Laser assembly and method for manufacturing the same, laser module, optical engine, and xr glass

Abstract

To provide a laser assembly, which is constituted to maintain predetermined gaps between laser element bases and an optical waveguiding substrate.SOLUTION: A laser assembly 100 of the present invention includes: a plurality of laser element bases 20 in which laser elements 30 are installed on main surfaces 21; an optical waveguiding substrate 40 in which an optical waveguiding layer 50 is provided on a main surface 41; a plurality of spacer films 72 which is disposed away from each other at positions corresponding to the laser element bases 20 on the bonding surface 42 of the optical waveguiding substrate 40; and a plurality of metal laminate films 70 which bonds the bonding surfaces 22 of the plurality of laser element bases 20 and the bonding surface 42 of the optical waveguiding substrate 40. The plurality of metal laminate films 70 is respectively disposed on the plurality of spacer films 72, and has a plurality of first metal films 73 and second metal films 74 that are disposed on the bonding surfaces 22 of the plurality of laser element bases 20 and made of metals capable of being eutectic with metals constituting the first metal films 73.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laser assembly and a manufacturing method thereof, a laser module, an optical engine and XR glasses. [Background technology]

[0002] XR glasses such as AR (Augmented Reality) glasses and VR (Virtual Reality) glasses are expected to become small wearable devices. The key to the widespread use of wearable devices such as AR and VR glasses is to miniaturize them so that their functions fit into the size of regular eyeglasses. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 149450 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses an integrated optical device that is miniaturized by bonding a base that holds a laser element to a substrate on which an optical waveguide is provided, with the light-emitting position of the laser element and the position of the optical waveguide precisely aligned via a metal layer. A configuration in which the base and the substrate are bonded via a metal layer provides greater bonding strength than a configuration in which the substrate is bonded with an adhesive, and also reduces the temperature dependency of the bonding strength.

[0005] Fig. 15 is a schematic plan view for explaining the integrated optical device disclosed in Patent Document 1. Fig. 16A and Fig. 16B are schematic perspective views of a base for holding a laser element (base for laser element) and a substrate (substrate for optical waveguide) on the surface of which an optical waveguide is provided, respectively, before bonding, as disclosed in Patent Document 1, Fig. 16A is a schematic perspective view of the base for holding a laser element, and Fig. 16B is a schematic perspective view of the substrate on which an optical waveguide is provided. In the figure, the same reference numerals are used for components similar to those of the laser assembly of this embodiment described later, and descriptions thereof will be omitted below as appropriate.

[0006] The integrated optical device shown in the figure comprises three laser elements 30-1, 30-2, 30-3, three individual bases 20 (20-1, 20-2, 20-3) on which the laser elements 30 are mounted on main surfaces 21-1, 21-2, 21-3, respectively, and spaced apart from each other, an optical waveguide layer 50 having an optical waveguide 51 that guides the laser light emitted from the laser elements 30-1, 30-2, 30-3, a substrate 40 on whose surface the optical waveguide layer 50 is provided, and a metal film that bonds the bases 20 (20-1, 20-2, 20-3) to the substrate 40. In the integrated optical device shown in the figure, the metal film has a three-layer structure consisting of metal layers 74 (74-1, 74-2, 74-3) disposed on each of the bonding surfaces 22 (22-1, 22-2, 22-3) of the individual bases 20, a metal layer 172 deposited continuously in a strip shape on the bonding surface 42 of the substrate 40, and a metal layer 173 deposited continuously in a strip shape so as to overlap metal layer 172.

[0007] By joining the base that holds the laser element and the substrate on which the optical waveguide is provided via metal bonding in this manner, it is possible to precisely position the light emission position of the laser element and the entrance position of the optical waveguide. In bonding, the metal film formed on the base and the substrate is melted at high temperature, brought into contact with a predetermined pressure, and a metal bond is formed to complete the bonding. Here, when the metal film is melted at high temperature to form a metal bond, it is pressed with a predetermined pressure, so there is a concern that the molten metal may leak out of the gap between the base and the substrate. Since the bonding surface is flat, the molten metal flows easily. If the molten metal leaks out of the gap, it may form a metal ball or come into contact with other metal members to form a current path, which may cause device failure or performance degradation.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a laser assembly configured to maintain a predetermined distance between a laser element base and an optical waveguide substrate, a manufacturing method thereof, a laser module, an optical engine, and XR glasses. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides the following means.

[0010] A first aspect of the present invention is a laser assembly comprising: a plurality of laser elements, a plurality of laser element bases having a main surface and a bonding surface, with each of the plurality of laser elements being mounted on the main surface; an optical waveguide substrate having a main surface and a bonding surface, with an optical waveguide layer having an optical waveguide for guiding laser light emitted from the plurality of laser elements being provided on the main surface; a plurality of spacer films arranged spaced apart from each other on the bonding surface of the optical waveguide substrate at positions corresponding to each of the plurality of laser element bases; and a plurality of metal laminate films bonding the bonding surfaces of the plurality of laser element bases and the bonding surface of the optical waveguide substrate, wherein the plurality of metal laminate films are arranged on each of the plurality of spacer films, and have a plurality of first metal films and a second metal film arranged on the bonding surfaces of the plurality of laser element bases, the second metal film being made of a metal capable of forming a eutectic with a metal constituting the first metal film.

[0011] A second aspect of the present invention is a laser assembly according to the first aspect, wherein the first metal film is made of Sn or an alloy containing Sn, and the second metal film is made of a metal selected from the group consisting of Au, Si, Al, Ni, Zn, Pt, and alloys thereof.

[0012] A third aspect of the present invention is the laser assembly according to the first or second aspect, wherein the spacer film has a thickness of 0.1 μm or more.

[0013] A fourth aspect of the present invention is the laser assembly according to any one of the first to third aspects, wherein the spacer film is made of a metal selected from the group consisting of Ta, Ti, Ni, Ta / Pt, Ti / Pt, and Ni / Pt.

[0014] A fifth aspect of the present invention is the laser assembly according to any one of the first to third aspects, wherein the spacer film is made of an oxide.

[0015] A sixth aspect of the present invention relates to the laser assembly of any one of the first to fifth aspects, wherein the second metal film is formed to have a larger area than the first metal film.

[0016] A seventh aspect of the present invention is a laser assembly according to any one of the first to sixth aspects, further comprising an anti-reflection film on a bonding surface of the optical waveguide substrate, and the spacer film is formed on the anti-reflection film.

[0017] Aspect 8 of the present invention is the laser assembly according to any one of aspects 1 to 7, wherein the optical waveguide layer is a PLC (Planar Lightwave Circuit) made of a glass material.

[0018] A ninth aspect of the present invention is the laser assembly according to any one of the first to seventh aspects, wherein the optical waveguide layer is a PLC made of a lithium niobate film.

[0019] A tenth aspect of the present invention is a laser module in which the laser assembly of any one of the eighth or ninth aspects is housed in a package.

