Optical element, laser device and method for manufacturing optical element

Abstract

An optical element according to an embodiment comprises: a laser medium; a first intermediate layer provided on the laser medium; a first metal layer that is formed on the first intermediate layer and contains a Group 4 element or a Group 6 element; and a heat sink that is provided on the first metal layer and contains metal, the first intermediate layer being formed on the laser medium and including a dielectric multilayer film that totally reflects laser light generated or amplified by the laser medium, and the first intermediate layer being thicker than the penetration depth of an evanescent wave generated by reflection of light incident from the laser medium side by the dielectric multilayer film.

Description

Optical element, laser device, and method of manufacturing optical element

[0001] The present invention relates to an optical element, a laser device, and a method for manufacturing an optical element.

[0002] Techniques relating to optical elements including laser media and laser devices including the same are described in Patent Document 1, Patent Document 2, Non-Patent Document 1, Non-Patent Document 2, Non-Patent Document 3, Non-Patent Document 4, and Non-Patent Document 5.

[0003] For example, Non-Patent Document 2 discloses an optical element in which a heat sink is integrated with a laser medium and a total reflection film is provided between the laser medium and the heat sink.

[0004] Patent No. 6245587 Patent No. 4265287

[0005] Masaki Tsunekane and Takunori Taira, “300 W continuous-wave operation of a diode edge-pumped, hybrid composite Yb:YAG microchip laser,” OPTICS LETTERS, July 1, 2006, Vol. 31, No. 13, pp. 2003-2005. LIHE ZHENG, ARVYDAS KAUSAS, TAKUNORI TAIRA, “Drastic thermal effects reduction through distributed face cooling in a high-power giantpulse tiny laser,” OPTICAL MATERIALS EXPRESS, September 1, 2017, Vol. 7, No. 9, pp. 3214-3221. Eiji Higurashi and Tadachi Suga, “Wafer room-temperature bonding technology to achieve high heat dissipation structures in high-power semiconductor devices,” Journal of the Japan Institute of Electronics Packaging, 2015, Vol. 18, No. 7, pp. 463-468.Siva Sankar Nagisetty, Patricie Severova, Taisuke Miura, Martin Smrz, Hitoe Kon, Miyuki Uomoto, Takehito Shimatsu, Masato Kawasaki, Takeshi Higashiguchi, Akira Endo and Tomas Mocek, “Lasing and thermal characteristics of Yb:YAG / YAG composite with atomic diffusion bonding,” Laser Phys. Letters, 2017, Vol. 14, pp. 1-6.Masaki Tsunekane and Takunori Taira, “High-power operation of diode edge-pumped, composite all-ceramic Yb:Y3Al5O12 microchip laser,” APPLIED PHYSICS LETTERS, 2007, Vol. 90, pp. 121101-1 to 121101-3.

[0006] When a laser medium and a heat sink are integrated, as in Non-Patent Document 2, heat generated in the laser medium is dissipated through the heat sink. Metals are used as heat sinks because they have higher thermal conductivity than dielectrics. In Non-Patent Document 2, a total reflection film is provided between the laser medium and the heat sink. Therefore, laser light generated or amplified using the laser medium is totally reflected by the total reflection film and output from the side opposite the heat sink as viewed from the laser medium. The total reflection film can function, for example, as part of an optical resonator. When the total reflection film and the heat sink are in contact with each other, as in Non-Patent Document 2, and the heat sink is made of metal, the total reflection film and the metal are in contact with each other. In such a configuration, if the laser light output is extremely high, the metal in contact with the total reflection film can be damaged, resulting in the instability of an optical element including a laser medium, a total reflection film, and a metal heat sink.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an optical element that can be stably used with high-power laser light, a laser device including the same, and a method for manufacturing the optical element.

[0008] The present inventors discovered that in a configuration in which a laser medium, a total reflection film, and a metal member are laminated in this order, the metal member is damaged by the influence of evanescent waves generated when high-power laser light is incident on the total reflection film from the laser medium side, and arrived at the present invention. Specifically, the inventors discovered that evanescent waves generated by total reflection of laser light by the total reflection film seep into the metal member, causing a process in which the metal member absorbs the evanescent waves, resulting in damage to the metal member, and arrived at the present invention.

[0009] The optical element of the present invention comprises a laser medium, a first intermediate layer provided on the laser medium, a first metal layer formed on the first intermediate layer and containing a Group 4 element or a Group 6 element, and a heat sink provided on the first metal layer and containing a metal, wherein the first intermediate layer is formed on the laser medium and includes a dielectric multilayer film that totally reflects laser light generated or amplified by the laser medium, and the first intermediate layer is thicker than the penetration length of evanescent waves generated by reflection of light incident from the laser medium side by the dielectric multilayer film.

[0010] In the above configuration, a first intermediate layer and a first metal layer are disposed between the laser medium and the heat sink, from the laser medium side. The first intermediate layer is formed on the laser medium and includes a dielectric multilayer film that totally reflects laser light generated or amplified by the laser medium. In the above configuration, the dielectric multilayer film of the first intermediate layer functions as a total reflection film. The first intermediate layer is thicker than the penetration length of evanescent waves generated by reflection of light incident from the laser medium side by the dielectric multilayer film. Therefore, even if high-power laser light is totally reflected by the dielectric multilayer film, the resulting evanescent waves are not absorbed by the first metal layer and the heat sink. This allows the optical element to be used stably even with high-power laser light.

[0011] The optical element according to one embodiment may further include a second metal layer disposed between the first metal layer and the heat sink and containing a Group 10 element. In this case, the linear expansion coefficient of the second metal layer containing the Group 10 element is between the linear expansion coefficient of the first metal layer and the linear expansion coefficient of the heat sink. Therefore, even if the laser medium generates heat, the optical element is less likely to be damaged than an optical element not including the second metal layer.

[0012] Examples of the material for the second metal layer include nickel and platinum.

[0013] The optical element according to an embodiment may further include a second intermediate layer disposed between the first metal layer and the second metal layer, and an example of a material for the intermediate layer is gold or a gold alloy.

[0014] Examples of the material for the first metal layer include chromium and titanium.

[0015] Examples of the material of the heat sink can be copper, copper tungsten, copper molybdenum, iron, aluminum or an aluminum-silicon carbide composite.

[0016] The first intermediate layer may include the dielectric multilayer film and a non-metallic heat-conductive layer disposed between the dielectric multilayer film and the first metal layer.

[0017] Examples of materials for the non-metallic heat transfer layer can be diamond, silicon carbide or nitride.

[0018] A laser device according to another aspect of the present invention includes the optical element described above. Since the laser device includes the optical element described above, it is possible to stably output high-power laser light.

[0019] A method for manufacturing an optical element according to another aspect of the present invention includes a preparation step of preparing a first component including a laser medium and a second component including a heat sink including a metal, and a bonding step of bonding the first component to the second component, wherein the preparation step includes a step of forming a first intermediate layer on the laser medium and a step of forming a first metal layer on the first intermediate layer, the first metal layer including a Group 4 element or a Group 6 element, and the bonding step bonds the first component to the second component via the first metal layer, the first intermediate layer being formed on the laser medium and including a dielectric multilayer film that totally reflects laser light generated or amplified by the laser medium, and the step of forming the first intermediate layer includes forming the first intermediate layer so that the thickness of the first intermediate layer is thicker than the penetration length of evanescent waves generated by reflection of light incident from the laser medium side by the dielectric multilayer film.

[0020] This manufacturing method can produce an optical element in which a first intermediate layer and a first metal layer are arranged between the laser medium and the heat sink, from the laser medium side. The first metal layer contains a Group 4 element or a Group 6 element. In the optical element having the above configuration, the dielectric multilayer film of the first intermediate layer functions as a total reflection film. The first intermediate layer is thicker than the penetration length of evanescent waves generated by reflection of light incident from the laser medium side by the dielectric multilayer film. Therefore, even if high-power laser light is totally reflected by the dielectric multilayer film, the resulting evanescent waves are not absorbed by the first metal layer and the heat sink. Therefore, the optical element can be stably used even with high-power laser light. Therefore, the above manufacturing method can produce an optical element that can be stably used even with high-power laser light.

[0021] The preparation step may include a step of forming a second metal layer containing a Group 10 element on the heat sink, and the bonding step may include bonding the first component and the second component via the first metal layer and the second metal layer. In this case, an optical element having a second metal layer between the first metal layer and the heat sink can be manufactured. The linear expansion coefficient of the second metal layer containing a Group 10 element is a value between the linear expansion coefficient of the first metal layer and the linear expansion coefficient of the heat sink. Therefore, even if the laser medium generates heat, the optical element is less likely to be damaged than an optical element not having a second metal layer. In other words, a manufacturing method for an optical element including a step of forming a second metal layer containing a Group 10 element can manufacture an optical element that can be used more stably even with high-power laser light.

[0022] The preparation step may include a step of forming a layer on at least one of the first metal layer and the second metal layer to serve as a second intermediate layer disposed between the first metal layer and the second metal layer.

[0023] In the joining step, a surface of the first component that joins with the second component and a surface of the second component that joins with the first component may be subjected to a surface activation treatment, and then the surface-activated first component and the second component may be joined together. In this case, the first component and the second component can be directly and firmly joined together.

