Optical element assembly, method for manufacturing an optical element assembly, optical module, optical engine, and XR glasses

Abstract

The laser diode assembly is mounted with high precision to prevent thermal effects on other laser diode assemblies, and the optical element assembly offers a high degree of freedom in mounting position to match the shape of the laser diode assembly. [Solution] Multiple laser diode assemblies, The optical waveguide substrate comprises an optical waveguide layer having an optical waveguide for guiding laser light emitted from multiple laser diode assemblies, and An optical element assembly comprising a base and a laser diode formed on the base, wherein at least one of a plurality of laser diode assemblies is spaced apart from adjacent laser diode assemblies to satisfy a mounting pitch of equation (1). P≧W+0.9T···(1) (P: mounting pitch, W: base width, T: base thickness)

Description

TECHNICAL FIELD

[0001] The present invention relates to an optical element assembly, a method for manufacturing an optical element assembly, an optical module, an optical engine, and XR glasses. BACKGROUND ART

[0002] Optical element assemblies for XR glasses having a plurality of laser light sources, such as AR (Augmented Reality) glasses and VR (Virtual Reality) glasses, are expected as small wearable devices. For wearable devices such as AR glasses and VR glasses, miniaturization to fit each function into a standard glasses-type size is the key to widespread adoption.

[0003] As a general optical element assembly, light from a laser diode is guided to an optical element via an optical fiber or the like, and the fiber is aligned and joined with resin or the like (for example, Patent Document 1 and Patent Document 2). For an optical element assembly having a structure in which a laser diode is directly attached to such an optical element having a plurality of waveguides, a method is employed in which after the laser diode is bonded onto a subcarrier, one surface of the subcarrier is used as a bonding surface and bonded with an adhesive.

[0004] Also, there is known an element in which, for an optical element having a plurality of optical waveguides and performing some light conversion or photoelectric conversion, a laser diode is directly aligned with respect to the waveguides, joined and optically coupled. For such an element, a joining structure by eutectic bonding such as AuSn bonding has been proposed (for example, Patent Document 3). PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0005] PATENT DOCUMENT 1 International Publication No. 2019 / 239839 PATENT DOCUMENT 2 Japanese Patent Publication No. 2024-58375 [Patent Document 3] Japanese Patent Publication No. 2024-147277 [Overview of the project] [Problems that the invention aims to solve]

[0006] In structures like those described in Patent Documents 1 and 2, in the case of bonding, it is required to create a gap between laser diode assemblies by the coating method and bonding jig in the bonding process, thereby determining the waveguide pitch.

[0007] Even when utilizing eutectic bonding, the reflow method is crucial. Specifically, during reflow, care must be taken to ensure that laser diode units not currently being bonded are not affected by the heat of laser diodes being bonded, especially those placed in close proximity.

[0008] Furthermore, when joining multiple laser fibers, the waveguide pitch is constrained by the process and components, such as the size of the coupler at the joint, the arrangement of jigs, and the method of applying the adhesive.

[0009] The present invention has been made in view of the above circumstances, and aims to provide an optical element assembly, a method for manufacturing an optical element assembly, an optical module, an optical engine, and XR glasses, in which the laser diode assembly is mounted with high precision so as not to cause thermal effects on other laser diode assemblies when the base on which the laser diode is formed is joined to an optical waveguide substrate, and which has a high degree of freedom in mounting position to match the shape of the laser diode assembly. [Means for solving the problem]

[0010] To solve the above problems, the present invention provides the following means.

[0011] [1] An optical element assembly according to one aspect of the present invention is Multiple laser diode assemblies, The optical waveguide substrate comprises an optical waveguide layer having an optical waveguide for guiding laser light emitted from the plurality of laser diode assemblies, and an optical waveguide substrate having an optical waveguide layer on its main surface. The laser diode assembly comprises a base and a laser diode formed on the base. At least one of the plurality of laser diode assemblies is provided with a spacing from adjacent laser diode assemblies such that the mounting pitch satisfies equation (1). P≧W+0.9T···(1) (P: mounting pitch, W: base width, T: base thickness)

[0012] [2] In the optical element assembly described in [1] above, The plurality of laser diode assemblies may be arranged with unequal pitches.

[0013] [3] In the optical element assemblies described in [1] and [2] above, the plurality of laser diode assemblies may be spaced apart so that adjacent laser diode assemblies have a mounting pitch that satisfies formula (1).

[0014] [4] In the optical element assemblies described in [1] to [3] above, the plurality of laser diode assemblies may be arranged so that they are spaced equally apart from adjacent laser diode assemblies.

[0015] [5] In the optical element assemblies described in [1] to [4] above, each of the multiple laser diode assemblies may be bonded to the optical waveguide substrate via multiple metal films.

[0016] [6] In the optical element assemblies described in [1] to [5] above, the plurality of metal films may include Sn and Au.

[0017] [7] In the optical element assembly according to any one of [1] to [6] above, the plurality of laser diode assemblies may be formed to have a mounting pitch that satisfies formula (2). P≦Wo-nW···(2) (Wo: width of the optical element assembly, n: number of laser diode assemblies included in the optical element assembly)

[0018] [8] In the optical element assembly according to any one of [1] to [7] above, the plurality of laser diode assemblies include: at least two adjacent first laser diode assemblies bonded to the optical waveguide substrate via a plurality of metal films; and at least one second laser diode assembly bonded to the optical waveguide substrate via an adhesive layer, Among the plurality of laser diode assemblies, the adjacent first laser diode assemblies are provided with a spacing P therebetween such that the mounting pitch satisfies formula (1), The spacing between the second laser diode assembly and an adjacent laser diode assembly may be less than the spacing P.

[0019] [9] An optical module according to one aspect of the present invention has the optical element assembly according to any one of [1] to [8] above housed in a package.

[0020]

[10] An optical engine according to one aspect of the present invention includes the light source module according to [9] above, and an optical scanning mirror that reflects light emitted from the light source module by changing an angle thereof to display an image.

[0021]

[11] An XR glasses according to one aspect of the present invention, wherein the XR glasses is mounted with the optical engine according to

[10] above.

[0022]

[12] A method for manufacturing an optical element assembly according to one aspect of the present invention includes a bonding step of bonding a plurality of laser diode assemblies to an optical waveguide substrate via a plurality of metal films, The optical waveguide substrate comprises a substrate and an optical waveguide layer formed on the main surface of the substrate and having an optical waveguide, The laser diode assembly comprises a base and a laser diode formed on the base, The bonding process involves heating at least one of the plurality of laser diode assemblies by irradiating it with laser light while it is in contact with the substrate with a gap between it and adjacent laser diode assemblies, so that the mounting pitch satisfies equation (1). P≧W+0.9T···(1) (P: mounting pitch, W: base width, T: base thickness)

[0023]

[13] In the method for manufacturing the optical element assembly described in

[12] above, the bonding step may involve bringing the base on which a first metal film containing Au is formed and the substrate on which a second metal film containing Sn is formed into contact and heating them to form a eutectic film of Au and Sn.

[0024]

[14] The manufacturing method of the optical element assembly described in

[12] and

[13] above may use a Si substrate as the base and a YAG laser in the bonding step. [Effects of the Invention]

[0025] According to the present invention, when joining a base on which a laser diode is formed to an optical waveguide substrate, the laser diode assembly can be mounted with high precision so as not to cause thermal effects on other bases on which laser diodes are formed. Furthermore, it is possible to provide an optical element assembly with a high degree of freedom in mounting position to match the shape of the laser diode assembly, a method for manufacturing the optical element assembly, an optical module, an optical engine, and XR glasses. [Brief explanation of the drawing]

[0026] [Figure 1] This is a perspective view showing an example of the configuration of an optical element assembly according to one embodiment of the present invention. [Figure 2]Figure 1 is a plan view of the optical element assembly. [Figure 3] Figure 3(a) is a perspective view of a laser light source base on which three laser light sources are mounted, and Figure 3(b) is a perspective view of an optical waveguide substrate having an optical waveguide. [Figure 4] This is a cross-sectional view of the optical element assembly shown in Figure 1, along line AA'. [Figure 5] This is a cross-sectional view of the optical element assembly shown in Figure 2, along line BB'. [Figure 6] Figure 6(a) schematically shows a structure in which both the first metal film 74 and the second metal film 72 remain relatively intact, while Figure 6(b) schematically shows a structure in which the entirety of the first metal film 74 and the second metal film 72 are alloyed to form a eutectic layer. [Figure 7] This is a schematic diagram illustrating the configuration of a manufacturing method for an optical element assembly according to one embodiment of the present invention, and is a cross-sectional view showing the bonding process. [Figure 8] This is a schematic diagram illustrating the configuration of a manufacturing method for an optical element assembly according to one embodiment of the present invention, and is a cross-sectional view showing the bonding process. [Figure 9] This is a plan view showing an example of the configuration of an optical element assembly related to a modified example of Figure 1, and is an enlarged view of the peripheral structure of multiple laser diode assemblies. [Figure 10] A cross-sectional view showing an example of the configuration of an optical element assembly related to another modified example of Figure 1. [Figure 11] This is a plan view showing an example of the configuration of an optical module according to one embodiment of the present invention. [Figure 12] Figure 11 is a cross-sectional view of the optical module. [Figure 13] Figure 11 is a plan view illustrating the internal configuration of the optical module within the package. [Figure 14] This is a conceptual diagram illustrating an XR glasses relating to one embodiment of the present invention. [Figure 15] This is a conceptual diagram showing how an image is projected directly onto the retina by laser light emitted from an optical module according to one embodiment of the present invention. [Modes for carrying out the invention]

[0027] The embodiments will be described in detail below, with reference to the figures as appropriate. The drawings used in the following description may be enlarged for convenience to clearly illustrate the features, and the dimensional ratios of each component may differ from those in reality. The materials, dimensions, etc., exemplified in the following description are examples only, and the present invention is not limited to them. It is possible to modify and implement the invention as appropriate within the scope of achieving its effects.

[0028] [Optical element assembly] Figure 1 is a perspective view showing an example of the configuration of an optical element assembly according to one embodiment of the present invention. Figure 2 is a plan view of the optical element assembly of Figure 1. Figure 3(a) is a perspective view of a laser light source base on which three laser light sources are mounted, and Figure 3(b) is a perspective view of an optical waveguide substrate having an optical waveguide. Figure 4 is a cross-sectional view of the optical element assembly shown in Figure 1 along line AA'.

[0029] The optical element assembly 100 shown in Figures 1 to 4 comprises a plurality of laser diode assemblies 3 (3-1, 3-2, 3-3) and an optical waveguide layer 50 having an optical waveguide 51 for guiding the laser light emitted from the plurality of laser diode assemblies 3 on its main surface. The laser diode assembly 3 has a base 20 (20-1, 20-2, 20-3) and laser diodes 30 (30-1, 30-2, 30-3) formed on the base 20, and at least one of the plurality of laser diode assemblies 3 is formed with a spacing between adjacent laser diode assemblies 3 so as to satisfy the mounting pitch of equation (1). P≧W+0.9T···(1) (P: mounting pitch, W: base width, T: base thickness)

[0030] In this embodiment, when a component indicated by reference numeral ○ is described in a manner that distinguishes it from components indicated by reference numeral ○-1, ○-2, and ○-3, the reference numerals ○-1, ○-2, and ○-3 are used to distinguish and explain each component. However, for features common to all components, only reference numeral ○ is used, and the components are described collectively. In this embodiment, the base 20 is also referred to as the laser light source base or subcarrier. The laser diode 30 is also referred to as the laser light source.

[0031] The optical element assembly 100 shown in Figure 1 comprises three laser diodes 30, three laser light source bases 20 (20-1, 20-2, 20-3) on which each of the three laser diodes 30 is mounted on a main surface 21-1, 21-2, 21-3 and spaced apart from each other, an optical waveguide layer 50 having at least an optical waveguide 51 for guiding the laser light emitted from the three laser diodes 30 (30-1, 30-2, 30-3), an optical waveguide substrate 40 on which the optical waveguide layer 50 is provided on the main surface, and the laser light source bases 20 (20-1, The optical element assembly 100 includes a metal film M that joins the laser diode assemblies 20-2, 20-3 to the optical waveguide substrate 40. The metal film M (72, 73, 74) is positioned between the base-side joining surfaces 22 (22-1, 22-2, 22-3) of each laser light source base 20 (20-1, 20-2, 20-3) and the joining surface 42 of the optical waveguide substrate 40, with the metal film M (72, 73, 74) positioned between the base-side joining surfaces 22 (22-1, 22-2, 22-3) of each laser light source base 20 (20-1, 20-2, 20-3) and the optical waveguide substrate 40, which are spaced apart from each other, thereby joining the laser light source bases 20-1, 20-2, 20-3 to the optical waveguide substrate 40. In this way, in the optical element assembly 100, each of the multiple laser diode assemblies 3 is joined to the optical waveguide substrate 40 via a metal film M consisting of multiple metal films.

[0032] <Laser diode and base for laser diode> Various laser elements can be used as the laser diode 30. For example, commercially available laser diodes (LDs) for red light, green light, blue light, near-infrared light, and ultraviolet light can be used. For red light, light with a peak wavelength of 600 nm to 780 nm can be used; for green light, light with a peak wavelength of 500 nm to 560 nm can be used; and for blue light, light with a peak wavelength of 430 nm to 500 nm can be used. In addition, for near-infrared light, light with a peak wavelength of 830 nm to 2000 nm can be used.

[0033] In the optical element assembly 100 shown in Figure 1, the laser diodes 30-1, 30-2, and 30-3 are a red light emitting LD, a green light emitting LD, and a blue light emitting LD, respectively. The LDs 30-1, 30-2, and 30-3 can each be mounted as bare chips (unpackaged chips) on individual laser light source bases (subcarriers; hereinafter sometimes referred to as subcarriers) 20-1, 20-2, and 20-3, respectively. Subcarriers 20-1, 20-2, and 20-3 are composed of, for example, aluminum nitride (AlN) and silicon (Si).

[0034] A first metal layer 75 and a second metal layer 76 are provided between the subcarrier 20 and the LD30 (see Figure 4). The subcarrier 20 and the LD30 are connected via the first metal layer 75 and the second metal layer 76. While known methods can be used to form the first metal layer 75 and the second metal layer 76, known techniques such as sputtering, vapor deposition, and coating of paste-formed metal are available. The first metal layer 75 and the second metal layer 76 may consist of 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.

[0035] As shown in Figures 2 and 4, the base 20 has a width W corresponding to the length in the x direction and a thickness T corresponding to the length in the z direction. The length in the y direction of the base 20 is sometimes referred to as the depth.

[0036] Figure 3(a) shows an enlarged view of the configuration of the LD30 formed on the base 20. As shown in Figure 3(a), the LD30 is formed on the base 20 together with an active layer corresponding to the emission section and electrode sections such as the cathode and anode that are electrically connected to the active layer. The mounting pitch P in the above formula (1) is the distance between adjacent laser diode assemblies 3 in the multiple laser diode assemblies 3, and corresponds to the distance between the lasers irradiated from the LD30. That is, in each of the LD30-1, 30-2, and 30-3 in Figure 3(a), in the laser diode assembly 3 from which laser light is emitted parallel to the widthwise centers C30-1, C30-2, and C30-3 of the emission section, the mounting pitch P is the distance between the widthwise centers C30-1 and C30-2, and the distance between C30-2 and C30-3. Figure 3(a) shows the width W and thickness T of the base 20. Figure 3(b) shows the width Wo of the optical waveguide layer 50. The width of the optical waveguide layer 50 is, for example, the same as the width of the substrate 40. Figure 3(b) shows the substrate-side joints 42-1, 42-2, 42-3 and the second metal films 72-1, 72-2, 72-3 provided in these regions. The positions and spacing of these can be adjusted according to the positions and spacing of the subcarriers 20-1, 20-2, 20-3. The substrate-side joints 42-1, 42-2, 42-3 are provided facing the first metal films 74-1, 74-2, 74-3 provided on the subcarriers 20-1, 20-2, 20-3.

[0037] In the optical element assembly 100 shown in Figures 1 to 4, the multiple laser diode assemblies 3 are spaced apart from each other so that the mounting pitch satisfies equation (1). In the optical element assembly 100 shown in Figures 1 to 4, the thickness T and width W of the base of the multiple laser diode assemblies 3 are constant, and adjacent laser diode assemblies 3 are spaced equally apart. As an example, the base 20 can have a width W of 0.37 mm, a thickness T of 0.40 mm, and a depth of 0.40 mm, and the optical functional layer 50 can have a width of 2.25 mm, a height of 3.42 mm, and a depth of 0.415 mm. When using such a base 20, W + 0.9T = 0.37 + 0.90 × 0.40 = 0.73 (mm). Therefore, according to equation (1), the mounting pitch P can be set to a size greater than 0.73 mm, for example, 0.75 mm. In this case, the mounting pitch P satisfies the relationship W + 0.9T + 0.02 (mm). For example, among three laser diode assemblies 3, adjacent laser diode assemblies 3 can be mounted at equal intervals with the above value for mounting pitch P.

[0038] In the optical element assembly 100, it is preferable that the multiple laser diode assemblies 3 are spaced apart from adjacent laser diode modules so as to satisfy the following equation (2), in order to ensure sufficient positional accuracy and to reduce size. P ≤ Wo―nW···(2) (Wo: width of the optical element assembly, n: number of laser diode assemblies included in the optical element assembly)

[0039] <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 light source. There are no particular restrictions on the optical waveguide layer, and for example, known configurations can be used. Examples of optical waveguide layers are shown below.

[0040] The optical waveguide layer 50 is referred to as a PLC (Planar lightwave circuit). Hereafter, the optical waveguide layer 50 may be referred to as PLC50. Also, the optical waveguides 51-1, 51-2, and 51-3 may be referred to as cores 51-1, 51-2, and 51-3.

[0041] The optical waveguide layer 50 is formed on the optical waveguide substrate 40, and as described above, the laser light source 30 is mounted on the subcarrier 20. The optical waveguide substrate 40 and the subcarrier 20 are integrated by metal bonding. This metal bonding enables precise optical axis alignment and also allows for miniaturization.

[0042] Figure 5 shows a schematic cross-sectional view of the optical element assembly 100 shown in Figure 2, cut along the BB' line. The optical waveguide substrate 40 is made of, for example, silicon (Si). The PLC 50 is manufactured on the top surface 41 so as to be integrated with the optical waveguide substrate 40 by a semiconductor process including known photolithography and dry etching used when forming fine structures such as integrated circuits. As shown in Figure 2, the PLC 50 is provided with the same number of cores 51-1, 51-2, 51-3 as LD30-1, 30-2, 30-3, and a cladding 52 surrounding the cores 51-1, 51-2, 51-3. The thickness of the cladding 52 and the width dimensions of the cores 51-1, 51-2, 51-3 are not particularly limited. For example, cores 51-1, 51-2, 51-3 with width dimensions of a few microns are arranged in a cladding 52 with a thickness of about 50 μm.

[0043] Cores 51-1, 51-2, 51-3 and cladding 52 are made of, for example, quartz. Hereinafter, this will be referred to as quartz-based PLC50. The refractive index of cores 51-1, 51-2, and 51-3 is higher than that of cladding 52 by a predetermined value. As a result, light incident on each of cores 51-1, 51-2, and 51-3 propagates through each core while undergoing total internal reflection at the interface between each core and cladding 52. Cores 51-1, 51-2, and 51-3 are doped with impurities such as germanium (Ge) in an amount corresponding to the aforementioned predetermined value.

[0044] As shown in Figures 1, 2, and 4, cores 51-1, 51-2, and 51-3 are brought together into one on the side just before reaching the emission surface 64 of the PLC 50. That is, cores 51-1, 51-2, and 51-3 merge sequentially as they move forward in the x-direction, and merge into a single core 51-4. To prevent light leakage from cores 51-1, 51-2, and 51-3, it is preferable that each of cores 51-1, 51-2, and 51-3 is connected to core 51-4 with a radius of curvature greater than or equal to a predetermined radius of curvature.

[0045] Through a metal bond between the optical waveguide substrate 40 and the subcarrier 20, the optical axes of each core and its corresponding LD are precisely aligned so that the center of the entrance port of each core 51-1, 51-2, 51-3 of the PLC 50 and the optical axis of the light emitted from the corresponding LDs 30-1, 30-2, 30-3 are nearly aligned, and each core and its corresponding LD are positioned opposite each other.

[0046] As shown in Figure 4, the incident surface 50A of PLC50 is positioned opposite the exit surface 31 of LD30. More specifically, the exit surface 31-1 of LD30-1 is opposite the incident port 51A-1 of optical waveguide 51-1. In the x and z directions, the optical axis of the red light emitted from LD30-1 and the center of the incident port 51A-1 approximately coincide. Similarly, the exit surface 31-2 of LD30-2 is opposite the incident port 51A-2 of optical waveguide 51-2. In the x and z directions, the optical axis of the green light emitted from LD30-2 and the center of the incident port 51A-2 approximately coincide. The exit surface 31-3 of LD30-3 is opposite the incident port 51A-3 of optical waveguide 51-3. In the x and z directions, the optical axis of the blue light emitted from LD30-3 and the center of the incident port 51A-3 approximately coincide. With this configuration and arrangement, at least a portion of the red, green, and blue light emitted from LD30-1, 60-2, and 60-3 can be incident on the optical waveguides 51-1, 51-2, and 51-3.

