposite direction of the travel direction (i.e., the +X-axis direction). The pump beam thus returned becomes a pump beam with undesirable properties and direction in the previous stage of the multi-stage amplification module, which may have an adverse effect on the characteristics of the amplified signal of the entire amplification module. Therefore, it is necessary to release the unwanted pump beam outside the gain medium 110.

[0090] Figure 4 FIG. 1 is a diagram showing a cross section of an optical amplifier 100 according to an embodiment of the present disclosure.

[0091] Reference Figure 4 , the pump beam 20 may be incident through the first surface 31 of the gain medium 110. The pump beam 20 may travel in the -X axis direction while repeating total reflection inside the gain medium 110.

[0092] The gain medium 110 may include a pump beam removal region A1. The pump beam removal region A1 may be a region for sending at least a portion of the pump beam 20 remaining inside the gain medium 110 to the outside of the gain medium 110. The pump beam removal region A1 may be provided on a side of the gain medium 110 adjacent to the first surface 31. In the pump beam removal region A1, the surface of the gain medium 110 may be non-flat after surface treatment. For example, the surface treatment may include at least one of grinding, etching, or wire processing.

[0093] Specifically, when viewed from a horizontal direction (i.e., Y-axis direction) perpendicular to the length direction (i.e., X-axis direction) of the gain medium 110, the depth of the vertical direction (i.e., Z-axis direction) of the surface may be uneven. For example, when viewed from a horizontal direction, the surface of the gain medium 110 in the pump beam removal area A1 may have a zigzag pattern. The zigzag pattern may be an irregular shape or a regular shape. In addition, the edge portion of the zigzag pattern may be a sharp shape or a smooth shape.

[0094] At least a portion of the pump beam 20 inside the gain medium 110 can be released to the outside of the gain medium 110 through the pump beam removal area A1. For example, when encountering the pump beam removal area A1 at an angle less than the critical angle, the first pump beam P1 can penetrate the pump beam removal area A1. The first pump beam P1, as the above-mentioned unnecessary pump beam, can be, for example, a reverse signal. The transmitted first pump beam P1 can be absorbed by the metal layer 120 and converted into heat energy and released to the outside. Since the gain medium 110 of the pump beam removal area A1 has a concave-convex surface, the probability that the first pump beam P1 encounters the side of the gain medium 110 at an angle less than the critical angle can be increased.

[0095] The pump beam removal area A1 may be located between the first face 31 and a region 41 on the side of the gain medium 110 where the pump beam 20 is first reflected. When the portion closest to the first face 31 is referred to as the start portion of the pump beam removal area A1 and the portion farthest from the first face 31 is referred to as the end portion of the pump beam removal area A1, the end portion of the pump beam removal area A1 may be located closer to the first face 31 than the region 41. When the end portion of the pump beam removal area A1 is located farther from the first face 31 than the region 41, a considerable portion of the pump beam 20 may be removed by the pump beam removal area A1 during the initial pumping process, and in this case, the seed beam 10 may not be amplified as expected.

[0096] The metal layer 120 may have two surfaces having different morphologies from each other. The metal layer 120 may include a first surface in contact with the gain medium 110 (i.e., an interface with the gain medium 110) and a second surface opposite to the first surface (i.e., an interface with the filling layer 130). For example, the second surface may have the same morphology regardless of the X-axis position. Specifically, the second surface may have a flat morphology.

[0097] On the contrary, the first surface of the metal layer 120 may have different morphologies according to the X-axis position. For example, the side area of ​​the gain medium 110 may be divided into a first area having the pump beam removal area A1 and a second area as the remaining area. The first surface is non-flat in the first area and may be flat in the second area.

[0098] Figure 5 FIG. 1 is a diagram showing a cross section of an optical amplifier 100 according to another embodiment of the present disclosure.

[0099] Reference Figure 5 , the pump beam 20 may be incident through the first surface 31 of the gain medium 110. The pump beam 20 may travel in the -X axis direction while repeating total reflection inside the gain medium 110.

[0100] The gain medium 110 may include a pump beam removal region A2. The pump beam removal region A2 may be a region for sending at least a portion of the pump beam 20 remaining inside the gain medium 110 to the outside of the gain medium 110. The pump beam removal region A2 may be provided on a side of the gain medium 110 adjacent to the second face 32. In the pump beam removal region A2, the surface of the gain medium 110 may be non-flat by surface treatment (e.g., polishing).

