Optical waveguide substrate, package for housing electronic element, electronic module, and electronic device

Abstract

This optical waveguide substrate comprises: a base body including a substrate (11); cladding (12); and a core (13). A first surface (S1), which is the upper surface of the base body, and a second surface (S2) of the cladding (12) face a first region (M). A first end surface (eR) of a first core (13R) is exposed from the second surface (S2) to the first region (M). The base body includes, within an area overlapping the first region (M) in plan view, a first section, and second sections (11a) located where the first surface (S1) is lower than the first section. The first section has a flat area (120a) and raised areas (120b). In plan view, the flat area (120a) extends in a first direction (Y) along the first end surface (eR), and the second sections (11a) are positioned on at least part of either side of the raised areas (120b) in the first direction (Y).

Description

Optical waveguide substrate, package for housing electronic elements, electronic module and electronic device

[0001] The present disclosure relates to an optical waveguide substrate, a package for housing an electronic element, an electronic module, and an electronic device.

[0002] There is an optical waveguide that guides light emitted by a light-emitting element to a desired position and direction. JP 2022-169006 A discloses a technology in which light emitted from a plurality of laser diodes is input into separate optical waveguides and output from the output ends of the optical waveguides at closely spaced intervals.

[0003] (1) An optical waveguide substrate according to the present disclosure comprises a substrate-containing base, a clad located above a first surface of the base, and a core located within the clad. The first surface and a second surface of the clad face a first region. The core includes a first core having a first end surface exposed from the second surface of the clad to the first region. The base includes, in a range overlapping the first region in a planar view, a first portion and a second portion in contact with the first portion and positioned at a lower position on the first surface than the first portion. The first portion has a flat portion spaced apart from the second surface in a planar view, and a convex portion connected to the flat portion and extending toward the first end surface in a planar view. The flat portion extends in a first direction along the first end surface in a planar view. The second portion is located at least partially on each side of the convex portion in the first direction. (2) In the optical waveguide substrate described in (1) above, the second portion is a portion where the surface of the substrate is exposed. (3) In the optical waveguide substrate described in (1) or (2) above, the minimum width of the convex portion in the first direction is ⅓ to 3 times the minimum width of the first core in the first direction. (4) In the optical waveguide substrate described in any one of (1) to (3) above, the convex portion has at least a tip portion that contacts the second surface in a planar view, and the tip portion is higher than the rest of the convex portion. (5) In the optical waveguide substrate described in (4) above, the first portion is located between the second portion and the second surface in a planar view, and has an intermediate portion that is higher than the second portion and lower than the tip portion. (6) In the optical waveguide substrate described in any one of (1) to (5) above, the connecting portion between the convex portion and the flat portion has a fillet shape or a tapered shape in a planar view. (7) In the optical waveguide substrate described in any one of (1) to (6) above, the first portion is integral with the clad. (8) In the optical waveguide substrate described in any one of (1) to (7) above, the first portion is integral with the substrate. (9) In the optical waveguide substrate described in any one of (1) to (8) above, the clad has a protruding portion that protrudes into the first region at a position spaced apart from the first core in a planar view.(10) In the optical waveguide substrate described in (9) above, the protrusions are located on both sides of the first core in the first direction in a planar view. (11) In the optical waveguide substrate described in any one of (1) to (10) above, the core includes a second core located within the cladding and having a second end face that is spaced from the second surface of the cladding and exposed to the first region and spaced from the first end face. (12) In the optical waveguide substrate described in (11) above, the cladding has a protrusion that is located between the first end face and the second end face in a planar view and protrudes into the first region at a position spaced from the first core and the second core. (13) In the optical waveguide substrate described in (11) or (12) above, the first end face and the second end face are located at different positions in a second direction perpendicular to the first direction in a planar view. (14) An electronic element storage package according to the present disclosure includes the optical waveguide substrate according to any one of (1) to (13) above, an electrode located in the first portion, and the clad having a wall portion surrounding the first region in a planar view. (15) An electronic module according to the present disclosure includes the package for storing an electronic element according to (14) above, an electronic element located on the electrode and facing the end face of the core exposed to the first region, and a lid located on the clad and covering the first region. (16) An electronic device according to the present disclosure includes the electronic module according to (15) above, and a display unit, wherein the electronic element is a light-emitting element, and the display unit displays using light emitted from the electronic module.

[0004] 5A is a perspective view showing the appearance of a light-emitting module having an optical waveguide substrate of this embodiment. FIG. 5B is a plan view with the lid of the light-emitting module removed. FIG. 1C is a cross-sectional view of the light-emitting module taken along the cross-sectional line AA of FIG. 1B. FIG. 1D is a cross-sectional view of the light-emitting module taken along the cross-sectional line BB of FIG. 1B. FIG. 5E is a perspective view showing an enlarged view of the accommodating section and the second surface. FIG. 5F is a cross-sectional perspective view taken along the cross-sectional line CC of FIG. 1B. FIG. 5G is a perspective view showing an enlarged view of a modified example of the accommodating section and the second surface. FIG. 5H is a perspective view showing an enlarged view of another modified example of the accommodating section and the second surface. FIG. 5I is a cross-sectional view taken along the cross-sectional line DD of FIG. 5A. FIG. 5I is a cross-sectional perspective view of a modified example near the recess. FIG. 5I is a view showing a modified example of the second surface and its periphery in the plan view of FIG. 1B. FIG. 5I is a view showing a modified example of the second surface and its periphery in the plan view of FIG. 1B. FIG. 5I is an exploded perspective view of another modified example of the optical waveguide module, disassembled into a substrate, an insulating layer, and a cladding. FIG. 5I is a perspective view showing an example of the present AR glass using a light-emitting module.

[0005] An embodiment will be described below with reference to the drawings. Figures 1A and 1B are diagrams showing the appearance of a light-emitting module 1 having an optical waveguide substrate according to this embodiment. Figure 1A is a perspective view, and Figure 1B is a plan view with a cover 40 removed.

[0006] The light emitting module 1, which is an electronic module of this embodiment, includes an optical waveguide module 10, a lens 20, a light emitting element 30, a lid 40, and the like.

[0007] The optical waveguide module 10, which is a package for housing an electronic element according to this embodiment, includes a substrate 11, a cladding 12, a core 13, and electrodes 14. Hereinafter, a plane parallel to a plane including the central axis of the core 13 is defined as the XY plane, and the X axis is defined along the direction of light incidence / emission. The Y axis is a direction perpendicular to the X axis within the XY plane. The Z axis is defined as the direction perpendicular to the XY plane. In the present disclosure, the X axis is along the first direction, and the Y axis is along the second direction. In one embodiment, the optical waveguide module 10 has a substantially rectangular shape when viewed from above along the Z axis, but is not limited to this.

[0008] In one embodiment, the substrate 11 may be a silicon substrate. Alternatively, the material of the substrate 11 may be an insulating material such as a ceramic material. Examples of the ceramic material include an aluminum oxide sintered body, a mullite sintered body, a silicon carbide sintered body, an aluminum nitride sintered body, a silicon nitride sintered body, and a glass ceramic sintered body. Alternatively, the material of the substrate 11 may be an organic material. Examples of the organic material include an epoxy resin, a polyimide resin, a polyester resin, an acrylic resin, a phenolic resin, and a fluororesin. As described below, the substrate 11 is not a flat plate but has an uneven upper surface.