[0024] A manufacturing method for an optical element according to one embodiment further includes a step of performing a surface activation treatment on a surface of the first component on the bonding side with the second component and a surface of the second component on the bonding side with the first component, the preparation step further includes a step of forming a second metal layer containing a Group 10 element on the first metal layer, the second component being the heat sink, and the bonding step may include bonding the first component and the second component via the second metal layer.

[0025] In this case, an optical element having a second metal layer between the first metal layer and the heat sink can be manufactured. The linear expansion coefficient of the second metal layer containing a Group 10 element is a value between the linear expansion coefficient of the first metal layer and the linear expansion coefficient of the heat sink. Therefore, even if the laser medium generates heat, the optical element is less likely to be damaged than an optical element without a second metal layer. In other words, a manufacturing method for an optical element including a step of forming a second metal layer containing a Group 10 element can manufacture an optical element that can be used more stably even with high-power laser light. The first and second components are bonded by performing a surface activation treatment on the surface of the first component that is bonded to the second component and the surface of the second component that is bonded to the first component, thereby enabling the first and second components to be bonded firmly and directly.

[0026] The step of forming the first intermediate layer may include the steps of forming the dielectric multilayer film on the laser medium, and forming a non-metallic heat-conductive layer on the dielectric multilayer film.

[0027] According to the present invention, it is possible to provide an optical element that can be stably used with high-power laser light, a laser device including the same, and a method for manufacturing the optical element.

[0028] FIG. 1 is a diagram showing a schematic configuration of an optical element according to a first embodiment. FIG. 2 is a diagram for explaining an example of a method for manufacturing the optical element shown in FIG. 1. FIG. 3 is a diagram for explaining another example of a method for manufacturing the optical element shown in FIG. 1. FIG. 4 is a schematic diagram showing a schematic configuration of an optical element according to a second embodiment. FIG. 5 is a diagram for explaining an example of a method for manufacturing the optical element shown in FIG. 4. FIG. 6 is a diagram for explaining another example of a method for manufacturing the optical element shown in FIG. 4. FIG. 7 is a schematic diagram showing a schematic configuration of an optical element according to a third embodiment. FIG. 8 is a diagram for explaining an example of a method for manufacturing the optical element shown in FIG. 7. FIG. 9 is a schematic diagram of an example of a laser device using an optical element. FIG. 10 is a schematic diagram showing another example of a laser device that is a laser oscillator. FIG. 11 is a schematic diagram showing another example of a laser device that is a laser oscillator. FIG. 12 is a schematic diagram showing another example of a laser device that is a laser oscillator. FIG. 13 is a schematic diagram showing another example of a laser device using an optical element. FIG. 14 is a schematic diagram showing another example of a laser device as a laser amplifier. Fig. 15 is a schematic diagram of another example of a laser device using an optical element. Fig. 16 is a schematic diagram showing another example of a laser device as a regenerative laser amplifier. Fig. 17 is a schematic diagram showing another example of a laser device that is a regenerative laser amplifier. Fig. 18 is a schematic diagram showing another example of a laser device that is a regenerative laser amplifier. Fig. 19 is a schematic diagram showing a general configuration of another example of an optical element. Fig. 20 is a schematic diagram showing a general configuration of another example of an optical element. Fig. 21 is a schematic diagram showing a general configuration of another example of an optical element.

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements will be designated by the same reference numerals, and redundant description will be omitted. The dimensional proportions of the drawings do not necessarily correspond to those in the description.

[0030] First Embodiment FIG. 1 is a diagram showing a schematic configuration of an optical element 10 according to one embodiment. The optical element 10 shown in FIG. 1 includes a laser medium 11, a dielectric multilayer film (first intermediate layer) 12, a first metal layer 13, and a heat sink 14. The optical element 10 is a laser medium with a heat sink that has a total reflection function due to the dielectric multilayer film 12. The optical element 10 is applied to laser oscillators, laser amplifiers, and the like. The optical element 10 may include an intermediate layer (second intermediate layer) 15. The optical element 10 may include a second metal layer 16. Unless otherwise specified, the following describes an embodiment having the intermediate layer 15 and the second metal layer 16.

[0031] The laser medium 11 is a material that forms a population inversion in an excited state in which gain exceeds loss, and amplifies light by utilizing stimulated emission. The laser medium 11 is an optical component for oscillating or amplifying laser light L. The laser medium 11 is also called a gain medium.

[0032] Examples of the material of the laser medium 11 include optical gain materials formed from oxides doped with rare earth ions that serve as luminescence centers, optical gain materials formed from oxides doped with transition metal ions that serve as luminescence centers, optical gain materials formed from oxides that serve as color centers, optical gain materials formed from semiconductors, and the like.

[0033] Examples of the rare earth ions include Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb. Examples of transition metal ions include Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. Examples of host materials to which rare earth ions, transition metal ions, etc. are added include garnet-based materials such as YAG, YSAG, YGAG, YSGG, GGG, GSGG, and LuAG, YLF, LiSAF, LiCAF, and MgF. ２ , CaF ２ Fluoride-based materials such as YVO ４ , GdVO ４ , LuVO ４ vanadate-based materials such as FAP, sFAP, VAP, sVAP, and other apatite-based materials; Al ２ O ３ ,BeAl ２ O ３ Alumina-based materials such as Y ２ O３ , Sc ２ O ３ , Lu ２ O ３ Examples of semiconductors include oxide-based materials such as ZnO, ZnS, and tungstate-based materials such as KGW and KYW. The laser medium 11 may be in a single crystal, amorphous (including glass), or ceramic state. The host material may be various amorphous glasses. Examples of semiconductors include GaAs, GaAlAs, GaAlP, GaP, GaN, InGaN, AlGaN, and GaAlN.

[0034] A dielectric multilayer film 12 is formed on the first surface 11a of the laser medium 11. The dielectric multilayer film 12 totally reflects the laser light L generated or amplified by stimulated emission of the laser medium 11. In one embodiment, the dielectric multilayer film 12 functions as an HR coating layer for the laser light L. The dielectric multilayer film 12 may also reflect light of wavelengths other than the wavelength of the laser light L. The dielectric multilayer film 12 is configured by alternately stacking multiple high-refractive-index layers and multiple low-refractive-index layers (layers having a refractive index smaller than that of the high-refractive-index layers). Desired reflection characteristics can be achieved by adjusting the refractive index and thickness of each of the high-refractive-index layers and the low-refractive-index layers. The dielectric multilayer film 12 has a thickness such that evanescent waves EW generated when the laser light L is totally reflected do not reach the first metal layer 13. In other words, the thickness t of the dielectric multilayer film 12 is longer than the penetration length d of the evanescent waves EW. The dielectric multilayer film 12 is a multilayer film composed of a plurality of layers, each having a thickness of, for example, 10 nm to 9000 nm (100 Å to 90000 Å). Therefore, the thickness t of the dielectric multilayer film 12 is, for example, about several μm. Depending on the wavelength of light reflected by the dielectric multilayer film 12, the thickness t may be 10 μm or more. However, it is preferable that the dielectric multilayer film 12 is thin. The material of the layer of the dielectric multilayer film 12 closest to the first metal layer 13 is mainly Al, which has a high thermal conductivity. ２ O ３ is suitable, but SiO ２ But that's okay.

[0035] The first metal layer 13 is formed on the first surface 12a of the dielectric multilayer film 12. The first surface 12a is the surface of the dielectric multilayer film 12 opposite the laser medium 11. The first metal layer 13 functions as a buffer layer when bonding the laser medium 11 and the heat sink 14, which have different linear expansion coefficients. The first metal layer 13 includes a metal material with a linear expansion coefficient close to that of the laser medium 11. The first metal layer 13 includes a Group 4 element or a Group 6 element. An example of a Group 4 element is titanium (Ti), and an example of a Group 6 element is chromium (Cr). The thickness of the first metal layer 13 is, for example, 1 nm to 900 nm (10 Å to 9000 Å). To prevent migration, which may occur when a temperature rise process is required, a Ni layer or a Pt layer may be provided on the first metal layer 13 on the side opposite the dielectric multilayer film 12. The thickness of the Ni layer or Pt layer is, for example, 10 nm or more and 900 nm or less (100 Å or more and 9000 Å or less).

[0036] The heat sink 14 is a heat conductor for cooling the laser medium 11 and contains a metal. The heat sink 14 is, for example, a metal heat sink. The material of the heat sink 14 is a material with high thermal conductivity. Examples of the material of the heat sink 14 include copper, copper alloy, aluminum, iron, and an aluminum-silicon carbide composite. Examples of copper alloys include copper tungsten and copper molybdenum.

[0037] The intermediate layer 15 is formed on the first surface 13a of the first metal layer 13. The first surface 13a is the surface of the first metal layer 13 opposite the dielectric multilayer film 12. The intermediate layer 15 also functions as a buffer layer. The material of the intermediate layer 15 is gold or a gold alloy. The thickness of the intermediate layer 15 is, for example, 5 nm to 10 μm.

