Manufacturing method of q-switch structure

Abstract

To provide a Q-switch structure that contributes to the miniaturization of a laser device and has high beam quality.SOLUTION: A Q switch structure includes a solid-state laser medium and a magneto-optical material, the solid-state laser medium and the magneto-optical material are bonded together, and a first anti-adhesive anti-reflection film is formed on one surface of the solid-state laser medium, a second anti-adhesive anti-reflection film is formed on one surface of the magneto-optical material, and the first anti-adhesive anti-reflection film of the solid-state laser medium and the second anti-adhesive anti-reflection film of the magneto-optical material are bonded together via a translucent material that is translucent at the laser oscillation wavelength of a laser emitted from the solid-state laser medium.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a Q-switch structure and a method for manufacturing a Q-switch structure. [Background technology]

[0002] In recent years, increasing the output power and miniaturizing the laser media that serve as the light source have become important issues in laser application equipment such as optical measurement and magneto-optical recording. From the perspective of miniaturization and high output, Q switches that use magneto-optical materials (also known as "MO materials") as their transmission mechanism have attracted attention.

[0003] Known laser devices equipped with a Q switch include a laser device in which a first resonant mirror, a solid-state laser material, a Q switch, and a second resonant mirror are arranged in that order. That is, a laser device is known in which a solid-state laser material and a Q switch are arranged between a pair of resonant mirrors consisting of a first resonant mirror and a second resonant mirror.

[0004] Non-Patent Document 1 discloses a small laser device in which a solid-state laser material and a Q-switch are placed between a pair of resonant mirrors. However, the Q-switch is a passive Q-switch that utilizes the saturable phenomenon, and the Q-switch cannot be actively controlled.

[0005] Non-patent document 2 discloses a technology for actively controlling a Q-switch by utilizing the electro-optic effect, but the thickness of the solid-state laser material is 0.5 mm, while the thickness of the Q-switch is 5 mm, making the Q-switch an obstacle to miniaturization of the laser device.

[0006] Non-Patent Document 3 discloses a technique for actively controlling a Q-switch by utilizing the acousto-optic effect, but the thickness of the Q-switch is as much as 32 mm, which is an obstacle to miniaturization of the laser device.

[0007] In conventional technology, actively controlling the Q-switch would result in the Q-switch becoming larger, which was an obstacle to miniaturizing the laser device. Therefore, there was a need to achieve both miniaturization of the laser device and active Q-switching.

[0008] Patent Document 1 discloses a Q-switched solid-state laser device that, as a technology for activating a Q-switch within the constraint of not hindering the miniaturization of the laser device, has a solid-state laser material and a Q-switch arranged between a pair of resonant mirrors, and the Q-switch is composed of a combination of a film that exhibits a magneto-optical effect and a magnetic flux generator, and emits a pulsed laser when excitation light is incident on the solid-state laser material and a pulse is applied to the magnetic flux generator. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2017-79283 [Non-patent literature]

[0010] [Non-Patent Document 1] T.Taira, M.Tsunekane, K.Kanehara, S.Morishima, N.Taguchi and A. Sugiura: “7. Promise of Giant Pulse Micro-Laser for Engine Ignition”, Journal of Plasma and Fusion Research, Vol. 89, No.4, pp.238-241(2013) [Non-patent document 2] T.Taira, and T.Kobayashi: “Q-Switching and Frequency Doubling of Solid-State Lasers by a Single Intracavity KTP Crystal”, IEEE Journal of Quantum Electronics of Vol. 30, No.3, pp.800-804(1994) [Non-patent document 3] Gooch & Housego Co.Ltd., Product number 1-QS041-1, 8C10G-4-GH21 Summary of the Invention [Problem to be solved by the invention]

[0011] As mentioned above, Patent Document 1 describes a Q switch using a magneto-optical (MO) mechanism. From the viewpoint of miniaturizing a laser device, it is desirable to minimize the space between the solid-state laser medium and the magneto-optical mechanism. In FIG. 13 of Patent Document 1, a configuration is proposed in which the solid-state laser medium and the magneto-optical film are integrated. However, no specific integration method is proposed.

[0012] Furthermore, in Q switches using magneto-optical mechanisms, issues include vibrations that occur when the magnetic switch (generated by changes in magnetic flux) is activated, optical resonance between the magneto-optical mechanism and the solid-state laser medium, output instability due to changes in the magnetic domain pattern caused by distortion due to differences in the fixation of the magneto-optical material, variations in switching speed, and an increase in the resonator length due to the spatial generation of both, resulting in a deterioration in switching speed.