[0101] At least a portion of the pump beam 20 inside the gain medium 110 can be released to the outside of the gain medium 110 through the pump beam removal area A2. For example, when encountering the pump beam removal area A2 at an angle less than the critical angle, the second pump beam P2 can penetrate the pump beam removal area A2 and be absorbed by the metal layer 120. The second pump beam P2, as the above-mentioned unnecessary pump beam, can be, for example, a reverse signal. Since the gain medium 110 of the pump beam removal area A2 has a concave-convex surface, the probability of the second pump beam P2 encountering the side of the gain medium 110 at an angle less than the critical angle can be increased. Since the second pump beam P2 is removed, the pump beam 20 exceeding the requirement will not remain inside the gain medium 110, so it is possible to prevent the characteristics of the seed beam 10 from being deteriorated due to the second pump beam P2.

[0102] The pump beam removal area A2 may be located in an area adjacent to the second surface 32. In an area corresponding to the pump beam removal area A2, the metal layer 120 may have an uneven surface. For example, the metal layer 120 may have a concavo-convex surface along the surface of the gain medium 110. In an area not corresponding to the pump beam removal area A2, the metal layer 120 may have a uniform (or flat) surface. In an area corresponding to the pump beam removal area A2, the filling layer 130 may have an uneven surface. For example, the filling layer 130 may have a concavo-convex surface along the surface of the gain medium 110. In an area not corresponding to the pump beam removal area A2, the filling layer 130 may have a uniform (or flat) surface.

[0103] On the other hand, the pump beam removal area A2 may be larger than Figure 4 The pump beam removal area A1 of the pump beam removal area A2 can be longer in the X-axis direction than the pump beam removal area A1. Since the seed beam 10 traveling to the pump beam removal area A2 is already amplified to a sufficient size, there is no need to prevent the pump beam 20 from contacting the pump beam removal area A2.

[0104] In yet another embodiment, the gain medium 110 may include Figure 4 The pump beam removal area A1 is Figure 5 In addition, in the present disclosure, any one of the two areas A1 and A2 may also be referred to as an additional pump beam removal area.

[0105] In yet another embodiment, the metal layer 120 may not exist in at least a portion of the pump beam removal areas A1 and A2. For example, the metal layer 120 may not exist in the pump beam removal area A1. In this case, the metal layer 120 may exist only in the remaining areas of the side surface of the gain medium 110 except the pump beam removal area A1. Since the metal layer 120 can reflect the pump beam again into the gain medium 110, the pump beam escaping to the outside of the gain medium 110 may increase in the absence of the metal layer 120. That is, the pump beam removal amount in the pump beam removal area A1 can be increased.

[0106] As described above, the pump beam removal area A1 can be used to remove unnecessary pump beams, thereby improving the amplification efficiency, safety, and laser quality of the optical amplifier 100. In addition, the pump beam removal area A1 can be used to weaken the reverse signal entering the gain medium.

[0107] Figure 6 FIG. 1 is a diagram showing a cross section of an optical amplifier 100 according to an embodiment of the present disclosure.

[0108] Reference Figure 6, the exit surface of the gain medium 110, that is, the second surface 32, may have an inclined shape. For example, the second surface 32 may be inclined at a preset first angle 61 based on the Z axis. That is, the second surface 32 may have a wedge shape. The preset first angle 61 may be 5 degrees.

[0109] If the second surface 32 is in a wedge shape, the reverse signal of the pump beam 20 can be reduced compared to the case where the second surface 32 is parallel to the Z axis. That is, the amount of the pump beam 20 that is reflected inside the gain medium 110 and is directed toward the first surface 31 can be reduced. As described above, the reverse signal can have an adverse effect on the quality of the laser beam. Since the second surface 32 has a wedge shape, the reverse signal is reduced, and thus the quality of the laser beam can be improved.

[0110] [Table 1] shows experimental data showing the reverse signal reduction effect of the wedge shape.

[0111]

[0112] Specifically, for the case where the input signal (i.e., the seed beam 10) is input to the gain medium 110 and the case where the input signal (i.e., the seed beam 10) is not input to the gain medium 110, the intensity of the reverse signal of the pump beam 20 is measured while adjusting the intensity of the pump beam 20. Ppump represents the intensity of the pump beam 20, and Pbackward represents the intensity of the reverse signal. The input signal represents the seed beam 10. The intensity of the reverse signal is measured when the gain medium 110 is a general shape and when it is a wedge shape. In this article, the general shape refers to a shape that is not a wedge shape, for example, a shape in which the incident surface and the exit surface are horizontal.