[0038] The second metal layer 16 is formed on the first surface 15a of the intermediate layer 15. The first surface 15a is the surface of the intermediate layer 15 opposite the first metal layer 13. In the arrangement shown in FIG. 1 , the second metal layer 16 is formed on the first surface 14a of the heat sink 14. The second metal layer 16 also functions as a buffer layer. The second metal layer 16 is formed from a material having a linear expansion coefficient close to (or between) the linear expansion coefficients of the first metal layer 13 and the heat sink 14. The second metal layer 16 includes a Group 10 element. Examples of materials for the second metal layer 16 include nickel (Ni) or platinum (Pt). The thickness of the second metal layer 16 is, for example, 10 nm to 900 nm (100 Å to 9000 Å). If a temperature-elevated treatment is required, the thickness of the second metal layer 16 is, for example, approximately 0.1 μm to 10 μm.

[0039] A dielectric multilayer film 17 for suppressing reflection of the laser light L may be formed on the second surface 11b of the laser medium 11 of the optical element 10. The dielectric multilayer film 17 functions as an anti-reflection film (AR coating) for the laser light L.

[0040] An example of a method for manufacturing the optical element 10 will be described with reference to Fig. 2. Fig. 2 is a diagram for explaining an example of a method for manufacturing the optical element 10 shown in Fig. 1. The following describes the case of manufacturing the optical element 10 having the dielectric multilayer film 12, the first metal layer 13, the intermediate layer 15, and the second metal layer 16 between the laser medium 11 and the heat sink 14 as shown in Fig. 1.

[0041] When manufacturing the optical element 10, a first component 20 including the laser medium 11 and a second component 30 including the heat sink 14 are prepared (preparation step).

[0042] The preparation process includes a process of preparing the first component 20 and a process of preparing the second component 30. The order of the processes of preparing the first component 20 and the second component 30 is not limited.

[0043] The process of preparing the first component 20 sequentially involves forming a dielectric multilayer film 12 on the laser medium 11, forming a first metal layer 13 on the dielectric multilayer film 12, and forming an intermediate layer 151 on the first metal layer 13. The dielectric multilayer film 12, the first metal layer 13, and the intermediate layer 151 can be formed by film formation technology, thin film technology, or the like.

[0044] The conditions satisfied by the dielectric multilayer film 12 and the first metal layer 13 have been described above, and therefore further description will be omitted. The intermediate layer 151 is a layer that constitutes the intermediate layer 15 shown in FIG. 1 by being joined to an intermediate layer 152 of the second component 30, which will be described later. Therefore, the material of the intermediate layer 151 is the same as that of the intermediate layer 15. The thickness of the intermediate layer 151 is such that the sum of the thicknesses of the intermediate layer 151 and the intermediate layer 152 corresponds to the thickness of the intermediate layer 15.

[0045] When the optical element 10 has a dielectric multilayer film 17 , the step of preparing the first component 20 includes the step of forming the dielectric multilayer film 17 .

[0046] The process of preparing the second component 30 includes sequentially forming a second metal layer 16 on the heat sink 14 and forming an intermediate layer 152 on the second metal layer 16. The second metal layer 16 and the intermediate layer 152 can be formed by a film deposition technique, a thin film technique, or the like.

[0047] The conditions satisfied by the second metal layer 16 have been described above, and therefore further description will be omitted. The intermediate layer 152 is a layer that constitutes the intermediate layer 15 shown in FIG. 1 by being joined to the intermediate layer 151 of the first component 20 described above. Therefore, the material of the intermediate layer 152 is the same as that of the intermediate layer 15. The thickness of the intermediate layer 152 is such that the sum of the thicknesses of the intermediate layer 152 and the intermediate layer 151 corresponds to the thickness of the intermediate layer 15.

[0048] After the first component 20 and the second component 30 are prepared, they are bonded together (a bonding process). An example of a bonding method will be described in detail. In this embodiment, the first component 20 and the second component 30 are bonded together using surface activated bonding. Surface activated bonding is a method for bonding flat bonding surfaces with exposed constituent atoms, and can significantly reduce the bonding temperature compared to other bonding methods.

[0049] Specifically, the first component 20 and the second component 30 are placed in a chamber 40, and a substantially vacuum environment is created inside the chamber 40. In the substantially vacuum environment, a surface active beam 42 is irradiated from a beam source 41 onto the joining surface 20 a of the first component 20 and the joining surface 30 a of the second component 30.

[0050] The joining surface 20a is the surface of the first component 20 that is joined to the second component 30. In the embodiment shown in Fig. 2, the joining surface 20a is the first surface 151a of the intermediate layer 151. The joining surface 30a is the surface of the second component 30 that is joined to the first component 20. In the embodiment shown in Fig. 2, the joining surface 30a is the first surface 152a of the intermediate layer 152.

[0051] Examples of the surface active beam 42 include an ion beam of argon (Ar) or the like, or a fast atom beam (FAB). As a result, the surfaces (the bonding surfaces 20a and 30a in this embodiment) irradiated with the surface active beam 42 are activated. Specifically, oxygen and the like adsorbed on the surfaces are removed, and new surfaces containing dangling bonds are formed. The nearly vacuum environment has a background pressure of, for example, 1×10 －６ The pressure is a vacuum or reduced pressure atmosphere of 0.1 Pa or more and less than atmospheric pressure.

[0052] As the ion beam or FAB, a beam using a rare gas or an inert gas such as neon (Ne), krypton (Kr), xenon (Xe), or helium (He) can be used in addition to argon. Rare gases are less likely to cause chemical reactions, so they do not significantly change the chemical properties of the irradiated surface. An example of the beam source 41 is a particle beam source or a plasma generator. By using the particle beam source or the plasma generator to accelerate the particles of the ion beam toward the bonding surface 20 a and the bonding surface 30 a, a predetermined kinetic energy can be imparted to the ion beam or FAB.

[0053] After surface activation treatment is performed on the bonding surfaces 20a and 30a, the bonding surfaces 20a and 30a are brought into contact with each other. At room temperature, the newly formed surfaces (the bonding surfaces 20a and 30a that have been surface activated) of the first component 20 and the second component 30, where the bonding hands are exposed, are brought into contact with each other in a substantially vacuum environment. This generates a bonding force due to atomic interactions. As a result, the first component 20 and the second component 30 are firmly bonded together, and the optical element 10 is obtained. The substantially vacuum environment may have a background pressure of, for example, 1.5×10 －６ The atmosphere is a vacuum or reduced pressure of not more than 100 Pa. A predetermined pressure (1.5 to 2.0 MPa) may be applied to the first component 20 and the second component 30 that are in contact with each other.

[0054] The bonding surfaces 20a and 30a may be made amorphous by the surface activation treatment. In this case, the first component 20 and the second component 30 are bonded via an amorphous layer. An amorphous material is a material that does not have long-range order like a crystal, but has short-range order. An amorphous state is a state in which the crystalline structure is broken. An amorphous layer is a layer with crystallinity below a certain level.

[0055] The amorphous layer contains, as impurities other than the materials constituting the heat sink 14 and the laser medium 11, elements constituting the ion beam or FAB (hereinafter referred to as "beam elements") and a housing material constituting the beam housing of the ion beam or FAB. The beam elements are, for example, Ar (argon) or Ne (neon). The housing material is, for example, Fe (iron), Ni (nickel), or Cr (chromium). The amount of the beam elements contained in the amorphous layer is so small that it does not affect the oscillation or amplification of the laser light L.

[0056] After bonding the first component 20 and the second component 30 via the amorphous layer, the optical element 10 may be heated in a heating furnace to raise the temperature of the optical element 10 to a predetermined temperature. This anneals the optical element 10, causing the amorphous layer of the optical element 10 to grow epitaxially and crystallize.

[0057] The predetermined temperature (also referred to as the crystallization temperature or epitaxial growth temperature) is lower than the melting points of the heat sink 14 and the laser medium 11. The predetermined temperature is equal to or higher than 100°C and lower than the melting point of the material constituting the amorphous layer. In one embodiment, the predetermined temperature is approximately 865°C, which is about half the melting point of the heat sink 14 and the laser medium 11, which is approximately 2000°C. The predetermined temperature is, for example, 1900°C or lower. The predetermined temperature is a low temperature that does not affect the dielectric multilayer film 12, such as 200°C or 300°C. The heating time of the optical element 10 is, for example, several hours to several tens of hours. For example, in the case of a long-term heating process, the predetermined temperature may be 100°C or lower.

[0058] Here, the case where the surface activation treatment is performed in the bonding process has been described. However, the surface activation treatment may be omitted. Au is the most stable material, and can be stored for a long period of time while maintaining its surface activation by adjusting the storage conditions. Therefore, if the intermediate layer 15 is made of Au and can be stored for a long period of time while maintaining its surface activation, the surface activation treatment may be omitted.

[0059] In the optical element 10, the dielectric multilayer film 12 functions as a total reflection film. The thickness t of the dielectric multilayer film 12 is greater than the seepage length d of evanescent waves EW generated by reflection of the laser light L incident from the laser medium 11 side. With this configuration, even if high-power laser light L is totally reflected by the dielectric multilayer film 12, the evanescent waves EW generated thereby are not absorbed by the first metal layer 13, the heat sink 14, etc. Therefore, the optical element 10 can be stably used even with high-power laser light L. The high-power laser light L is laser light having an average output of 1 kW or more (for example, a megawatt or more).