[0020] An eleventh aspect of the present invention is an optical engine including the laser module of the tenth aspect and an optical scanning mirror that scans the light emitted from the laser module.

[0021] A twelfth aspect of the present invention is an XR glass comprising the optical engine of the eleventh aspect.

[0022] A thirteenth aspect of the present invention is a method for manufacturing a laser assembly, comprising: an optical waveguide substrate fabrication step of sequentially forming a plurality of spacer films and a first metal film on a bonding surface of an optical waveguide substrate; a laser element base fabrication step of forming a second metal film on a bonding surface of a laser element base; and a bonding step of eutectic bonding the laser element base and the optical waveguide substrate after the optical waveguide substrate fabrication step and the laser element base fabrication step.

[0023] A fourteenth aspect of the present invention is characterized in that, in the manufacturing method of a laser assembly of Aspect 13, the optical waveguide substrate preparation process forms the spacer film and the first metal film using a photoresist mask having a plurality of holes corresponding to the patterns of a plurality of the spacer films arranged at a distance from each other on the bonding surface of the optical waveguide substrate, and the bonding process eutectic bonds the first metal film of the optical waveguide substrate and the second metal film of the laser element base using active alignment bonding. Effect of the Invention

[0024] According to the laser assembly of the present invention, it is possible to provide a laser assembly configured so that a predetermined distance is maintained between the laser element base and the optical waveguide substrate. [Brief description of the drawings]

[0025] [Figure 1] FIG. 2 is a schematic plan view of a portion of a laser assembly according to the present embodiment. [Diagram 2] 2 is a schematic cross-sectional view of the laser assembly shown in FIG. 1 taken along line AA'. [Figure 3A] FIG. 2 is a schematic perspective view of a laser element base before bonding the laser element base to an optical waveguide substrate. [Figure 3B] 2 is a schematic perspective view of the optical waveguide substrate before the laser element base and the optical waveguide substrate are bonded to each other. FIG. [Figure 4] 2 is a schematic cross-sectional view of the laser assembly shown in FIG. 1 taken along line BB'. [Figure 5A] FIG. 2 is a schematic diagram showing a step of bonding a laser element base and an optical waveguide substrate, showing the state before bonding. [Figure 5B] 1 is a schematic diagram showing a step of bonding a laser element base and an optical waveguide substrate, showing the state after bonding. FIG. [Figure 6] FIG. 5C is a schematic diagram showing a joint with different features than that shown in FIG. 5B. [Figure 7A] FIG. 2 is a schematic cross-sectional view showing an example of a laser assembly in which an anti-reflection film is provided on the bonding surface of an optical waveguide substrate. [Figure 7B] FIG. 2 is a schematic cross-sectional view showing an example of a laser assembly in which an anti-reflection film is provided on the bonding surface of an optical waveguide substrate. [Figure 8] FIG. 2 is a schematic plan view of the laser module according to the embodiment. [Figure 9] 9 is a diagram showing a cross section of a laser assembly in which a part of the laser module shown in FIG. 8 is cut in the XZ plane and placed inside. [Figure 10] FIG. 2 is a schematic plan view of a laser module with a cover removed, in which a laser assembly having an optical waveguide substrate with an optical waveguide layer made of a lithium niobate film is housed. [Figure 11] 11 is a schematic plan view of the laser assembly shown in FIG. 10 as viewed from the emission surface of visible laser light and near-infrared laser light. FIG. [Figure 12] FIG. 1 is a conceptual diagram for explaining XR glasses according to the present embodiment. [Figure 13]1 is a conceptual diagram showing a state in which an image is directly projected onto a retina by laser light emitted from a laser module according to an embodiment. FIG. [Figure 14A] 1 is a flowchart of a process for producing an optical waveguide substrate. [Figure 14B] 1 is a flowchart of a laser element base fabrication process. [Figure 14C] 1 is a flowchart of a bonding process. [Figure 15] FIG. 2 is a schematic plan view of a portion of an integrated optical device. [Figure 16A] 16 is a schematic perspective view of a laser element base on which three laser elements are mounted, the laser elements being provided in the integrated optical device shown in FIG. 15. [Figure 16B] 16 is a schematic perspective view of an optical waveguide substrate included in the integrated optical device shown in FIG. 15. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and may be appropriately modified and implemented within the scope of the effects of the present invention.

[0027] [Laser Assembly] Fig. 1 is a schematic plan view of a portion of the laser assembly of this embodiment. Fig. 2 is a schematic cross-sectional view taken along line AA' in the laser assembly shown in Fig. 1. Figs. 3A and 3B are schematic perspective views of the laser element base and the optical waveguide substrate before they are bonded together, with Fig. 3A being a schematic perspective view of the laser element base and Fig. 3B being a schematic perspective view of the optical waveguide substrate. Fig. 4 is a schematic cross-sectional view taken along line B-B' in the laser assembly shown in Fig. 1.

[0028] The laser assembly 100 shown in Fig. 1 includes a plurality of laser elements 30 (30-1, 30-2, 30-3), a plurality of bases 20 (20-1, 20-2, 20-3) for laser elements, which have main surfaces 21 (21-1, 21-2, 21-3) and bonding surfaces 22 (22-1, 22-2, 22-3), and each of the plurality of laser elements 30 (30-1, 30-2, 30-3) is installed on the main surface 21 (21-1, 21-2, 21-3); an optical waveguide substrate 40 for an optical waveguide, which has a main surface 41 and a bonding surface 42, and an optical waveguide layer 50 having an optical waveguide 51 for guiding the laser light emitted from the plurality of laser elements 30 (30-1, 30-2, 30-3) is provided on the main surface 41; a plurality of spacer films 72 (72-1, 72-2, 72-3) spaced apart from each other at positions corresponding to the respective bonding surfaces 22 (22-1, 22-2, 22-3) of the plurality of bases 20 (20-1, 20-2, 20-3) on the bonding surface 42 of the optical waveguide substrate 40; and a plurality of metal laminated films 70 (70-1, 70-2, 70-3) for bonding the bonding surface 22 (22-1, 22-2, 22-3) of the plurality of bases 20 (20-1, 20-2, 20-3) and the bonding surface 42 of the optical waveguide substrate 40. The plurality of metal laminated films 70 (70-1, 70-2, 70-3) are disposed on each of the plurality of spacer films 72 (72-1, 72-2, 72-3), and have a plurality of first metal films 73 (73-1, 73-2, 73-3) and a second metal film 74 (74-1, 74-2, 74-3) made of a metal eutectic with the metal constituting the first metal film 73 (73-1, 73-2, 73-3), and the plurality of first metal films 73 (73-1, 73-2, 73-3) are disposed on the bonding surfaces 22 (22-1, 22-2, 22-3) of the plurality of bases 20 (20-1, 20-2, 20-3).

[0029] <Laser Element and Base for Laser Element> Various laser elements can be used as the laser element 30. For example, commercially available laser diodes (hereinafter sometimes referred to as LDs) for red light, green light, blue light, near-infrared light, ultraviolet light, etc. can be used. For red light (R), light with a peak wavelength of 630 nm or more and 830 nm or less can be used, for green light (G), light with a peak wavelength of 500 nm or more and 550 nm or less can be used, and for blue light (B), light with a peak wavelength of 380 nm or more and 500 nm or less can be used. For near-infrared light, light with a peak wavelength of 830 nm or more and 2000 nm or less can be used. In the laser assembly 100 shown in Fig. 1, the laser elements 30-1, 30-2, and 30-3 will be described as LDs that emit red light, LDs that emit green light, and LDs that emit blue light, respectively, for the sake of convenience. The laser elements 30-1, 30-2, and 30-3 can be mounted on individual laser element bases 20-1, 20-2, and 20-3, for example, as bare chips (unpackaged chips). The number of laser elements shown in Fig. 1 is three, but this is just an example, and any number of multiple laser elements can be used. The laser element bases 20-1, 20-2, and 20-3 are made of, for example, aluminum nitride (AlN) or aluminum oxide (Al 2 O 3 ), silicon (Si), etc.

[0030] Metal films 75, 76 are provided between the laser element base 20 and the laser element 30 (see FIG. 2). The laser element base 20 and the laser element 30 are connected via the metal films 75, 76. As a method for forming the metal films 75, 76, any known method can be used, and there is no particular restriction on the method, but known methods such as sputtering, vapor deposition, and application of a metal paste can be used. The metal films 75 and 76 may include one or more metals selected from the group consisting of, for example, gold (Au), platinum (Pt), silver (Ag), lead (Pb), indium (In), nickel (Ni), titanium (Ti) and tantalum (Ta), tungsten (W), an alloy of gold (Au) and tin (Sn), a tin (Sn)-silver (Ag)-copper (Cu) solder alloy (SAC), SnCu, InBi, SnPdAg, SnBiIn, and PbBiIn, and may be made of one or more metals selected from this group.

[0031] <Optical Waveguide Layer and Optical Waveguide Substrate> The optical waveguide layer 50 has at least an optical waveguide that guides the laser light emitted from the laser element. There are no particular limitations on this optical waveguide layer, and for example, a known configuration can be adopted. Examples of the optical waveguide layer are shown below.

[0032] The optical waveguide layer 50 is a layer that performs the function of a PLC (Planar lightwave circuit). The optical waveguides 51-1, 51-2, and 51-3 correspond to cores in optical fibers. The optical waveguide layer 50 is formed on the optical waveguide substrate 40, and as described above, the laser element 30 is placed on the laser element base 20. The optical waveguide substrate 40 and the laser element base 20 are integrated by eutectic bonding. This eutectic bonding allows for accurate optical axis positioning and also realizes miniaturization.

[0033] The optical waveguide substrate 40 is made of, for example, silicon (Si). The optical waveguide layer 50 is formed on the main surface 41 by a semiconductor process including known photolithography and dry etching used when forming fine structures such as integrated circuits, so as to be integrated with the optical waveguide substrate 40. As shown in FIG. 1, the optical waveguide layer 50 is provided with the same number of optical waveguides (cores) 51-1, 51-2, 51-3 as the laser elements 30-1, 30-2, 30-3, and a clad 52 surrounding the optical waveguides 51-1, 51-2, 51-3. The thickness of the clad 52 and the widthwise dimensions of the optical waveguides 51-1, 51-2, 51-3 are not particularly limited. For example, optical waveguides 51-1, 51-2, 51-3 having widthwise dimensions of about several microns are disposed in a clad 52 having a thickness of about 50 μm.

[0034] The optical waveguides 51-1, 51-2, 51-3 and the clad 52 are made of, for example, a glass material (e.g., fused silica). In this case, the optical waveguide layer 50 may be referred to as a silica-based PLC. The refractive index of the optical waveguides 51-1, 51-2, 51-3 is higher than that of the clad 52 by a predetermined value. Thus, the light incident on each of the optical waveguides 51-1, 51-2, 51-3 propagates through each optical waveguide while undergoing total reflection at the interface between each optical waveguide and the clad 52. The optical waveguides 51-1, 51-2, 51-3 are doped with an amount of impurities such as germanium (Ge) according to the aforementioned predetermined value.

[0035] As shown in FIG. 1, the optical waveguides 51-1, 51-2, 51-3 are gathered together into one before reaching the exit surface 64 of the optical waveguide layer 50. That is, the optical waveguides 51-1, 51-2, 51-3 merge successively as they go forward in the x direction and merge into one optical waveguide 51-4. In order to prevent leakage light from occurring from the optical waveguides 51-1, 51-2, 51-3, it is preferable that each of the optical waveguides 51-1, 51-2, 51-3 is connected to the optical waveguide 51-4 with a radius of curvature equal to or greater than a predetermined radius of curvature.

[0036] By eutectic bonding between the optical waveguide substrate 40 and the laser element base 20, each optical waveguide and the corresponding laser element are arranged opposite each other with the optical axis aligned precisely so that the center of the entrance of each optical waveguide 51-1, 51-2, 51-3 of the optical waveguide layer 50 approximately coincides with the optical axis of the output light from each corresponding laser element 30-1, 30-2, 30-3.

[0037] As shown in FIG. 2, the incident surface 50A of the optical waveguide layer 50 is disposed so as to face the exit surface 30A (30-1A) of the laser element 30. In detail, the exit 31-1 of the laser element 30-1 faces the entrance 51-1A of the waveguide 51-1. In the x direction and the z direction, the optical axis of the red light emitted from the laser element 30-1 and the center of the entrance 51-1A are approximately overlapped. Similarly, the exit of the laser element 30-2 faces the entrance of the waveguide 51-2. In the x direction and the z direction, the optical axis of the green light emitted from the laser element 30-2 and the center of the entrance are approximately overlapped. The exit of the laser element 30-3 faces the entrance of the waveguide 51-3. In the x direction and the z direction, the optical axis of the blue light emitted from the laser element 30-3 and the center of the entrance are approximately overlapped.

[0038] As shown in Fig. 1, red light, green light, and blue light emitted from laser elements 30-1, 30-2, and 30-3 are incident on optical waveguides 51-1, 51-2, and 51-3, respectively, and then propagate through each optical waveguide. The red light and green light propagating through optical waveguides 51-3 and 51-2 are combined at a junction position 57-1. The combined red light and green light and the blue light propagating through 51-3 are combined at a junction position 57-2. The RGB light combined at the junction position 57-2 propagates through optical waveguide 51-4, reaches exit surface 64, and is emitted from exit surface 64.

[0039] <Joint between laser element base and optical waveguide substrate> The individual laser element bases 20-1, 20-2, 20-3 and the optical waveguide substrate 40 are bonded together via a plurality of metal laminated films 70 (70-1, 70-2, 70-3).