[0009] The core 13 is located within the cladding 12 and transmits light. The cladding 12 and the core 13 are optically transparent materials, such as silicon dioxide, glass (e.g., quartz), or resin. The materials of the cladding 12 and the core 13 may be the same or different, e.g., the cladding 12 may be resin and the core 13 may be glass. More specifically, the cladding 12 may be silicon dioxide and the core 13 may be silicon oxynitride (SiON), also known as silicon oxynitride. The core 13 has a higher refractive index than the cladding 12. The difference in refractive index is within a range that sufficiently reduces leakage of incident light from the core 13 to the cladding 12. This difference depends on the structure, such as the shape of the core 13, but can be set to, for example, approximately 0.01 to 2.0. This results in the optical waveguide of this embodiment, in which light incident at one end of the core 13 propagates along the core 13. In one embodiment, there may be three independent cores 13. In one embodiment, the cross section of each core 13 perpendicular to the central axis, i.e., the extending direction of the core 13, may be rectangular or trapezoidal.

[0010] The clad 12 is located above one surface of the substrate 11, here the surface on the +Z side. The cores 13 in the clad 12 are exposed from the clad 12 at a second surface S2 and a third surface S3, which are two different surfaces in the longitudinal direction of the optical waveguide module 10, i.e., the X direction. In one embodiment, the three cores 13 may be arranged spaced apart from each other in the Y direction. The spacing between the cores 13 may decrease from the second surface S2 side toward the third surface S3 side. Light incident on each of the three cores 13 from the second surface S2 side is emitted from the third surface S3. That is, in one embodiment, the second surface S2 may be the light incident surface, and the third surface S3 may be the light exit surface.

[0011] The cladding 12 may have a protruding portion 121 that protrudes upward from the planar upper surface along the core 13 within a range that includes the core 13 in a planar view. In this disclosure, "planar view" includes a planar perspective view in which an invisible portion is seen through. The height of the protruding portion 121 is approximately the same as the thickness of the core 13 in the Z direction, but may be smaller or larger than this. Hereinafter, "thickness" in this disclosure refers to the dimension in the Z direction.

[0012] An insulating layer 120 may be located between the substrate 11 and the clad 12. If the material of the insulating layer 120 is the same as the material of the clad 12, such as silicon dioxide, the insulating layer 120 and the clad 12 may have an integral structure. That is, when manufacturing the optical waveguide substrate, the insulating layer 120 and the clad 12 may be integrally molded. In FIG. 1A , the insulating layer 120 may be located below the dotted line shown on the side surface of the clad 12.

[0013] Alternatively, when the substrate 11 is made of an insulating ceramic material, the portion corresponding to the insulating layer 120 may have an integral structure with the substrate 11. When the material of the insulating layer 120 is, for example, silicon dioxide, the substrate 11, the insulating layer 120, and the clad 12 may all be integrally molded to form an integral structure.

[0014] The clad 12 may have a recessed accommodation portion C1 that is open upward, i.e., on the +Z side, on the -X side of the core 13. Thus, the clad 12 has an optical waveguide portion 12L on the +X side of the accommodation portion C1 in which the core 13 is located, and a wall portion 12W that is a sidewall portion that connects to the optical waveguide portion 12L and surrounds the accommodation portion C1 on three sides in the ±Y and -X directions. The accommodation portion C1 may penetrate the clad 12 so that the substrate 11 is exposed at the bottom. The portion of the optical waveguide module 10 that is the package for housing an electronic element of this embodiment, excluding the electrodes 14 and the clad 12 and the wall portion 12W, constitutes the optical waveguide substrate of this embodiment.

[0015] The internal space of the housing C1 is a first region M serving as an element mounting region on which the light-emitting element 30 is mounted. In one embodiment, a portion of the insulating layer 120 and a portion of the substrate 11 may be exposed on the bottom surface of the housing C1. Three sets of electrodes 14 may be arranged in the Y direction on the insulating layer 120 on the bottom surface. Each set of electrodes 14 includes a first electrode 141 connected to an electrode pad 141a and a second electrode 142 having a lead wire. In one embodiment, the substrate 11 and the insulating layer 120 located on the bottom surface of the housing C1 form a base. The bottom surface of the housing C1 is an area that overlaps with the first region M in a plan view. The insulating layer 120 that forms the base may include a flat portion 120a, a protruding portion 120b, and a tip portion 120c, which will be described later (see FIGS. 2A and 2B ). When the material of the insulating layer 120 is different from the material of the clad 12, the insulating layer 120 sandwiched between the substrate 11 and the clad 12 may also be included in the base body.

[0016] The light-emitting elements 30 may be located on the electrode pads 141a of the first electrodes 141, and electrically connected to the electrode pads 141a. Connection terminals (not shown) are located on the bonding surface of the light-emitting elements 30 with the electrode pads 141a. These connection terminals are bonded to the electrode pads 141a with, for example, a brazing material or a conductive adhesive. The electrode pads 141a may be located on part or all of the upper surface of an insulating element mounting portion protruding from the bottom surface of the accommodation portion C1. The material of the element mounting portion may be the same as the material of the insulating layer 120.

[0017] The second electrode 142 may be electrically connected to the other electrode of the light emitting element 30. The connection may be made by a bonding wire W. An electrode pad for joining the bonding wire W may also be provided at the tip of the second electrode 142.

[0018] Each electrode 14 may extend to the outside of the housing C1 through a gap between the wall 12W of the cladding 12 and the substrate 11. At least one of the electrodes 14 may be located on the wall 12W. At least one of the electrodes 14 may be located between the wall 12W of the cladding 12 and the insulating layer 120. Outside the housing C1, the light-emitting element 30 emits light between each pair of the first electrode 141 and the second electrode 142.

[0019] Of the side wall surfaces of the housing C1, i.e., the first region M, the surface on the +X side, i.e., the surface of the optical waveguide portion 12L, is the second surface S2, and the core 13 is exposed on the second surface S2. An end face of the core 13 may face the light emitting end of the light emitting element 30.

[0020] 1A and 1B, a lens 20 may be located on the third surface S3 side of the optical waveguide module 10. The exposed surface of the core 13 at the third surface S3 can emit light to the lens 20. The lens 20 may be, for example, a convex lens, a diffractive lens, a rod lens, or a ball lens. The lens 20 may be a member having a function of converting light emitted from the exposed surface of the core 13 at the third surface S3 into parallel light.

[0021] On the second surface S2, protrusions 122 in the −X direction may be located between the end faces of the cores 13, i.e., on both sides of the central core 13. The protrusions 1221 may be located between the end faces of the cores 13 corresponding to the light emitting elements 30G and 30R, and spaced apart from the end faces of the cores 13. The protrusions 1222 may be located between the end faces of the cores 13 corresponding to the light emitting elements 30R and 30B, and spaced apart from the end faces of the cores 13. These protrusions 122 protrude further into the first region M on the light emitting element 30 side than the end faces of the cores 13, thereby reducing the incidence of light emitted from the light emitting element 30 as stray light on other uncorresponding cores.