[0060] The first metal layer 13 includes a Group 4 element (for example, Ti) or a Group 6 element (for example, Cr). The linear expansion coefficient of such a first metal layer 13 is between the linear expansion coefficient of the dielectric (laser medium 11, dielectric multilayer film 12, etc.) and the linear expansion coefficient of the heat sink 14. Therefore, the linear expansion coefficient changes stepwise from the laser medium 11 side toward the heat sink 14 inside the optical element 10 compared to when the first metal layer 13 is not provided. In other words, the rate of change in the linear expansion coefficient from the laser medium 11 side toward the heat sink 14 is smaller than when the first metal layer 13 is not provided. Therefore, for example, even if heat is generated in the laser medium 11 due to the influence of high-power laser light L, the optical element 10 is less likely to be damaged.

[0061] The second metal layer 16 includes a tenth element (for example, Ni, Pt, etc.). The linear expansion coefficient of such a second metal layer 16 is between the linear expansion coefficient of the first metal layer 13 and the linear expansion coefficient of the heat sink 14. Therefore, in the embodiment including the second metal layer 16, the linear expansion coefficient changes stepwise from the laser medium 11 side toward the heat sink 14 inside the optical element 10 compared to the embodiment not including the second metal layer 16. In other words, the rate of change in the linear expansion coefficient from the laser medium 11 side toward the heat sink 14 is smaller than the embodiment not including the second metal layer 16. Therefore, in the embodiment including the second metal layer 16, the optical element 10 is less likely to be damaged even if heat is generated in the laser medium 11 due to the influence of high-power laser light L, for example.

[0062] The optical element 10 can be manufactured by the example of the method for manufacturing an optical element described with reference to Fig. 2. That is, the optical element 10 that can be stably used with respect to high-power laser light L can be manufactured by the example of the method for manufacturing an optical element described with reference to Fig. 2.

[0063] 2, when the optical element 10 is manufactured using surface activated bonding, the first component 20 including the laser medium 11 and the second component 30 including the heat sink 14 can be directly bonded (specifically, by using a bonding force due to atomic interactions), and therefore they can be firmly bonded together. In this case, since no adhesive layer or the like is used, the optical element 10 is less likely to be damaged by the heat generated by the laser medium 11.

[0064] In a configuration including an intermediate layer 15 formed from Au or an Au alloy, the optical element 10 can be manufactured using a first component 20 and a second component 30 having intermediate layers 151 and 152, which will become the intermediate layer 15, on the bonding side, as in the example of the manufacturing method described with reference to FIG. 2 . Because Au and other metals are resistant to oxidation, it is easy to keep the bonding surfaces 20a and 30a clean. As a result, the first component 20 and the second component 30 can be bonded more firmly. When the intermediate layer 15 is formed from Au, as described above, the surface activation process may be omitted. As a result, the optical element 10 can be easily manufactured.

[0065] 2, intermediate layer 15 is divided into intermediate layer 151 and intermediate layer 152 and disposed on first component 20 and second component 30. However, as shown in FIG. 3, optical element 10 may be manufactured using second component 30A that does not have intermediate layer 152 and first component 20A that has intermediate layer 15 instead of intermediate layer 151.

[0066] The first part 20A is the same as the first part 20 except that it has an intermediate layer 15 instead of the intermediate layer 151. In the first part 20A, the first surface 15a of the intermediate layer 15 is the joining surface 20a. The preparation method of the first part 20A is also the same as the preparation method of the first part 20 except that the intermediate layer 15 is formed instead of the intermediate layer 151.

[0067] The second component 30A is the same as the second component 30 except that it does not have the intermediate layer 152. The second component 30 is a laminate of the heat sink 14 and the second metal layer 16, and the first surface 16a of the second metal layer 16 is the joining surface 30a. The first surface 16a is the surface of the second metal layer 16 opposite to the heat sink 14. The preparation method for the second component 30A is the same as the preparation method for the second component 30 except that the intermediate layer 152 is not formed.

[0068] The manufacturing method of optical element 10 when first component 20A and second component 30A are used is the same as that described with reference to Fig. 2, except that first component 20A and second component 30A are used instead of first component 20 and second component 30. Therefore, the manufacturing method of modification 1 has the same effects as the manufacturing method described with reference to Fig. 2.

[0069] The joining surface 30a of the second component 30A is the first surface 16a of the second metal layer 16. Because an oxide film is easily formed on the first surface 16a of the second metal layer 16, in Modification 1, before joining the first component 20A and the second component 30A, a surface activation treatment is performed on the joining surface 30a using a surface activation beam 42, as described with reference to FIG. 2 . The conditions for the surface activation treatment are the same as those described with reference to FIG. 2 . Since the surface activation treatment is performed on the second component 30A, the first component 20A is also typically subjected to a surface activation treatment. However, the first component 20A has an intermediate layer 15. Therefore, as with the first component 20, if the intermediate layer 15 is made of Au, the material is stable, and the first component 20A has good storage conditions, the surface activation treatment may be omitted.

[0070] Second Embodiment FIG. 4 is a schematic diagram showing the general configuration of an optical element 10A according to a second embodiment. The optical element 10A differs from the optical element 10 in that the optical element 10 does not have an intermediate layer 15. In the optical element 10A, the first metal layer 13 and the second metal layer 16 are in contact with each other. Other than the above differences, the configuration of the optical element 10A is the same as that of the optical element 10. Therefore, the optical element 10A has the same effects as the optical element 10. Although not shown in FIG. 4, the optical element 10A may also have a dielectric multilayer film 17 that functions as an anti-reflection film.

[0071] An example of a manufacturing method for optical element 10A will be described. The manufacturing method for optical element 10A is similar to the manufacturing method for optical element 10, except that first component 20B and second component 30A shown in FIG. 5 are prepared and then bonded together to manufacture optical element 10A. Therefore, the manufacturing method for optical element 10A has the same effects as the manufacturing method for optical element 10.

[0072] The first component 20B differs from the first component 20 in that it does not have the intermediate layer 151. Other than this difference, the configuration of the first component 20B is the same as that of the first component 20. The joining surface 20a of the first component 20B is the first surface 13a of the first metal layer 13. The preparation method of the first component 20B is the same as that of the first component 20, except that the intermediate layer 151 is not formed.

[0073] The second component 30A is the same as the second component 30A described in Modification 1, and therefore a description thereof will be omitted. The joining surface 30a of the second component 30A is the first surface 16a of the second metal layer 16.

[0074] The joining surface 20a of the first component 20B is the first surface 13a of the first metal layer 13, and the joining surface 30a of the second component 30A is the first surface 16a of the second metal layer 16. An oxide film is likely to form on the first surface 13a and the first surface 16a. Therefore, when surface activation bonding the first component 20B and the second component 30A, a surface activation treatment is performed on the joining surfaces 20a and 30a using a surface activation beam 42, as in the case described with reference to FIG. 2. The conditions for the surface activation treatment are the same as those described with reference to FIG. 2.

[0075] 5, the second component 30A has the second metal layer 16. However, as shown in FIG. 6, the optical element 10A may be manufactured using a first component 20C having the second metal layer 16 and a second component 30B not having the second metal layer 16.

[0076] The first component 20C is similar to the first component 20B, except that a second metal layer 16 is formed on the first metal layer 13. The joining surface 20a of the first component 20C is the second surface 16b of the second metal layer 16. The second surface 16b is the surface of the second metal layer 16 opposite to the first surface 16a. The preparation method for the first component 20C is the same as the preparation method for the first component 20B, except that the second metal layer 16 is further formed on the first metal layer 13.

[0077] The second component 30B is similar to the second component 30A except that it does not have the second metal layer 16. Therefore, in the second modification, the second component 30B is the heat sink 14, and the joining surface 30a of the second component 30B is the first surface 14a of the heat sink 14.

[0078] The manufacturing method of the optical element 10A using the first component 20C and the second component 30B is the same as that described with reference to FIG. 5 , except that the first component 20C and the second component 30B are used instead of the first component 20B and the second component 30A. Oxide films are likely to form on the second surface 16b of the second metal layer 16, which is the bonding surface 20a, and the first surface 14a of the heat sink 14, which is the bonding surface 30a. Therefore, in Modification 2, when surface-activating bonding the first component 20C and the second component 30B, a surface activation treatment is performed on the bonding surfaces 20a and 30a using a surface activation beam 42, as in the case described with reference to FIG. 2 . The conditions for the surface activation treatment are the same as those described with reference to FIG. 2 .

[0079] Except for using first component 20C and second component 30B instead of first component 20B and second component 30A, the manufacturing method of Modification 2 is similar to the manufacturing method of optical element 10A described with reference to Fig. 5. Therefore, the manufacturing method of Modification 2 has the same effects as the manufacturing method of optical element 10A described with reference to Fig. 5.