[0013] The present invention has been made in view of the above problems, and has an object to provide a Q-switch structure that contributes to the miniaturization of laser devices and has high beam quality. [Means for solving the problem]

[0014] In order to solve the above problems, the present invention provides a Q switch structure comprising a solid-state laser medium and a magneto-optical material, wherein the solid-state laser medium and the magneto-optical material are bonded together, a first anti-adhesive anti-reflection film is formed on one surface of the solid-state laser medium, a second anti-adhesive anti-reflection film is formed on one surface of the magneto-optical material, and the first anti-adhesive anti-reflection film of the solid-state laser medium and the second anti-adhesive anti-reflection film of the magneto-optical material are bonded via a translucent material that is translucent at the laser oscillation wavelength of the laser oscillated from the solid-state laser medium.

[0015] In such a Q switch structure, the solid-state laser medium and the magneto-optical material are bonded together, making it possible to create a compact Q switch structure. Furthermore, since the solid-state laser medium and the magneto-optical material are bonded via a light-transmitting material, it is possible to create a Q switch structure with high beam quality. In other words, it is possible to mitigate the deterioration of optical characteristics due to bonding strain. In the present invention, the integrated combination of the solid-state laser medium and the magneto-optical material is referred to as a Q switch structure. The Q switch structure can function as a Q switch when combined with a magnetic flux generator.

[0016] The light-transmitting material is preferably an organic adhesive having a Shore D hardness of 80 or less, or an inorganic light-transmitting material.

[0017] In the Q-switch structure of the present invention, when an organic adhesive with a Shore D hardness of 80 or less is used as the light-transmitting material, distortion when joining the solid laser medium and the magneto-optical material can be reduced, and high beam quality can be obtained. Furthermore, when an inorganic light-transmitting material is used as the light-transmitting material, deterioration due to light action is suppressed, and high beam quality can be obtained.

[0018] The organic adhesive is preferably at least one of a silicone resin, a silicone-modified epoxy resin, and an epoxy resin.

[0019] Such organic adhesives have a low Shore D hardness, which can more effectively reduce distortion when joining a solid-state laser medium and a magneto-optical material. They also have excellent weather resistance and light resistance.

[0020] The inorganic light-transmitting material is preferably a glass material made of water glass or low-melting glass having a glass transition point of 500° C. or less.

[0021] These glass materials are stable and have relatively low hardness for inorganic optically transparent materials, so they effectively contribute to mitigating distortion at the joint between the solid-state laser medium and the magneto-optical material. They also have excellent weather resistance and light resistance.

[0022] Furthermore, it is preferable that the light-transmitting material has a transmittance of 95% or more at the laser oscillation wavelength.

[0023] In the Q switch structure of the present invention, the light-transmitting material has such a high transmittance, so that the light-transmitting property of the Q switch can also be increased.

[0024] The magneto-optical material is preferably a bismuth-substituted rare earth iron garnet.

[0025] The solid-state laser medium is Y3Al5O4 doped with one element selected from the group consisting of Nd, Yb, and Cr. 12 , Gd3Ga5O 12 and YVO4.

[0026] These materials can be preferably used as the Q-switch structure of the present invention.

[0027] The present invention also provides a Q-switched solid-state laser device, characterized in that the above-mentioned Q-switch structure and a magnetic flux generator are disposed between a pair of resonant mirrors.

[0028] A Q-switched solid-state laser device equipped with such a Q-switching structure of the present invention can be a small-sized Q-switching structure with high beam quality, since the solid-state laser medium and the magneto-optical material are bonded together with a translucent material that is translucent at the laser oscillation wavelength.

[0029] The present invention also provides a method for manufacturing a Q switch structure comprising a solid-state laser medium and a magneto-optical material, the solid-state laser medium and the magneto-optical material being bonded together, the method comprising the steps of: preparing the solid-state laser medium and the magneto-optical material; forming a first anti-adhesive anti-reflection film on one side of the solid-state laser medium; forming a second anti-adhesive anti-reflection film on one side of the magneto-optical material; and bonding the first anti-adhesive anti-reflection film of the solid-state laser medium and the second anti-adhesive anti-reflection film of the magneto-optical material via a translucent material that is translucent at the laser oscillation wavelength of the laser emitted from the solid-state laser medium.

[0030] This manufacturing method of the Q switch structure allows for easy integration of the solid-state laser medium and the magneto-optical material. Furthermore, since the solid-state laser medium and the magneto-optical material are bonded via a light-transmitting material, the Q switch structure can be small in size and has high beam quality.

[0031] The bonding is preferably performed using an organic adhesive having a Shore D hardness of 80 or less as the light-transmitting material, or an inorganic light-transmitting material.

[0032] In the manufacturing method of the Q-switch structure of the present invention, when an organic adhesive having a Shore D hardness of 80 or less is used as the light-transmitting material, distortion when joining the solid laser medium and the magneto-optical material can be reduced, and high beam quality can be obtained. Furthermore, when an inorganic light-transmitting material is used as the light-transmitting material, deterioration due to light action is suppressed, and high beam quality can be obtained.

[0033] The organic adhesive preferably comprises at least one of a silicone resin, a silicone-modified epoxy resin, and an epoxy resin.

[0034] Such organic adhesives have a low Shore D hardness and can more effectively reduce distortion when joining a solid-state laser medium and a magneto-optical material.

[0035] It is also preferable to use a glass material made of water glass or low-melting glass having a glass transition point of 500° C. or less as the inorganic light-transmitting material.

[0036] These glass materials are stable and have a relatively low hardness as inorganic light-transmitting materials, and therefore effectively contribute to the relaxation of strain at the joint between the solid laser medium and the magneto-optical material.

[0037] It is also preferable that the glass material be bonded to the first anti-adhesive anti-reflection film and the second anti-adhesive anti-reflection film by thermal diffusion bonding or close contact bonding under vacuum.

[0038] By such thermal diffusion bonding or close contact bonding under vacuum, the solid laser medium and the magneto-optical material can be easily bonded via the glass material.

[0039] Furthermore, it is preferable that the light-transmitting material has a light transmittance of 95% or more at the laser oscillation wavelength.

[0040] By using a light-transmitting material with such a high transmittance, the light-transmitting property of the Q-switch structure can also be increased.

[0041] The magneto-optical material is preferably a bismuth-substituted rare earth iron garnet.

[0042] The solid-state laser medium is preferably Y3Al5O4 doped with one element selected from the group consisting of Nd, Yb, and Cr. 12 , Gd3Ga5O 12and YVO4.

[0043] These materials can be preferably used in the method for producing the Q-switch structure of the present invention.

[0044] The present invention also provides a method for manufacturing a Q-switched solid-state laser device, which comprises using a Q-switched structure manufactured by the above-mentioned method for manufacturing a Q-switched solid-state laser device and disposing the Q-switched structure and a magnetic flux generator between a pair of resonant mirrors.

[0045] In this method of manufacturing a Q-switched solid-state laser device, the solid-state laser medium and the magneto-optical material are bonded together via a light-transmitting material, so that the Q-switched solid-state laser device can be small in size and can have high beam quality. [Effects of the Invention]

[0046] The Q switch structure of the present invention can be made compact because the solid-state laser medium and magneto-optical material are bonded together. Furthermore, because the solid-state laser medium and magneto-optical material are bonded via a light-transmitting material, a Q switch structure with high beam quality can be obtained. In other words, deterioration of optical characteristics due to bonding strain can be alleviated. This makes it possible to suppress vibrations, prevent optical resonance between the solid-state laser medium and the magneto-optical material, shorten the resonator length, and thereby improve switching speed. Furthermore, the manufacturing method of the Q switch structure of the present invention can easily manufacture such a Q switch structure. [Brief explanation of the drawings]

[0047] [Figure 1] FIG. 1 is a schematic diagram showing an example of the structure of a Q-switch structure of the present invention. [Figure 2] 1 is a cross-sectional view schematically showing an example of the structure of the Q switch structure of the present invention. [Figure 3] FIG. 1 is a cross-sectional view schematically showing one example (first embodiment) of the structure of a Q-switch structure of the present invention. [Figure 4] FIG. 1 is a cross-sectional view schematically showing one example (second embodiment) of the structure of the Q-switch structure of the present invention. [Figure 5] FIG. 1 is a cross-sectional view schematically showing one example (third embodiment) of the structure of the Q switch structure of the present invention. [Figure 6] 1 is a cross-sectional view schematically showing an example of a Q-switched solid-state laser device equipped with a Q-switch structure of the present invention. [Figure 7] FIG. 1 is a flow chart showing an example of a method for producing a Q switch structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0048] The present invention will be described in detail below with reference to the drawings, but the present invention is not limited thereto.

[0049] An example of the structure of the Q switch structure of the present invention will be described with reference to Figures 1 and 2. Figure 1 shows a schematic diagram of the structure of the Q switch structure, and Figure 2 shows a cross-sectional view thereof.

[0050] The Q switch structure 100 of the present invention comprises a solid-state laser medium 1 and a magneto-optical material 2, which are bonded together as an integrated unit. Furthermore, in the present invention, a first anti-adhesive anti-reflection film 1a is formed on one surface of the solid-state laser medium 1, and a second anti-adhesive anti-reflection film 2a is formed on one surface of the magneto-optical material 2. Furthermore, the first anti-adhesive anti-reflection film 1a of the solid-state laser medium 1 and the second anti-adhesive anti-reflection film 2a of the magneto-optical material 2 are bonded together via a light-transmitting material 3 that is transparent at the laser oscillation wavelength of the laser emitted from the solid-state laser medium 1.

[0051] In such a Q switch structure, the solid laser medium 1 and the magneto-optical material 2 are bonded together, making it possible to create a compact Q switch structure 100. Furthermore, since the solid laser medium 1 and the magneto-optical material 2 are bonded together via the light-transmitting material 3, it is possible to create a Q switch structure with high beam quality.

[0052] Furthermore, the light-transmitting material 3 preferably has a transmittance of 95% or more (insertion loss of 0.2 dB or less) at the laser oscillation wavelength, and more preferably a transmittance of 98% or more (insertion loss of 0.1 dB or less). It is easy to select the type and thickness of the light-transmitting material so as to have such a transmittance. Note that the transmittance also depends on the thickness, and the thicker the material, the lower the transmittance.

[0053] In the description of the present invention, the definition of transmittance is as follows: Here, the "workpiece" refers to an object through which light (electromagnetic waves) passes. Transmittance (%) = (light amount when transmitted through workpiece / light amount when no workpiece is present) x 100 Insertion loss (dB) = -10 × log 10 (Light intensity when passing through workpiece / light intensity when no workpiece is present)

[0054] In the Q-switch structure 100 of the present invention, the material of the solid-state laser medium 1 can be any material that can be used as a solid-state laser medium. Among them, Y3Al5O4 doped with one element selected from the group consisting of Nd, Yb, and Cr is preferred. 12 , Gd3Ga5O 12 and YVO4. In the Q switch structure 100 of the present invention, the magneto-optical material 2 may be made of any material that can be used as a magneto-optical material. Among these, bismuth-substituted rare earth iron garnet is preferred.

[0055] In the Q switch structure 100 of the present invention, the first adhesive anti-reflection film 1a and the second adhesive anti-reflection film 2a may be made of a two-layer structure in which a TiO2 layer or Ta2O5 layer is formed as the first layer on the surface of the solid laser medium 1 or the magneto-optical material 2, and an SiO2 layer is formed thereon. These adhesive anti-reflection films function as films that can suppress light reflection that occurs at the interface between different materials.

[0056] Furthermore, in the present invention, it is preferable that the light-transmitting material 3 shown in Figures 1 and 2 is an organic adhesive having a Shore D hardness of 80 or less, or an inorganic light-transmitting material. Hereinafter, a case in which the light-transmitting material 3 is an organic adhesive having a Shore D hardness of 80 or less will be described as a first embodiment, and a case in which the light-transmitting material 3 is an inorganic light-transmitting material will be described as a second embodiment and a third embodiment. Note that duplicated explanations of matters common to Figures 1 and 2 will be omitted.

[0057] [First aspect] 3 shows a cross-sectional view of one example (first embodiment) of the structure of the Q-switch structure of the present invention. In this embodiment, the solid-state laser medium 1 and the magneto-optical material 2 are bonded together via an organic adhesive 13, which serves as a light-transmitting material and has a Shore D hardness of 80 or less. In this case, the light-transmitting material 13, which is an organic adhesive, is preferably at least one of silicone resin, silicone-modified epoxy resin, and epoxy resin.

[0058] This Q-switch structure 10 uses an organic adhesive 13 with a relatively low hardness, a Shore D hardness of 80 or less, as the light-transmitting material, thereby reducing distortion when bonding the solid-state laser medium and the magneto-optical material and achieving high beam quality. The thickness of the organic adhesive 13 layer is preferably 0.005 to 0.040 mm (5 to 40 μm). With an organic adhesive 13 of this thickness, distortion can be alleviated while maintaining high light transmittance. In particular, although this thickness depends on the material, the transmittance of the organic adhesive 13 layer at around a laser oscillation wavelength of 1064 nm can be increased to 95% or more.

[0059] [Second and third aspects] Next, we will explain embodiments (second and third embodiments) in which the light-transmitting material 3 is an inorganic light-transmitting material. In this case, as shown in Figures 1 and 2, the solid laser medium 1 and the magneto-optical material 2 are joined via the light-transmitting material 3 (in this case, an inorganic light-transmitting material). In particular, it is preferable that the inorganic light-transmitting material is a glass material made of water glass or low-melting glass having a glass transition point of 500°C or less. Hereinafter, "low-melting glass having a glass transition point of 500°C or less" will also be simply referred to as "low-melting glass." It is more preferable that the glass transition point is 400°C or less.

[0060] Thus, instead of using an organic adhesive to bond the solid-state laser medium 1 and the magneto-optical material 2 as in the first embodiment, an inorganic light-transmitting material may be used in the present invention. The advantages of using an inorganic light-transmitting material as the light-transmitting material 3 are as follows. In recent years, the power of light emitted by solid-state laser devices equipped with Q-switches has exceeded 1 mJ with a beam diameter of approximately 0.3 mm, and output power is becoming increasingly stronger. In the future, when even greater power than before passes through the bonding interface, if the light-transmitting material 3 is an organic adhesive, there is a concern that the organic bond may break and affect the surrounding area. In this case, replacing the bonding material between the solid-state laser medium 1 and the magneto-optical material 2 with an inorganic material would eliminate such concerns about high output. However, depending on the type of inorganic material, bonding strain may cause deterioration of the light beam. To prevent this effect, a strain relaxation layer can be inserted in advance at the bonding interface.

[0061] As the inorganic light-transmitting material, it is preferable to use a light-transmitting material having a linear expansion coefficient between the linear expansion coefficient of the solid laser medium 1 and the linear expansion coefficient of the magneto-optical material 2 .

[0062] <Second aspect> In the Q switch structure 20 of the second embodiment shown in Fig. 4, the solid-state laser medium 1 and the magneto-optical material 2 are bonded together via an inorganic light-transmitting material 23 as a light-transmitting material. The first adhesive anti-reflection film 1a of the solid-state laser medium 1 and the inorganic light-transmitting material 23, and the second adhesive anti-reflection film 2a of the magneto-optical material 2 and the inorganic light-transmitting material 23 are bonded together via strain relaxation layers 25 and 26, respectively.

[0063] <Third aspect> In the third embodiment of the Q switch structure 30 shown in FIG. 5, the solid-state laser medium 1 and the magneto-optical material 2 are directly bonded together with an inorganic light-transmitting material 33 interposed between the first anti-adhesive anti-reflection film 1a of the solid-state laser medium 1 and the second anti-adhesive anti-reflection film 2a of the magneto-optical material 2.

[0064] Examples of inorganic light-transmitting materials include glass materials such as water glass or low-melting-point glass, as well as borosilicate glass, quartz glass, and paramagnetic garnet.

[0065] Among these, glass materials made of water glass or low-melting-point glass can be used in both the second and third embodiments. Borosilicate glass, quartz glass, and paramagnetic garnet are preferred for the second embodiment. In the second embodiment, the strain relaxation layers 25 and 26 can be made of a glass material made of water glass or low-melting-point glass. That is, both the material in contact with the solid-state laser medium 1 (the first anti-adhesive anti-reflection coating 1a formed on the solid-state laser medium 1) and the material in contact with the magneto-optical material 2 (the second anti-adhesive anti-reflection coating formed on the magneto-optical material 2) are preferably made of a glass material made of water glass or low-melting-point glass. These glass materials are stable and have relatively low hardness as inorganic translucent materials, and therefore effectively contribute to strain relaxation at the junction between the solid-state laser medium and the magneto-optical material.

[0066] The above-described Q switch structures 100, 10, 20, and 30 function as a Q switch by combining a magneto-optical material 2 and a magnetic flux generator. FIG. 6 shows an example of the structure of a Q-switched solid-state laser device. The Q switch structure 100 shown in FIGS. 1 and 2 is shown as a representative example. In a Q-switched solid-state laser device 80, the above-described Q switch structure 100 and a magnetic flux generator 83 are disposed between a pair of resonant mirrors (a first resonant mirror 81 and a second resonant mirror 82). FIG. 6 shows an example in which all of these structures are bonded together. However, in the present invention, it is sufficient that the solid-state laser medium 1 and the magneto-optical material 2 constituting the Q switch structure 100 are bonded together, and other structural materials can be arranged as appropriate. For example, the magnetic flux generator can be a combination of a permanent magnet and an excitation coil, and the excitation coil can be disposed around the permanent magnet.

[0067] [Manufacturing method of Q-switch structure] Next, a manufacturing method of the Q switch structure of the present invention will be described. The manufacturing method of the Q switch structure of the present invention is a method for manufacturing a Q switch structure 100, which includes a solid-state laser medium 1 and a magneto-optical material 2, and which is integrally bonded to the solid-state laser medium 1 and the magneto-optical material 2, as shown in Figures 1 and 2. The manufacturing method of the Q switch structure of the present invention includes the steps of preparing the solid-state laser medium 1 and the magneto-optical material 2, forming a first anti-adhesive anti-reflection film 1a on one surface of the solid-state laser medium 1, forming a second anti-adhesive anti-reflection film 2a on one surface of the magneto-optical material 2, and bonding the first anti-adhesive anti-reflection film 1a of the solid-state laser medium 1 and the second anti-adhesive anti-reflection film 2a of the magneto-optical material 2 via a light-transmitting material 3 that is transparent at the laser oscillation wavelength of the laser oscillated from the solid-state laser medium 1.

[0068] The manufacturing method of the Q-switch structure of the present invention will be described in more detail with reference to Fig. 7. First, as shown in S1 of Fig. 7, a solid-state laser medium 1 and a magneto-optical material 2 are prepared (step S1). The solid-state laser medium 1 and magneto-optical material 2 prepared here can be made of the above-mentioned materials.

[0069] Next, as shown in S2 of FIG. 7, a first anti-adhesive anti-reflection film 1a is formed on one surface of the solid-state laser medium 1 (step S2). Furthermore, as shown in S3 of FIG. 7, a second anti-adhesive anti-reflection film 2a is formed on one surface of the magneto-optical material 2 (step S3). The materials for these anti-adhesive anti-reflection films can be the same as those mentioned above. The anti-reflection film can be formed by ion-assisted electron beam vacuum deposition, ion beam sputtering, or the like. It is constructed by forming a TiO2 or Ta2O5 layer as a first layer on the surface of the material, and then forming a SiO2 layer on top of that as a second layer. The order of steps S2 and S3 does not matter.

[0070] 7, the first anti-adhesive anti-reflection film 1a of the solid-state laser medium 1 is adhered to the second anti-adhesive anti-reflection film 2a of the magneto-optical material 2 (step S4). At this time, a light-transmitting material that is transparent to the laser oscillation wavelength of the laser oscillated from the solid-state laser medium 1 is used.

[0071] The bonding step in step S4 is preferably carried out using an organic adhesive having a Shore D hardness of 80 or less as the light-transmitting material (first embodiment shown in FIG. 3) or an inorganic light-transmitting material (second embodiment shown in FIG. 4 and third embodiment shown in FIG. 5).

[0072] [First aspect] The organic adhesive 13 of the first embodiment can be at least one of silicone resin, silicone-modified epoxy resin, and epoxy resin. A typical organic adhesive can bond the first adhesive anti-reflection film 1a of the solid-state laser medium 1 and the second adhesive anti-reflection film 2a of the magneto-optical material 2. This allows the Q-switch structure 10 shown in FIG. 3 to be manufactured. When an organic adhesive with a Shore D hardness of 80 or less is used as the light-transmitting material, distortion during bonding of the solid-state laser medium 1 and the magneto-optical material 2 can be reduced by a simple method, and high beam quality can be obtained.

[0073] [Second and third aspects]

[0074] There are various methods for bonding using inorganic light-transmitting materials, and known methods can be used. In particular, it is preferable to bond the materials as follows.

[0075] <Second aspect> In the second embodiment, as described above, borosilicate glass, quartz glass, or paramagnetic garnet can be used as the inorganic light-transmitting material 23. In this case, as described above, it is preferable to use a glass material made of water glass or low-melting-point glass for the strain relaxation layers 25 and 26. A method for manufacturing the Q-switch structure 20 in this embodiment will be described in more detail.

[0076] An example will be described in which Bi-RIG is used as the magneto-optical material 2. First, the magneto-optical material (Bi-RIG) 2 and the inorganic translucent material 23 are bonded together. The inorganic translucent material 23 used here preferably has a linear expansion coefficient between that of Bi-RIG and that of the solid-state laser medium. In this case, it is conceivable that the inorganic translucent material 23 itself is made of water glass or low-melting-point glass. In this case, water glass or low-melting-point glass can also be used for the strain relaxation layers 25 and 26, resulting in a configuration similar to that of the third embodiment described below.

[0077] In the second embodiment, an anti-reflection film (metal oxide film) 2a is formed in advance on the magneto-optical material 2, Bi-RIG, by electron beam evaporation, and a water glass or low-melting-point glass layer is formed on top of this as the strain relaxation layer 26. Of these, water glass can be formed by heating an aqueous sodium silicate solution to form a viscous liquid, which is then applied to the surface of the medium. The low-melting-point glass layer can also be formed by chemical vapor deposition, such as electron beam evaporation. The low-melting-point glass to be formed can be a conventional glass material containing PbO, BO, TeO, BiO, or the like as its main component. In this case, the thickness of the water glass or low-melting-point glass is 1×10 -8 m~1×10 -5It is preferable that the thickness of the water glass or low-melting point glass layer that is the strain relaxation layer 26 is 1×10 -8 By making the thickness 1×10 -5 By setting the thickness to m or less, it is possible to suppress a decrease in light transmittance.

[0078] Next, the bonding surfaces of the inorganic translucent material 23 and the strain relaxation layer 26 (water glass or low-melting glass) formed on the Bi-RIG (magneto-optical material 2) are bonded together and heat treated. This results in the Bi-RIG (magneto-optical material 2) and the inorganic translucent material 23 being integrally molded. Since a low bonding temperature can reduce the thermal stress on the bonding surfaces, it is preferable to melt and bond them at as low a temperature as possible. This bonding temperature can be, for example, the glass transition point +30°C or less.

[0079] Furthermore, water glass or low-melting glass is formed as the strain relaxation layer 25 on the inorganic light-transmitting material 23. This method can be carried out in the same manner as above.

[0080] Next, the water glass or low-melting-point glass forming the strain relaxation layer 25 is bonded to the solid-state laser medium 1. This bonding method is similar to the method used in manufacturing semiconductor wafers with an SOI structure, and the bonding force in this case may be van der Waals forces, hydrogen bonds, covalent bonds, etc. The surfaces to be bonded on both sides are hydrophilized, and the surfaces are bonded together. Sufficient bonding strength can then be achieved by heat treatment.

[0081] More specifically, the water glass or low-melting-point glass forming the strain relaxation layer 25 can be bonded to the solid-state laser medium 1 as follows. First, the workpiece surface is cleaned and hydrophilized. While conventional wet cleaning is effective, combining it with short-wavelength ultraviolet (UV) treatment or plasma treatment is also effective. For hydrophilization, a common solution, such as ammonia-hydrogen peroxide mixture (a mixture of ammonia water, hydrogen peroxide, and pure water), a diluted solution of nitric acid or hydrochloric acid, or a solution of these diluted solutions with hydrogen peroxide added, is effective. Next, the workpiece is cleaned with pure water to remove the hydrophilic treatment solution. The pretreated bonding surfaces are then bonded together in a facing relationship. To facilitate bonding, it is desirable to apply a liquid primarily composed of polar molecules, such as pure water, to the bonding surfaces, and then bond them together via the liquid. The bonded body is then air-dried or vacuum-dried to secure it with a weak bonding strength. A heat treatment at a temperature of approximately 80 to 200°C then achieves sufficient bonding strength.

[0082] <Third aspect> 5, the first adhesive antireflection film 1a of the solid-state laser medium 1 and the second adhesive antireflection film 2a of the magneto-optical material 2 are directly bonded together via an inorganic light-transmitting material 33 as a light-transmitting material. In this method, when the solid-state laser medium 1 is a garnet material such as Nd:YAG, it is preferable to use a glass material made of water glass or low-melting point glass having a similar expansion coefficient as the inorganic light-transmitting material 33. The direct bonding method can be the same as the bonding of the water glass or low-melting point glass that constitutes the strain relaxation layers 25, 26 of the second embodiment to the solid-state laser medium 1 and / or the magneto-optical material 2.

[0083] As described above, in either the second or third embodiment, the glass material is preferably bonded to the first adhesive anti-reflection film or the second adhesive anti-reflection film by thermal diffusion bonding or close contact bonding under vacuum.

[0084] Using the Q switch structure manufactured by the above-described manufacturing method for a Q switch structure, a Q switch solid-state laser device can be manufactured by placing the Q switch structure and a magnetic flux generator between a pair of resonant mirrors. [Example]

[0085] EXAMPLES The present invention will be explained in more detail below by showing examples and comparative examples, but the present invention is not limited to these.

[0086] [Examples 1-1 to 1-8] The Q-switch structure 100 shown in FIGS. 1 and 2 was manufactured as follows.

[0087] First, we used Nd:YAG as the solid-state laser medium 1 and bismuth-substituted rare-earth iron garnet ((RBi)3Fe5O) as the magneto-optical material 2. 12 A Bi-RIG (commonly known as Bi-RIG) was prepared (step S1 in FIG. 7).

[0088] Next, an anti-reflection film for air (made of Ta2O5 on the medium surface with SiO2 on top) was formed on one surface of the solid-state laser medium 1, and an anti-reflection film for adhesive (made of TiO2 on the medium surface with SiO2 on top) was formed on the other surface (the surface to be bonded) (step S2 in FIG. 7). Also, an anti-reflection film for adhesive (made of TiO2 on the magneto-optical material surface with SiO2 on top) was formed on one surface (the surface to be bonded) of the magneto-optical material 2, and an anti-reflection film for air (made of Ta2O5 on the magneto-optical material surface with SiO2 on top) was formed on the other surface (step S3 in FIG. 7).

[0089] Next, an organic adhesive (organic adhesive translucent material 13 in FIG. 3) was used as the translucent material 3 to perform bonding (step S4 in FIG. 7). At this time, organic adhesives with different Shore D hardness after curing were used for bonding. The adhesives used were KJR9022, LPS5400, LPS5547F, KJR632 (all manufactured by Shin-Etsu Chemical Co., Ltd.), Epo-tek OD2002, Epo-tek 302-3M, Epo-tek 353ND, Epo-tek 301 (all manufactured by Epoxy Technology).

[0090] The joint distortion was evaluated by placing the joint work between a polarizer / analyzer in an optical system in which parallel light is extracted from a laser light source and input to a photodetector via a polarizer / analyzer, illuminating the surface of the solid laser medium 1, and measuring the extinction ratio of the light emitted from the magneto-optical material 2. Table 1 shows the adhesives used, their Shore D hardness, and light transmittance in the 1064 nm range.

[0091] [Table 1]

[0092] In Examples 1-1 to 1-8, a small Q-switch structure with reduced distortion was obtained. Furthermore, while an extinction ratio of 30 dB or more is sufficient, if a value of 35 dB or more is defined as a particularly favorable value with low distortion, Examples 1-1 to 1-6 achieved particularly favorable values. Furthermore, even when the optical output increased, a Q-switch with little output degradation could be obtained by reviewing the bonding conditions.

[0093] [Example 2] The Q-switch structure 100 shown in FIGS. 1 and 2 was manufactured as follows.

[0094] First, we used Nd:YAG as the solid-state laser medium 1 and bismuth-substituted rare-earth iron garnet ((RBi)3Fe5O) as the magneto-optical material 2. 12A film (commonly known as Bi-RIG) was prepared (step S1 in FIG. 7). Next, an anti-reflection film for air (TiO2 on the surface of the medium with SiO2 on top of that) was formed on one surface of the solid-state laser medium 1, and an anti-reflection film for adhesive (TiO2 on the surface of the medium with SiO2 on top of that) was formed on the other surface (the surface to be bonded) (step S2 in FIG. 7). Furthermore, an anti-reflection film for adhesive (TiO2 on the surface of the magneto-optical material with SiO2 on top of that) was formed on one surface (the surface to be bonded) of the magneto-optical material 2, and an anti-reflection film for air (TiO2 on the surface of the magneto-optical material with SiO2 on top of that) was formed on the other surface (step S3 in FIG. 7).

[0095] Next, an inorganic light-transmitting material (inorganic light-transmitting material 33 in FIG. 5) was used as the light-transmitting material 3, and bonding was performed as follows (step S4 in FIG. 7).

[0096] A low-melting-point glass layer (PbO-ZnO-B2O3) serving as inorganic translucent material 33 was formed by chemical vapor deposition on the adhesive-resistant anti-reflection coating of magneto-optical material 2. The thickness was 0.050 mm. Next, the surface of magneto-optical material 2 on which inorganic translucent material 33 was formed and the surface of solid-state laser medium 1 were cleaned with ammonia-hydrogen peroxide and subjected to hydrophilic treatment. Then, the surfaces were cleaned with pure water. The thus pretreated bonding surfaces were placed facing each other and bonded together. The bonded body was then vacuum-dried and fixed. The inorganic translucent material 33 and the surface of solid-state laser medium 1 were then bonded by heat treatment at a temperature of 400°C. In this manner, the Q-switch structure 30 shown in FIG. 5 was manufactured.

[0097] The manufactured Q-switch structure was subjected to junction strain evaluation by transmitting laser light in the same manner as in Examples 1-1 to 1-8, and an extinction ratio of 35 dB or more was obtained. Furthermore, this Q-switch structure was incorporated into a Q-switch solid-state laser device, and the output was increased to 10 mJ and used continuously, but no deterioration of the output over time was observed.

[0098] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention. [Explanation of symbols]

[0099] 100, 10, 20, 30...Q switch structure, 1...solid-state laser medium, 1a...first anti-adhesive anti-reflection film, 2... magneto-optical material, 2a... second anti-adhesive anti-reflection film, 3...Translucent material, 13...Translucent material that is an organic adhesive, 23, 33...Inorganic translucent material, 25, 26...strain relaxation layer, 80...Q-switched solid-state laser device, 81...first resonant mirror, 82...second resonant mirror, 83...magnetic flux generator.

Claims

1. a solid-state laser medium; a magneto-optical material; A method for manufacturing a Q-switch structure in which the solid-state laser medium and the magneto-optical material are bonded together, comprising: providing the solid-state laser medium and the magneto-optical material; forming a first anti-adhesive anti-reflection film on one surface of the solid-state laser medium; forming a second anti-adhesive anti-reflection film on one surface of the magneto-optical material; a step of adhering a first anti-adhesive anti-reflection film of the solid-state laser medium and a second anti-adhesive anti-reflection film of the magneto-optical material via a light-transmitting material that is transparent at the laser oscillation wavelength of the laser oscillated from the solid-state laser medium; and A method for manufacturing a Q-switch structure, characterized in that the bonding is performed using an organic adhesive having a Shore D hardness of 80 or less as the light-transmitting material.

2. 2. The method for manufacturing a Q-switch structure according to claim 1, wherein the organic adhesive is at least one of a silicone resin, a silicone-modified epoxy resin, and an epoxy resin.

3. 3. The method for manufacturing a Q-switch structure according to claim 1, wherein the light-transmitting material has a transmittance of 95% or more at the laser oscillation wavelength.

4. 4. The method for manufacturing a Q-switch structure according to claim 1, wherein the magneto-optical material is a bismuth-substituted rare earth iron garnet.

5. The solid-state laser medium is doped with one selected from the group consisting of Nd, Yb, and Cr. ３ Al ５ O １２ , Gd ３ Ga ５ O １２ and YVO ４ 5. The method for manufacturing a Q switch structure according to claim 1, wherein the material is selected from one kind of ceramics selected from the group consisting of:

6. 6. A method for manufacturing a Q-switched solid-state laser device, comprising: using a Q-switched structure manufactured by the method for manufacturing a Q-switched structure according to any one of claims 1 to 5; and disposing the Q-switched structure and a magnetic flux generator between a pair of resonant mirrors to manufacture a Q-switched solid-state laser device.

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