[0022] A lid 40 is bonded to the upper surface of the clad 12 around the upper periphery of the housing C1, covering the first region M and sealing the housing C1. Here, the upper surface of the light-emitting element 30 bonded to the electrode 14 is lower in the Z direction than the upper surface of the clad 12. Therefore, the material of the lid 40 is, for example, a glass material, a silicon material, or a metal material. Examples of glass materials include quartz, borosilicate, and sapphire. Examples of metal materials include aluminum, copper, iron, and alloys such as Fe-Ni-Co. When the lid 40 is made of a metal material, the surface of the lid 40 may have a plating layer. Examples of materials for the plating layer include gold and nickel. A ring-shaped conductor may be positioned between the lid 40 and the optical waveguide module 10, particularly the clad 12. Bonding via a conductor improves the airtightness of the housing C1 compared to when the lid 40 and the optical waveguide module 10 are directly bonded with a resin-based adhesive.

[0023] The light-emitting elements 30 are electronic elements of this embodiment and may be, for example, laser diodes (LDs), each emitting light at a predetermined wavelength. In one embodiment, the light-emitting module 1 may have three light-emitting elements 30 corresponding to the three cores 13, respectively. These light-emitting elements 30 may include, for example, a light-emitting element 30R that is a red-emitting LD, a light-emitting element 30G that is a green-emitting LD, and a light-emitting element 30B that is a blue-emitting LD. In one embodiment, the light-emitting element 30R may be located in the center of the three light-emitting elements 30 in the Y direction. In this case, the light-emitting element 30G and the light-emitting element 30B are located on either side of the light-emitting element 30R.

[0024] Fig. 2A is a cross-sectional view of the light emitting module 1 taken along the cross-sectional line AA in Fig. 1B. Fig. 2B is a cross-sectional view of the light emitting module 1 taken along the cross-sectional line BB in Fig. 1B. For the sake of explanation, the ratios of the width, length, and spacing of the core 13 do not necessarily reflect actual values.

[0025] As shown in FIG. 2A , along cross-sectional line AA passing through the accommodation portion C1, wall portions 12W of the cladding 12 are located at both upper ends of the substrate 11. Within the accommodation portion C1, the upper surface (front surface) of the substrate 11 is exposed as partially recessed second portions 11a. Between these second portions 11a, first portions of the insulating layer 120 extending in the X direction from the second surface S2 are located as protruding portions 120b. That is, the second portions 11a are located on both sides of the protruding portions 120b in the Y direction. Within the accommodation portion C1, as described above, in the exposed portion of the substrate 11, the upper surface of the exposed portion, i.e., the surface on the +Z side, is the first surface S1, which is the upper surface of the base. In the portion of the substrate 11 where the insulating layer 120, such as the protruding portions 120b, is located, the upper surface of the insulating layer 120 is the first surface S1. That is, the second portions 11a can be rephrased as the bottom surface of the recessed portion of the first surface S1.

[0026] On the +X side of the cross-section line AA, i.e., further back than the cross-section shown in FIG. 2A , the second end face eG of the second core 13G, the first end face eR of the first core 13R, and the third end face eB of the third core 13B may be located on the second surface S2 and spaced apart from each other in the Y direction. The second end face eG is an entrance for light emitted by the light-emitting element 30G. The first end face eR is an entrance for light emitted by the light-emitting element 30R. The third end face eB is an entrance for light emitted by the light-emitting element 30B. The first end face eR, the second end face eG, and the third end face eB are each located within the range in which the convex portion 120b is located in the Y direction. A tip portion 120c on the side of the cladding 12 where the convex portion 120b connects to the second surface S2 may be one step higher than the convex portion 120b. Between the second surface S2 and the second portion 11a, except for the tip portion 120c, an intermediate portion 11b whose height changes stepwise may be located. The intermediate portion 11b is the edge of the step portion 11b0 of the substrate 11, and is located higher in the Z direction than the second portion 11a and the convex portion 120b, i.e., on the +Z side, and lower in the Z direction than the tip portion 120c, i.e., on the -Z side. In other words, the upper surfaces of the insulating layer 120 and the tip portion 120c may be one step higher than the upper surfaces of the convex portion 120b and the flat portion 120a, with the step portion 11b0 as the boundary. The tip portion 120c is located at the highest position in the Z direction compared to the flat portion 120a, the convex portion 120b, and the intermediate portion 11b, i.e., on the +Z side. The tip portion 120c of the convex portion 120b, in particular, may be in contact with the second surface S2.

[0027] In one embodiment, the thicknesses of the first core 13R, the second core 13G, and the third core 13B in the Z direction may be uniform among all three cores. Furthermore, the shapes of the first end face eR, the second end face eG, and the third end face eB and the cross-sectional shapes perpendicular to the extension direction of the first core 13R, the second core 13G, and the third core 13B are rectangular in one embodiment, but are not limited thereto. For example, they may have a trapezoidal shape with different lengths of upper and lower sides, particularly with the lower side being longer than the upper side.

[0028] As shown in FIG. 2B , along cross-sectional line BB passing through the optical waveguide portion 12L, the upper surface of the substrate 11 has a stepped portion 11b0 that is one step higher in a range that does not contact both ends in the Y direction. The edge of the stepped portion 11b0 on the −X direction side may be the intermediate portion 11b. This stepped portion 11b0 may continue on the +X side to the third surface S3 of the substrate 11, as shown by the dotted line in FIG. 1A . The insulating layer 120 has an upper surface that is one step higher along this stepped portion 11b0 in a range that includes the stepped portion 11b0 in a planar view. If the material of the insulating layer 120 is the same as the material of the cladding 12, the first surface S1 is located along the upper surface of the substrate 11, including the stepped portion 11b0, as shown in the figure.

[0029] Fig. 3A is an enlarged perspective view of the housing portion C1 and the second surface S2. Fig. 3B is a cross-sectional view of Fig. 3A taken along the same cross-sectional line CC as Fig. 1B. In Fig. 3B, the material of the insulating layer 120 is shown separately from the material of the cladding 12.

[0030] As described above, the convex portion 120b of the insulating layer 120 extends linearly in the X direction toward the second portion 11a where the substrate 11 is exposed on the -X side, which is in front of the second surface S2. The end of the convex portion 120b opposite the tip portion 120c is connected to the flat portion 120a of the insulating layer 120, which extends toward the -X side and away from the second surface S2 within the accommodation section C1. That is, the convex portion 120b extends from the flat portion 120a toward the first end eR, the second end eG, and the third end eB in a plan view, respectively, connecting the flat portion 120a and the tip portion 120c. Note that the insulating layer 120 may also extend from the flat portion 120a to the vicinity of the corner where the wall portion 12W and the optical waveguide portion 12L are connected.

[0031] The light-emitting element 30 generates heat in response to light-emitting operation. This heat is transferred to the optical waveguide module 10, raising the temperature of the optical waveguide module 10, particularly in the area between the position overlapping the light-emitting element 30 in a planar view and the first end face eR, the second end face eG, and the third end face eB. The heated optical waveguide module 10 generates distortion due to thermal expansion. In areas where distortion is likely to be large between the light-emitting element 30 and the optical waveguide portion 12L and the core 13, the optical waveguide module 10 has an uneven shape formed by the second portion 11a and the convex portion 120b. This makes the optical waveguide module 10 less susceptible to deformation and reduces the risk of deterioration, breakage, or the like due to stress. Furthermore, by selectively increasing the thickness of the core 13, particularly along the extension line in a planar view, the heat capacity of the optical waveguide module 10 is increased along the core 13, thereby reducing the temperature rise of the optical waveguide module 10.

[0032] Furthermore, by increasing the unevenness between the light emitting element 30 and the core 13 in this way, stray light emitted by the light emitting element 30 that does not directly enter the core 13 is scattered by the unevenness, thereby reducing the incidence of stray light from a specific light emitting element 30 unintentionally entering another core 13.

[0033] A first electrode 141 and a second electrode 142 are located on the flat portion 120a. An electrode pad 141a is located at the tip of the first electrode 141 on the +X side. Here, there is a gap between the tip of the electrode pad 141a on the second surface S2 side and the second portion 11a, but this gap does not have to be present. Alternatively, the tip of the electrode pad 141a may further overlap the second portion 11a in a planar view. Furthermore, the light-emitting element 30 may protrude from above the electrode pad 141a toward the second portion 11a in a planar view. In this case, a portion of the light-emitting element 30 is separated from the bottom surface of the accommodation portion C1.

[0034] The width of the convex portion 120b in the Y direction may be greater than or equal to one-third and less than three times the width of the core 13. When the core 13 is trapezoidal, as described above, and has a non-uniform width, the minimum width of the core 13 is used as the standard. A certain size of the second portion 11a is required to adequately relieve stress caused by heat, etc. Therefore, the width of the convex portion 120b should not be significantly larger than the width of the core 13. Furthermore, since the air within the second portion 11a has significantly lower thermal conductivity than the insulating layer 120 and the substrate 11, a wider second portion 11a allows heat to be transmitted relatively more easily in the -Z and -X directions, thereby reducing the amount of heat transmitted to the core 13 and the optical waveguide portion 12L.

[0035] While the above restrictions apply, for example, by increasing the width of the protrusion 120b to about three times the width of the core 13, the heat capacity is appropriately increased and temperature rise near the first end face eR, the second end face eG, and the third end face eB is reduced. Furthermore, since the substrate 11 and the protrusion 120b are joined to widen the thicker portion, the rigidity of the optical waveguide module 10 is increased. On the other hand, if the width of the protrusion 120b is too narrow, the rigidity, i.e., the strength of the optical waveguide module 10, will be insufficient. Therefore, by making the width of the protrusion 120b at least about one-third the width of the core 13, stress can be effectively alleviated while the required structural strength can be obtained.

[0036] The length of the convex portion 120b in the X direction needs to be long enough to alleviate the stress. While not strictly required, the length of the convex portion 120b may be approximately the same as the minimum distance between the light-emitting end, which is the end on the +X side of the light-emitting element 30, and the end face of the core 13 onto which light from the light-emitting end is incident. In other words, if the length of the convex portion 120b in the X direction is approximately the same as the minimum distance, when the light-emitting element 30 is mounted near the +X side end on the electrode pad 141a, i.e., on the second surface S2 side, light emitted by the light-emitting element 30 is incident from the end face into the core 13 with little loss, and heat generated by the operation of the light-emitting element 30 is transmitted to the optical waveguide portion 12L within an allowable range.

[0037] The intermediate portion 11b of the substrate 11 may extend along the second surface S2 in the Y direction on both sides of the tip portion 120c. The intermediate portion 11b extends along the boundary between the second portion 11a, which is relatively thin, and the core 13 and the optical waveguide portion 12L, thereby increasing the rigidity of the optical waveguide module 10 and reducing breakage due to thermal expansion or the like.

[0038] As described above, the second surface S2 may have protrusions 1221, 1222 on both sides of the first end face eR of the first core 13R that is central in the Y direction. That is, the first end face eR of the first core 13R, the second end face eG of the second core 13G, and the third end face eB of the third core 13B may each be separated by the protrusions 1221, 1222. This makes it difficult for light emitted from the light-emitting element 30 to enter any core other than the corresponding core 13. Furthermore, light that does not directly enter the core 13 is scattered by the unevenness, reducing the incidence of stray light on the core 13.

[0039] The second surface S2 may be located at different positions in the X direction for each core 13, with the first end face eR, second end face eG, and third end face eB being offset from each other. In one embodiment, the first end face eR of the first core 13R may be located furthest back, i.e., lowered toward the +X side, and the second end face eG of the second core 13G may be located furthest forward, i.e., protruding toward the -X side. As described above, the protrusions 1221 and 1222 effectively reduce stray light entering the core 13. However, the end faces located closer to the +X side than the other end faces are more likely to receive stray light from uncorresponding light-emitting elements 30. In response to this, the size of the protrusions 1221 and 1222, i.e., the length in the X direction and the width in the Y direction, as well as the distance between the side surfaces of the protrusions 1221 and 1222 and the end faces, may be changed depending on the positional relationship of the end faces in the X direction. Alternatively, if stray light can be blocked from entering the light source 13 without any particular consideration to the width of the protrusion 122, the protrusion 122 may be as thin as possible within the range that can be manufactured.

[0040] These lengths can be determined based on, for example, the luminous efficiency of each light-emitting element 30 and the magnitude of loss in the core 13. A light-emitting element 30 with low luminous efficiency generates more heat to obtain the same amount of light as other light-emitting elements 30, so it is better for the core 13 to be farther away from the light-emitting element 30. On the other hand, if loss in each core 13 is likely to be large, the loss can be reduced by shortening the core 13. Therefore, in this case, the end face of the core 13 can be closer to the third surface S3. For example, the first core 13R, which guides light with high loss, such as red light, of the light-emitting element 30 can be adjusted to be shorter than the other second core 13G and third core 13B, thereby reducing the difference in loss.

[0041] Furthermore, the light emitting efficiency of the light emitting element 30R changes more significantly with temperature compared to other wavelengths. In other words, by placing the light emitting element 30R, which has poor temperature characteristics, in the center where heat dissipation efficiency is good, the heat dissipation area can be increased more efficiently and heat can be dissipated, thereby reducing the temperature rise due to heat generation of the light emitting element 30R. As a result, deterioration of the light emitting module 1, particularly the light emitting element 30R and its surrounding components, can be reduced.

[0042] The intermediate portion 11b may include a portion that snakes in the X direction along the unevenness of the protrusions 1221 and 1222 in a plan view, and a portion whose width in the X direction increases to fill in a portion that is relatively recessed toward the +X side compared to the protrusions 1221 and 1222. These combinations are not limited to those shown in the above embodiment. The intermediate portion 11b may have a uniform width and extend along the unevenness of the protrusions 1221 and 1222. The width here refers to the length perpendicular to the extension direction of the intermediate portion 11b extending along the second surface S2 in a plan view. Alternatively, the end surface of the intermediate portion 11b on the -X side may be flat, without corresponding to the unevenness of the second surface S2. The width in the X direction of the tip portion 120c may be a dimension corresponding to the width in the X direction of the intermediate portion 11b.

[0043] 4A, 4B, 5A, and 5B are perspective views showing several modified examples of the insulating layer 120 in the accommodation portion C1. The illustrated range is the same as that of FIG. 3A, and instead of the protrusion 120b, FIG. 4A shows a protrusion 120b1, and FIG. 4B shows a protrusion 120b2.

[0044] As shown in Figures 4A and 4B, the widths of the convex portions 120b1 and 120b2 in the Y direction are not uniform. The convex portion 120b1 in Figure 4A has a uniform width on the second surface S2 side. On the other hand, the convex portion 120b1 in Figure 4A has a tapered shape in plan view at the connection portion with the flat portion 120a, with the width increasing toward the flat portion 120a side. That is, the convex portion 120b1 has a shape that combines a tapered shape on a portion of the flat portion 120a side with a uniform-width linear shape on the second surface S2 side. Furthermore, the convex portion 120b2 in Figure 4B has a fillet shape in plan view, with both side surfaces extending in an arc toward the flat portion 120a and connected to each other at a portion of the flat portion 120a side.

[0045] In this case, the minimum width of the convex portions 120b1 and 120b2 in the Y direction may be in the range of 1 / 3 to 3 times the minimum width of the core 13.

[0046] As described above, the width of the convex portions 120b1 and 120b2 increases as they connect to the flat portion 120a, thereby alleviating stress caused by thermal expansion and the like. Furthermore, the increased rigidity of the wider portions increases the strength of the optical waveguide module 10 against irreversible deformation and breakage. Therefore, the optical waveguide module 10 can be further reduced in breakage and the like.

[0047] 5A, the intermediate portion 11b may not be present between the second portion 11a and the second surface S2, and the tip portion 120c may not be present at the connection portion of the convex portion 120b with the second surface S2. In this case, the second portion 11a and the convex portion 120b may be in direct contact with the second surface S2. When the intermediate portion 11b is part of the substrate 11, the shape of the stepped portion of the substrate 11 in this optical waveguide module 10 may also be different from that of the above embodiment and other modified examples.

[0048] 5B is a cross-sectional view taken along the cross-sectional line DD in FIG. 5A. The cross-sectional line DD passes through the convex portion 120b, the first core 13R, and the protruding portion 121. As shown in this cross-sectional view, the second surface S2 does not necessarily have to be aligned along the Z-axis direction. Furthermore, the angle of the cladding 12 with respect to the Z-axis direction, i.e., the tilt angle with respect to the XY plane, and the angle of the core 13 with respect to the Z-axis direction, i.e., the tilt angle with respect to the XY plane, may be different from each other. Note that the tilt angles shown in FIG. 5B are for illustrative purposes and do not necessarily reflect the actual angles.

[0049] 6 shows a cross-sectional perspective view of a modified example of the enlarged portion shown in FIG. 3B. In this modified example, the flat portion 120a and the convex portion 120b have different upper surface heights. This increases the number of uneven corners between the light-emitting element 30 and the second surface S2 when light emitted from the light-emitting element 30 on the electrode pad 141a does not directly enter the core 13. This further reflects stray light, making it less likely to enter the end surface, improving the quality of the light emitted from the light-emitting module 1.

[0050] Here, the substrate 11 extends upward from the bottom surface of the second portion 11 a at the portion overlapping the flat portion 120 a in a plan view, but is not limited to this. The upper surface of the substrate 11 may be flush with the second portion 11 a at the portion overlapping the flat portion 120 a in a plan view, and the thickness of the flat portion 120 a may be thicker than the thickness of the protruding portion 120 b.

[0051] 7A and 7B are diagrams showing modified examples of the second surface S2 and its periphery in the plan view of FIG. 1B. For illustrative purposes, the first core 13R, second core 13G, and third core 13B located inside the cladding 12 are shown instead of the protruding portion 121 that would normally be visible in a plan view. In the modified example of FIG. 7A, the relative positional relationship between the first end face eR, second end face eG, and third end face eB of the first core 13R, second core 13G, and third core 13B on the second surface S2 is different. The positions of the end faces may be adjusted appropriately depending on the length and shape of the core 13 onto which light of each wavelength is incident. Furthermore, as in this modified example, the width of the intermediate portion 11b may be approximately constant and extend along the irregularities of the second surface S2 in a plan view. In this manner, the width of the intermediate portion 11b may be specified. Furthermore, the protruding portions 1221 and 1222 may have rounded corners. A smaller radius of curvature of the corners scatters stray light more effectively, but a certain degree of radius of curvature relieves stress caused by thermal expansion and the like, making the light-emitting module 1 less susceptible to damage. Alternatively, the corners of the protrusions 1221 and 1222 may be chamfered instead of rounded.

[0052] As shown in the modified example of FIG. 7B , the protrusions 1221 and 1222 may be removed from the modified example of FIG. 7A . That is, the optical waveguide module 10 does not need to have the protrusions 1221 and 1222. There is inherent misalignment in the X direction between the first end face eR, the second end face eG, and the third end face eB. That is, the first end face eR at the center and the second end face eG and the third end face eB on either side are not in the same plane in the Y direction. This reduces the possibility that light from a light-emitting element other than the light-emitting element corresponding to a certain end face will be incident on that end face. Furthermore, the cladding 12 has uneven corners at the boundaries between the surface including the first end face eR, the surface including the second end face eG, and the surface including the third end face eB. Therefore, the unevenness effectively scatters stray light even without the protrusions 1221 and 1222.

[0053] FIG. 8 is an exploded perspective view of another modified example of the optical waveguide module 10, broken down into the substrate 11, insulating layer 120, and cladding 12. In this modified optical waveguide module 10, the second surface S2 may include a surface including the second end face eG and a surface including the third end face eB at the same position in the X direction. In this case, the second end face eG and the third end face eB sandwich a surface including the protrusions 1221, 1222 and the first end face eR between them. This reduces stray light incident on the second end face eG and the third end face eB, particularly light incident on the second end face eG from light-emitting elements 30 other than the light-emitting element 30G, and light incident on the third end face eB from light-emitting elements 30 other than the light-emitting element 30B. As described above, the substrate 11 has a step 11b0 extending from the +X side edge to the vicinity of the second surface S2, making it one step higher than the surrounding area.

[0054] The insulating layer 120 may have a hole 120d corresponding to the second portion 11a. A protrusion 120b extends in the X direction across this hole. The tip of the protrusion 120b on the +X side is tip portion 120c, which is located higher in the +Z direction than the protrusion 120b. The portion of the -X side of the protrusion 120b that corresponds to the bottom surface of the accommodation portion C1 is the first surface S1.

[0055] The clad 12 includes a first core 13R, a second core 13G, and a third core 13B in the +X-side optical waveguide portion 12L. The first end face eR of the first core R13, the second end face eG of the second core 13G, and the third core 13B are exposed facing the second surface S2. The first core 13R, the second core 13G, and the third core 13B each extend within the clad 12 along a range that overlaps with the protruding portion 121 in a planar view. The first core 13R may not have a uniform width in the Y direction. The second core 13G and the third core 13B may have a curved shape at any position. The first electrode 141 and the second electrode 142 located at the -X-side end of the clad 12 extend in the +X direction, passing through the wall portion 12W in a planar view and extending into the first region M. The +X-side end of the first electrode 141 is an electrode pad 141a.

[0056] 9 is a perspective view showing an example of AR (Augmented Reality) glasses G, which are electronic devices of this embodiment that use the light-emitting module 1. The AR glasses G are also called smart glasses.

[0057] The AR glasses G may have temples T and a display unit 80. The light-emitting module 1 may be located inside the temples T. The temples T may be bendable or non-bendable. If the temples T are bendable, the light-emitting module 1 may not emit light when bent.

[0058] The display unit 80 may have a scanning mirror 81 and a light guiding unit 82. The scanning mirror 81 is a MEMS (Micro-Electro Mechanical Systems) mirror that scans the light emitted from the light-emitting module 1. The scanned light is input to a light guide plate or a half mirror of the light guiding unit 82. The scanning mirror 81 may be located inside the temple T.

[0059] The light guide unit 82 may have a light guide plate or a half mirror as described above, and may project incident light onto the user's eyeball. The light guide unit 82 may also be optically transparent. For example, the light guide unit 82 may use a waveguide system or a half mirror system, allowing the user to view the projected image by superimposing it on the actual image transmitted through the display unit 80. In the case of a half mirror system, the light guide unit 82, which is a half mirror, may be separated from the glass surface. The display unit 80 may be transparent, or may be colored to block some of the transmitted light.

[0060] The projection image data is not particularly limited, but may be received from the outside via wireless communication or may be generated by the control unit 90 based on the measurement results of a sensor (not shown) provided in the AR glasses G. In addition, these types of image data may be used in combination.

[0061] The control unit 90 may have a CPU, RAM, and non-volatile memory, and may perform control processing related to image display. In addition to the above, the control unit 90 may also have an LD driver for controlling the LD and a MEMS driver for scanning and controlling the MEMS mirror. The communication unit, control unit 90, battery, etc. may be located inside or on the side of the temple T, or may be located externally via a cable.

[0062] Although the glass surfaces including the light guide section 82 are shown separately on the left and right here, the AR glasses G may have a single glass surface in the case of goggles, etc. Furthermore, the glass surface may have a large curved surface, particularly in the case of a half-mirror system.

[0063] In addition, the AR glasses G may be a head-mounted display that has a band or support for wearing on a person's head instead of temples T.

[0064] As described above, the optical waveguide substrate of this embodiment includes a base body including a substrate 11, a clad 12 located above the first surface S1, and a core 13 located within the clad 12. The base body may include an insulating layer 120. The first surface S1 and the second surface S2 of the clad 12 face the first region M. The core 13 includes a first core 13R. The first core 13R has a first end face eR exposed from the second surface S2 of the clad 12 to the first region M. The base body includes, in a range overlapping the first region M in a planar view, a first portion and a second portion 11a that contacts the first portion and is located at a position lower on the first surface S1 than the first portion. The first portion has a flat portion 120a that is separated from the second surface S2 in a planar view, and a convex portion 120b that is connected to the flat portion 120a and extends toward the first end face eR in a planar view. The flat portion 120a extends in the Y direction along the first end face eR in a plan view. The second portion 11a is located at least partially on both sides of the convex portion 120b in the Y direction. This optical waveguide substrate has the convex portion 120b at the portion where the first core 13R extends from the first end face eR in a plan view, and has relatively thin second portions 11a on both sides of the convex portion 120b. This non-uniform structure can alleviate stress when bending or distortion occurs in the optical waveguide substrate. Furthermore, since the convex portion 120b maintains its thickness, the rigidity of the bottom surface of the optical waveguide substrate is maintained. Therefore, the optical waveguide substrate is less susceptible to breakage due to bending or distortion, and can emit light stably and accurately. Furthermore, since the second portions 11a are provided on both sides of the flat portion 120a on which the light emitting element 30 is mounted in a plan view along the direction toward the first end face eR of the core 13, heat generated by the light emitting element 30 is less likely to be transmitted to the optical waveguide portion 12L of the cladding 12 or the core 13 than in other directions. At the same time, the presence of the protrusions 120b increases the heat capacity in the heat-transferring portion, thereby reducing the temperature rise in the optical waveguide substrate, particularly near the first end face eR, with a small amount of heat. As a result, thermal expansion can be reduced on the optical waveguide path side of the light emitting element 30, thereby reducing adverse effects on light transmission.Furthermore, since the convex portion 120b is located at a position corresponding to the first core 13R in the Y direction when viewed in a plane, it becomes easier to align the light-emitting element 30 with the optical waveguide substrate when manufacturing the light-emitting module 1, thereby reducing the effort required to manufacture the light-emitting module 1.

[0065] Furthermore, the second portion 11a may be an exposed surface of the substrate 11. If the substrate 11 is transparent, stray light that strikes the bottom surface of the second portion 11a can be transmitted through the substrate 11 and escape to the outside. This reduces the amount of stray light that enters the core 13. Even if the substrate 11 is opaque, the second portion 11a can absorb or reflect the stray light, thereby reducing the possibility of the stray light entering the core 13.

[0066] Furthermore, the minimum width of the convex portion 120b in the Y direction may be ⅓ to 3 times the minimum width of the first core 13R in the Y direction. If the width of the convex portion 120b is too small, the strength of the bottom surface of the light-emitting module 1 will be insufficient. Therefore, by making the width of the convex portion 120b not too small, damage due to deformation or distortion caused by thermal expansion, etc. will be reduced. On the other hand, if the width is small and the second portion 11a becomes relatively wide, heat generated by the light-emitting element 30 will not be easily transmitted to the optical waveguide portion 12L and the core 13, thereby reducing the adverse effects of heat on optical transmission.

[0067] Furthermore, the protrusion 120b may have a tip portion 120c that contacts at least the second surface S2 in a plan view. The tip portion 120c may be higher in the Z direction than the portion of the protrusion 120b other than the tip portion 120c. The presence of irregularities directly below the end face of the core 13 makes it easier for stray light to be scattered by the irregularities, thereby reducing the penetration of stray light into the core 13.

[0068] Furthermore, the optical waveguide module 10, which is a package for housing an electronic element including an optical waveguide substrate, may have an intermediate portion 11b, which is located between the second portion 11a and the second surface S in a plan view and is higher than the second portion 11a and lower than the tip portion 120c, as a portion higher than the second portion 11a. Such a step structure further scatters stray light, reducing the incidence of stray light on the core 13.

[0069] Furthermore, as shown in the modified example, the connection portions between the convex portions 120b1, 120b2 and the flat portion 120a may have a fillet shape or a tapered shape in a planar view. By gradually thickening the connection portions between the convex portions 120b1, 120b2 and the flat portion 120a, stress caused by distortion, which tends to increase due to thermal expansion or the like, particularly on the side of the connection portions closer to the light-emitting element 30 of the optical waveguide module 10, can be alleviated. Furthermore, by increasing the rigidity of the wider portions, the strength of the optical waveguide module 10 against distortion also increases. Therefore, the optical waveguide module 10 can be further reduced in damage and the like.

[0070] Furthermore, the insulating layer 120 may be integral with the clad 12. When the material of the insulating layer 120 is the same as the material of the clad 12, such as silicon dioxide, the insulating layer 120 is formed integrally with the clad 12, which reduces the effort required to manufacture the optical waveguide substrate compared to when the clad 12 and the insulating layer 120 are formed separately.

[0071] Furthermore, the insulating layer 120 may be integral with the substrate 11. When the surface of the substrate 11 is made of an insulating material, particularly silicon dioxide, the insulating layer 120 and the substrate 11 are integrally formed, thereby reducing the manufacturing effort. This makes it easier to obtain the optical waveguide module 10. Furthermore, when the inside of the second portion 11a is insulating, it can function as a groove for retaining overflowing adhesive when bonding the light emitting element 30 to the electrode pad 141a. This reduces the possibility of overflowing adhesive adhering to the light emitting end surface of the light emitting element 30 and interfering with light emission.

[0072] The cladding 12 may also have a protrusion 122 that protrudes from the second surface S2 into the first region M at a position separated from the first core 13R in a planar view. Positioning the protrusion 122 adjacent to the first end face eR of the first core 13R at a small distance reduces the possibility that stray light, which is emitted from the light-emitting element 30R and does not directly enter the first core 13R, enters the first core 13R. More specifically, scattering of the stray light by the protrusion 122 or the like reduces the possibility that the stray light enters the first core 13R. Meanwhile, the protrusion 122 reduces the possibility that light other than that from the light-emitting element 30R is directed toward the first core 13R, thereby reducing the possibility that unwanted light enters the first core 13R.

[0073] Furthermore, the protrusions 1221 and 1222 may be located on both sides of the first core 13R in the Y direction in a plan view. Since the stray light and other light entering the first core 13R is reduced on both sides of the first core 13R, the quality of the light entering the first core 13R can be further improved.

[0074] The core 13 may also include a second core 13G located within the cladding 12 and having a second end face eG exposed in the first region M, spaced apart from the first end face eR from the second surface S2 of the cladding 12. In this way, the optical waveguide module 10 can appropriately guide light of multiple wavelengths in parallel along the core 13 as described above. This allows incident light to be emitted more stably and accurately.

[0075] Furthermore, the cladding 12 may have a protrusion 1221 that protrudes into the first region M at a position between the first end face eR and the second end face eG in a planar view and that is spaced apart from the first core 13R and the second core 13G. By positioning the protrusion 1221 in this manner, the optical waveguide module 10 of the light-emitting module 1 can appropriately cause light emitted by the light-emitting element 30R to enter the first core 13R and light emitted by the light-emitting element 30G to enter the second core 13G. Therefore, the optical waveguide module 10 can accurately emit the light emitted by the light-emitting elements 30R and 30G.

[0076] The first end face eR and the second end face eG may be located at different positions in the X direction in a plan view. The difference in position in the X direction may be used to adjust the amount of light loss in response to adjustment of the path length between the first core 13R and the second core 13G. Furthermore, due to the misalignment in the X direction between the first end face eR and the second end face eG, the first end face eR and the second end face eG are not in the same plane, which can reduce the incidence of stray light on the first end face eR and the second end face eG.

[0077] The optical waveguide module 10 of this embodiment may also include an optical waveguide substrate including an optical waveguide portion 12L and a core 13, and an electrode 14 located on the flat portion 120a of the insulating layer 120. The cladding 12 may have a wall portion 12W surrounding the first region M in a planar view. With this optical waveguide module 10, as described above, adverse effects such as distortion of the optical waveguide module 10 due to stress caused by heat generated by operation of the light-emitting element 30 can be reduced. Therefore, the optical waveguide module 10 can more accurately and stably emit light from the light-emitting element 30 mounted in the first region M. Furthermore, the optical waveguide module 10 can easily seal the mounted light-emitting element 30 with the lid 40.

[0078] Furthermore, the light-emitting module 1 of this embodiment may include the above-described optical waveguide module 10, a light-emitting element 30 which is an electronic element located on the electrode 14 and facing the first end face eR, the second end face eG, and the third end face eB of the core 13 exposed to the first region M, and a lid 40 located on the cladding 12 and covering the first region M. Such a light-emitting module 1 is resistant to distortion as described above, reduces the adverse effects of heat generation, and can emit light from the light-emitting element 30 more accurately and stably.

[0079] Furthermore, the AR glasses G, which are the electronic device of this embodiment, may include the light-emitting module 1 described above and a display unit 80. The electronic element may be a light-emitting element 30. The display unit 80 may display an image using light emitted from the light-emitting module 1. With such AR glasses G, the light-emitting module 1 can display a stable and accurate image. In particular, the light-emitting module 1 can emit light stably and accurately even when used with a mobile device, so a stable image can be displayed even when the user uses the AR glasses G while moving.

[0080] The above embodiment is merely illustrative and various modifications are possible. For example, although the above description assumes that the surface of the second portion 11a is made of silicon from the substrate 11, this is not limiting. The insulating layer 120 may also be located on the surface of the second portion 11a. That is, the surface of the second portion 11a and the surface of the convex portion 120b may both be made of the insulating layer 120 but at different heights. When the second portion 11a is made of an insulating material, the second portion 11a also functions as a groove that can contain excess adhesive when bonding the light-emitting element 30 to the electrode pad 141a. This reduces the likelihood of problems such as the adhesive blocking the light-emitting end of the light-emitting element 30.

[0081] Furthermore, if the tip portion 120c is higher than the convex portion 120b and the intermediate portion 11b is higher than the second portion 11a, the heights of the second portion 11a and the intermediate portion 11b do not have to have the above-mentioned relationship.

[0082] In the above description, the flat portion 120a extending over the bottom surface of the first region M has a planar shape, but this is not limiting. The flat portion 120a only needs to be located at a minimum near the connection portion with the protruding portion 120b. The optical waveguide module 10 may have, for example, a portion of the insulating layer 120 having irregularities between the flat portion 120a and the wall portion 12W.

[0083] In the above description, the protrusions 120b are each described as having the same length on both sides in the Y direction facing the second portion 11a, but this is not limited to this. The length of the protrusions 120b facing the second portion 11a on the left and right sides may be different.

[0084] Furthermore, the shape of the protrusion 120b is not limited to the shape shown above. As long as the protrusion 120b extends in the X direction at the connection position on the second surface S2 side of the protrusion 120b, other portions may be bent or folded.

[0085] The material of the convex portion 120b may be the same as the material of the substrate 11, the same as the material of the insulating layer 120, or the same as the material of the clad 12. The material of the flat portion 120a may be the same as the material of the substrate 11, the same as the material of the insulating layer 120, or the same as the material of the clad 12. The flat portion 120a only needs to be flat at least in the portion connected to the convex portion 120b, and may have irregularities in the portion separated from the convex portion 120b, such as the portion where the electrode 14 is located.

[0086] In the above description, the first end face eR, the second end face eG, and the third end face eB are positioned differently in the X direction, but this is not limited to this. Two or more end faces may be positioned at the same position in the X direction. In this case, too, the protrusion 122 does not have to be positioned between the end faces. Furthermore, the protrusion 122 may be positioned only partially between three or more end faces.

[0087] Furthermore, in the above description, an embodiment in which the first region M is surrounded by the cladding 12 and the opening is covered with the lid 40 has been given as an example, but the present invention is not limited to this. As long as the first region M faces the bottom surface on which the light-emitting element 30 is mounted and the second surface S2 including the first end face eR, the second end face eG, and the third end face eB, other portions may be open in the optical waveguide module 10. All open surfaces may be sealed with the lid 40 or other members.

[0088] Although the above description has been given assuming that the second core 13G corresponds to the second core, the third core 13B may also be the second core. That is, there may be multiple second cores. Furthermore, in the above embodiment, the optical waveguide substrate has three cores that transmit light of three wavelengths, i.e., red light, green light, and blue light, respectively. However, this is not limited to this. The number of cores may be two or four or more. When the optical waveguide substrate has four or more cores, the fourth and subsequent cores may transmit light of the same wavelength as the other optical waveguides, or may include a core that transmits infrared light. Furthermore, although the three cores extend independently from the input end to the output end, this is not limited to this. Multiple cores may be combined along the way. Furthermore, the other ends and intermediate paths of the cores 13 other than the first end face eR, the second end face eG, and the third end face eB may be determined appropriately depending on the application, etc.

[0089] In the above description, the protrusion 120b and the second portions 11a on both sides thereof are provided for each of the multiple cores 13, but this is not limiting. It is sufficient that the protrusion 120b and the second portions 11a on both sides thereof are provided for at least one of the cores 13. For example, the second portions 11a may not be provided for the cores 13 corresponding to the light-emitting elements 30 that are expected to have little effect on temperature rise.

[0090] Furthermore, the above description has been given of the light-emitting module 1 in which light emitted by the light-emitting element 30 is input from the first end face eR, the second end face eG, and the third end face eB, respectively, and then output to approximately the same position. However, the present invention is not limited to this. The electronic module may, for example, have a light-receiving element as the electronic element, and the light guided along the core and output from the first end face eR, the second end face eG, and the third end face eB may be received by the light-receiving element. Furthermore, the light may include electromagnetic waves other than visible light, such as infrared light, as long as the wavelength is capable of being transmitted by the optical waveguide. Accordingly, the electronic element may also include a temperature measuring element for measuring temperature.

[0091] Furthermore, in the above description, smart glasses including a head-mounted display, AR glasses in this example, have been used as an example of an electronic device equipped with a light-emitting module having an optical waveguide. However, the present invention can also be used in other electronic devices. Examples of other electronic devices include head-up displays and projectors. Furthermore, various combinations of the embodiments and modifications are not limited to the examples of the above-described embodiments. Furthermore, combinations of the embodiments and modifications are also possible. Furthermore, the specific configurations, structures, positional relationships, materials, etc. shown in the above embodiments can be modified as appropriate without departing from the spirit of the present disclosure. The scope of the present invention includes the scope of the invention described in the claims and their equivalents.

[0092] The present disclosure can be used in optical waveguide substrates, packages for housing electronic elements, electronic modules, and electronic devices.

[0093] 1 Light emitting module 10 Optical waveguide module 11 Substrate 11a Second portion 11b Intermediate portion 11b0 Step portion 12 Cladding 120 Insulating layer 120a Flat portion 120b, 120b1, 120b2 Convex portion 120c Tip portion 121 Protruding portion 122, 1221, 1222 Protruding portion 12L Optical waveguide portion 12W Wall portion 13 Core 13R First core 13G Second core 13B Third core 14 Electrode 141 First electrode 141a Electrode pad 142 Second electrode 20 Lens 30, 30R, 30G, 30B Light emitting element 40 Lid 80 Display portion 81 Scanning mirror 82 Light guiding portion 90 Control portion C1 Storage portion G AR glass M First region S1 First surface S2 Second surface S3 Third surface T Temple W Bonding wire eR First end surface eG Second end surface eB Third end surface

Claims

1. An optical waveguide substrate comprising: a base including a substrate; a clad located above a first surface side of the base; and a core located within the clad, wherein the first surface and a second surface of the clad face a first region, the core includes a first core having a first end surface exposed from the second surface of the clad to the first region, the base includes, in an area overlapping with the first region in a planar view, a first portion and a second portion in contact with the first portion and at a position where the first surface is lower than the first portion, the first portion has a flat portion separated from the second surface in a planar view, and a convex portion connected to the flat portion and extending toward the first end surface in a planar view, the flat portion extends in a first direction along the first end surface in a planar view, and the second portion is located on at least a portion of each of both sides of the convex portion in the first direction.

2. The optical waveguide board according to claim 1, wherein the second portion is an exposed portion of the surface of the board.

3. An optical waveguide substrate according to claim 1 or 2, wherein the minimum width of said convex portion in said first direction is greater than or equal to 1 / 3 and less than or equal to 3 times the minimum width of said first core in said first direction.

4. An optical waveguide substrate according to any one of claims 1 to 3, wherein the convex portion has a tip portion that contacts at least the second surface in a planar view, and the tip portion is higher than the rest of the convex portion.

5. An optical waveguide board as claimed in claim 4, wherein said first portion is located between said second portion and said second surface in a plan view, and has an intermediate portion which is higher than said second portion and lower than said tip portion.

6. The optical waveguide substrate according to any one of claims 1 to 5, wherein a connection portion between the convex portion and the flat portion has a fillet shape or a tapered shape in a plan view.

7. The optical waveguide substrate according to any one of claims 1 to 6, wherein the first portion is integral with the cladding.

8. The optical waveguide substrate according to any one of claims 1 to 7, wherein the first portion is integral with the substrate.

9. An optical waveguide substrate according to any one of claims 1 to 8, wherein the cladding has a protruding portion that protrudes into the first region at a position spaced apart from the first core in a plan view.

10. The optical waveguide board according to claim 9, wherein the protrusions are located on both sides of the first core in the first direction in a plan view.

11. An optical waveguide substrate according to any one of claims 1 to 10, wherein the core includes a second core located within the cladding and having a second end face exposed to the first region from the second surface of the cladding, spaced apart from the first end face.

12. An optical waveguide substrate as claimed in claim 11, wherein the cladding has a protruding portion that is between the first end face and the second end face in a planar view and that protrudes into the first region at a position spaced apart from the first core and the second core.

13. The optical waveguide substrate according to claim 11 or 12, wherein the first end face and the second end face are located at different positions in a second direction perpendicular to the first direction in a plan view.

14. A package for housing an electronic element, comprising: an optical waveguide substrate according to any one of claims 1 to 13; and an electrode located in the first portion, wherein the cladding has a wall portion surrounding the first region in a plan view.

15. An electronic module comprising: a package for housing an electronic element as claimed in claim 14; an electronic element located on said electrode and facing the end face of said core exposed to said first region; and a lid located on said clad to cover said first region.

16. An electronic device comprising: the electronic module according to claim 15; and a display unit, wherein the electronic element is a light-emitting element, and the display unit performs display using light emitted from the electronic module.

Images