[0080] Third Embodiment Fig. 7 is a schematic diagram showing the general configuration of an optical element 10B according to a third embodiment. The optical element 10B differs from the optical element 10 in that it does not have an intermediate layer 15 or a second metal layer 16. In the optical element 10B, a heat sink 14 is disposed on the first metal layer 13. Other than the above differences, the configuration of the optical element 10B is the same as that of the optical element 10. Therefore, the optical element 10B has the same effects as the optical element 10.

[0081] An example of a manufacturing method for optical element 10B will be described. The manufacturing method for optical element 10B is similar to the manufacturing method for optical element 10, except that the optical element 10B is manufactured by preparing a first component 20B and a second component 30B shown in FIG. 8 and bonding them together. Therefore, the manufacturing method for optical element 10B has the same effects as the manufacturing method for optical element 10.

[0082] The first part 20B is the same as the first part 20B shown in Fig. 5, and therefore a description thereof will be omitted. The second part 30B is the same as the second part 30B shown in Fig. 6, and therefore a description thereof will be omitted.

[0083] As described with reference to FIG. 5 , the bonding surface 20a of the first component 20B is the first surface 13a of the first metal layer 13. As described with reference to FIG. 6 , the bonding surface 30a of the second component 30B is the first surface 14a of the heat sink 14. An oxide film is likely to form on the first surface 13a and the first surface 14a. When surface activation bonding the first component 20B and the second component 30B in the manufacture of the optical element 10B, a surface activation treatment is performed on the bonding surfaces 20a and 30a using a surface activation beam 42, as in the case described with reference to FIG. 2 . The conditions for the surface activation treatment are the same as those in the case described with reference to FIG. 2 .

[0084] Next, various embodiments of laser devices using optical elements will be described. Below, embodiments using the optical element 10 will be described, but optical elements 10A and 10B may be employed instead of the optical element 10. Laser devices using the optical element 10 (optical element 10A or optical element 10B) are applicable to measurement, analysis, display, processing, and medicine (including diagnosis and treatment), and may be incorporated into devices in the exemplified fields.

[0085] (Fourth embodiment) Fig. 9 is a schematic diagram of an example of a laser device using an optical element. The laser device 100 shown in Fig. 9 is a laser oscillator. As shown in Fig. 9, the laser device 100 has an optical element 10 and an output mirror 111.

[0086] In the laser device 100, the dielectric multilayer film 12 of the optical element 10 functions as a total reflection mirror for the laser light L. In the laser device 100, the dielectric multilayer film 12 and the output mirror 111 form an optical resonator 101. The optical element 10 is arranged so that the laser medium 11 is located within the optical resonator 101. The output mirror 111 only needs to have the reflection and transmission characteristics to function as the output mirror 111 in the optical resonator 101. The output mirror 111 may be a partial reflection mirror.

[0087] When the laser device 100 outputs laser light L, the laser medium 11 is irradiated with excitation light 102. This generates stimulated emission light within the laser medium 11, and the stimulated emission light propagates within the optical resonator 101. As a result, laser oscillation occurs, and the laser light L is output from the output mirror 111.

[0088] The laser device 100 may have a light source unit 103 that outputs excitation light 102. The laser device 100 may have a Q-switching element 104 between the optical element 10 and the output mirror 111 in the optical resonator 101. The Q-switching element 104 may be a known Q-switching element. The laser device 100 may have a mode-locking element or a wavelength conversion element instead of the Q-switching element 104. The mode-locking element and the wavelength conversion element may also be known mode-locking elements and wavelength conversion elements. When the laser device 100 includes a wavelength conversion element that is arranged on the output side of the laser device 100 with respect to the optical element 10, the output mirror 111 may have a wavelength separation function.

[0089] The laser device 100 includes an optical element 10. As described in the first embodiment, the optical element 10 is not easily damaged by the high-power laser light L, and as a result, the laser device 100 can be used stably. Therefore, the laser device 100 can also stably output the high-power laser light L.

[0090] The laser device 100 includes the optical element 10 that can be stably used with high-power laser light L, and therefore can easily stably output high-power short-pulse laser light using the Q-switching element 104. Therefore, the optical element 10 can be more effectively applied to laser devices that have the Q-switching element 104.

[0091] 10 is a schematic diagram showing another example of a laser device that is a laser oscillator. Laser device 100A differs from laser device 100 mainly in that laser device 100A further includes a first total reflection mirror 112A, and optical resonator 101A is formed by dielectric multilayer film 12 of optical element 10, output mirror 111, and first total reflection mirror 112A. Laser device 100A also includes optical element 10, and therefore has the same effects as laser device 100.

[0092] The laser device 100A may include a Q-switching element 104, similar to the case of the laser device 100. The laser device 100A may include a mode-locking element or a wavelength conversion element instead of the Q-switching element 104. When the laser device 100A includes a wavelength conversion element, the output mirror 111 may have a wavelength separation function, similar to the case of the laser device 100.

[0093] In the laser device 100A, the optical resonator 101 is formed by the dielectric multilayer film 12, the output mirror 111, and the first total reflection mirror 112A, and therefore the optical path of the laser light L from the first total reflection mirror 112A to the output mirror 111 is bent at the position of the dielectric multilayer film 12.

[0094] The laser device 100A may also include a light source unit 103 that outputs excitation light 102.

[0095] 11 is a schematic diagram showing another example of a laser device that is a laser oscillator. Laser device 100B differs from laser device 100A mainly in that laser device 100B includes multiple optical elements 10 between first total reflection mirror 112A and output mirror 111. Laser device 100B is a multi-stage medium type laser oscillator.

[0096] Since the laser device 100B also includes the optical element 10, the laser device 100B has the same effects as the laser device 100 and the laser device 100A. The laser device 100B includes multiple optical elements 10, and the laser light L is amplified by each optical element 10. Therefore, the laser device 100B can output a higher-power laser light L. In this way, even when the output of the laser light L is higher, the use of the optical element 10 makes the laser device 100B less likely to be damaged, and as a result, it is easier to use stably. Therefore, the optical element 10 can be more effectively applied to a multi-stage medium type laser oscillator such as the laser device 100B.

[0097] The laser device 100B may include a Q-switching element 104, similar to the laser device 100 and the laser device 100A. The laser device 100B may include a mode-locking element or a wavelength conversion element instead of the Q-switching element 104. When the laser device 100B includes a wavelength conversion element, the output mirror 111 may have a wavelength separation function, similar to the laser device 100 and the laser device 100A.

[0098] In the laser device 100B, an optical resonator 101B is configured by the dielectric multilayer film 12 of each of the plurality of optical elements 10, the output mirror 111, and the first total reflection mirror 112A. Therefore, the optical path of the laser light L from the total reflection mirror to the output mirror 111 is bent at the position of each dielectric multilayer film 12.

[0099] The laser device 100B may also include a light source unit 103 that outputs excitation light 102.

[0100] 12 is a schematic diagram showing another example of a laser device that is a laser oscillator. A laser device 100C is another example of a multi-stage medium type laser oscillator.

[0101] Laser device 100C includes first total reflection mirror 112A, output mirror 111, and a plurality of element sets 120. First total reflection mirror 112A and output mirror 111 are arranged along first direction X.

[0102] Each of the plurality of element sets 120 includes a first optical element 121A, a second optical element 121B, a polarizing beam splitter 122, a first wave plate 123A, and a second wave plate 123B.

[0103] The first optical element 121A and the second optical element 121B are the same elements as the optical element 10. The first optical element 121A and the second optical element 121B are spaced apart in a direction transverse to the first direction X (in FIG. 12 , a direction perpendicular to the first direction X), and are arranged such that the laser media 11 of the first optical element 121A and the second optical element 121B face each other.

[0104] The polarizing beam splitter 122 is disposed between the first optical element 121A and the second optical element 121B.

[0105] The first wave plate 123A is disposed between the first optical element 121A and the polarizing beam splitter 122. The first wave plate 123A is an element for changing the polarization state of the laser light L when the laser light L is directed from the polarizing beam splitter 122 to the first optical element 121A and when the laser light L is directed from the first optical element 121A to the polarizing beam splitter 122, so that the optical path of the laser light L is changed by the polarizing beam splitter 122. An example of the first wave plate 123A is a λ / 4 plate.

[0106] The second wave plate 123B is disposed between the second optical element 121B and the polarizing beam splitter 122. The second wave plate 123B is an element for changing the polarization state of the laser light L when the laser light L is directed from the polarizing beam splitter 122 to the second optical element 121B and when the laser light L is directed from the second optical element 121B to the polarizing beam splitter 122, so that the optical path of the laser light L is changed by the polarizing beam splitter 122. An example of the second wave plate 123B is a λ / 4 plate.

[0107] The plurality of element sets 120 are arranged such that the first total reflection mirror 112A, the plurality of polarizing beam splitters 122, and the output mirror 111 are aligned along the first direction X.

[0108] In the laser device 100C, an optical resonator 101C is configured by the dielectric multilayer film 12 of the first optical element 121A and the second optical element 121B, the first total reflection mirror 112A, and the output mirror 111. The plurality of polarizing beam splitters 122, the plurality of first wave plates 123A, and the plurality of second wave plates also affect the optical path of the laser light L, and therefore may also be part of the optical resonator 101.