[0113] Referring to Table 1, it can be seen that in each case, the wedge shape has a smaller reverse signal strength than the general shape (i.e., the shape in which the incident surface and the exit surface are horizontal). Thus, if the reverse signal strength is reduced, the amplification efficiency, safety, and laser quality of the optical amplifier 100 can be improved.

[0114] On the other hand, the second surface S2 of the heat dissipation structure 140 may be located in the same plane as the second surface 32 of the gain medium 110. Therefore, the second surface S2 of the heat dissipation structure 140 may also have a wedge shape that is inclined at a preset first angle 61 based on the z-axis. However, this is only an embodiment, and the second surface S2 of the heat dissipation structure 140 and the second surface 32 of the gain medium 110 may not be located in the same plane.

[0115] Figure 7 FIG. 1 is a diagram showing a cross section of an optical amplifier 100 according to another embodiment of the present disclosure.

[0116] Reference Figure 7, the incident surface of the gain medium 110, that is, the first surface 31, may have an inclined shape. For example, the first surface 31 may be inclined at a preset second angle 71 based on the Y axis. That is, the first surface 31 may have a wedge shape. The preset second angle 71 may be 5 degrees.

[0117] like Figure 6 As shown in FIG. 1 , when the second surface 32 has a wedge shape tilted with respect to the Z axis, aberration (e.g., astigmatism) of the output beam may be generated in the Z axis direction. At this time, if the first surface 31 has a wedge shape tilted with respect to an axis perpendicular to the Z axis (e.g., the Y axis) as a reference, the aberration of the output beam can be improved.

[0118] According to various embodiments, the first face 31 of the gain medium 110 has a wedge shape, or the second face 32 has a wedge shape, or both the first face 31 and the second face 32 may have a wedge shape.

[0119] On the other hand, the first surface S1 of the heat dissipation structure 140 may be located in the same plane as the first surface 31 of the gain medium 110. Therefore, the first surface S1 of the heat dissipation structure 140 may also have a wedge shape inclined at a preset second angle 71 based on the Y axis. However, this is only an embodiment, and the first surface S1 of the heat dissipation structure 140 and the first surface 31 of the gain medium 110 may not be located in the same plane.

[0120] exist Figure 4 and Figure 5 In the method of removing the unnecessary pump beam by surface treatment of the side of the gain medium 110, it is described. Figure 6 and Figure 7 In the embodiment, a method for reducing the unwanted pump beam (especially the reverse signal) by the structure of the incident surface or the exit surface of the gain medium 110 is described. According to the embodiment, the surface treatment of the side surface of the gain medium 110 and the structure of the incident surface or the exit surface can be selectively applied or applied simultaneously.

[0121] Figure 8 is a block diagram conceptually showing a laser processing apparatus according to an embodiment of the present disclosure.

[0122] Reference Figure 8 The laser processing device 1000 may include an optical amplifier 100 and a laser oscillator 200. The optical amplifier 100 may include a gain medium 110 and a pump source for providing a pump beam to the gain medium 110.

[0123] The pump source may provide a pump beam via the first surface 31 and / or the second surface 32 of the gain medium 110. For example, the pump source may provide a pump beam via the first surface 31 of the gain medium 110. The pump beam incident on the gain medium 110 may cause density inversion in the gain medium 110. In the process of the seed beam passing through the gain medium 110 where density inversion occurs, amplification of the seed beam may occur.

[0124] The laser oscillator 200 may generate a seed beam (or a signal beam). The laser oscillator 200 may transmit the seed beam to the optical amplifier 100. The seed beam may be a pulse laser beam.

[0125] According to an embodiment of the present disclosure, a laser processing device including an optical amplifier 100 may be provided. The laser processing device may include a laser oscillator and a pump beam light source. The laser oscillator may output a seed beam or a signal beam provided by the optical amplifier 100. For example, the laser oscillator may be a picosecond seed laser light source or a femtosecond seed laser light source.

[0126] The pump beam light source may output a pump beam provided by the optical amplifier 100. The pump beam may be incident through the first surface 31 or the second surface 32 of the optical amplifier 100. Alternatively, the pump beam may be incident through the first surface 31 and the second surface 32 of the optical amplifier 100, respectively.