[0047] As shown in Figure 2, the red, green, and blue light emitted from LD30-1, 30-2, and 30-3 are incident on cores 51-1, 51-2, and 51-3, respectively, and then propagate through each core. The red and green light propagating through cores 51-3 and 51-2 are combined at a predetermined confluence point 57-1 located behind confluence point 57-2 in the y-direction. The combined red and green light and the blue light propagating through 51-2 combine at confluence point 57-2. The RGB light combined at confluence point 57-2 propagates through core 51-4, reaches the exit surface 64, and is emitted from the exit surface 64.

[0048] <Joint part> The three individual laser light source bases 20-1, 20-2, and 20-3 and the optical waveguide substrate 40 are joined via a metal film M. The metal film M is placed between the base-side bonding surfaces 22-1, 22-2, and 22-3 of each of the three individual laser light source bases 20-1, 20-2, and 20-3, and three substrate-side bonding portions 42-1, 42-2, and 42-3 that are spaced apart from each other on the bonding surface 42 of the optical waveguide substrate 40, which correspond to each of the base-side bonding surfaces 22-1, 22-2, and 22-3. The metal film M is placed only at the substrate-side junctions 42-1, 42-2, and 42-3, which are spaced apart. Because it is a separated film rather than a continuously formed film, the occurrence of capacitive coupling is suppressed, and crosstalk is prevented.

[0049] For convenience, the metal film M shown in Figures 2 and 4 is depicted as a three-layer structure, reflecting the fabrication process of the metal film M (or, more precisely, the bonding process between the laser light source base and the optical waveguide substrate). Furthermore, when describing the metal film M, each of the three layers may also be explained individually. In other words, for convenience, the metal film M shown in the figure is depicted as consisting of three layers: a first metal film 74 (74-1, 74-2, 74-3) placed on the base-side bonding surfaces 22-1, 22-2, 22-3 of the individual laser light source bases 20-1, 20-2, 20-3; a second metal film 72 (72-1, 72-2, 72-3) placed on three spaced-apart substrate-side bonding portions 42-1, 42-2, 42-3 on the bonding surface 42 of the optical waveguide substrate 40, corresponding to the base-side bonding surfaces 22-1, 22-2, 22-3; and a eutectic layer 73 placed between the first metal film 74 and the second metal film 72. In actual bonding, if the first and second metal films are sufficiently thin, an alloy layer (eutectic layer) is formed, and the first and second metal films remain. On the other hand, if either the first or second metal film is thick, the thicker metal film may eutectic only on the surface side, leaving the portion on the laser light source base side or the optical waveguide substrate side intact, while the other metal film may eutectic completely. However, it becomes difficult to clearly distinguish between the layers (distinguish between interfaces). Thus, in actual bonding, the film structure of the metal film M differs depending on the conditions of the metal film M fabrication process, and the figure conceptually depicts the characteristic surfaces of the film structure. For example, the structure can be one or both of the first metal film 74 and the second metal film 72 remaining relatively intact, or the entire first metal film 74 and the second metal film 72 can be alloyed to form a eutectic layer. Figure 6(a) schematically shows the former structure in which both the first metal film 74 and the second metal film 72 remain relatively intact, and Figure 6(b) schematically shows the latter structure in which the entire first metal film 74 and the second metal film 72 can be alloyed to form a eutectic layer.

[0050] The first metal film 74 is formed, for example, over the entire bonding surface 22 of the base 20, or over the entire surface except for the edges. In order to achieve bonding by forming a eutectic with the second metal film 72 by heating the first metal film 74, it is necessary to heat the first metal film 74 and the second metal film 72 so that they are completely melted, and this needs to be taken into consideration in order to define the mounting pitch P of the laser diode assembly 3.

[0051] The first metal film 74 and the second metal film 72 are aligned to overlap, and when laser light is shone on the subcarrier 20, or directly through the subcarrier, they are heated and the first metal film 74 and the second metal film 72 melt. When the first metal film 74 and the second metal film 72 are in contact with each other and heated by laser light, the components of the second metal film 72 eutectic and diffuse into the first metal film 74.

[0052] The second metal film 72, which is placed on the substrate-side bonding portions 42-1, 42-2, and 42-3, is preferably made of Sn or an alloy containing Sn such as Sn-Ag-Cu. The first metal film 74, which is placed on the base-side bonding surfaces 22-1, 22-2, and 22-3, is preferably made of a metal that can eutectic with Sn, and can include, for example, one selected from the group consisting of Au, Si, Al, Ni, Pb, Zn, and Pt, or an alloy thereof. The first metal film 74 is preferably made of Au or Pt among the metals that can eutectic with Sn. These metals require particularly high-temperature treatment when forming a eutectic with Sn by reflow during the bonding process. Therefore, they tend to easily affect nearby components such as the metal film of the laser diode assembly adjacent to the laser diode assembly 3 during bonding with the optical waveguide substrate 40. However, in this embodiment, the adjacent laser diode assemblies 3 to be bonded are provided with a mounting pitch P between them, thereby suppressing the thermal effects on the surrounding laser diode assemblies 3 and resulting in an optical element assembly with highly precise mounting position adjustments.

[0053] Furthermore, the three-layer structure of the metal films M(72,73,74) shown in Figure 6 may be in the reverse order. That is, the second metal film 72 may be placed on the laser light source base 20 side, and the first metal film 74 may be provided on the optical waveguide substrate 40 side.

[0054] [Manufacturing method for optical element assemblies] Hereinafter, a method for manufacturing an optical element assembly according to one embodiment of the present invention will be described, using the method for manufacturing the optical element assembly 100 according to the above embodiment as an example. Figures 7 and 8 are schematic diagrams illustrating the configuration of the method for manufacturing an optical element assembly according to one embodiment of the present invention, and are cross-sectional views showing the bonding process.

[0055] A method for manufacturing an optical element assembly according to one embodiment of the present invention includes a bonding step of bonding a plurality of laser diode assemblies 3 to an optical waveguide substrate 40 via a plurality of metal films 72, 74. In the bonding step, at least one of the plurality of laser diode assemblies 3 is brought into contact with the substrate with a gap between it and adjacent laser diode assemblies 3, so as to satisfy the mounting pitch of formula (1), and is heated by irradiating it with laser light. P≧W+0.9T···(1) (P: mounting pitch, W: base width, T: base thickness)

[0056] The laser diode assembly 3 is formed by mounting a bare chip LD30 on the upper surface of the base 20 using a known method. For example, a first metal layer 75 is formed on the upper surface 21 of the base 20 using sputtering or vapor deposition. Furthermore, a second metal layer 76 is formed on the lower surface 33 of the LD30 (for example, the lower surface 33-1 of LD30-1) using sputtering or vapor deposition. Next, the base 20 is irradiated with laser light and heated to an extent that only the base 20 does not melt or deform. The first metal layer 75 and the second metal layer 76 are softened or melted by heat transfer from the base 20, and then cooled. As a result, the LD30 is bonded to the upper surface 21 of the base 20 via the first metal layer 75 and the second metal layer 76, and the laser diode assembly 3 is formed.

[0057] Furthermore, a first metal film 74 is formed on the base-side bonding surface 22 of the base 20 either before or after mounting the LD30 onto the base 20. The first metal film 74 can be formed using sputtering or vapor deposition.

[0058] Next, a PLC 50 is formed on the upper surface 41 of the substrate 40 by a known semiconductor process. Furthermore, a second metal film 72 is formed on the substrate-side bonding portions 42-1, 42-2, and 42-3 of the substrate 40 by sputtering or deposition.

[0059] Next, in the x and z directions, the emission surfaces 31 and incidence surfaces 61 of the corresponding LD30 and cores 51-1, 51-2, and 51-3 are positioned opposite each other with a gap in the y direction. The optical axes of each color of light emitted from the LD30 are roughly aligned with the centers of the incidence surfaces 61 of the corresponding cores, and the base 20 on which the first metal film 74 is formed and the substrate 40 on which the second metal film 72 is formed are brought into contact. Here, the laser diode assemblies 3 on the base 20 are joined to adjacent laser diode assemblies 3 with a gap in between so that the mounting pitch satisfies equation (1), as described later.

[0060] Specifically, as shown in Figures 7 and 8, laser light is irradiated from the laser 90 onto the subcarrier 20, and the first metal film 74, the second metal film 72, and the third metal film (eutectic film) 73 are softened or melted by heat transfer from the subcarrier 20. The relative positions of the LD 30 and the PLC 50 are adjusted, and the subcarrier 20 on which the LD 30 is mounted is joined to the substrate 40 on which the PLC 50 is formed, so that the bottom surface 23 of the subcarrier 20 and the bottom surface 43 of the substrate 40 are substantially on the same plane.

[0061] As the laser 90, any known laser capable of heating the first metal film 74 and the second metal film 72 to a temperature at which they eutectic can be used, but it is preferable to use a laser capable of emitting laser light with a wavelength of 1064 nm or longer, such as a YAG laser. When irradiating with short-wavelength laser light during the bonding process, the metal film M is indirectly heated through the base 20. In this embodiment, it is preferable to use a base 20 made of Si and to use a laser with a wavelength of 1064 nm or longer, such as a YAG laser, during the bonding process. When a base 20 made of Si is used and a laser with a wavelength of 1064 nm or longer, such as a YAG laser, is used during the bonding process, the laser light irradiated from the laser 90 passes through the base 20 and can directly heat the metal film M. Therefore, the effect of thermal radiation from the base 20 to the adjacent laser diode assembly 3 can be further suppressed.

[0062] The method for manufacturing an optical element assembly according to this embodiment is particularly effective when a metal film containing Au is used as the first metal film 74 and a metal film containing Sn is used as the second metal film 72. When eutectic formation of Sn and Au in such metal films, the temperature becomes higher, raising concerns that the temperature of the laser diode assembly 3 adjacent to the laser diode assembly 3 to be bonded will also increase. However, according to this embodiment, by bonding the base 20 and the substrate 40 of the laser diode assembly 3 to be bonded by forming a eutectic film of Au and Sn, with a mounting pitch that satisfies formula (1) above, it is possible to suppress the temperature rise of the metal film M of the adjacent laser diode assembly 3 and manufacture an optical element assembly 100 with high precision alignment.

[0063] (modified version) The optical element assembly according to one embodiment of the present invention is not limited to the configuration according to the above embodiment, and various modifications are possible. For example, the optical element assembly according to one embodiment of the present invention can have the following configuration. Figure 9 is a plan view showing an example of the configuration of an optical element assembly according to a modified example of Figure 1, and is a magnified view showing the peripheral structure of a plurality of laser diode assemblies. In the optical element assembly 100B shown in Figure 9, components similar to those in the optical element assembly according to the above embodiment are denoted by the same reference numerals and their description is omitted.

[0064] The optical element assembly 100B shown in Figure 9 includes laser diode assemblies 3-1, 30-2, and 3-3, as well as laser diode assembly 3-4. Similar to the other laser diode assemblies 3, laser diode assembly 3-4 has an LD30 provided on a base 20 via, for example, a first metal layer 75 and a second metal layer 76. The base and LD provided in laser diode assembly 3-4 are referred to as base 20-4 and LD30-4, respectively. Laser diode assembly 3-4 is bonded to the optical waveguide substrate 40 via, for example, an adhesive layer 77. The adhesive layer 77 is composed of, for example, an adhesive.

[0065] In the optical element assembly 100B, considering the distance between the laser diode assemblies described later, the laser diodes bonded to the optical waveguide substrate via a metal film may be referred to as the first laser diode assembly, and the laser diode assemblies bonded to the optical waveguide substrate 40 via an adhesive layer may be referred to as the second laser diode assembly. The optical element assembly 100B according to this modified example comprises at least two first laser diode assemblies and at least one second laser diode assembly. Laser diode assemblies 3-1, 3-2, and 3-3 correspond to the first laser diode assemblies, and laser diode assembly 3-4 corresponds to the second laser diode assembly.

[0066] In the optical element assembly 100B, the first laser diode assembly is spaced apart from adjacent laser diode assemblies 3 so as to satisfy the mounting pitch of equation (1). The optical element assembly 100B is arranged such that multiple laser diode assemblies 3-1, 3-2, 3-3, and 3-4 are spaced apart. That is, at least one of the adjacent laser diode assemblies 3 is spaced apart from the adjacent laser diode assemblies 3, which is different from the distance between other adjacent laser diode assemblies 3. In the optical element assembly 100B, adjacent laser diode assemblies, which are the first laser diode assemblies, are spaced apart from each other so as to satisfy the mounting pitch of equation (1). The distance P1 between laser diode assemblies 3-1 and 3-2, and the distance P2 between laser diode assemblies 3-2 and 3-3 are, for example, the same length, and laser diode assemblies 3-1, 3-2, and 3-3 are equally spaced. On the other hand, the distance P3 between adjacent laser diode assemblies 3-3 and 3-4, which is the distance between the first and second laser diode assemblies, does not satisfy equation (1) and is, for example, shorter than the distances P1 and P2 mentioned above. Note that distance P3 may be greater than or equal to the distances P1 and P2.

[0067] The first laser diode assembly is bonded to the optical waveguide substrate by a metal film M and is formed by the same method as the bonding process in the manufacturing method of the optical element assembly according to the above embodiment. Therefore, it is preferable that the distance between these laser diode assemblies is formed to satisfy the mounting pitch P in order to suppress misalignment of laser diode assemblies that are not to be bonded during the bonding process. On the other hand, since the second laser diode assembly is bonded to the optical waveguide substrate 40 by an adhesive layer 77, the influence on bonding the adjacent first laser diode assembly to the optical waveguide substrate 40 is minimal, and vice versa. Therefore, even with the optical element assembly 100B, the alignment of laser diode assemblies 3-1, 3-2, and 3-3 can be performed with high precision, and the possibility of misalignment occurring in laser diode assembly 3-4 during the bonding of laser diode assembly 3-3 is minimal, so that all laser diode assemblies 3 can be mounted to the optical waveguide substrate 40 with high precision.

[0068] Furthermore, although the optical element assembly according to the above embodiment is illustrated in which all bases 20 have the same dimensions, at least one base may have different dimensions from the other bases. In such a configuration, equations (1) and (2) use the larger values ​​for width W and thickness T from the dimensions of the bases 20 of adjacent laser diode assemblies 3. The optical element assembly according to this embodiment has a high degree of flexibility because, in this way, the distance between laser diode assemblies 3 is not set to a specific value, but is designed to match the dimensions of the laser diode assemblies 3.

[0069] Furthermore, according to the optical element assembly of the above embodiment, by providing a plurality of independent laser diode assemblies 3, it becomes possible to isolate electrical influences between each laser diode assembly 3 and to mutually eliminate thermal and other influences. In addition, it is possible to eliminate the need for strict precision control of each component and the electrical, thermal, and optical influences that occur when, for example, multiple laser diodes are mounted on a single subcarrier and then attached to a substrate 40. When attaching a separated and independent laser diode assembly like the one in this embodiment to a substrate 40, various dimensions are affected by the reflow method due to the process and bonding method. The optical element assembly of this embodiment has defined subcarrier dimensions and waveguide pitch that take this into consideration.

[0070] Figure 10 is a cross-sectional view showing an example of the configuration of an optical element assembly according to another modification of Figure 1. In the optical element assembly 100C shown in Figure 10, an anti-reflective film 81 is provided between the LD30 and the PLC50. For example, the anti-reflective film 81 is integrally formed on the bonding surface 42 of the substrate 40 and the incident surface 50A of the PLC50. However, the anti-reflective film 81 may be formed only on the incident surface 50A of the PLC50.

[0071] In the optical element assembly 100C shown in Figure 10, an anti-reflective coating 82 is provided not only on the incident surface 50A but also on the exit surface 64.

[0072] The anti-reflective films 81 and 82 are films that prevent incident or outgoing light to the PLC 50 from being reflected in the opposite direction to the direction in which it enters each surface from the incident surface 50A or the outgoing surface 64, thereby increasing the transmittance of the incident or outgoing light. The anti-reflective films 81 and 82 are multilayer films formed by alternately stacking multiple types of dielectrics with predetermined thicknesses corresponding to the wavelengths of the incident light, which are red, green, and blue light. Examples of the aforementioned dielectrics include titanium oxide (TiO2), tantalum oxide (Ta2O5), silicon oxide (SiO2), and aluminum oxide (Al2O3).

[0073] The exit surface 31 of LD30 and the incident surface 50A of PLC50 are positioned at a predetermined distance. The incident surface 50A faces the exit surface 31, and there is a gap K between the exit surface 31 and the incident surface 50A in the x-direction. Considering that the optical element assembly 100C is used in XR glasses and the amount of light required by the XR glasses, the size of the gap (spacing) K in the x-direction is, for example, greater than 0 μm and 5 μm or less. The optical element assembly 100C shown in Figure 10 will be described below, but the same principles can be applied to the optical element assembly 100.

[0074] In the optical element assembly 100C, the bottom surface (base bottom surface) 20b facing the upper surface (surface) 20a of the subcarrier (laser light source base) 20 (20-1, 20-2, 20-3) and the bottom surface (substrate bottom surface) 43 facing the upper surface (surface) 41 of the substrate 40 are positioned on substantially the same plane S. In the optical element assemblies 100 and 100C, the subcarrier 20 and the substrate 40 are connected via a metal film, so the occurrence of positional misalignment due to the bonding process is significantly suppressed compared to when they are connected by adhesive. In this context, the nearly identical plane S allows for a slight misalignment between the bottom surface (base bottom surface) 20b and the bottom surface (substrate bottom surface) 43. Specifically, a misalignment of 20 μm or less is allowed with respect to the thickness of the substrate 40 along the z-direction, but the smaller the misalignment, the better, more preferably 10 μm or less, and even more preferably 5 μm or less.

[0075] As shown in the illustrated optical element assembly 100C, if the bottom surface 20b of the subcarrier 20 and the bottom surface 43 of the substrate 40 are formed to lie on substantially the same plane S, both the subcarrier 20 and the substrate 40 can be joined to a single plane, such as a package or heat sink. Compared to a case where the bottom surfaces of the subcarrier and the substrate are not substantially the same plane and can only be joined on one of the bottom surfaces, the optical element assembly 100C can efficiently dissipate the heat generated by the operation of the LD (optical semiconductor element) 30 from both the bottom surface 20b of the subcarrier 20 and the bottom surface 43 of the substrate 40.

[0076] Furthermore, as shown in the illustrated optical element assembly 100C, by arranging the bottom surface 20b of the subcarrier 20 and the bottom surface 43 of the optical waveguide substrate 40 on substantially the same plane S, when joining the optical module onto one plane such as another substrate, both the bottom surface 20b of the subcarrier 20 and the bottom surface 43 of the optical waveguide substrate 40 can be joined onto the same plane such as the substrate. This makes it possible to maintain high bonding strength and realize an optical element assembly 100C with excellent impact resistance. For example, when the bottom surface of the subcarrier is located in the +z direction relative to the bottom surface of the substrate, that is, when the bottom surface of the subcarrier is positioned above the base 180 of the package 110 (see Figure 12) relative to the bottom surface of the substrate, the size of the first side surface of the subcarrier is small, making efficient heat dissipation difficult, and the bonding strength with the substrate is insufficient. In the case of wire bonding described later, the subcarrier may slide off. However, in the optical element assemblies 100 and 100C shown in the figure, the size of the side surface of the base 20 is sufficiently secured, and heat dissipation from the bottom surface 20b and side surface of the base 20 and bonding with the optical waveguide substrate 40 can be sufficiently achieved, thereby improving heat dissipation and shock resistance. By improving shock resistance, for example, the LD30 is maintained in the optimal position relative to the PLC50. Therefore, the optical element assembly 100C can exhibit the desired light utilization efficiency and optical characteristics, and the reliability of the optical element assemblies 100 and 100C can be increased.

[0077] [Optical Module] Figure 11 is a schematic plan view of the optical module of this embodiment. Figure 12 is a schematic cross-sectional view of the optical module shown in Figure 11, cut in the XZ plane. The optical module 1000 shown in Figure 11 houses the optical element assembly according to the above embodiment within a package 110. The optical element assembly shown in Figure 11 is also referred to as a laser assembly.

[0078] The package 110 may contain known components other than the optical element assembly according to the above embodiment. For example, a photodetector (PD) can be housed within it. By incorporating a photodiode (PD), fluctuations in the optical output of the LD can be checked by observing the current flowing through the PD. Furthermore, the drive current of the LD can be controlled to maintain a constant output by monitoring the current flowing through the PD.

[0079] Package 110 comprises a main body 102 having a cavity structure and a cover 105 that covers the main body 102. The main body 102 has a bottom portion on which the components to be housed inside are placed, and wall portions (side wall portions) 102a arranged to surround those components from the sides. A light-transmitting window 101 is formed in the wall portion (side wall portion) 102a, which is positioned in the direction from which the laser light is emitted, allowing the laser light L emitted from the laser light source 30 to pass through optically.

[0080] A light-transmitting window (aperture) 101 is formed in the side wall portion 102a of the housing portion 107, near the laser beam L emitted from the optical module 1000. The aperture 101 is formed approximately at the point where it intersects with the optical axis of the laser beam emitted from the side wall portion 102a. The aperture 101 is completely covered from the outside of the side wall portion 102a by a glass plate 220. In other words, the housing portion 107 is hermetically sealed by the glass plate 220 in addition to the cover 105. Although a glass plate 220 is used for hermetically sealing, it is not limited to a glass plate as long as it is a material that can transmit laser light. Anti-reflective coatings (not shown) may be provided on both surfaces of the glass plate 220.

[0081] The electrode section 108 is positioned towards the front of the housing section 107 in the x-direction, i.e., towards the rear in the x-direction. The upper surface of the electrode section 108 is located below the upper surface of the housing section 107. The bottom surface of the electrode section 108 is located at approximately the same height as the bottom surface of the housing section 107. Multiple external electrode pads 210 are provided on the upper surface of the electrode section 108 at intervals in the y-direction.

[0082] As shown in Figure 10, a base 180 is provided at a predetermined position at the bottom of the housing section 107 for installing an optical module including the LD30 and the subcarrier 20 on which it is placed, and the PLC50 and the optical waveguide substrate 40 on which it is formed. This optical module is mounted on the base 180. In other words, this optical module is located in the internal space of the housing section 107. This optical module is formed such that the bottom surface (base bottom surface) 20b of the subcarrier (laser light source base) 20 and the bottom surface (substrate bottom surface) 43 of the optical waveguide substrate 40 are located on substantially the same plane S. Therefore, in this optical module, both the subcarrier 20 and the optical waveguide substrate 40 are joined to the upper surface 180a (one inner surface) of the base 180.

[0083] The bottom surface (base bottom surface) 20b of the subcarrier 20 and the bottom surface (substrate bottom surface) 43 of the optical waveguide substrate 40 should be joined to the top surface 180a (one inner surface) of the base 180 via an adhesive layer 182. This adhesive layer 182 is made of a material in which a filler is mixed with resin to improve thermal conductivity. Examples of resins that make up the adhesive layer 182 include epoxy resin. In addition, copper powder, aluminum powder, alumina powder, etc. can be used as fillers to improve the thermal conductivity of the resin. Furthermore, in order to maintain a certain level of thermal conductivity, the thermal conductivity of the adhesive layer 182 is preferably 0.5 W / m·K or higher, preferably 1 W / m·K or higher, and even more preferably 4 W / m·K or higher.

[0084] In this way, by bonding both the subcarrier 20 of the optical module and the optical waveguide substrate 40 to the upper surface 180a of the base 180 of the package 110, the heat generated by the operation of the LD30 can be efficiently dissipated toward the base 180 from both the bottom surface (base bottom surface) 20b of the subcarrier 20 and the bottom surface (substrate bottom surface) 43 of the optical waveguide substrate 40. Furthermore, by bonding both the bottom surface 20b of the subcarrier 20 and the bottom surface 43 of the optical waveguide substrate 40 using an adhesive layer made of resin mixed with filler, heat can be efficiently propagated toward the base 180 from both the bottom surface 20b of the subcarrier 20 and the bottom surface 43 of the optical waveguide substrate 40.

[0085] Figure 13 is a conceptual diagram of an optical module equipped with an optical waveguide layer, and shows a plan view illustrating the internal configuration of the package in the optical module shown in Figure 11. Components common to the optical element assembly described above may be given the same reference numerals and their descriptions may be omitted. Figure 13 shows an example in which the optical element assembly has a near-infrared laser light source in addition to an RGB laser light source. Since near-infrared lasers are invisible, they can be used for eye tracking.

[0086] In the optical module 2000 shown in Figure 13, an optical element assembly 100B is housed in a package 110, comprising an RGB laser light source 30 and a laser light source base 20 on which the RGB laser light source 30 is mounted, a near-infrared laser light source 35 and a laser light source base 20-4 on which the near-infrared laser light source 35 is mounted, an optical waveguide substrate 140 on which a PLC 150 is formed on the main surface, and metal films 72, 73, and 74 that join the laser light source base 20 and the laser light source base 20-4 to the optical waveguide substrate 140.

[0087] The near-infrared laser light source 35 is mounted on the subcarrier 20-4, similar to the laser light source 30, and the PLC 150 is formed on the optical waveguide substrate 140.

[0088] The optical module 2000 includes a PLC 150 within the package 110, which includes optical waveguides 151 (151-1, 151-2, 151-3) for guiding laser light emitted from the laser light source 30, and an optical waveguide 152 for guiding near-infrared laser light emitted from the near-infrared laser light source 35. In the optical module 2000, the optical waveguide substrate 140 on which the PLC 150 is formed, the subcarrier 20 on which the laser light source 30 is mounted, and the subcarrier 20-4 on which the near-infrared laser light source 35 is mounted are metal-bonded and integrated. This metal joint allows for precise optical axis alignment and enables miniaturization.

[0089] Examples of optical waveguide substrates 140 include sapphire substrates, Si substrates, and thermally oxidized silicon substrates.

[0090] As shown in Figure 13, optical waveguides 151-1, 151-2, and 151-3 are joined together just before reaching the output surface of the PLC 150. That is, optical waveguides 151-1, 151-2, and 151-3 merge sequentially as they move forward in the x-direction, converging into a single optical waveguide 151-4. To prevent light leakage from optical waveguides 151-1, 151-2, and 151-3, it is preferable that optical waveguides 151-1, 151-2, and 151-3 are each connected to optical waveguide 151-4 with a radius of curvature greater than or equal to a predetermined radius of curvature.

[0091] Through a metal joint between the optical waveguide substrate 140 and the subcarrier 20, the optical axes of the PLC50 are precisely aligned so that the center of the entrance opening of each ridge 151-1, 151-2, 151-3, and 152 of the PLC50 and the optical axis of the light emitted from the corresponding LDs 30-1, 30-2, 30-3, and 35 are nearly coincided and optically connected, with each ridge and its corresponding LD positioned opposite each other.

[0092] The entrance ports of each optical waveguide 151-1, 151-2, 151-3, and 152 face the exit ports of each LD30-1, 30-2, 30-3, and 35, and the light emitted from the exit ports of each LD30-1, 30-2, 30-3, and 35 is positioned to enter each entrance port, so that each LD30-1, 30-2, 30-3, and 35 is optically connected to each optical waveguide 151-1, 151-2, 151-3, and 152.

[0093] As shown in Figure 13, the red, green, and blue light emitted from LD30-1, 30-2, and 30-3 enter the respective entry points of optical waveguides (ridges) 151-1, 151-2, and 151-3, and then propagate through each ridge. The red and green light propagating through ridges 151-3 and 151-2 are combined at a predetermined confluence point 157-1 located behind confluence point 157-2 in the x-direction. The combined red and green light and the blue light propagating through 151-2 are combined at confluence point 57-2. The RGB light combined at confluence point 57-2 propagates through ridge 151-4, reaches the exit surface, and is emitted from the exit surface. Furthermore, the near-infrared light emitted from LD35 propagates along ridge 152, reaches the emission surface, and is emitted from the emission surface.

[0094] Each of the optical waveguides 151-1, 151-2, 151-3, and 152 in the PLC150 may be a Mach-Zehnder type optical waveguide.

[0095] [XR Glasses] The XR glasses according to this embodiment have the optical module according to the above embodiment mounted on the glasses. XR glasses are glasses-type devices, and XR is a general term for virtual reality (VR), augmented reality (AR), and mixed reality.

[0096] Figure 15 shows a conceptual diagram illustrating the XR glasses according to this embodiment. The XR glasses 10000 shown in Figure 15 have an optical module 1001 mounted on a frame 10010. The code L represents the image display light.

[0097] In Figure 15, the optical module 1001, the optical scanning mirror 3001, and the optical system 2001 connecting the optical module 1001 and the optical scanning mirror 3001 are collectively referred to as the optical engine 5001 in this specification. The optical module 1001 can be any of the optical modules according to the above embodiment. The optical engine is also referred to as the optical engine module.

[0098] For example, the optical module 1001 can be used as a light source comprising RGB laser light sources, such as a red laser light source 30-1, a green laser light source 30-2, and a blue laser light source 30-3, and a near-infrared laser light source 35.

[0099] For example, the optical module 1001 can be used as a light source comprising RGB laser light sources, such as a red laser light source 30-1, a green laser light source 30-2, and a blue laser light source 30-3, and a near-infrared laser light source 35. As shown in Figure 16, laser light emitted from the optical module 1001 attached to the eyeglass frame is reflected by the optical scanning mirror 3001, and the reflected light is reflected by a mirror 4001 that reflects towards the human eyeball E, enters the human eyeball E, and can project an image (video) directly onto the retina M. By incorporating an eye-tracking mechanism, images are projected directly onto the retina while eye tracking is performed. A known eye-tracking mechanism can be used.

[0100] The optical scanning mirror 3001 is, for example, a MEMS mirror. To project a 2D image, it is preferable to use a two-axis MEMS mirror that vibrates to reflect laser light by changing the angle in the horizontal (X direction) and vertical (Y direction).

[0101] The optical system 2001 for optically processing the laser light emitted from the optical module 1001 includes a collimator lens 2001a, a slit 2001b, and an ND filter 2001c. This optical system is an example, and other configurations are also possible.

[0102] The optical engine 5001 includes a laser driver 1100, an optical scanning mirror driver 1200, and a video controller 1300 that controls these drivers.

[0103] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various omissions, substitutions, modifications, and changes are possible within the scope of the gist of the present invention as described in the claims. These embodiments and their variations are included in the scope and gist of the invention, as well as in the scope of the invention and its equivalents as described in the claims. [Explanation of symbols]

[0104] 3,3-1,3-2,3-3,3-4 Laser diode assembly 20, 20-1, 20-2, 20-3, 20-4 Base (Laser light source base, subcarrier) 20a Top surface (front surface) 20b Bottom (base bottom) 21 Top side 21-1, 21-2, 21-3 Main surface 22,22-1, 22-2, 22-3 Base side joint surface 23 Bottom 30, 30-1, 30-2, 30-3 Laser diodes (laser light sources) 30-1 Red laser light source 30-2 Green laser light source 30-3 Blue laser light source 31, 31-1, 31-2, 31-3 Exit surface 33,33-1 Bottom surface 35 Near-infrared laser light source 40 Optical waveguide substrate (substrate) 41 Top surface (front surface) 42 Joint surface 42-1, 42-2, 42-3 Substrate-side bonding section 43 Bottom (bottom of board) 50 Optical waveguide layer 50A entrance plane 51, 51-1, 51-2, 51-3 Optical waveguide (core) 51A-1, 51A-1, 51A-2, 51A-3 Inlet 52 Clad 57-1,57-2 Merging position 61 Entrance plane 64 Ejection surface 72, 73, 74 Metal film 72,72-1, 72-2, 72-3 Second metal film 73 Third metal film (eutectic film) 74,74-1, 74-2, 74-3 First metal film 75 1st metal layer 76 Second metal layer 77 Adhesive layer 81,82 Anti-reflection coating 90 Lasers 100, 100B, 100C Optical Element Assembly 101 Light-transmitting window (opening) 102 Main Unit 102a Wall part (side wall part) 105 Cover 107 Storage Unit 108 Electrode section 110 packages 140 Optical waveguide substrate 151-1, 151-1, 151-2, 151-3 Optical waveguide (ridge) 157-1,157-2 Merging position 180 base 180a top 182 Adhesive layer 1000, 1001, 2000 Optical Modules 1100 Laser Driver 1200 Optical Scanning Mirror Driver 1300 Video Controller 2001a Collimator lens 2001b Slit 2001c ND filter 3001 Optical scanning mirror 4001 Mirror 5001 Optical Engine 10000 XR Glasses 10010 Frame

Claims

1. Multiple laser diode assemblies, The optical waveguide substrate comprises an optical waveguide layer having an optical waveguide for guiding laser light emitted from the plurality of laser diode assemblies, and an optical waveguide substrate having an optical waveguide layer on its main surface. The laser diode assembly comprises a base and a laser diode formed on the base. An optical element assembly in which at least one of the plurality of laser diode assemblies is provided spaced apart from adjacent laser diode assemblies so as to satisfy the mounting pitch of equation (1). P≧W+0.9T...(1) (P: mounting pitch, W: base width, T: base thickness)

2. The optical element assembly according to claim 1, wherein the plurality of laser diode assemblies are arranged to have unequal pitches.

3. The optical element assembly according to claim 1, wherein the plurality of laser diode assemblies are spaced apart so that adjacent laser diode assemblies have a mounting pitch that satisfies formula (1).

4. The optical element assembly according to claim 3, wherein the plurality of laser diode assemblies are arranged such that they are spaced equally apart from adjacent laser diode assemblies.

5. The optical element assembly according to claim 1, wherein each laser diode assembly is bonded to the optical waveguide substrate via a plurality of metal films.

6. The optical element assembly according to claim 5, wherein the plurality of metal films include Sn and Au.

7. The optical element assembly according to claim 1, wherein the plurality of laser diode assemblies are formed to have a mounting pitch that satisfies formula (2). P≦Wo-nW...(2) (Wo: width of the optical element assembly, n: number of laser diode assemblies included in the optical element assembly)

8. The plurality of laser diode assemblies include at least two adjacent first laser diode assemblies bonded to the optical waveguide substrate via a plurality of metal films, and at least one second laser diode assembly bonded to the optical waveguide substrate via an adhesive layer. Of the plurality of laser diode assemblies, adjacent first laser diode assemblies are provided with a spacing P such that the mounting pitch satisfies formula (1). The optical element assembly according to claim 2, wherein the second laser diode assembly is spaced less than the spacing P between adjacent laser diode assemblies.

9. An optical module comprising an optical element assembly according to any one of claims 1 to 8 housed in a package.

10. The light source module according to claim 9, An optical engine comprising: a light scanning mirror that reflects light emitted from the aforementioned light source module at a different angle to display an image.

11. XR glasses equipped with the optical engine described in claim 10.

12. The process involves bonding multiple laser diode assemblies to an optical waveguide substrate via multiple metal films. The optical waveguide substrate comprises a substrate and an optical waveguide layer formed on the main surface of the substrate and having an optical waveguide, The laser diode assembly comprises a base and a laser diode formed on the base, The bonding step is a method for manufacturing an optical element assembly, in which at least one laser diode assembly among the plurality of laser diode assemblies is brought into contact with the substrate at a distance from adjacent laser diode assemblies so as to satisfy the mounting pitch of formula (1), and then heated by irradiating it with laser light. P≧W+0.9T...(1) (P: mounting pitch, W: base width, T: base thickness)

13. The method for manufacturing an optical element assembly according to claim 12, wherein the bonding step involves bringing the base on which a first metal film containing Au is formed and the substrate on which a second metal film containing Sn is formed into contact and heating them to form a eutectic film of Au and Sn.

14. Using a Si substrate as the base, The method for manufacturing an optical element assembly according to claim 2, wherein a YAG laser is used in the bonding step.

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