[0109] In the laser device 100C, the first optical element 121A and the second optical element 121B are optical elements 10. Therefore, the laser device 100C has the same functions and effects as the laser device 100. The laser device 100C includes the first optical element 121A and the second optical element 121B, and therefore includes a plurality of optical elements 10. The functions and effects that result from the laser device 100C including a plurality of optical elements 10 are similar to those of the laser device 100B.

[0110] The laser apparatus 100C may include a Q-switching element 104, similar to the laser apparatuses 100, 100A, and 100B. The Q-switching element 104 may be disposed, for example, between the output mirror 111 and a polarizing beam splitter 122 located upstream of the output mirror 111 (closest to the output mirror 111). The laser apparatus 100C may include a mode-locking element or a wavelength conversion element instead of the Q-switching element 104. When the laser apparatus 100C includes a wavelength conversion element, the output mirror 111 may have a wavelength separation function, similar to the laser apparatus 100.

[0111] The laser device 100C may also include a light source unit 103 that outputs excitation light 102.

[0112] Fifth Embodiment Fig. 13 is a schematic diagram showing another example of a laser device using an optical element. The laser device 100D shown in Fig. 13 is a laser amplifier. The laser device 100D has an optical element 10, a first polarizing beam splitter 105A, and a Faraday element 106.

[0113] The optical element 10 is disposed so that the laser medium 11 faces the first polarizing beam splitter 105A.

[0114] The Faraday element 106 is disposed between the optical element 10 and the first polarizing beam splitter 105A. An example of the Faraday element 106 is a Faraday rotator. The Faraday element 106 controls the polarization state of the laser light L so that the amplified laser light L is reflected by the first polarizing beam splitter 105A and output from the laser device 100D.

[0115] When amplifying laser light L in the laser device 100D, excitation light 102 is irradiated onto the optical element 10, putting the laser medium 11 into an excited state. In this state, input laser light L is incident on the side of the first polarizing beam splitter 105A opposite the optical element 10. The laser light L passes through the first polarizing beam splitter 105A and the Faraday element 106 and enters the optical element 10. The incidence of the laser light L causes stimulated emission in the laser medium 11, amplifying the laser light L. The amplified laser light L is totally reflected by the dielectric multilayer film 12, passes through the Faraday element 106, and enters the first polarizing beam splitter 105A. The polarization state of the laser light L is changed as it passes through the Faraday element 106 from the optical element 10 toward the first polarizing beam splitter 105A. As a result, the amplified laser light L is reflected by the first polarizing beam splitter 105A and output from the laser device 100D.

[0116] The laser device 100D may include a light source unit 103, similar to the laser device 100.

[0117] The laser device 100D includes the optical element 10. Therefore, the laser device 100D is less likely to be damaged even when it generates high-power laser light L by amplifying the input laser light L. This allows the laser device 100D to be used stably. Therefore, the optical element 10 can be effectively applied to the laser device 100D.

[0118] 14 is a schematic diagram showing another example of a laser device as a laser amplifier. Laser device 100E differs from laser device 100D mainly in that laser device 100E has a first total reflection mirror 112A.

[0119] The first total reflection mirror 112A is disposed on the same side as the first polarizing beam splitter 105A with respect to the optical element 10 (more specifically, with respect to the laser medium 11). The first total reflection mirror 112A is disposed with respect to the optical element 10 so that the optical path of the laser light L between the first polarizing beam splitter 105A and the optical element 10 is different from the optical path of the laser light L between the optical element 10 and the first total reflection mirror 112A.

[0120] The Faraday element 106 is disposed between the optical element 10 and the first total reflection mirror 112A. The Faraday element 106 may be disposed between the optical element 10 and the first polarizing beam splitter 105A.

[0121] The laser device 100E has the same configuration as the laser device 100D, except that the optical path of the laser light L differs from that of the laser device 100D due to the provision of the first total reflection mirror 112A. Therefore, the laser device 100E has the same effects as the laser device 100D.

[0122] The laser device 100E may include a light source unit 103, similar to the case of the laser device 100.

[0123] Sixth Embodiment Fig. 15 is a schematic diagram of another example of a laser device using optical elements. The laser device 100F shown in Fig. 15 is a regenerative laser amplifier. The laser device 100F includes an optical element 10, a first total reflection mirror 112A, a first polarizing beam splitter 105A, an electro-optical element 107, a second polarizing beam splitter 105B, and a Faraday element 106.

[0124] Optical element 10 is disposed so that laser medium 11 faces first total reflecting mirror 112A. Second polarizing beam splitter 105B and electro-optical element 107 are disposed between first total reflecting mirror 112A and optical element 10. Second polarizing beam splitter 105B and electro-optical element 107 are disposed in this order from first total reflecting mirror 112A toward optical element 10. That is, optical element 10, electro-optical element 107, second polarizing beam splitter 105B, and first total reflecting mirror 112A are disposed in this order along one direction.

[0125] The first polarizing beam splitter 105A and the Faraday element 106 are arranged in the order of the Faraday element 106 and the first polarizing beam splitter 105A relative to the second polarizing beam splitter 105B. That is, the second polarizing beam splitter 105B, the Faraday element 106, and the first polarizing beam splitter 105A are arranged in this order along one direction.

[0126] The direction in which the optical element 10, the electro-optical element 107, the second polarizing beam splitter 105B, and the first total reflection mirror 112A are arranged is different from the direction in which the second polarizing beam splitter 105B, the Faraday element 106, and the first polarizing beam splitter 105A are arranged.

[0127] In the configuration of the laser device 100F, the first total reflection mirror 112A and the dielectric multilayer film 12 of the optical element 10 constitute an optical resonator 101D. The laser light L is amplified by repeatedly propagating within the optical resonator 101D.

[0128] The electro-optical element 107 functions as an optical switch for extracting the laser light L propagating within the optical resonator 101D to the Faraday element 106 and the first polarizing beam splitter 105A via the second polarizing beam splitter 105B. An example of the electro-optical element 107 is a Pockels cell.

[0129] In the laser device 100F, the laser light L is amplified while making multiple round trips within the optical resonator 101D. By controlling the electro-optical element 107, the amplified laser light L is output to the outside of the laser device 100F via the second polarizing beam splitter 105B, the Faraday element 106, and the first polarizing beam splitter 105A.

[0130] In the laser device 100F, the laser light L is amplified while making multiple round trips within the optical resonator 101D, and therefore, it is possible to output a higher-power laser light L. Even in such a case, the optical element 10 is unlikely to be damaged by the high-power laser light L, and therefore the laser device 100F can stably output a high-power laser light L. Therefore, the optical element 10 can be more effectively applied to the laser device 100F.

[0131] 15 , the laser device 100F may include a wave plate 123 between the electro-optical element 107 and the optical element 10, which contributes to extracting the laser light L from the optical resonator 101D together with the electro-optical element 107. An example of the wave plate 123 is a λ / 4 plate.

[0132] The laser device 100F may include a light source unit 103 that outputs excitation light 102, similar to the case of the laser device 100.

[0133] 16 is a schematic diagram showing another example of a laser device as a regenerative laser amplifier. The laser device 100G differs from the laser device 100F mainly in that it further includes a second total reflection mirror 112B.

[0134] Second total reflection mirror 112B is disposed on the same side as second polarizing beam splitter 105B with respect to optical element 10 (more specifically, with respect to laser medium 11). Second total reflection mirror 112B is disposed with respect to optical element 10 so that the optical path of laser light L between second polarizing beam splitter 105B and optical element 10 is different from the optical path of laser light L between optical element 10 and second total reflection mirror 112B.

[0135] In the laser device 100G, an optical resonator 101E is formed by a first total reflection mirror 112A, a dielectric multilayer film 12 of the optical element 10, and a second total reflection mirror 112B.

[0136] 16, the electro-optic element 107 is disposed between the optical element 10 and the second total reflecting mirror 112B. The electro-optic element 107 functions as an optical switch for extracting the laser light L propagating within the optical resonator 101E to the Faraday element 106 and the first polarizing beam splitter 105A side via the second polarizing beam splitter 105B.

[0137] The laser device 100G has the same configuration as the laser device 100F, except that the optical path of the laser light L differs from that of the laser device 100F due to the provision of the second total reflection mirror 112B. Therefore, the laser device 100G has the same effects as the laser device 100F.

[0138] The laser device 100G may include a light source unit 103 that outputs excitation light 102, similar to the laser device 100. The laser device 100G may include a wave plate 123 that contributes to extracting laser light L from the optical resonator 101E, similar to the laser device 100F shown in FIG. 15 . An example of the wave plate 123 is a λ / 4 plate. The wave plate 123 is disposed between the electro-optic element 107 and the second total reflection mirror 112B.

[0139] (Variation 8) Fig. 17 is a schematic diagram showing another example of a laser device that is a regenerative laser amplifier. The laser device 100H shown in Fig. 17 differs from the laser device 100G mainly in that it includes multiple optical elements 10 between a first total reflection mirror 112A and a second total reflection mirror 112B. The laser device 100H is a multi-stage regenerative laser amplifier.

