JP2011139011A - Planar waveguide laser device, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar waveguide laser device facilitating adjustment and simplifying assembling work, and to provide a method of manufacturing the same. <P>SOLUTION: The device includes a waveguide solid laser element (3) including a laser medium (3c) having a waveguide structure, a waveguide optical element (4) including a non-linear material (4c) having a waveguide structure, and a heat sink (1) integrally structured to mount the both elements (3, 4). The method includes the step of forming a first abutment surface and a second abutment surface defining an end surface direction on the exciting light incidence side of the waveguide solid laser element (3), and a third abutment surface and a fourth abutment surface defining an end surface direction on the laser light outgoing side of the waveguide optical element (4) so as to be parallel to the end surface direction on the exciting light incidence side of the waveguide solid laser element on the heat sink (1), and the step of disposing the waveguide solid laser element and the waveguide optical element using the abutment surfaces. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a planar waveguide laser device having a planar waveguide structure suitable for a light source such as a printer or a projection television, and a method for manufacturing the planar waveguide laser device.

  An example of a planar waveguide laser device is a waveguide wavelength conversion laser device. This waveguide type wavelength conversion laser device is composed of a semiconductor laser element, a waveguide type solid state laser element, and a waveguide type wavelength conversion element (for example, see Patent Document 1). The semiconductor laser element generates excitation light, and the waveguide type solid-state laser element absorbs the excitation light and generates a fundamental wave. Furthermore, the waveguide type wavelength conversion element generates a second harmonic of the fundamental wave.

  Here, as an optical connection method by adjusting the optical axis position between two optical elements typified by a semiconductor laser and an optical waveguide, the following active alignment is generally used. In this active alignment, the amount of light emitted from a semiconductor laser and propagated through an optical waveguide optically connected to the semiconductor laser is measured with a power meter or the like so that the amount of light is maximized. The position will be adjusted (see, for example, Patent Documents 2 and 3).

  FIG. 12 is a configuration diagram of a conventional waveguide type wavelength conversion laser device. A manufacturing method of a conventional waveguide type wavelength conversion laser device will be described with reference to FIG. The conventional waveguide type wavelength conversion laser device includes heat sinks 301 a and 301 b, a semiconductor laser element 2, a waveguide type solid laser element 3, and a waveguide type wavelength conversion element 4.

  Here, the waveguide type solid-state laser element 3 is composed of the substrate 3a, the clad 3b, the laser medium 3c, the clad 3d, the end face 3e, and the end face 3f. The waveguide type wavelength conversion element 4 is composed of the substrate 4a, the clad 4b, the nonlinear material 4c, the clad 4d, the end face 4e, and the end face 4f.

  In order to form a resonator of the laser device at the end face 3e of the waveguide type solid-state laser element 3 and the end face 4f of the waveguide type wavelength conversion element 4, each element is arranged so that the end face 3e and the end face 4f are optically parallel to each other. Need to be placed. Therefore, in the assembly of the conventional waveguide type wavelength conversion laser device, after each element is joined to the separate heat sinks 301a and 301b, each element is aligned while the laser output is detected by the photodetector 20. Active alignment is used.

WO2006 / 103767 pamphlet JP-A-1-18057 JP 2004-109256 A

  However, the prior art has the following problems. In the conventional assembling method, when aligning each element while detecting the laser output, a very high accuracy is required, the number of adjustment points is large, and the assembling work takes time.

  The present invention has been made to solve the above problems, and provides a planar waveguide laser device and a planar waveguide laser device manufacturing method capable of facilitating adjustment and simplifying assembly work. Aim to get.

  The planar waveguide laser device manufacturing method according to the present invention has a flat plate shape, a waveguide solid state laser element including a laser medium having a waveguide structure in a thickness direction of a cross section perpendicular to the optical axis, and a flat plate shape. None, integrated for mounting a waveguide type optical element including a nonlinear material having a waveguide structure in the thickness direction of a cross section perpendicular to the optical axis, a waveguide type solid state laser element, and a waveguide type optical element A method of manufacturing a planar waveguide laser device including a heat sink, wherein the first contact surface and the second contact surface for defining the end face direction on the excitation light incident side of the waveguide solid laser element; A third contact surface and a fourth contact surface for defining the end surface direction on the laser light emission side of the waveguide type optical element so as to be parallel to the end surface direction on the excitation light incident side of the waveguide type solid state laser device; In the four corners of the heat sink The step of forming and placing the end face on the excitation light incident side of the waveguide type solid-state laser element against the first contact surface and the second contact surface formed on the heat sink, And a step of placing the end face on the laser beam emission side of the waveguide type optical element against the third contact surface and the fourth contact surface.

  The planar waveguide laser device according to the present invention has a flat plate shape, a waveguide solid state laser element including a laser medium having a waveguide structure in a thickness direction of a vertical cross section with respect to the optical axis, and a flat plate shape. A planar optical device including a waveguide type optical element including a nonlinear material having a waveguide structure in a thickness direction perpendicular to the optical axis, and a heat sink for mounting the waveguide type solid state laser element and the waveguide type optical element. In the waveguide type laser apparatus, the waveguide type solid state laser element and the waveguide type optical element are mounted on a heat sink that is integrally formed.

  According to the planar waveguide laser device and the method for manufacturing the planar waveguide laser device according to the present invention, the waveguide solid-state laser element and the waveguide wavelength conversion element are assembled and adjusted on the same integrally constructed heat sink. As a result, it is possible to obtain a planar waveguide laser device and a method of manufacturing the planar waveguide laser device that can facilitate adjustment and simplify assembly work.

It is a block diagram of the waveguide type wavelength conversion laser apparatus in Embodiment 1 of this invention. It is a top view of the waveguide type solid-state laser element-waveguide type | mold wavelength conversion element integrated element before the cutting | disconnection in the planar waveguide type laser apparatus of Embodiment 1 of this invention. It is a side view of the waveguide type solid-state laser element-waveguide type wavelength conversion element integrated element before cutting in the planar waveguide laser apparatus of Embodiment 1 of the present invention. It is a figure which shows the cutting position of a waveguide type solid state laser element-waveguide type wavelength conversion element integrated element. It is a figure which shows an example of the processing method of the planar waveguide type laser apparatus in which the molten material does not generate | occur | produce in Embodiment 1 of this invention. It is a block diagram of the waveguide type wavelength conversion element in Embodiment 2 of this invention. It is a top view of the waveguide type solid-state laser element-waveguide type wavelength conversion element integrated element in the planar waveguide type laser apparatus of Embodiment 3 of the present invention. It is a side view of the waveguide type solid-state laser element-waveguide type wavelength conversion element integrated element in the planar waveguide laser apparatus of Embodiment 3 of the present invention. It is a structure figure of the heat sink for waveguide type solid-state laser elements-waveguide type wavelength conversion element integrated elements in Embodiment 4 of the present invention. It is sectional drawing in the surface perpendicular | vertical to the optical axis of the waveguide type wavelength conversion element junction part of the waveguide type solid state laser element-waveguide type wavelength conversion element in Embodiment 4 of this invention. FIG. 7 shows the relationship between the thermal stress applied to the wavelength conversion element and the shear stress applied to the comb teeth with respect to the duty (comb width / inter-comb distance) of the comb teeth in the heat sink having the comb-like structure according to the fourth embodiment of the present invention. It is a figure. In Embodiment 4 of this invention, it is the figure which expanded a part of sectional drawing of the heat sink-nonlinear material in FIG. 7B. It is a structural diagram at the time of providing a comb-tooth in the x direction in the heat sink for a waveguide type solid state laser element-waveguide type wavelength conversion element integrated element in Embodiment 4 of the present invention. FIG. 10 is a structural diagram in the case where a comb-type solid-state laser element-waveguide type wavelength conversion element integrated element heat sink according to Embodiment 4 of the present invention is provided with comb teeth in both the x and y directions. It is a block diagram of the conventional waveguide type wavelength conversion laser apparatus.

  Preferred embodiments of a planar waveguide laser device and a planar waveguide laser device manufacturing method of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a waveguide type wavelength conversion laser device according to Embodiment 1 of the present invention. The waveguide type wavelength conversion laser device includes a heat sink 1, a semiconductor laser element 2, a waveguide type solid state laser element 3, and a waveguide type wavelength conversion element 4. Compared with the conventional waveguide type wavelength conversion laser device shown in FIG. 12, the waveguide type wavelength conversion laser device in the present invention has a waveguide type solid state laser element 3 and a waveguide type on the same heat sink 1. The difference is that the wavelength conversion element 4 is mounted. Here, the waveguide type solid-state laser element 3 and the waveguide type wavelength conversion element 4 have a planar waveguide structure in the thickness direction of the cross section perpendicular to the optical axis 6 representing the laser oscillation direction.

  The shape of the laser medium 3c is typically several to several tens of μm in the waveguide thickness direction (corresponding to the z direction described later), and several hundred μm to several mm in the optical axis 6 direction (corresponding to the x direction described later). A rectangular parallelepiped of several hundred μm to several mm in a direction perpendicular to the waveguide thickness direction and the optical axis 6 direction (corresponding to a y direction described later). The laser medium 3 c has end faces 3 e and 3 f perpendicular to the optical axis 6. The clad 3b and the clad 3d are made of a material having a refractive index smaller than that of the laser medium 3c. The clad 3b and the clad 3d may be made of the same material. Moreover, the material of the board | substrate 3a is not ask | required. However, typically, the same material as the laser medium 3c or a glass plate is used.

A general solid-state laser material can be used as the laser medium 3c. For example, Nd: YAG, Nd: YLF, Nd: Glass, Nd: YVO ₄ , Nd: GdVO ₄ , Yb: YAG, Yb: YLF, Yb: KGW, Er: Glass, Er: YAG, Tm: YAG, Tm: YLF, Ho: YAG, Ho: YLF, Ti: Sapphire, Cr: LiSAF, etc. are used.

  The non-linear material 4 c has a cross section perpendicular to the optical axis 6 having substantially the same shape as the laser medium 3 c, and has end faces 4 e and 4 f perpendicular to the optical axis 6. Further, the end face 4e is disposed close to the end face 3f of the waveguide type solid laser element 3 as shown in FIG.

  For the clad 4b and the clad 4d, a material having a refractive index smaller than that of the nonlinear material 4c is used. The clad 4b and the clad 4d may use the same material. Moreover, the material of the board | substrate 4a is not ask | required. However, typically, the same material as the nonlinear material 4c is used.

As the nonlinear material 4c, a general wavelength conversion material can be used. For example, KTP, KN, BBO, LBO, CLBO, LiNbO ₃ , LiTaO ₃ or the like is used. Further, if MgO-added LiNbO ₃ , MgO-added LiTaO ₃ , and specific ratio LiTAO ₃ that are resistant to optical damage are used, the power density of the incident fundamental wave laser beam can be increased. For this reason, highly efficient wavelength conversion becomes possible. Furthermore, the use of MgO-added LiNbO ₃ with periodic reversal polarization structure, MgO-added LiTaO ₃ , specific ratio LiNbO ₃ , specific ratio LiTaO ₃ , and KTP can increase the nonlinear constant and enable more efficient wavelength conversion. It becomes.

  The semiconductor laser element 2 is disposed in the vicinity of the end surface 3e of the laser medium 3c, and a cooling heat sink (not shown) is joined as necessary. The size in the direction perpendicular to the waveguide thickness direction and the optical axis 6 direction of the semiconductor laser element 2 is substantially the same as the size in the waveguide thickness direction of the laser medium 3c and the direction perpendicular to the optical axis 6 direction. Then, the semiconductor laser element 2 outputs the excitation light substantially uniformly in the size in the direction perpendicular to the waveguide thickness direction and the optical axis 6 direction. The excitation light output from the semiconductor laser element 2 enters the laser medium 3c from the end face 3e and is absorbed by the laser medium 3c.

  Here, the end surface 3e of the laser medium 3c has a total reflection film that reflects the fundamental laser beam, and the end surface 3f has an antireflection film that transmits the fundamental laser beam. On the other hand, the end face 4e of the nonlinear material 4c has an optical film that transmits the fundamental laser light and reflects the second harmonic laser light, and the end face 4f reflects the fundamental laser light and reflects the second harmonic laser light. The optical film which permeate | transmits.

  These total reflection film, antireflection film, and optical film are configured, for example, by laminating dielectric thin films. When the excitation light output from the semiconductor laser element 2 is incident from the end face 3e of the laser medium 3c, the total reflection film on the end face 3e is an optical film that transmits the excitation light and reflects the fundamental laser light. Become. The heat sink 1 is made of a material having a high thermal conductivity. For example, Si or the like is used.

  Next, a manufacturing method of the waveguide type solid-state laser element-waveguide type wavelength conversion element integrated element, which is a feature of the first embodiment, will be described with reference to FIGS. 2A, 2B, and 3. FIG. FIG. 2A is a top view of a waveguide solid-state laser element-waveguide wavelength conversion element integrated element before cutting in the planar waveguide laser apparatus according to Embodiment 1 of the present invention. FIG. 2B is a side view of the waveguide solid-state laser element-waveguide wavelength conversion element integrated element before cutting in the planar waveguide laser apparatus according to Embodiment 1 of the present invention. Further, FIG. 3 is a diagram showing a cutting position of the waveguide type solid-state laser element-waveguide type wavelength conversion element integrated element.

In addition, the x direction, y direction, and z direction shown in each figure of FIG. 2A, FIG. 2B, and FIG. 3 mean the following directions, respectively.
x direction: direction of the optical axis 6 y direction: means the width direction (longitudinal direction) of the waveguide type solid-state laser element 3 and the waveguide type wavelength conversion element 4 in a cross section perpendicular to the optical axis 6.
z direction: means the thickness direction of the waveguide type solid-state laser element 3 and the waveguide type wavelength conversion element 4 in a cross section perpendicular to the optical axis 6.
These directions are the same in FIGS. 6A and 6B described later.

  In order to form a resonator of the laser device with the end face 3e of the laser medium 3c and the end face 4f of the nonlinear material 4c, the end face 3e and the end face 4f need to be arranged in parallel. Therefore, in the planar waveguide laser device of the present invention, the contact surfaces 5 are provided at the four corners of the heat sink 1. By disposing the waveguide type solid-state laser element 3 and the waveguide type wavelength conversion element 4 so as to contact the contact surface 5, the end face 3e and the end face 4f can be easily made parallel.

  The contact surface 5 is made of metal plating (for example, gold plating), and the shape thereof is typically a rectangular shape having a xy direction of 100 μm to several mm, and a z-direction thickness of several hundred μm to several mm. And The contact surface 5 is composed of four parts 5a to 5d, and a line connecting the surfaces that contact the end surfaces 3e of the contact surfaces 5a and 5b and a line connecting the surfaces that contact the end surfaces 4f of the contact surfaces 5c and 5d are parallel to each other. As shown, the heat sinks 1 are arranged at the four corners.

  The heat sink 1 may be provided in the dotted line areas 1a and 1b in FIG. 2A, but it is preferable that the heat sink 1 is not processed by etching or the like. Since the end face 3e is disposed close to the end face of the semiconductor laser element 2, when the heat sink is present in the dotted line area, the size of the dotted line area 1a in the x direction is set to 100 μm or less.

  In order to obtain the parallelism between the end face 3e of the laser medium 3c and the end face 4f of the nonlinear material 4c with higher accuracy, the waveguide type solid-state laser element 3 and the waveguide type wavelength conversion element 4 have a bar shape that is long in the y direction. And the distance between the contact surfaces 5a and 5b and the distance between the contact surfaces 5c and 5d are made as long as possible. The sizes in the y direction of the bar-shaped waveguide type solid-state laser element 3 and the waveguide type wavelength conversion element 4 are typically several to several tens of mm.

  After joining the bar-shaped waveguide type solid-state laser element 3 and the waveguide type wavelength conversion element 4 on the heat sink 1, it is cut into a desired length in the y direction (see FIG. 3). As a cutting method, laser processing that does not generate chips is used. However, since laser processing melts and cuts the workpiece with laser light, it is necessary to prevent the melt from entering between the end surface 3f of the laser medium 3c and the end surface 4e of the nonlinear material 4c.

  FIG. 4 is a diagram showing an example of a processing method of the planar waveguide laser device that does not generate a melt in the first embodiment of the present invention. When the laser beam 10 is condensed by the lens 9 and irradiated onto the workpiece, the focused point is set inside the workpiece, the surface is not melted, only the inside is melted, and the modified region 11 is formed inside the workpiece. Form. Specifically, the modified regions 11a and 11b are formed inside the waveguide type solid-state laser element 3 and inside the waveguide type wavelength conversion element 4 along the cutting line in FIG.

  Moreover, you may form the modification | reformation area | region 11c also in the inside of the heat sink 1 as needed. After the modified regions 11a, 11b, and 11c are formed, a stress is applied from the lower surface of the heat sink 1, whereby the element is cut starting from the modified regions 11a, 11b, and 11c.

  In order for the fundamental laser beam emitted from the end face 3f of the laser medium 3c to enter the end face 4e of the nonlinear material 4c, the waveguide medium is formed by matching the positions (heights) of the laser medium 3c and the nonlinear material 4c in the z direction. The type solid laser element 3 and the waveguide type wavelength conversion element 4 need to be arranged. For this purpose, as the bonding agents 7a and 7b (see FIG. 2B) used for bonding the waveguide type solid-state laser element 3 and the waveguide type wavelength conversion element 4 to the heat sink 1, vapor-deposited solder (see FIG. 2B) can be easily controlled. For example, it is desirable to use AuSn solder.

  The bonding agent 7a used for bonding the waveguide type solid-state laser element 3 and the bonding agent 7b used for bonding the waveguide type wavelength conversion element 4 do not need to be the same material. In order to perform solder bonding, a metal film (for example, Cr / Ni / Au) is provided on the bonding surface of the heat sink 1, the waveguide type solid-state laser element 3, and the waveguide type wavelength conversion element 4. Also good.

  As described above, according to the first embodiment, the waveguide type solid-state laser element and the waveguide type wavelength conversion element are arranged on the same heat sink. In particular, a contact surface for positioning the parallelism between the waveguide type solid-state laser element and the waveguide type wavelength conversion element is provided on the heat sink to facilitate adjustment and simplify assembly work. Can be planned.

  In the first embodiment, an example in which a wavelength conversion element is used as the waveguide type optical element has been described. However, the present invention is not limited to this. The present invention can also be applied to the case where another optical element is used as the waveguide type optical element. For example, instead of the waveguide type wavelength conversion element 4, a waveguide type polarizer, a waveguide type Q switch element or the like can be used.

Embodiment 2. FIG.
In the first embodiment, when the MgO-added LiNbO ₃ having a periodically inverted polarization structure is used as the nonlinear material 4c, LiNbO ₃ which is the same material as the nonlinear material 4c is usually used as the substrate 4a. However, LiNbO _{3 has} a thermal expansion coefficient of 14.8 × 10 ⁻⁶ K ⁻¹ and Si has a thermal expansion coefficient of 2.6 × 10 ⁻⁶ K ⁻¹ . Therefore, when a general Si heat sink is used as the heat sink 1, the difference in thermal expansion coefficient is large, and it is difficult to join the heat sink 1 and the waveguide type wavelength conversion element 4 at a high temperature.

  On the other hand, as a bonding agent for bonding the heat sink 1 and the waveguide type wavelength conversion element 4, it is desirable to use vapor-deposited AuSn solder or the like. However, the melting point of AuSn solder is 280 ° C., and bonding at a high temperature is required.

  Therefore, in the second embodiment, a case will be described in which a material having a thermal expansion coefficient equivalent to that of the heat sink 1 is used as the substrate in order to solve such a high temperature problem. FIG. 5 is a configuration diagram of a waveguide type wavelength conversion element according to the second embodiment of the present invention. Si, which is the same material as the heat sink 1, is used as the substrate 104a of the waveguide type wavelength conversion element 104 in the second embodiment. Note that other materials may be used for the substrate 104a as long as the thermal expansion coefficient is substantially the same as that of Si. The other structures of the waveguide type wavelength conversion element 104 are the same as those of the waveguide type wavelength conversion element 4 shown in the first embodiment. The structure and manufacturing method other than the waveguide type wavelength conversion element 104 are the same as those in the first embodiment.

  By using a material having a thermal expansion coefficient equivalent to that of the heat sink 1 as the substrate 104a, stress applied to the waveguide type wavelength conversion element 104 and the heat sink 1 during cooling after high-temperature bonding can be relaxed. As a result, bonding with AuSn solder having a high melting point becomes possible.

  As described above, according to the second embodiment, in addition to the configuration in the first embodiment, a material having a thermal expansion coefficient equivalent to that of a heat sink is used as the substrate of the waveguide type wavelength conversion element. As a result, in addition to the effects in the first embodiment, stress applied to the waveguide type wavelength conversion element and the heat sink during cooling after high-temperature bonding can be relieved, and bonding with AuSn solder having a high melting point becomes possible.

Embodiment 3 FIG.
In the second embodiment, the case where a high melting point material is used as the bonding agent has been described. On the other hand, in this Embodiment 3, the case where a low melting-point thing is used as an adhesive agent is demonstrated.

  A method for manufacturing a waveguide solid-state laser element-waveguide wavelength conversion element integrated element, which is a feature of the third embodiment, will be described with reference to FIGS. 6A and 6B. FIG. 6A is a top view of a waveguide solid-state laser element-waveguide wavelength conversion element integrated element in the planar waveguide laser apparatus according to Embodiment 3 of the present invention. FIG. 6B is a side view of a waveguide solid-state laser element-waveguide wavelength conversion element integrated element in the planar waveguide laser apparatus according to Embodiment 3 of the present invention.

  In the case of the third embodiment, SnBi-based solder (for example, Bi-57Bi-1Ag solder, melting point: 137 ° C.) having a low melting point is used as the bonding agent 107b in the bonding between the heat sink 101 and the waveguide type wavelength conversion element 4. Is used. As a method for supplying the solder, vapor deposition is desirable, but when using a solder that is difficult to deposit such as SnBi solder, a general solder paste may be used.

  As the bonding agent 107b, other solder may be used as long as it has a melting point of 150 ° C. or lower. As a result, the heat sink 101 and the waveguide wavelength conversion element 4 can be reliably bonded at a low temperature of 150 ° C. or less, and even when the difference in thermal expansion coefficient between the two is large, the heat sink 101 and the waveguide type wavelength conversion element 4 are not easily affected. Can be joined.

  Note that as the bonding agent 107a in the bonding of the heat sink 101 and the waveguide type solid-state laser element 3, a solder capable of vapor deposition (for example, AuSn solder) may be used as in the first embodiment.

  In general, when joining using a solder paste, a scrubbing operation is required to remove an oxide film formed on the solder surface. This scrubbing is an operation of moving the elements to be joined back and forth and left and right to stir the melted solder while the solder is melted at the time of joining. When scrubbing the waveguide type wavelength conversion element 4, if it is moved in the x direction, it will come into contact with the waveguide type solid state laser element 3, so that scrubbing is performed only in the y direction.

  Also, the solder paste has a larger amount of solder than the solder supplied by vapor deposition. Therefore, the solder protrudes from the joint surface of the waveguide type wavelength conversion element 4 due to scrubbing or a load applied to the waveguide type wavelength conversion element 4 at the time of joining, and contacts the end face 3f of the waveguide type solid laser element 3. It is necessary to avoid it. For this reason, the heat sink 101 in the third embodiment is provided with a groove 101a so as to release the protruding solder. The dimensions of the groove 101a are typically about 100 μm in the x direction and 100 to several hundred μm in the depth direction (z direction).

  Except for the material of the adhesive 107b and the structure of the heat sink 101, the structure of the planar waveguide laser device and the manufacturing method thereof in the third embodiment are the same as those in the first embodiment.

  As described above, according to the third embodiment, a low melting point having a melting point of 150 ° C. or lower is used as the bonding agent in the bonding between the heat sink and the waveguide type wavelength conversion element. As a result, the heat sink 101 and the waveguide type wavelength conversion element 4 can be reliably bonded at a low temperature of 150 ° C. or less, and even when the difference in thermal expansion coefficient between the two is large, the heat sink 101 and the waveguide type wavelength conversion element 4 are not easily affected. Can be joined.

  Furthermore, in the heat sink of the third embodiment, a groove is formed in an unjoined region located between the waveguide type solid laser element and the waveguide type optical element. Thereby, it can avoid that solder protrudes from the joint surface of a waveguide type wavelength conversion element, and contacts the end surface of a waveguide type solid laser element.

Embodiment 4 FIG.
In the second embodiment, the method of using a material having a thermal expansion coefficient equivalent to that of the heat sink as the substrate of the waveguide type wavelength conversion element has been described. On the other hand, in the fourth embodiment, a method of reducing the thermal stress applied to the waveguide type wavelength conversion element by providing a comb structure on the heat sink will be described.

  FIG. 7A is a structural diagram of a heat sink for a waveguide type solid-state laser element-waveguide type wavelength conversion element integrated element according to Embodiment 4 of the present invention. Here, comb teeth 202 are provided on the joint surface of the heat sink 201.

  FIG. 7B is a cross-sectional view taken along a plane perpendicular to the optical axis of the waveguide-type wavelength conversion element junction of the waveguide-type solid-state laser element-waveguide-type wavelength conversion element in Embodiment 4 of the present invention. The cross section perpendicular to the optical axis of the heat sink 201 has a comb-like structure, and the tip of the comb is bonded to the bonding surface of the wavelength conversion element 4 via the bonding agent 203.

  The comb teeth 202 are formed by metal plating (for example, Cu, Ni, etc.), and solder (for example, AuSn solder) capable of vapor deposition or plating is used as the bonding agent 203. By creating the comb teeth 202 by plating, the comb width and the inter-comb distance can be easily changed only by changing the mask pattern.

When LiNbO ₃ is used for the substrate 4a, the coefficient of thermal expansion is different from that of the Si heat sink. Therefore, thermal bonding is generated in the wavelength conversion element if it is bonded at a high temperature with AuSn solder. Therefore, the bonding surface of the Si heat sink has a comb structure as shown in FIGS. 7A and 7B, so that the thermal stress of the wavelength conversion element acts as a shear stress on each comb tooth. Therefore, a shear strain is generated in each comb tooth, and the thermal stress of the wavelength conversion element is relaxed by the amount of the strain.

  Here, the shear stress applied to each comb tooth is inversely proportional to the comb width (joint area). For this reason, when the comb width is narrowed, the shear distortion of the comb teeth increases and the stress of the wavelength conversion element is further relaxed (see FIG. 7B).

However, when the comb width is narrowed, there is a possibility that the comb teeth break due to an increase in shear stress applied to the comb teeth. FIG. 8 shows the thermal stress applied to the wavelength conversion element and the shear stress applied to the comb teeth with respect to the duty (comb width / inter-comb distance) of the comb teeth in the heat sink 201 having the comb-like structure according to the fourth embodiment of the present invention. It is the figure which showed each relationship. This relationship is determined by the physical properties (thermal expansion coefficient, elastic modulus, etc.) of the material used. For this reason, the optimum duty is set according to the material to be used. When LiNbO ₃ is used for the substrate 4a and Si is used for the heat sink 201, it is desirable to set the duty to 80% or less.

  Next, the temperature distribution generated in the nonlinear material 4c will be described. FIG. 9 is an enlarged view of a part of a cross-sectional view of heat sink 201 to nonlinear material 4c in FIG. 7B in Embodiment 4 of the present invention. The heat generated in the nonlinear material 4 c is exhausted to the heat sink 201 through the clad 4 d and the bonding agent 203.

  At this time, the heat sink 201 in the fourth embodiment has a comb shape, and the range bonded by the bonding agent 203 is only the tip portion of the comb teeth. For this reason, in the intermediate part between two comb teeth, a heat flow is generated on both sides in the y-axis direction from the approximate center of the two comb teeth. Therefore, the temperature at the approximate center of the two comb teeth is maximized, and the temperature decreases as the portion approaches the comb tooth portion.

  The refractive index of the optical material such as the nonlinear material 4c changes almost in proportion to the temperature difference. When a material having a positive refractive index change dn / dT per unit temperature is used as the optical material of the nonlinear material 4c, the refractive index at the center of the two comb teeth having a high temperature increases, and the comb tooth portion As the value approaches, the refractive index decreases. As a result, in the y-axis direction, a thermal lens effect is generated with the center portion of the two comb teeth as the optical axis, and the laser oscillation mode in the y-axis direction can be stabilized. The interval between the comb teeth corresponds to the light emitting point of the semiconductor laser element 2.

  The comb teeth are applied to the entire bonding surface of the heat sink including the bonding surface of the waveguide type solid laser element. Thus, the effect of stabilizing the oscillation mode by the temperature distribution can be further increased by adopting a comb-teeth structure on the joint surface with the waveguide type solid-state laser element.

  In the heat sink 201, a comb pattern is removed from an unjoined region located between the waveguide type solid-state laser element and the waveguide type optical element. Thereby, it is possible to avoid the solder protruding from the joint surface from coming into contact with the end face of the waveguide type solid laser element and the end face of the waveguide type optical element.

  As described above, according to the fourth embodiment, by providing the comb-like structure on the heat sink, the thermal stress applied to the waveguide type wavelength conversion element can be relieved, and joining with AuSn solder having a high melting point is possible. It becomes. Furthermore, by creating comb teeth by plating, it is possible to easily change the comb width and the inter-comb distance by simply changing the mask pattern, and it is easy to have the desired characteristics regarding thermal stress relaxation. It becomes.

  In the fourth embodiment described above, stress relaxation in the y direction has been described. However, since stress in the x direction can be considered similarly, comb teeth may be provided in the x direction. FIG. 10 is a structural diagram in the case where comb-tooth is provided in the x direction in the waveguide type solid-state laser element-waveguide type wavelength conversion element integrated element heat sink according to the fourth embodiment of the present invention. When the comb teeth are provided in the x direction, the effect of beam stabilization by the thermal lens cannot be obtained, but the interval between the comb teeth can be freely set.

  It is more effective to provide comb teeth in both the x and y directions. FIG. 11 is a structural diagram when a comb-type solid-state laser element-waveguide-type wavelength conversion element integrated heat sink according to Embodiment 4 of the present invention is provided with comb teeth in both the x and y directions. In this case, the joint surface becomes a dot shape, and stress in all directions in the xy plane can be relaxed. In this case, the intervals between the comb teeth in the x direction need not be equal.

  Note that the use of the waveguide type wavelength conversion element 104 described in the second embodiment is more effective in terms of stress relaxation.

  DESCRIPTION OF SYMBOLS 1 Heat sink, 2 Semiconductor laser element, 3 Waveguide type solid state laser element, 3a board | substrate, 3b clad, 3c laser medium, 3d clad, 3e end surface, 3f end surface, 4 Waveguide type | mold wavelength conversion element (waveguide type optical element), 4a substrate, 4b cladding, 4c nonlinear material, 4d cladding, 4e end surface, 4f end surface, 5, 5a to 5d contact surface, 6 optical axes, 7a, 7b bonding agent, 8 cutting line, 9 lens, 10 laser beam, 11, 11a to 11c Modified region, 101 heat sink, 101a groove, 104 waveguide type wavelength conversion element, 104a substrate, 107a, 107b bonding agent, 201 heat sink, 202 comb teeth, 203 bonding agent.

Claims (14)

A waveguide type solid-state laser element including a laser medium having a plate shape and having a waveguide structure in a thickness direction of a vertical cross section with respect to an optical axis;
A waveguide-type optical element including a nonlinear material having a planar shape and having a waveguide structure in a thickness direction of a cross section perpendicular to the optical axis;
A method of manufacturing a planar waveguide laser device comprising: a heat sink integrally configured to mount the waveguide solid-state laser element and the waveguide optical element;
A first contact surface and a second contact surface for defining an end face direction on the excitation light incident side of the waveguide type solid laser element; and an end face direction on the excitation light incident side of the waveguide type solid laser element; Forming a third contact surface and a fourth contact surface for defining the end face direction on the laser light emission side of the waveguide type optical element so as to be parallel to the four corners on the heat sink;
An end face on the excitation light incident side of the waveguide type solid-state laser element is placed in contact with the first contact surface and the second contact surface formed on the heat sink, and is formed on the heat sink. And a step of placing the end face on the laser light emitting side of the waveguide type optical element against the third contact surface and the fourth contact surface. Device manufacturing method. In the manufacturing method of the planar waveguide type laser device according to claim 1,
The forming step includes forming a distance between the first contact surface and the second contact surface, and a distance between the third contact surface and the fourth contact surface apart from each other by a predetermined distance,
The arranging step includes the waveguide solid-state laser element and the waveguide optical element having a bar-like shape longer than the predetermined distance in a direction perpendicular to both the waveguide thickness direction and the optical axis direction. A method of manufacturing a planar waveguide laser device, characterized by comprising: In the manufacturing method of the planar waveguide type laser device according to claim 2,
After the step of arranging, the plane further comprising the step of cutting the waveguide type solid laser element and the waveguide type optical element arranged on the heat sink in the optical axis direction by laser processing. A method for manufacturing a waveguide laser device. In the manufacturing method of the planar waveguide type laser device according to any one of claims 1 to 3,
The forming step includes forming the first contact surface to the fourth contact surface using metal plating. A method of manufacturing a planar waveguide laser device, wherein: In the manufacturing method of the planar waveguide type laser device according to any one of claims 1 to 4,
The placing step includes joining the waveguide type solid-state laser element and the waveguide type optical element on the heat sink by using vapor-depositable solder as a joining agent. Type laser device manufacturing method. In the manufacturing method of the planar waveguide type laser device according to any one of claims 1 to 4,
In the planar waveguide laser device, the step of arranging includes using a bonding agent having a low melting point of 150 ° C. or lower when the waveguide type optical element is arranged on the heat sink. Production method. A waveguide type solid-state laser element including a laser medium having a plate shape and having a waveguide structure in a thickness direction of a vertical cross section with respect to an optical axis;
A waveguide-type optical element including a nonlinear material having a planar shape and having a waveguide structure in a thickness direction of a cross section perpendicular to the optical axis;
A planar waveguide laser device comprising: a heat sink for mounting the waveguide solid-state laser element and the waveguide optical element;
The planar waveguide laser device, wherein the waveguide solid-state laser element and the waveguide optical element are mounted on the heat sink formed integrally. The planar waveguide laser device according to claim 7, wherein
The waveguide type optical element has a substrate having a thermal expansion coefficient equivalent to that of the heat sink. The planar waveguide laser device according to claim 8, wherein
The waveguide-type solid-state laser element includes a substrate having a thermal expansion coefficient equivalent to that of the heat sink. The planar waveguide laser device according to claim 7, wherein
A planar waveguide laser device, wherein the heat sink has a groove formed in an unbonded region located between the waveguide solid-state laser element and the waveguide optical element. The planar waveguide laser device according to claim 7, wherein
A planar waveguide laser device, wherein the bonding surface of the heat sink has a comb structure in a cross section perpendicular to the optical axis. The planar waveguide laser device according to claim 7, wherein
A planar waveguide laser device, wherein the bonding surface of the heat sink has a comb structure in a cross section parallel to the optical axis and perpendicular to the waveguide. The planar waveguide laser device according to claim 7, wherein
The planar waveguide laser device, wherein the bonding surface of the heat sink has a comb structure in a cross section perpendicular to the optical axis and in a cross section parallel to the optical axis and perpendicular to the waveguide. The planar waveguide laser device according to any one of claims 7 to 13,
A planar waveguide laser device characterized in that a semiconductor laser is used as a laser for generating excitation light for a waveguide solid laser element.

Images