[0040] The multiple metal stack films 70 (70-1, 70-2, 70-3) are composed of multiple first metal films 73 (73-1, 73-2, 73-3) and multiple second metal films 74 (74-1, 74-2, 74-3). The metal stack films 70 are electrically and spatially separated from each other on adjacent laser element bases. Before bonding, the multiple first metal films 73 (73-1, 73-2, 73-3) are arranged on multiple spacer films 72 (72-1, 72-2, 72-3) spaced apart from each other and placed on the bonding surface 42 of the optical waveguide substrate 40, as shown in Figure 3B, and the multiple second metal films 74 (74-1, 74-2, 74-3) are arranged on each of the bonding surfaces 22-1, 22-2, 22-3 of the multiple laser element bases 20 (20-1, 20-2, 20-3) as shown in Figure 3A.

[0041] The portion where the laser element base and the optical waveguide substrate are joined is referred to as the joint. The joint is made of a metal laminate film 70 and a spacer film 72, and the joining is achieved by eutectic bonding between a first metal film 73 and a second metal film 74. A preferred eutectic bond is an Au-Sn bond. The materials of the first metal film 73 and the second metal film 74 are preferably a combination that forms an Au-Sn bond when bonded.

[0042] In the eutectic bond formed between the first metal film 73 and the second metal film 74, the degree of eutectic (alloying) can vary depending on the conditions, and there may be a structure in which there are relatively many portions of one or both of the first metal film 73 and the second metal film 74 that are not eutectic, or a structure in which the entire first metal film 73 and the entire second metal film 74 are alloyed to form a eutectic layer.

[0043] The metal laminate film 70 is not a continuously formed film but is a separate film arranged at a distance. Because it is a separate film, the occurrence of capacitive coupling is suppressed, and crosstalk is suppressed.

[0044] 5A and 5B are schematic diagrams showing a step of bonding a laser element base and an optical waveguide substrate, with FIG. 5A showing the state before bonding and FIG. 5B showing the state after bonding. In bonding the laser element base 20 and the optical waveguide substrate 40, as shown in FIG. 5A, the metal film M1, the spacer film Sp, and the metal film M2, which constitute the bonding portion, are formed in advance. That is, the spacer film Sp is formed on the bonding surface 42 of the optical waveguide substrate 40, and then the metal film M1 is formed on the spacer film Sp. Meanwhile, the metal film M2 is formed on the bonding surfaces 22 (22-1, 22-2, 22-3) of the laser element bases 20-1, 20-2, 20-3. Note that the metal film M1, the spacer film Sp, and the metal film M2 become the first metal film 73, the spacer film 72, and the second metal film 74 after bonding, but since their forms may change before and after bonding through melting and bonding (although the spacer film usually remains almost the same), they are given different reference numerals.

[0045] Next, the joint is heated by a known method such as laser irradiation to melt the metal film M1, and the laser element base and / or the optical waveguide substrate are pressed in to bond them by eutectic bonding. The metal films M1 and M2 are a combination of metals that can form a eutectic bond. The joint after bonding is composed of a spacer film 72, a first metal film 73, and a second metal film 74. The joint is formed by the metal films that were once melted and then bonded and solidified, so it is difficult to accurately show its shape in a diagram, but we will use diagrams as much as possible to explain it so that its features can be grasped. FIG. 5B illustrates an example of a characteristic joint. After the metal film M1 arranged on the spacer film Sp is melted, the laser element base 20 pushes (presses) it, so that a part of it spreads onto the bonding surface 42 around the spacer film Sp to form the first metal film 73. In the example shown in FIG. 5B, the second metal film 74 is formed with an area larger than the area of ​​the first metal film 73 that has spread. That is, when viewed from the direction (y direction) connecting the bonding surface 42 and the bonding surface 22, the second metal film 74 is formed with an area larger than the area of ​​the first metal film 73 so as to cover the first metal film 73. Other examples of characteristic forms will be described later with reference to FIG. 6.

[0046] In the laser assembly 100 of this embodiment, since the bonding surface 42 of the optical waveguide substrate 40 has the spacer film 72, the gap S (see FIG. 2) between the laser element base 20 and the optical waveguide substrate 40 can be maintained at a predetermined size even if the substrate is pressed in during the bonding process. In cases such as when the metal film M1 is completely melted during the bonding process, the gap S becomes very small. In this case, the melted metal film M1 is pushed out from the space between the laser element base 20 and the optical waveguide substrate 40. In contrast, in the laser assembly 100 of this embodiment, since the spacer film 72 is provided, the gap S is maintained at a thickness of the spacer film 72 or more, and as a result, the melted metal film M1 is prevented from being pushed out from the space between the laser element base 20 and the optical waveguide substrate 40. A seed layer may be formed when the metal films M1 and M2 are formed on the respective bonding surfaces. Since this seed layer is very thin compared to the thickness of the metal films M1 and M2, when the optical waveguide substrate 40 and the laser element base 20 are heated and pressed in, the gap between the optical waveguide substrate 40 and the laser element base 20 cannot be maintained, and the molten metal film M1 is pushed out from between them.

[0047] The gap S between the laser element base 20 and the optical waveguide substrate 40 depends on the thickness of the spacer film and the amount of the metal films M1 and M2, but a specific example of the size is about 0.2 to 1.2 μm. The gap volume between the laser element base 20 and the optical waveguide substrate 40 can be determined based on the volume of the dissolved metal.

[0048] The thickness of the spacer film 72 can be determined according to the volume of the metal films M1, M2 required to prevent the metal film M1 from overflowing from the space between the laser element base 20 and the optical waveguide substrate 40 when it melts, and to achieve the desired strength of the eutectic bond between the laser element base 20 and the optical waveguide substrate 40.

[0049] The spacer film 72 may be made of alumina (Al 2 O 3Examples of the oxide include oxides such as titanium oxide (TiOx), tantalum oxide (TaOx), and silicon oxide (SiOx), and metals such as Ti and Ta.

[0050] Rare metals such as Ti and Ta are used as materials for so-called seed films. Therefore, when the spacer film 72 is made of a rare metal such as Ti or Ta, the material is the same as that of the seed film, but the seed film is usually used with a thickness of about several tens of nm, whereas the spacer film 72 is preferably 0.1 μm or more in thickness, more preferably 0.2 μm or more, in order to sufficiently secure the interval S. By securing the interval S that can form a space (gap) to a degree that can maintain the condition that the volume of the space (gap) between the laser element base 20 and the optical waveguide substrate 40 is larger than the volume of the metal film M1 that melts during bonding, the metal films M1 and M2 can be retained in this space (gap). In this case, from the viewpoint of material costs, the upper limit of the spacer film 72 is about 0.4 μm.

[0051] On the other hand, when the spacer film 72 is made of an oxide such as alumina, the thickness of the spacer film 72 is preferably 0.1 μm or more, and more preferably 0.2 μm or more, as in the case of a rare metal, for the purpose of providing the spacer film 72. On the other hand, the upper limit can be relaxed from the viewpoint of material cost, but deformation due to internal stress caused by excessive thickness is a concern, so the upper limit of the thickness of the spacer film 72 is preferably set to, for example, 1 μm. It is preferable to select a material with small internal stress.

[0052] At least a portion of the first metal film 73 is disposed on the spacer film 72. The first metal films 73-1, 73-2, and 73-3 are disposed spaced apart from each other. By using the same photomask used in forming the spacer films 72 (72-1, 72-2, 72-3) in forming the first metal films 73 (73-1, 73-2, 73-3), the first metal films 73-1, 73-2, 73-3 having the same size as the spacer films can be laminated on the spacer films 72-1, 72-2, 72-3. Also, by using a photomask having a smaller hole size than the photomask used in forming the spacer films 72 (72-1, 72-2, 72-3) in forming the first metal films 73 (73-1, 73-2, 73-3), the first metal films 73 having a smaller size than the spacer films 72 can be laminated.

[0053] When the laser element base and the optical waveguide substrate are joined, the first metal film 73 is melted. Depending on the difference in size between the first metal film 73 and the spacer film 72, part of the first metal film 73 will be positioned not only on the spacer film 72, but also on the joining surface 42 around the spacer film 72 (see Figures 5B and 6).

[0054] The first metal film 73 is preferably made of Sn or an alloy containing Sn, such as Sn-Ag-Cu (SAC).

[0055] The first metal film 73 formed in advance on the spacer film 72 before bonding to the laser element base can have a thickness of, for example, about 0.2 to 0.6 μm.

[0056] When forming the first metal film 73 on the spacer film 72, a seed film of a metal film selected from the group consisting of Ta, Ti, Ni, Ta / Pt, Ti / Pt, and Ni / Pt may be used. Here, the metal films of Ta / Pt, Ti / Pt, and Ni / Pt are two-layered films of a Ta film, a Ti film, or a Ni film, and a Pt film, and the Pt film is disposed on the side of the two-layered film that directly contacts the first metal film 73. By inserting the Pt film, it is expected that the bonding strength between the first metal film 73 and the seed film will be increased. For example, from the viewpoint of preventing the metal of the first metal film 73 from flowing out of the gap during bonding, it is preferable to form the first metal film 73 with a small area, but if the first metal film 73 becomes smaller, the bonding strength with the seed film will be weakened. It is expected that the decrease in bonding strength will be suppressed by inserting the Pt film.

[0057] Since Sn films and alloy films containing Sn do not form eutectic alloys with Ta films, Ti films, or Ni films, the interfaces between Sn films and alloy films containing Sn and Ta films, Ti films, or Ni films can be identified in electron microscope images, but peeling off occurs at these interfaces. On the other hand, since Sn films and alloy films containing Sn form eutectic alloys with Pt films, the interfaces between Sn films and alloy films containing Sn and Pt films are not clear, and may not be identified in electron microscope images.

[0058] The second metal film 74 is preferably made of a metal capable of forming a eutectic alloy with Sn, for example, a metal selected from the group consisting of Au, Si, Al, Ni, Zn, Pt, and alloys thereof. The second metal film 74 is most preferably an Au film that forms a strong eutectic alloy with Sn.

[0059] The second metal film 74 that is formed in advance on the bonding surface 22 of the laser element base 20 before bonding to the optical waveguide substrate 40 can have a thickness of, for example, about 0.2 to 1.0 μm.

[0060] The second metal film 74 is formed to have an area larger than that of the spacer film 72, and is formed so as to cover the spacer film 72 when viewed in a direction perpendicular to the films. The second metal film 74 is preferably formed to have a larger area than the first metal film 73, and is preferably formed so as to cover the first metal film 73 when viewed in a direction perpendicular to the films. Before bonding the laser element base and the optical waveguide substrate, each film is formed, and at that time, the second metal film 74 is formed with an area larger than the spacer film 72 and also with an area larger than the first metal film 73.

[0061] When forming the second metal film 74 on the bonding surface 22 of the laser element base 20, a seed film of a metal film selected from the group consisting of Ta, Ti, Ta / Pt, and Ti / Pt may be used. Here, the Ta / Pt and Ti / Pt metal films are two-layered films of a Ta film or a Ti film and a Pt film, and the Pt film is disposed on the side of the two-layered film that comes into direct contact with the second metal film 74. By inserting the Pt film, it is expected that the bonding strength between the second metal film 74 and the seed film will be increased.

[0062] FIG. 6 shows an example of a film structure of a metal laminate film 70 and a spacer film 72 that constitute a joint, the film structure having different characteristics from those shown in FIG. 5B. In the example shown in Figure 6, after the metal film M1 placed on the spacer film Sp is melted, the laser element base 20 is pressed in, and a part of it spreads onto the bonding surface 42 around the spacer film Sp to form the first metal film 73, which is similar to Figure 5B. However, the difference is that the second metal film 74 is formed with an area approximately the same as the area of ​​the first metal film 73.

[0063] 7A and 7B show a configuration in which an antireflection film 81 is provided on the bonding surface 42 of the optical waveguide substrate 40. Figures 7A and 7B correspond to Figures 5B and 6, respectively. In this configuration, the spacer film 72 is formed on the antireflection film 81.

[0064] The anti-reflection film 81 is a film for preventing the incident light or outgoing light to the optical waveguide layer 50 from being reflected in a direction opposite to the direction in which the light enters the optical waveguide layer 50 from the incident surface 50A or the outgoing surface 64, and for increasing the transmittance of the incident light or outgoing light. The anti-reflection film 81 is a multi-layer film formed by alternately laminating, for example, a plurality of types of dielectrics with predetermined thicknesses according to the wavelengths of the incident light, that is, red light, green light, and blue light. Examples of the dielectrics include titanium oxide (TiO2), tantalum oxide (Ta 2 O 5 ), silicon oxide (SiO 2 ), aluminum oxide (Al 2 O 3 ) etc.

[0065] The emission surface 30A of the laser element 30 and the incidence surface 50A of the optical waveguide layer 50 are disposed at a predetermined distance. The incidence surface 50A faces the emission surface 30A, and there is a gap between the emission surface 30A and the incidence surface 50A in the x direction. Considering that the laser assembly 100 is used in an XR glass and the amount of light required in the XR glass, the size of the gap in the y direction is, for example, greater than 0 μm and equal to or less than 5 μm.

[0066] [Laser module] Fig. 8 is a schematic plan view of the laser module of this embodiment, and Fig. 9 is a cross-sectional view of a laser assembly disposed inside the laser module shown in Fig. 8 after cutting a part of the laser module in the XZ plane. In the laser module 1000 shown in FIG. 8, the laser assembly 100 according to the above embodiment is installed on an upper surface 180a of a base 180 within a package 110 and housed therein.

[0067] The laser assembly 100 housed in the package 110 is preferably bonded such that the bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40 are positioned on approximately the same plane. In the laser assembly 100, the laser element base 20 and the optical waveguide substrate 40 are bonded by metal eutectic bonding, so that the occurrence of positional deviation due to the heating process is significantly suppressed compared to a configuration in which they are bonded by adhesive. Note that the term "approximately flush" here allows for a slight misalignment between the bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40. Specifically, a misalignment of 20 μm or less is allowed with respect to the thickness of the optical waveguide substrate 40 along the z direction, but the smaller the misalignment, the better, and it is more preferable for it to be 10 μm or less, and even more preferable for it to be 5 μm or less.

[0068] When the bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40 are joined so as to be positioned on approximately the same plane, heat generated by the operation of the laser element 30 can be efficiently dissipated from both the bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40. Furthermore, when the bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40 are joined so as to be positioned on approximately the same plane, both the bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40 can be joined to a single plane on the upper surface 180a of the base 180, thereby maintaining high joining strength and realizing a laser assembly 100 with excellent impact resistance. In this manner, in a configuration in which the bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40 are joined so as to be positioned on approximately the same plane, heat dissipation and impact resistance can be improved.

[0069] In addition to the laser assembly according to the above embodiment, other known components may be provided inside the package 110. For example, a photodetector (PD) may be housed inside the package 110. By equipping a PD, it is possible to check fluctuations in the optical output of the laser element by observing the current flowing through the PD. It is also possible to control the drive current of the laser element so that the output remains constant by monitoring the current flowing through the PD.

[0070] The package 110 includes a body 102 having a cavity structure and a cover 105 that covers the body 102 . The main body 102 has a bottom portion on which the members to be contained therein are placed, and a sidewall portion 102a disposed so as to surround those members from the sides. A light transmitting window 101 through which the laser light L emitted from the laser element 30 can optically pass is formed in the side wall portion 102a arranged in the direction in which the laser light is emitted.

[0071] A light-transmitting window (opening) 101 is formed in the side wall 102a of the storage section 107 near the emission section of the laser light L emitted from the laser module 1000. The opening 101 is formed with its center at a position where it intersects with the optical axis of the laser light emitted from the side wall 102a. The opening 101 is covered with a glass plate 220 from the outside of the side wall 102a without any gaps. That is, the storage section 107 is hermetically sealed by the glass plate 220 in addition to the cover 105. Although the glass plate 220 is used for hermetically sealing, it is not limited to a glass plate as long as it is a material through which the laser light can pass. An anti-reflection film (not shown) may be provided on both plate surfaces of the glass plate 220.

[0072] The electrode unit 108 is disposed on the front side of the housing portion 107 in the x direction, i.e., rear side in the x direction. The upper surface of the electrode unit 108 is located lower than the upper surface of the housing portion 107. The bottom surface of the electrode unit 108 is located at approximately the same height as the bottom surface of the housing portion 107. A plurality of external electrode pads 210 are provided on the upper surface of the electrode unit 108 at intervals in the y direction.

[0073] The bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40 may be joined to the upper surface 180a (one inner surface) of the base 180 via an adhesive layer 182. The adhesive layer 182 is made of a material in which a filler is mixed with a resin in order to improve thermal conductivity. An example of the resin that constitutes the adhesive layer 182 is epoxy resin. Furthermore, copper powder, aluminum powder, alumina powder, or the like can be used as a filler that improves the thermal conductivity of the resin. In order to maintain a certain level of thermal conductivity, the adhesive layer 182 preferably has a thermal conductivity of 0.5 W / m·K or more, more preferably a thermal conductivity of 1 W / m·K or more, and even more preferably a thermal conductivity of 4 W / m·K or more.

[0074] In this way, by bonding both the laser element base 20 and the optical waveguide substrate 40 of the laser assembly to the upper surface 180a of the base 180 in the package 110, heat generated by the operation of the laser element 30 can be efficiently dissipated from both the bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40 toward the base 180. Furthermore, by bonding both the bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40 using an adhesive layer made of a resin mixed with a filler, heat can be efficiently propagated toward the base 180 from both the bottom surface 20b of the laser element base 20 and the bottom surface 43 of the optical waveguide substrate 40.

[0075] Next, the optical waveguide layer of the laser assembly is a lithium niobate film (LiNbO 3 In contrast to the silica-based PLC described above, the optical waveguide layer in this case is sometimes called an LN-based PLC.

[0076] Fig. 10 is a schematic plan view of a laser module with a cover removed, which houses a laser assembly having an optical waveguide substrate with an optical waveguide layer made of a lithium niobate film. Fig. 11 is a schematic plan view of the laser assembly shown in Fig. 10, viewed from the emission surface of the laser element. The same reference numerals may be used to designate components common to the above-mentioned laser assembly and laser module, and the description thereof may be omitted. FIG. 10 shows an example in which the laser assembly has a near-infrared laser element as a laser element in addition to the RGB laser element. Since the near-infrared laser is invisible, it can be used for eye tracking. The above-mentioned laser assembly may also be configured to include a near-infrared laser element.

[0077] In the laser module 2000 shown in FIG. 10, a laser assembly 100B is housed in a package 110, the laser assembly 100B including: laser elements 30 (30-1, 30-2, 30-3) and laser element bases 20 (20-1, 20-2, 20-3) on which the laser elements 30 (30-1, 30-2, 30-3) are respectively mounted; a near-infrared laser element 35 and a laser element base 20-4 on which the near-infrared laser element 35 is mounted; an optical waveguide substrate 140 having an LN-based PLC 150 formed on its main surface; and a joint between the laser element base 20 and the laser element base 20-4 and the optical waveguide substrate 140, the joint being made of a spacer film and a eutectic-bonded metal laminate film.

[0078] The near-infrared laser element 35 is mounted on a laser element base 20-4 in the same manner as the laser element 30, and the LN-based PLC 150 is formed on the optical waveguide substrate 140.

[0079] The laser module 2000 includes, within a package 110, an LN-based PLC 150 including an optical waveguide 151 (151-1, 151-2, 151-3) that guides the laser light emitted from the laser element 30, and an optical waveguide 152 that guides the near-infrared laser light emitted from the near-infrared laser element 35. In the laser module 2000, the optical waveguide substrate 140 on which the LN-based PLC 150 is formed, the laser element base 20 on which the laser element 30 is mounted, and the laser element base 20-4 on which the near-infrared laser element 35 is mounted are also integrated by eutectic bonding. This eutectic bonding enables accurate optical axis positioning and also realizes compactness.

[0080] Examples of the optical waveguide substrate 140 include a sapphire substrate, a Si substrate, and a thermally oxidized silicon substrate. The optical waveguide 151 and the optical waveguide 152 are made of lithium niobate (LiNbO 3When the substrate is made of a lithium niobate film, there is no particular limitation as long as the refractive index is lower than that of the lithium niobate film, but a sapphire single crystal substrate or a silicon single crystal substrate is preferred as a substrate on which the single crystal lithium niobate film can be formed as an epitaxial film. The crystal orientation of the single crystal substrate is not particularly limited, but since, for example, a c-axis oriented lithium niobate film has three-fold symmetry, it is desirable that the underlying single crystal substrate also has the same symmetry, and in the case of a sapphire single crystal substrate, a c-plane substrate is preferred, and in the case of a silicon single crystal substrate, a (111) plane substrate is preferred.

[0081] In the laser module 2000, the optical waveguide layer (LN-based PLC) 150 has an optical waveguide film 150A having an optical waveguide 151 and an optical waveguide 152, and a waveguide clad film 150B formed on the optical waveguide film 150A so as to cover the optical waveguide 151 and the optical waveguide 152. The waveguide clad film 150B has a lower refractive index than the optical waveguide film 150A. The waveguide clad film 150B is made of, for example, SiInO, SiO 2 , Al 2 O 3 , MgF 2 , La 2 O 3 , ZnO, HfO 2 , MgO, Y 2 O 3 , CaF 2 , In 2 O 3 etc. or mixtures thereof.

[0082] The lithium niobate film (optical waveguide film 150A) is, for example, a c-axis oriented lithium niobate film. The lithium niobate film is, for example, an epitaxial film epitaxially grown on the optical waveguide substrate 140. The epitaxial film is a single crystal film whose crystal orientation is aligned by the underlying substrate. The epitaxial film is a film having a single crystal orientation in the z direction and the xy in-plane direction, and the crystals are aligned in the x-axis, y-axis, and z-axis directions. Whether the film formed on the optical waveguide substrate 140 is an epitaxial film can be proved by, for example, checking the peak intensity and pole at the orientation position in 2θ-θ X-ray diffraction.

[0083] The composition of lithium niobate is Li x NbA y O z A is an element other than Li, Nb, and O. x is 0.5 or more and 1.2 or less, and preferably 0.9 or more and 1.05 or less. y is 0 or more and 0.5 or less. z is 1.5 or more and 4.0 or less, and preferably 2.5 or more and 3.5 or less. The element A is, for example, K, Na, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ti, Zr, Hf, V, Cr, Mo, W, Fe, Co, Ni, Zn, Sc, or Ce, and two or more of these elements may be combined.

[0084] The thickness of the lithium niobate film is, for example, 2 μm or less. The thickness of the lithium niobate film refers to the thickness of the portion other than the ridge portion. If the lithium niobate film is too thick, there is a risk of the crystallinity being reduced. The thickness of the lithium niobate film is, for example, at least about 1 / 10 of the wavelength of the light used. If the lithium niobate film is too thin, the light is less confined, and the light leaks into the optical waveguide substrate 140 and the waveguide clad film 150B.

[0085] The optical waveguide 151 and the optical waveguide 152 are optical paths through which light propagates. The optical waveguide 151 and the optical waveguide 152 are ridges protruding from a first surface 150AA of a slab layer 150Aa of the optical waveguide film 150A. Hereinafter, the optical waveguide 151-1, the optical waveguide 151-2, the optical waveguide 151-3, and the optical waveguide 152 may be referred to as a ridge 151-1, a ridge 151-2, a ridge 151-3, and a ridge 152, respectively. The first surface 150AA is the upper surface of the portion (slab layer 150Aa) other than the ridge portion of the optical waveguide film 150A. The optical waveguide film 150A is composed of ridges 151-1, 151-2, 151-3, and 152, and a slab layer 150Aa.

[0086] 11 is rectangular in cross section, any shape capable of guiding light may be used, for example, a trapezoid, a triangle, a semicircle, etc. The width Wa in the y direction is preferably 0.3 μm or more and 5.0 μm or less, and the height of the ridge (protruding height Ha from first surface 150AA) is preferably, for example, 0.1 μm or more and 1.0 μm or less.

[0087] 10, the optical waveguides 151-1, 151-2, and 151-3 are gathered together before reaching the emission surface of the optical waveguide layer 150. That is, the optical waveguides 151-1, 151-2, and 151-3 are successively merged toward the front in the x-direction to merge into one optical waveguide 151-4. In order to prevent leakage of light from the optical waveguides 151-1, 151-2, and 151-3, it is preferable that the optical waveguides 151-1, 151-2, and 151-3 are each connected to the optical waveguide 151-4 with a curvature radius equal to or greater than a predetermined curvature radius.

[0088] As shown in Fig. 10, the red light, green light, and blue light emitted from the laser elements 30-1, 30-2, and 30-3 are incident on the ridges 151-1, 151-2, and 151-3, respectively, and then propagate through each ridge. The red light and green light propagating through the ridges 151-3 and 151-2 are combined at a predetermined junction position 157-1 located behind the junction position 157-2 in the x direction. The combined red light and green light and the blue light propagating through 151-2 are combined at the junction position 57-2. The RGB light combined at the junction position 57-2 propagates through the ridge 151-4, reaches the exit surface, and is emitted from the exit surface. Further, the near-infrared light emitted from the laser element 35 propagates through the ridge 152, reaches the emission surface, and is emitted from the emission surface.

[0089] Each of the optical waveguides 151-1, 151-2, 151-3, and 152 included in the LN-based optical waveguide layer 150 may be a Mach-Zehnder type optical waveguide. In this case, the optical waveguide has a known Mach-Zehnder type optical modulation section such as an electrode (not shown) for applying an electric field to the optical waveguide.

[0090] [XR Glasses] The XR glasses according to this embodiment are equipped with the laser module according to the above embodiment. XR glasses are glasses-type devices, and XR is a general term for virtual reality (VR), augmented reality (AR), and mixed reality.

[0091] FIG. 12 is a conceptual diagram for explaining the XR glasses according to this embodiment. 12, the XR glasses 10000 have a laser module 1001 mounted on a frame 10010. The symbol L denotes an image display light.

[0092] 12, the laser module 1001, the optical scanning mirror 3001, and the optical system 2001 connecting the laser module 1001 and the optical scanning mirror 3001 are collectively referred to in this specification as an optical engine 5001. As the laser module 1001, any of the laser modules according to the above embodiments is used.

[0093] As the light source in the laser module 1001, for example, one having RGB laser elements of a red laser element 30-1, a green laser element 30-2, and a blue laser element 30-3, and a near-infrared laser element 35 can be used.

[0094] As the light source in the laser module 1001, for example, one having RGB laser elements of a red laser element 30-1, a green laser element 30-2, and a blue laser element 30-3, and a near-infrared laser element 35 can be used. As shown in Figure 13, laser light emitted from a laser module 1001 attached to a glasses frame is reflected by an optical scanning mirror 3001, and the reflected light is reflected by a mirror 4001 that reflects it toward the person's eyeball E, enters the person's eyeball E, and an image (video) can be projected directly onto the retina M. By providing an eye-tracking mechanism, an image is projected directly onto the retina while performing eye tracking. A known eye-tracking mechanism can be used.

[0095] The optical scanning mirror 3001 is, for example, a MEMS mirror. In order to project a 2D image, it is preferable that the optical scanning mirror 3001 is a two-axis MEMS mirror that vibrates so as to reflect the laser light by changing the angle in the horizontal direction (X direction) and the vertical direction (Y direction).

[0096] A collimator lens 2001a, a slit 2001b, and an ND filter 2001c are included as an optical system 2001 that optically processes the laser light emitted from the laser module 1001. This optical system is just one example, and other configurations may be used.

[0097] The optical engine 5001 includes a laser driver 1100, an optical scanning mirror driver 1200, and a video controller 1300 that controls these drivers.

[0098] [Method of Manufacturing Laser Assembly] 14A to 14C show a flowchart of an example of a method for manufacturing a laser assembly. The method for manufacturing a laser assembly includes a step of preparing an optical waveguide substrate, a step of preparing a laser element base, and a step of bonding the optical waveguide substrate and the laser element base obtained from the respective steps.

[0099] As shown in Fig. 14A, in the process of preparing a substrate for optical waveguide, first, a plurality of optical waveguide layers are formed on a wafer. These optical waveguide layers are optical waveguide layers (optical waveguide layer 50 in Fig. 1) for all laser assemblies to be obtained from the wafer. Next, the wafer is cut to cut out a plurality of bar members for optical waveguide substrates having optical waveguide layers on their main surfaces. Each of the cut out bar members for optical waveguide substrates can include optical waveguide layers the number of which is calculated by dividing the total number of laser assemblies to be obtained from the wafer by the number of bar members for optical waveguide substrates. Next, a laminated film of a spacer film and a first metal film is formed on the bonding surface of each bar member for optical waveguide substrate by using a photolithography technique. Specifically, a plurality of bar members for optical waveguide substrate are arranged, and a spacer film and a first metal film are sequentially formed on the bonding surface of the bar members simultaneously using a photoresist mask having a plurality of holes corresponding to the pattern of a plurality of spacer films disposed at a distance from each other, to form a laminated film of a spacer film and a first metal film for each hole.

[0100] As shown in FIG. 14B, in the laser element base fabrication step, first, the wafer is cut to cut out a plurality of laser element base bar members. Next, a plurality of laser element base bar members are lined up, and a second metal film is formed simultaneously on each bonding surface. At this time, the second metal film may be formed on the entire bonding surface of each laser element base bar member, or the second metal film may be formed in an area narrower than the bonding surface. Since the laser element base bar members are later cut into laser element bases for each laser element, the second metal film may be a continuous film for each laser element base bar member. Next, a plurality of laser elements are mounted on the main surface of each of the laser element base bar members. Next, each laser element base bar member is cut into laser element bases for each laser element.

[0101] As shown in FIG. 14C, the laser element bases prepared in the laser element base preparation step are individually bonded to the bonding surfaces of the optical waveguide substrate bar members prepared in the optical waveguide substrate preparation step. For the bonding, active alignment bonding can be used. Specifically, a current is supplied to an electrode provided on the laser element base, and the laser is oscillated while electrically connected to the laser element. In this state, the bar member for the optical waveguide substrate is brought close to the input port of the optical waveguide while adjusting its position. Then, the light intensity is observed with a light sensor at the output port, and the position where the intensity is maximum is found, and the laser element base and the bar member for the optical waveguide substrate are eutectic bonded at that position. Eutectic bonding can be performed, for example, by irradiating a YAG laser and melting a metal film formed on the bonding surface.

[0102] Next, after all the laser element bases have been joined for each laser element base, the bar members for the optical waveguide substrate are cut for each laser assembly. This completes the laser assembly. [Explanation of symbols]

[0103] 20 Laser element base 30 Laser elements 40, 140 Optical waveguide substrate 50, 150 optical waveguide layer 100, 100B Laser Assembly 110 Packages 1000, 1001, 2000 Laser Module 5001 Optical Engine 10000 XR Glasses

Claims

1. A plurality of laser elements; a plurality of laser element bases each having a main surface and a bonding surface, and each of the plurality of laser elements is disposed on the main surface; an optical waveguide substrate having a main surface and a bonding surface, the main surface being provided with an optical waveguide layer having an optical waveguide for guiding laser light emitted from the plurality of laser elements; a plurality of spacer films disposed at positions on the bonding surface of the optical waveguide substrate corresponding to the plurality of laser element bases, the spacer films being spaced apart from one another; a plurality of metal laminated films for bonding the bonding surfaces of the plurality of laser element bases and the bonding surface of the optical waveguide substrate; The plurality of metal laminate films are arranged on each of the plurality of spacer films, and have a plurality of first metal films, and a second metal film is arranged on the bonding surfaces of the plurality of laser element bases and is made of a metal that can form a eutectic with the metal constituting the first metal film.

2. 2. The laser assembly of claim 1, wherein the first metal film is made of Sn or an alloy containing Sn, and the second metal film is made of a metal selected from the group consisting of Au, Si, Al, Ni, Zn, Pt, and alloys thereof.

3. 10. The laser assembly of claim 1, wherein the spacer film has a thickness of 0.1 μm or more.

4. 2. The laser assembly of claim 1, wherein the spacer film is made of a metal selected from the group consisting of Ta, Ti, Ni, Ta / Pt, Ti / Pt, and Ni / Pt.

5. The laser assembly of claim 1 , wherein the spacer film is made of an oxide.

6. The laser assembly according to claim 1 , wherein the second metal film is formed to have a larger area than the first metal film.

7. 2. The laser assembly according to claim 1, further comprising an anti-reflection film on a bonding surface of the optical waveguide substrate, the spacer film being formed on the anti-reflection film.

8. 8. The laser assembly according to claim 1, wherein the optical waveguide layer is a PLC (Planar Lightwave Circuit) made of a glass material.

9. 8. The laser assembly according to claim 1, wherein the optical waveguide layer is a PLC made of a lithium niobate film.

10. A laser module comprising the laser assembly according to claim 8 housed in a package.

11. A laser module comprising the laser assembly of claim 9 housed in a package.

12. A laser module according to claim 10; an optical scanning mirror that scans the light emitted from the laser module.

13. A laser module according to claim 11; an optical scanning mirror that scans the light emitted from the laser module.

14. XR glasses comprising an optical engine according to claim 12.

15. XR glasses comprising an optical engine according to claim 13.

16. an optical waveguide substrate fabrication step of sequentially forming a plurality of spacer films and a first metal film on a bonding surface of the optical waveguide substrate; a laser element base fabrication step of forming a second metal film on a bonding surface of the laser element base; A method for manufacturing a laser assembly, comprising, after the optical waveguide substrate fabrication step and the laser element base fabrication step, a bonding step of eutectic bonding the laser element base and the optical waveguide substrate.

17. The optical waveguide substrate manufacturing step includes: the spacer film and the first metal film are formed using a photoresist mask having a plurality of holes corresponding to a pattern of a plurality of the spacer films disposed at a distance from each other on the bonding surface of the optical waveguide substrate; 17. The method for manufacturing a laser assembly according to claim 16, wherein the bonding step comprises eutectic bonding of the first metal film of the optical waveguide substrate and the second metal film of the laser element base using active alignment bonding.

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