[0140] In the laser device 100H, multiple optical elements 10 are arranged on the optical path between the first total reflecting mirror 112A and the second total reflecting mirror 112B, and therefore the optical path between the first total reflecting mirror 112A and the second total reflecting mirror 112B is bent multiple times.

[0141] In the laser device 100H, the first total reflection mirror 112A, the dielectric multilayer films 12 of the plurality of optical elements 10, and the second total reflection mirror 112B constitute an optical resonator 101F.

[0142] 17, the electro-optic element 107 is disposed on the optical path between the second polarizing beam splitter 105B and the second total reflecting mirror 112B. In the embodiment shown in Fig. 17, the electro-optic element 107 is disposed between the second total reflecting mirror 112B and the optical element 10 that is closest to the second total reflecting mirror 112B in the optical path of the laser light L. The electro-optic element 107 functions as an optical switch for extracting the laser light L propagating within the optical resonator 101F to the Faraday element 106 and the first polarizing beam splitter 105A side via the second polarizing beam splitter 105B.

[0143] The laser device 100H also includes the optical element 10, and therefore has the same effects as the laser device 100G. The laser device 100H includes a plurality of optical elements 10, and therefore can further amplify the laser light L. Even in such a case, the optical elements 10 are less likely to be damaged by the high-power laser light L, and therefore the laser device 100H can stably output high-power laser light L. Therefore, the optical element 10 can be applied even more effectively to the laser device 100H.

[0144] The laser device 100H may include a light source unit 103 that outputs excitation light 102, similar to the laser device 100. The laser device 100H may include a wave plate 123 that contributes to extracting laser light L from the optical resonator 101F, similar to the laser device 100F shown in FIG. 15 . An example of the wave plate 123 is a λ / 4 plate. The wave plate 123 is disposed between the electro-optic element 107 and the second total reflection mirror 112B.

[0145] 18 is a schematic diagram showing another example of a laser device that is a regenerative laser amplifier. Laser device 100I differs from laser device 100G in that it has multiple element sets 120 between first total reflection mirror 112A and second total reflection mirror 112B. In the explanation of modification 9, the first direction X and second direction Y set in modification 5 are also used.

[0146] In laser device 100I, first total reflection mirror 112A, second polarizing beam splitter 105B, multiple element sets 120, and second total reflection mirror 112B are arranged along first direction X.

[0147] The configuration of the plurality of element sets 120 is similar to the configuration of the element set 120 described with reference to Fig. 12. That is, the element set 120 includes a first optical element 121A, a second optical element 121B, a polarizing beam splitter 122, a first wave plate 123A, and a second wave plate 123B.

[0148] The first optical element 121A and the second optical element 121B are the same elements as the optical element 10. The first optical element 121A and the second optical element 121B are spaced apart in a direction transverse to the first direction X (in FIG. 18 , a direction perpendicular to the first direction X), and are arranged such that the laser media 11 of the first optical element 121A and the second optical element 121B face each other.

[0149] The polarizing beam splitter 122 is disposed between the first optical element 121A and the second optical element 121B.

[0150] The first wave plate 123A is disposed between the first optical element 121A and the polarizing beam splitter 122. The first wave plate 123A is an element for changing the polarization state of the laser light L when the laser light L is directed from the polarizing beam splitter 122 to the first optical element 121A and when the laser light L is directed from the first optical element 121A to the polarizing beam splitter 122, so that the optical path of the laser light L is changed by the polarizing beam splitter 122. An example of the first wave plate 123A is a λ / 4 plate.

[0151] The second wave plate 123B is disposed between the second optical element 121B and the polarizing beam splitter 122. The second wave plate 123B is an element for changing the polarization state of the laser light L when the laser light L is directed from the polarizing beam splitter 122 to the second optical element 121B and when the laser light L is directed from the second optical element 121B to the polarizing beam splitter 122, so that the optical path of the laser light L is changed by the polarizing beam splitter 122. An example of the second wave plate 123B is a λ / 4 plate.

[0152] The plurality of element sets 120 are arranged such that the first total reflection mirror 112A, the plurality of polarizing beam splitters 122, and the second total reflection mirror 112B are aligned along the first direction X.

[0153] In the laser device 100I, the optical resonator 101G is configured by the first total reflection mirror 112A, the dielectric multilayer film 12 of the first optical element 121A and the second optical element 121B, and the second total reflection mirror 112B. The plurality of polarizing beam splitters 122, the plurality of first wave plates 123A, and the plurality of second wave plates 123B also affect the optical path of the laser light L, and therefore may also be part of the optical resonator 101G.

[0154] The electro-optic element 107 is disposed between the second polarizing beam splitter 105B and the second total reflection mirror 112B in the first direction X. In the example shown in Fig. 18, the electro-optic element 107 is disposed between the second polarizing beam splitter 105B and the element set 120 that is closest to the second polarizing beam splitter 105B among the multiple element sets 120. The electro-optic element 107 functions as an optical switch for extracting the laser light L propagating within the optical resonator 101G to the Faraday element 106 and first polarizing beam splitter 105A side via the second polarizing beam splitter 105B.

[0155] The laser device 100I includes a first optical element 121A and a second optical element 121B, which are optical elements 10. That is, the laser device 101I includes a plurality of optical elements 10. Therefore, the laser device 100I has the same effects as the laser device 100H.

[0156] The laser device 100I may include a light source unit 103 that outputs excitation light 102, similar to the laser device 100. The laser device 100I may include a wave plate 123 that contributes to extracting laser light L from the optical resonator 101G, similar to the laser device 100F shown in FIG. 15. An example of the wave plate 123 is a λ / 4 plate. The wave plate 123 is disposed outside the element set 120, between the electro-optic element 107 and the second total reflection mirror 112B. In FIG. 18, the wave plate 123 is disposed between the polarizing beam splitter 122 of the element set 120 that is closest to the second total reflection mirror 112B among the multiple element sets 120, and the second total reflection mirror 112B.

[0157] The present invention is not limited to the various embodiments exemplified, but includes the scope indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0158] The optical element may have a parasitic oscillation prevention portion 18 on the second surface 11b of the laser medium 11, as in the optical element 10C shown in FIG. 19. The optical element 10C corresponds to an element including the optical element 10 and the parasitic oscillation prevention portion 18 provided on the optical element 10. The optical element 10C may include the optical element 10A or the optical element 10B instead of the optical element 10. The parasitic oscillation prevention portion 18 is transparent to the laser light L and the excitation light 102. Examples of materials for the parasitic oscillation prevention portion 18 include non-doped laser materials (e.g., YAG), sapphire (Al ２ O ３ In one embodiment, the material of the laser medium 11 is Yb-doped YAG (Yb:YAG), and the material of the parasitic oscillation prevention unit 18 is YAG or Al. ２ O ３ By providing the parasitic oscillation prevention portion 18, the generated parasitic oscillation light escapes to the gainless region of the parasitic oscillation prevention portion 18, thereby suppressing amplification and preventing parasitic oscillation. A dielectric multilayer film 17 (see FIG. 1) for preventing parasitic oscillation may be formed on the surface of the parasitic oscillation prevention portion 18 (the surface opposite to the laser medium 11).

[0159] The optical element may have an absorbing portion 19 for preventing parasitic oscillation on the side of the laser medium 11, as in the optical element 10D shown in FIG. 20 . In this case, a dielectric multilayer film 12 or the like is disposed on the layer formed by the laser medium 11 and the absorbing portion 19. For example, for a laser oscillation wavelength of 1 μm, the absorbing portion 19 may be made of YAG doped with Cr or Sm (Cr:YAG or Sm:YAG) or a garnet-based material doped with Cr or Sm. In one embodiment, the laser medium 11 is made of Yb:YAG, and the absorbing portion 19 is made of Cr:YAG. The absorbing portion 19 may be made of Nd:YAG or another material doped with Yb or Nd. For a wavelength of 1.3 μm, the absorbing portion 19 may be made of vanadium-doped YAG (V:YAG), and for a wavelength of 1.5 μm, the absorbing portion 19 may be made of Co spinel. In the embodiment including the absorbing portion 19, the generated parasitic oscillation light is absorbed by the absorbing portion 19 (for example, Cr:YAG). In this way, the parasitic oscillation light can be eliminated by the absorbing portion 19, so that parasitic oscillation can be prevented. A dielectric multilayer film may be formed as an anti-reflection film on the surface of the layer formed by the laser medium 11 and the absorbing portion 19 opposite to the dielectric multilayer film 12.

[0160] In the explanations up to this point, the first intermediate layer of the optical element has been described as being the dielectric multilayer film 12. However, the first intermediate layer may be the intermediate layer 50 shown in FIG. 21 . FIG. 21 is a schematic diagram showing an optical element 10E including the intermediate layer 50. The optical element 10E differs from the optical element 10 in that the optical element 10E has an intermediate layer (first intermediate layer) 50 instead of the dielectric multilayer film 12, but is otherwise similar in configuration to the optical element 10.

[0161] The intermediate layer 50 includes a dielectric multilayer film 51 formed on the laser medium 11 and a non-metallic heat transfer layer 52 formed on the dielectric multilayer film 51 .