[0127] The preferred embodiments of the present disclosure are illustrated and described above, but the present disclosure is not limited to the above-mentioned specific embodiments, and various modified implementations can be implemented by technicians in the technical field to which the present disclosure belongs without departing from the gist of the present disclosure requested in the scope of the claims, and these modified implementations cannot be understood individually from the technical ideas or prospects of the present disclosure.

Claims

1. An optical amplifier, characterized in that: include: A gain medium having a first surface for a seed beam to be incident on, a second surface located on the opposite side of the first surface, and a side surface connecting the first surface and the second surface, wherein the incident seed beam is amplified during movement to the second surface and is emitted through the second surface; as well as a pump source, providing a pump beam via at least one of the first surface or the second surface, In a region of the side surface of the gain medium, A pump beam removal region is provided which is surface-treated so that at least a portion of the pump beam existing inside the gain medium is released to the outside of the gain medium. The pump beam removal region is located closer to the first face than a region where the pump beam is first reflected at the side of the gain medium.

2. The optical amplifier according to claim 1, characterized in that The surface treatment includes at least one of grinding, etching or wire processing, In the pump beam removal region, the gain medium has a non-flat surface with a non-uniform depth.

3. The optical amplifier according to claim 1, characterized in that The gain medium further comprises: an additional pump beam removal area located at the side surface adjacent to the second surface, The additional pump beam removal region has a length greater than a length of the pump beam removal region.

4. The optical amplifier according to claim 2, characterized in that: Also includes: a metal layer surrounding the side of the gain medium, The metal layer comprises: a first surface in contact with the gain medium and a second surface opposite to the first surface, The first surface is non-flat along a profile of the non-flat surface of the gain medium in a first region corresponding to the pump beam removal region, is flat in a second region not corresponding to the pump beam removal region, The second surface is flat in the first region and the second region.

5. The optical amplifier according to claim 4, characterized in that The pump beam is released to the outside of the gain medium based on the difference in refractive index between the gain medium and the metal layer.

6. The optical amplifier according to claim 2, characterized in that: Also includes: a heat dissipation structure surrounding at least a portion of the side surface of the gain medium; as well as A filling layer is provided between the gain medium and the heat dissipation structure, The filling layer has a flat surface.

7. The optical amplifier according to claim 1, characterized in that: The second surface has a shape that is inclined at a preset first angle based on the first axis.

8. The optical amplifier according to claim 7, characterized in that: The first surface has a shape that is inclined at a preset second angle based on a second axis that is perpendicular to the first axis.

9. The optical amplifier according to claim 8, characterized in that The preset first angle is the same as the preset second angle.

10. The optical amplifier according to claim 1, characterized in that The gain medium comprises: Yttrium aluminum garnet crystals added to rare earth metals.

11. A laser processing device, characterized in that: include: a laser oscillator to generate a seed beam; as well as an optical amplifier for amplifying the seed beam generated by the laser oscillator, The optical amplifier comprises: A gain medium having a first surface for a seed beam to be incident on, a second surface located on the opposite side of the first surface, and a side surface connecting the first surface and the second surface, wherein the incident seed beam is amplified during movement to the second surface and is emitted through the second surface; as well as a pump source, providing a pump beam via at least one of the first surface or the second surface, In a region of the side surface of the gain medium, A pump beam removal region is provided which is surface-treated so that at least a portion of the pump beam existing inside the gain medium is released to the outside of the gain medium. The pump beam removal region is located closer to the first face than a region where the pump beam is first reflected at the side of the gain medium.

12. The laser processing device according to claim 11, characterized in that: The surface treatment includes at least one of grinding, etching or wire processing, In the pump beam removal region, the gain medium has a non-flat surface with a non-uniform depth.

13. The laser processing device according to claim 11, characterized in that: The gain medium further comprises: an additional pump beam removal area located at the side surface adjacent to the second surface, The additional pump beam removal region has a length greater than a length of the pump beam removal region.

14. The laser processing device according to claim 11, characterized in that: The second surface has a shape that is inclined at a preset first angle with the first axis as a reference.

15. The laser processing device according to claim 14, characterized in that: The first surface has a shape that is inclined at a preset second angle based on a second axis that is perpendicular to the first axis.

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