[0162] The dielectric multilayer film 51 totally reflects the laser light L generated or amplified by stimulated emission from the laser medium 11. In one embodiment, the dielectric multilayer film 51 functions as an HR coating layer for the laser light L. The material of the dielectric multilayer film 51 may be the same as that of the dielectric multilayer film 12.

[0163] The non-metallic heat transfer layer 52 may be made of a non-metallic material having high thermal conductivity. The non-metallic heat transfer layer 52 may be made of, for example, diamond, silicon carbide (SiC), or nitride. An example of the nitride is aluminum nitride (AlN). The non-metallic heat transfer layer 52 may function as a heat spreader.

[0164] The intermediate layer 50 has a thickness that prevents evanescent waves EW (see FIG. 1 ) generated when laser light generated or amplified by the laser medium 11 is totally reflected by the dielectric multilayer film 51 from reaching the first metal layer 13. In other words, the thickness of the intermediate layer 50 is longer than the penetration length of the evanescent waves EW and may be similar to the thickness of the dielectric multilayer film 12 shown in FIG. 1 . The intermediate layer 50 having the above thickness includes the dielectric multilayer film 51 and the non-metallic heat conduction layer 52, and therefore the thickness of the dielectric multilayer film 51 may be thinner than the thickness of the dielectric multilayer film 12. The non-metallic heat conduction layer 52 may be a layer for adjusting the thickness of the intermediate layer 50. The thickness of the intermediate layer 50 may be thicker than the dielectric multilayer film 12.

[0165] The optical element 10E can be manufactured in the same manner as the manufacturing method of the optical element 10, except that a first component having an intermediate layer 50 is used instead of the dielectric multilayer film 12 in the first component 20. The first component having the intermediate layer 50 can be prepared, for example, by performing a step of forming a dielectric multilayer film 51 on the laser medium 11 and a step of forming a non-metallic heat conduction layer 52 on the dielectric multilayer film 51. The non-metallic heat conduction layer 52 may be provided on the dielectric multilayer film 51 by bonding a heat conduction body made of diamond, as exemplified above, to the dielectric multilayer film 51.

[0166] Like the dielectric multilayer film 12, the intermediate layer 50 has a thickness that prevents the evanescent waves EW (see FIG. 1 ) from reaching the first metal layer 13. Therefore, the intermediate layer 50 and the optical element 10E including the intermediate layer 50 have the same effects as the optical element 10. The non-metallic heat transfer layer 52 of the intermediate layer 50 can function as a heat spreader. Therefore, heat generated in the laser medium 11 is easily dissipated because it is diffused in the in-plane direction, and local temperature increases are less likely to occur, making the optical element 10E less susceptible to damage.

[0167] In the optical elements 10A, 10B, 10C, and 10D, an intermediate layer 50 can be employed instead of the dielectric multilayer film 12.

[0168] 13, 14, 15, 16, 17, and 18, the Faraday element 106 is used as the optical path control element for extracting the laser beam L. However, other known elements that are used in laser amplifiers (including regenerative laser amplifiers) and that can achieve the same function may also be used. For example, a wavelength plate (e.g., a λ / 4 plate) may be used instead of the Faraday element.

[0169] In the laser devices (regenerative laser amplifiers) described using Figures 15, 16, 17, and 18, electro-optical elements are used as optical switch elements (or optical path control elements) for extracting laser light from the optical resonator. However, other known elements that are used in regenerative laser amplifiers and can achieve similar functions may also be used.

[0170] The number of stages in the multistage medium type laser oscillators in the above-mentioned Modifications 4 and 5 is not limited to the number of stages shown in Fig. 11 and Fig. 12. The number of stages in the multistage medium type laser oscillators is sufficient as long as it is two or more. Similarly, the number of stages in the multistage type regenerative laser amplifiers in the above-mentioned Modifications 8 and 9 is not limited to the number of stages shown in Fig. 17 and Fig. 18. The number of stages in the multistage type regenerative laser amplifiers is sufficient as long as it is two or more.

[0171] The various embodiments and modifications described above may be combined as appropriate without departing from the spirit of the invention.

[0172] 10, 10A, 10B, 10C, 10D, 10E...optical element, 11...laser medium, 11a...first surface, 11b...second surface, 12...dielectric multilayer film (first intermediate layer), 12a...first surface, 13...first metal layer, 13a...first surface, 14...heat sink, 14a...first surface, 15...intermediate layer (second intermediate layer), 15a...first surface, 16...second metal layer, 16a...first surface, 16b...second surface, 17...dielectric Dielectric multilayer film, 18...parasitic oscillation prevention portion, 19...absorption portion, 20, 20A, 20B, 20C...first component, 20a...bonding surface, 30, 30A, 30B...second component, 30a...bonding surface, 40...chamber, 41...beam source, 42...surface active beam, 50...intermediate layer (first intermediate layer), 51...dielectric multilayer film, 52...non-metallic heat transfer layer, 100, 100A, 100B, 100C, 100D, 100 E, 100F, 100G, 100H, 100I...laser device, 101, 101A, 101B, 101C, 101D, 101E, 101F, 101G...optical resonator, 102...excitation light, 103...light source unit, 104...Q switch element, 105A...first polarized beam splitter, 105B...second polarized beam splitter, 106...Faraday element, 107...electro-optical element, 111...output Mirror, 112A...first total reflection mirror, 112B...second total reflection mirror, 120...element set, X...first direction, 121A...first optical element, 121B...second optical element, 122...polarizing beam splitter, 123...wave plate, 123A...first wave plate, 123B...second wave plate, 151...intermediate layer, 151a...first surface, 152...intermediate layer, 152a...first surface, L...laser light, EW...evanescent wave.

Claims

1. a laser medium; a first intermediate layer provided on the laser medium; a first metal layer formed on the first intermediate layer and containing a Group 4 element or a Group 6 element; a heat sink disposed on the first metal layer and including a metal; Equipped with the first intermediate layer is formed on the laser medium and includes a dielectric multilayer film that totally reflects laser light generated or amplified by the laser medium; the first intermediate layer is thicker than the penetration length of an evanescent wave generated by reflection of light incident from the laser medium side by the dielectric multilayer film; Optical elements.

2. a second metal layer disposed between the first metal layer and the heat sink and including a Group 10 element; The optical element according to claim 1 .

3. the material of the second metal layer is nickel or platinum; The optical element according to claim 2 .

4. a second intermediate layer disposed between the first metal layer and the second metal layer; the material of the second intermediate layer is gold or a gold alloy; The optical element according to claim 2 or 3.

5. the material of the first metal layer is chromium or titanium; The optical element according to any one of claims 1 to 3.

6. The material of the heat sink is copper, copper tungsten, copper molybdenum, iron, aluminum or aluminum-silicon carbide composite; The optical element according to any one of claims 1 to 3.

7. The first intermediate layer is the dielectric multilayer film; a non-metallic heat transfer layer disposed between the dielectric multilayer film and the first metal layer; having The optical element according to any one of claims 1 to 3.

8. The material of the non-metallic heat transfer layer is diamond, silicon carbide or nitride. The optical element according to claim 7 .

9. The optical element according to any one of claims 1 to 3 is provided. Laser device.

10. a preparation step of preparing a first component including a laser medium and a second component including a heat sink including a metal; a joining step of joining the first component and the second component; Equipped with The preparation step includes: forming a first intermediate layer on the laser medium; forming a first metal layer containing a Group 4 element or a Group 6 element on the first intermediate layer; and In the joining step, the first component and the second component are joined via the first metal layer, the first intermediate layer is formed on the laser medium and includes a dielectric multilayer film that totally reflects laser light generated or amplified by the laser medium; In the step of forming the first intermediate layer, the first intermediate layer is formed so that the thickness of the first intermediate layer is greater than the penetration length of an evanescent wave generated by reflection of light incident from the laser medium side by the dielectric multilayer film. A method for manufacturing an optical element.

11. the preparing step includes a step of forming a second metal layer containing a Group 10 element on the heat sink; In the joining step, the first component and the second component are joined via the first metal layer and the second metal layer. The method for manufacturing an optical element according to claim 10 .

12. the preparing step includes a step of forming a layer to be a second intermediate layer disposed between the first metal layer and the second metal layer on at least one of the first metal layer and the second metal layer. The method for manufacturing an optical element according to claim 11 .

13. In the joining step, a surface of the first component on a joining side with the second component and a surface of the second component on a joining side with the first component are subjected to a surface activation treatment, and then the surface-activated first component and the second component are joined together. The method for manufacturing an optical element according to any one of claims 10 to 12.

14. The method further includes a step of performing a surface activation treatment on a surface of the first component that is bonded to the second component and a surface of the second component that is bonded to the first component, the preparing step further includes a step of forming a second metal layer containing a Group 10 element on the first metal layer, the second component is the heat sink, In the joining step, the first component and the second component are joined via the second metal layer. The method for manufacturing an optical element according to claim 10 .

15. The step of forming the first intermediate layer includes: forming the dielectric multilayer film on the laser medium; forming a non-metallic heat transfer layer on the dielectric multilayer film; The method for manufacturing an optical element according to any one of claims 10 to 12, comprising: