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

Abstract

This optical waveguide comprises: a cladding (12) having an emission surface (S1); and a core (13) located inside the cladding (12). The core (13) comprises a first core (13R) that linearly extends between a first end surface (eR1) and a second end surface (eR2), and a second core (13G) that is spaced apart from the first core (13R) in a direction (Y direction) orthogonal to the extension direction (X direction) of the first core and extends between a third end surface (eG1) and a fourth end surface (eG2). The first core (13R) has a first linear part (13R1) having one end that is the first end surface (eR1) and having a constant width, and a reduction part (13R2) connected to the first linear part (13R1) and having a cross-sectional area that decreases toward the second end surface (eR2). The second core (13G) has a first curved part (13G2) the distance of which from the first core (13R) decreases toward the fourth end surface (eG2). In side view, the reduction part (13R2) and the first curved part (13G2) have sections overlapping each other.

Description

Optical waveguide, package for storing electronic element, electronic module and electronic device

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

[0002] A multiplexer is known that combines optical waveguides that guide light of multiple wavelengths and outputs the combined light in the same direction and at the same position. On the other hand, International Publication No. 2017 / 090333 discloses an optical waveguide in which the optical waveguides are not combined, but the output end faces of the optical waveguides are brought close to each other and output the combined light in the same direction, thereby substantially combining the combined light.

[0003] (1) An optical waveguide according to the present disclosure includes a clad having a first surface and a core located within the clad. The core includes a first core extending in a first direction between a first end surface and a second end surface exposed from the first surface, and a second core spaced from the first core in a second direction perpendicular to the first direction and extending between a third end surface and a fourth end surface exposed from the first surface. The first core has a first linear portion having one end at the first end surface and a constant width in the second direction, and a tapered portion connected to the first linear portion, the cross-sectional area of ​​which in the second direction decreases as the second core approaches the second end surface. The second core has a first curved portion having a curved shape and the distance from the first core decreasing as the second core approaches the fourth end surface. In a side view along the second direction, the tapered portion and the first curved portion overlap each other. (2) In the optical waveguide described in (1) above, the third end face has a smaller area than the first end face. (3) In the optical waveguide described in (1) or (2) above, the second end face has a smaller area than the fourth end face. (4) In the optical waveguide described in any one of (1) to (3) above, the length of the tapered portion in the first direction is longer than the length of the first linear portion in the first direction. (5) In the optical waveguide described in any one of (1) to (4) above, the normal direction of the second end face is the same as the normal direction of the fourth end face, and the distance between the center position of the second end face and the center position of the fourth end face is 1 μm or more and 10 μm or less. (6) In the optical waveguide described in any one of (1) to (5) above, the path length of the first core is shorter than the path length of the second core. (7) In the optical waveguide described in any one of (1) to (6) above, the first core has one end at the second end face and a second straight portion having a constant width in the second direction. (8) In the optical waveguide described in any one of (1) to (7) above, the second core has one end at the third end face and a third straight portion connecting to the first curved portion, and one end at the fourth end face and connecting to the first curved portion, the first curved portion has a first arc portion connecting to the third straight portion and a second arc portion connecting to the fourth straight portion, and the radius of curvature of the first arc portion and the radius of curvature of the second arc portion are equal.(9) In the optical waveguide described in (8) above, the inclined angle of the first arc portion is equal to the inclined angle of the second arc portion. (10) In the optical waveguide described in any one of (1) to (9) above, the core includes a third core located on the opposite side of the first core in the second direction from the second core and spaced apart from the first core, the third core extending between a fifth end face and a sixth end face located on the first surface, the third core having a curved shape and including a second curved portion whose distance from the first core decreases as the third core approaches the first surface, and the second curved portion and the tapered portion have overlapping portions in a side view along the second direction. (11) In the optical waveguide described in (10) above, the area of ​​the third end face and the area of ​​the fifth end face are both smaller than the area of ​​the first end face. (12) In the optical waveguide described in (10) or (11) above, the distance between the center position of the third end face and the center position of the first end face is different from the distance between the center position of the fifth end face and the center position of the first end face. (13) In the optical waveguide described in (8) above, the core includes a third core positioned on the opposite side of the second core in the second direction across the first core, spaced apart from the first core, and extending between a fifth end face and a sixth end face located on the first surface, the third core having a curved shape and including a second curved portion whose distance to the first core decreases as it approaches the first surface, a fifth straight portion having one end at the fifth end face and connecting to the second curved portion, and a sixth straight portion having one end at the sixth end face and connecting to the second curved portion, the second curved portion including a third arc portion connecting to the fifth straight portion and a fourth arc portion connecting to the sixth straight portion, the radius of curvature of the third arc portion and the radius of curvature of the fourth arc portion being equal, and the second curved portion and the narrowing portion having an overlapping portion in a side view along the second direction. (14) In the optical waveguide described in (13) above, the circumferential angle of the third arc portion is equal to the circumferential angle of the fourth arc portion. (15) In the optical waveguide described in (13) or (14) above, the radius of curvature of the first arc portion is different from the radius of curvature of the third arc portion. (16) In the optical waveguide described in any one of (13) to (15) above, the path length of the fifth straight portion and the path length of the sixth straight portion are different from the path length of the first straight portion.(17) In the optical waveguide described in any one of (10) to (12) above, the width of a cross section perpendicular to the extension direction of the second core and the width of a cross section perpendicular to the extension direction of the third core are each constant. (18) An electronic element storage package according to the present disclosure includes a substrate having a second surface, the optical waveguide described in any one of (1) to (17) located on the second surface, and an electrode located in an element mounting area above the second surface, wherein the cladding has a wall portion surrounding the element mounting area, and the first end face and the third end face are exposed on a third surface of the wall portion. (19) An electronic module according to the present disclosure includes the package for electronic element storage according to (18) above, an electronic element located in the element mounting area, and a lid located on the cladding and covering the element mounting area, wherein the electrode includes a first electrode and a second electrode, and the electronic element includes a first electronic element connected to the first electrode and a second electronic element connected to the second electrode. (20) An electronic device according to the present disclosure includes the electronic module according to (19) 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] FIG. 2B is an overall perspective view of a light emitting module having an optical waveguide of this embodiment; FIG. 3 is a plan view of the light emitting module; FIG. 4 is a cross-sectional view taken along the cross-sectional line AA in FIG. 2A; FIG. 5 is a diagram illustrating a side view of an optical waveguide module; FIG. 6 is a diagram illustrating the shape of a core; FIG. 7 is a perspective view showing the overall structure of a light emitting module of a second embodiment; FIG. 8 is a perspective view showing the overall structure of a light emitting module of a third embodiment; and FIG. 9 is a perspective view showing an example of AR glasses using a light emitting module.

[0005] Hereinafter, an embodiment will be described with reference to the drawings. FIG. 1 is an overall perspective view of a light-emitting module 1 having an optical waveguide according to this embodiment. FIG. 2A is a plan view of the light-emitting module 1 as viewed from above. FIG. 2B is a cross-sectional view taken along the section line AA in FIG. 2A. FIG. 2C is a side view of the optical waveguide module 10 as viewed from the light emission surface S1 side. Note that FIG. 2A does not include the lid 40. The light-emitting module 1, which is an electronic module according to this embodiment, includes the optical waveguide module 10, a lens 20, a light-emitting element 30, and a lid 40.

[0006] An 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, as shown in FIGS. 1 and 2A, a plane parallel to a plane including the central axis of the waveguide path, particularly the core 13, is defined as an XY plane, and the X axis is defined along the longitudinal direction. The Y axis is a direction perpendicular to the X axis within the XY plane. The X axis is defined as a first direction, and the Y axis is defined as a second direction. The Z axis is defined as the direction perpendicular to the XY plane. In a plan view from above along the Z axis, the optical waveguide module 10 according to this embodiment has a substantially rectangular shape, but is not limited to this.

[0007] 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.

[0008] The core 13 is located inside 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 made of silicon dioxide and the core 13 may be made of 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 depends on the structure of the core 13, such as its shape, but can be set to, for example, approximately 0.01 or more and 2.0 or less. This results in the optical waveguide of this embodiment, in which light incident on one end of the core 13 propagates along the core 13. In one embodiment, there are three independent cores 13. In one embodiment, the cross section of each core 13 perpendicular to the central axis (extension direction) may be rectangular or trapezoidal.

[0009] The clad 12 is located on one surface of the flat substrate 11, here the top surface S2, which is the +Z side surface. The top surface S2 is the second surface. The cores 13 in the clad 12 are exposed from the clad 12 on two different surfaces in the X direction, which is the longitudinal direction of the optical waveguide module 10. The three cores 13 are spaced apart from one another in the Y direction. The end surface on the +X side of the clad 12 is the output surface S1. The output surface S1 is the first surface. As shown in FIG. 2C , the second end surface eR2, fourth end surface eG2, and sixth end surface eB2 of each of the three cores 13 may be exposed in the same direction, without contacting each other, at nearby positions on the output surface S1, i.e., with the normal directions of each end surface parallel to one another. Note that in each figure, for the sake of explanation, the ratios of the width, length, and spacing of the cores 13 do not necessarily reflect actual values.

[0010] In one embodiment, the thickness h of the cores 13 in the Z direction may be uniform among all three cores 13. When varying the cross-sectional area of ​​the cores 13 in a cross section perpendicular to the extension direction, it is easier to manufacture the cores 13 by making the thickness h uniform and varying the width along the cross section in a plan view, rather than by varying the thickness h. The cladding 12 has a protrusion 121 that protrudes upward along the core 13 within a range that includes the core 13 in a plan view (planar perspective). The height of the protrusion 121 is approximately the same as the thickness of the core 13, here about 2 to 10 μm, but it may be smaller or larger.

[0011] 1 and 2A, the cladding 12 may have a recess C1 on the -X side of the core 13, the recess C1 opening to the +Z side opposite the surface facing the top surface S2 of the substrate 11. Therefore, the cladding 12 has an optical waveguide portion 12L on the +X side of the recess C1 in which the core 13 is located, and wall portions 12W that are sidewall portions connected to the optical waveguide portion 12L and surround the recess C1 on three sides, i.e., in the ±Y and -X directions. The recess C1 may penetrate the cladding 12, exposing a portion of the substrate 11 at the bottom surface.

[0012] The substrate 11 may also have an insulating layer on its upper surface S2. More specifically, the insulating layer may be located, for example, in a portion of the clad 12 on the substrate 11 side, below the dotted line in FIG. 1 . This insulating layer may be exposed at the bottom surface of the recess C1. The insulating layer may extend over substantially the entire upper surface of the substrate 11, or may be selectively located only within the recess C1. The insulating layer does not have to be a uniform flat surface, and may have internal irregularities. If the insulating layer is made of the same material as the clad 12, for example, silicon dioxide, the insulating layer may be integral with the clad 12.

[0013] The inside of the recess C1 may be an element mounting region M on which the light emitting element 30 is mounted. Three sets of electrodes 14 may be arranged in the Y direction on the bottom surface of the recess C1. As shown in FIG. 2A , each set of electrodes 14 includes a first electrode 141 connected to an electrode pad 141 a and a second electrode 142.

[0014] The light-emitting elements 30 are positioned on the electrode pads 141a of the first electrodes 141, electrically connected to the electrode pads 141a. Connection terminals (not shown) may be positioned 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, for example, with a brazing material or a conductive adhesive. The electrode pads 141a may be positioned on part or all of the upper surface of an insulating element mounting portion protruding from the bottom surface of the recess C1. The element mounting portion may be made of the same material as the bottom surface of the recess C1. If an insulating layer is present on the substrate 11, the surface of the element mounting portion may be covered with this insulating layer, and the interior may be made of the same material as the substrate 11. If the bottom surface is not made of an insulating material, the element mounting portion is insulated from the bottom substrate 11 by an element mounting portion made of an insulating material different from the bottom surface.

[0015] The second electrode 142 may be electrically connected to the other electrode of the light-emitting element 30. The connection may be by a bonding wire W. Note that the tip of the second electrode 142 may also have an electrode pad for joining the bonding wire W.

[0016] Each electrode 14 may extend to the outside of the recess C1 through between the wall portion 12W of the cladding 12 and the substrate 11. When a drive voltage is applied between each pair of the first electrode 141 and the second electrode 142 outside the recess C1, the light-emitting element 30 emits light.

[0017] Of the sidewall surfaces facing the recess C1, the surface on the +X side, i.e., the surface of the optical waveguide portion 12L, may be an incident surface S3 where the first end face eR1, the third end face eG1, and the fifth end face eB1 of the core 13 are exposed side by side, as shown in FIG. 2B . The incident surface S3 is the third surface. The first end face eR1, the third end face eG1, and the fifth end face eB1 may each face the light-emitting ends of the three light-emitting elements 30, or may be end faces through which light is incident into the core 13. The core 13 connects the first end face eR1 and the second end face eR2, the third end face eG1 and the fourth end face eG2, and the fifth end face eB1 and the sixth end face eB2. The center positions of the first end face eR1 and the second end face eR2 may be the same in the Y direction, which is perpendicular to the X and Z directions.

[0018] The first end face eR1, the third end face eG1, and the fifth end face eB1 are spaced apart by distances d11 and d12 in the Y direction. The distances d11 and d12 are greater than the width of each light-emitting element 30 in the Y direction and can be determined so as to reduce stray light from the light emitted from each light-emitting element 30 entering each end face. In one embodiment, protrusions 122 of the cladding 12 may be located between the first end face eR1 and the third end face eG1 and between the first end face eR1 and the fifth end face eB1. This allows the incidence of stray light from each light-emitting element 30 to the other end faces to be reduced without making the distances d11 and d12 larger than the width of the light-emitting element 30.

[0019] 1 and other figures, a lens 20 may be located on the output side of the second end face eR2, the fourth end face eG2, and the sixth end face eB2 of the optical waveguide module 10. The second end face eR2, the fourth end face eG2, and the sixth end face eB2 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 component that has the function of converting the light emitted from the second end face eR2, the fourth end face eG2, and the sixth end face eB2 into parallel light.

[0020] A lid 40 may be bonded to the clad 12 around the upper portion of the recess C1. That is, the lid 40 may cover the element mounting region M and seal the recess C1. In one embodiment, the upper surface of the light-emitting element 30 bonded to the electrode 14 may be lower in the Z direction than the upper surface of the clad 12. Therefore, the lid 40 may be flat or have a small recess corresponding to the protrusion 121. When the upper surface of the light-emitting element 30 is higher than the upper surface of the clad 12, the lid 40 may have a recess on its lower surface, i.e., on the -Z side. The lid 40 may be made of, 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 lid 40 may have a plating layer on its surface. Examples of the plating layer include gold and nickel. A ring-shaped conductor may be positioned between the lid 40 and the optical waveguide module 10 (clad 12). By joining them with the conductor sandwiched between them, the airtightness of the recess C1 is improved compared to when the lid 40 and the optical waveguide module 10 are directly joined with a resin-based adhesive.

[0021] The light-emitting elements 30 are electronic elements of this embodiment, such as 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. As shown in FIG. 2A , these light-emitting elements 30 may include, for example, a light-emitting element 30R (first electronic element) that is a red-emitting LD, a light-emitting element 30G (second electronic element) 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 at the center of the three light-emitting elements 30 in the Y direction and emit red light to the first end face eR1. The light-emitting element 30G and the light-emitting element 30B are located on either side of the light-emitting element 30R, with the light-emitting element 30G emitting green light to the third end face eG1 and the light-emitting element 30B emitting blue light to the fifth end face eB1. The positions of the LDs are not limited to the above and may be changed as appropriate.

[0022] The shape of the core 13 in the cladding 12 will be described in more detail below. FIG.

[0023] Of the three cores 13, the central first core 13R may be a member for transmitting light from the light-emitting element 30R as described above. The second core 13G may be a member for transmitting light from the light-emitting element 30G. The third core 13B may be a member for transmitting light from the light-emitting element 30B.

[0024] The first core 13R has a linear shape extending in the X direction. The first core 13R has first linear portions 13R1 at both ends, each having a constant width in the Y direction (second direction) in a plan view, i.e., a direction perpendicular to the extension direction of the first core 13R. The first core 13R may further have a second linear portion 13R3. Between the first linear portion 13R1 and the second linear portion 13R3, there is a tapered portion 13R2 whose width in a plan view decreases, i.e., gradually decreases, as it approaches the second end face eR2. As described above, since the thickness h of the first core 13R is constant, if the width is constant, the cross-sectional area in a cross-sectional view perpendicular to the X direction and parallel to the Y direction is constant. As the width gradually decreases, the cross-sectional area also gradually decreases.

[0025] The second core 13G has a first curved portion 13G2. The first curved portion 13G2 is curved so that the distance from the first core 13R decreases as the second core 13G approaches the fourth end face eG2. The second core 13G may have a third straight portion 13G1 tangent to the third end face eG1 and a fourth straight portion 13G3 tangent to the fourth end face eG2. The third core 13B is located on the opposite side of the second core 13G in the Y direction across the first core 13R in a plan view. The third core 13B has a second curved portion 13B2. The second curved portion 13B2 is curved so that the distance from the first core 13R decreases as the second core 13B approaches the sixth end face eB2. The third core 13B may have a fifth straight portion 13B1 tangent to the fifth end face eB1 and a sixth straight portion 13B3 tangent to the sixth end face eB2. In the X direction, i.e., in a side view from the Y direction, the positions of the first curved portion 13G2 and the second curved portion 13B2 overlap with the position of the contracted portion 13R2. The contracted portion 13R2, the first curved portion 13G2, and the second curved portion 13B2 have greater light leakage than straight portions. In a plan view, the inclined portions of the side surfaces of these cores 13 are aligned in at least a portion of the same range in the longitudinal direction, making it difficult for light leaking from one core to enter another core. Therefore, by increasing the proportion of the overlapping portions as much as possible, the above-mentioned effects can be more effectively achieved. The overlapping portions may, for example, account for 90% or more, more preferably 95% or more, of the lengths of the first curved portion 13G2 and the second curved portion 13B2 in the X direction.

[0026] The distance d21 between the center of the second end face eR2 and the center of the sixth end face eB2 may be equal to the distance d22 between the center of the second end face eR2 and the center of the fourth end face eG2. The distances d21 and d22 may be 1 μm or more and 10 μm or less, for example, 7.0 μm or 9.5 μm. By positioning the second end face eR2, the fourth end face eG2, and the sixth end face eB2 at such approximately equal distances d21 and d22, the three wavelengths of light are emitted to approximately the same position and in the same direction with sufficient visual accuracy without being multiplexed into a single optical waveguide (core). Note that, if the required resolution is low, the distances may be 10 μm or more. If the distances d21 and d22 are 1 μm or less, the processing precision required during manufacturing increases, resulting in increased costs and effort. Furthermore, when the distances d21 and d22 are 1 μm or less, even if the cores do not merge, the light from one core may cross the thin cladding 12 and pass to the adjacent core.

[0027] Because the first core 13R is positioned linearly at the center of the core 13 in the width direction, i.e., the Y direction, the path length between both end faces of the first core 13R is shorter than the path lengths of the second core 13G and the third core 13B. For example, the brightness of a red-emitting LD is more likely to decrease with increasing temperature than that of a blue-emitting LD or a green-emitting LD. Therefore, by passing the light from the red-emitting LD through an optical waveguide with a relatively short path length, in this case the first core 13R, it is possible to reduce the possibility that the loss of red light will be uneven compared to the loss of blue and green light.

[0028] The third end face eG1, the fifth end face eB1, the fourth end face eG2, and the sixth end face eB2 may have the same width w2 in a planar view. Specifically, the width w2 may be, for example, approximately 2 to 8 μm. Furthermore, the width of a cross section perpendicular to the extension direction of each of the second core 13G and the third core 13B may be constant between the third end face eG1 and the fourth end face eG2 and between the fifth end face eB1 and the sixth end face eB2. When the thickness h is constant, the cross-sectional area of ​​the cross section is constant between the third end face eG1 and the fourth end face eG2 and between the fifth end face eB1 and the sixth end face eB2. In other words, by keeping the cross-sectional area of ​​the second core 13G and the third core 13B constant, it is possible to reduce the increase in the amount of light leakage from curved portions, which have greater light leakage than straight portions, thereby reducing light loss. Furthermore, since the second core 13G and the third core 13B have the same width, the energy density distribution of the light passing through them becomes symmetrical, and the heat distribution can also be made closer to symmetry, which makes it possible to disperse and alleviate stresses associated with deformation, particularly stresses caused by expansion due to temperature rise.

[0029] Meanwhile, the first end face eR1 has a width w11 in a plan view, and the second end face eR2 has a width w12 in a plan view. Specifically, the width w12 may be, for example, 1 to 5 μm. As described above, in the reduced portion 13R2, the width of the first core 13R in a plan view gradually decreases from width w11 to width w12. In one embodiment, the decrease from width w11 to width w12 may be at a constant rate. The rate of decrease represents the amount of decrease in width in the Y direction per length in the X direction. The line in a plan view of the side surface of the reduced portion 13R2 may be a straight, tapered shape. Furthermore, the reduction angle, which is the angle formed by the side surface of the reduced portion 13R2 with respect to the side surface of the first linear portion 13R1, may be the same on both the left and right sides. If the reduction angle is not the same on both the left and right sides, one of the reduction angles with respect to the first linear portion 13R1 will be larger than if the reduction angle is the same on both the left and right sides. Therefore, there is a tendency for light leakage from the first core 13R to increase as the reduction angle increases. For this reason, by making the reduction angles for both side surfaces of the first linear portion 13R1 the same, it is possible to reduce light leakage from the first core 13R.

[0030] The area of ​​the first end face eR1, which is the incident end of the first core 13R, may be larger than the area of ​​the third end face eG1 and / or the fifth end face eB1. For example, the width w11 of the first end face eR1 may be larger than the width w2 of the third end face eG1 and the fifth end face eB1. The width w11 may be, for example, 5 μm or more larger than the width w2. The wider end face width compared to the size of the light-emitting end of the light-emitting element 30 improves the tolerance for misalignment of the mounting position of the light-emitting element 30. Furthermore, the wider width of the first end face eR1 of the first core 13R than the widths of the other end faces reduces the energy density relative to the amount of incident light. For example, red-emitting LDs are more likely to experience a decrease in brightness due to temperature increases than other light-emitting LDs. However, the above-described configuration can reduce the energy density. This reduces the possibility of a significant temperature increase near the first end face eR1 compared to other areas. This reduces the possibility of a decrease in brightness of the red-emitting LD.

[0031] Each core 13 may have a first linear portion 13R1, a third linear portion 13G1, and a fifth linear portion 13B1 whose width, cross-sectional area, and orientation do not change near the first end face eR1, the third end face eG1, and the fifth end face eB1, respectively. Each core 13 may also have a second linear portion 13R3, a fourth linear portion 13G3, and a sixth linear portion 13B3 whose width, cross-sectional area, and orientation do not change near the second end face eR2, the fourth end face eG2, and the sixth end face eB2, respectively. This reduces light leakage from the core 13. Furthermore, the beam shape of the emitted light can be stabilized by passing light through the second linear portion 13R3, the fourth linear portion 13G3, and the sixth linear portion 13B3 before emission. The length of each linear portion on the emission side is at least as long as necessary to stabilize the beam shape according to the resolution of the output image, and is within a range in which the disadvantages of loss due to excessive length are not significant. Therefore, the length of each straight line portion may be determined appropriately depending on the above conditions, and may be, for example, 50 μm or more and approximately 200 μm in the range of visible light. When the second straight line portion 13R3, the fourth straight line portion 13G3, and the sixth straight line portion 13B3 are each parallel to the X direction, the lengths of the second straight line portion 13R3, the fourth straight line portion 13G3, and the sixth straight line portion 13B3 are equal to the lengths in the X direction.

[0032] The length of the reduced portion 13R2 may be longer than the length of the first linear portion 13R1 and the length of the second linear portion 13R3. Specifically, the length of the reduced portion 13R2 may be, for example, 500 μm or more and 3000 μm or less. The length of the first linear portion 13R1 may be, for example, 50 μm or more and 300 μm or less. Since the light is not sharply narrowed in the reduced portion 13R2, light leakage is reduced. In this case, if the second end face eR2 becomes too small, the emitted light is likely to diffuse. By narrowing the second end face eR2 for red light to a smaller size than the fourth end face eG2 for green light and the sixth end face eB2 for blue light, which are relatively more easily diffused than red light, the degree of diffusion of light of each wavelength can be made closer.

[0033] The second core 13G and the third core 13B may have a uniform width perpendicular to the extension direction in a plan view. The width w2 of the second core 13G and the third core 13B may be smaller than the width w11 of the first end face eR1 of the first core 13R. The width w2 of the second core 13G and the third core 13B may be larger than the width w12 of the second end face eR2 of the first core 13R. The thickness h of the core 13 may be approximately the same as the widths of the second end face eR2, the fourth end face eG2, and the sixth end face eB2. For example, the thickness h of the core 13 may be larger than the width w12 of the second end face eR2 of the first core 13R and smaller than the width w2 of the end faces of the second core 13G and the third core 13B.

[0034] The first curved portion 13G2 of the second core 13G may have a shape that combines a first arc portion 13G21 and a second arc portion 13G22, which have the same radius of curvature R1 and the same circumferential angle T1 (length LG = R1 × T1) and have opposite rotation axes. The first arc portion 13G21 may be connected to the third straight portion 13G1. The second arc portion 13G22 may be connected to the fourth straight portion 13G3. The second curved portion 13B2 of the third core 13B may have a shape that combines a third arc portion 13B21 and a fourth arc portion 13B22, which have the same radius of curvature R2 and the same circumferential angle T2 (length LB = R2 × T2) and have opposite rotation axes. The third arc portion 13B21 may be connected to the fifth straight portion 13B1. The fourth arc portion 13B22 may be connected to the sixth linear portion 13B3. This allows the first curved portion 13G2 and the second curved portion 13B2 to have shapes symmetrical with respect to their respective midpoints, thereby reducing light loss in the second core 13G and the third core 13B. Furthermore, since the first curved portion 13G2 and the second curved portion 13B2 have shapes that are approximately symmetrical with respect to the first core 13R, it is easy to cancel out, for example, the Y-direction component of the stress that the optical waveguide module 10 receives due to heat from the light-emitting element 30. This reduces the amount of distortion in the optical waveguide as a whole and makes it less likely that distortion will be biased in one direction.

[0035] The curvature radius R1 and the curvature radius R2 may be different from each other. In one embodiment, the curvature radius R1 may be greater than the curvature radius R2. Specifically, for example, the curvature radius R1 may be 3.5 mm or greater and 5.0 mm or less. The curvature radius R2 may be 3.0 mm or greater and 4.5 mm or less. On the other hand, the circumferential angle T1 may be smaller than the circumferential angle T2. Specifically, the circumferential angle T1 and the circumferential angle T2 may be 10.0° or greater and 15.0° or less. In one embodiment, the circumferential angle T1 may be smaller than the circumferential angle T2 by approximately 0.5° or greater and 3° or less. Therefore, the length LG of the first curved portion 13G2 and the length LB of the second curved portion 13B2 may be approximately the same. In one embodiment, the length LB may be slightly greater than the length LG. On the other hand, the distance d12 may be smaller than the distance d11. Specifically, the distances d11 and d12 may be, for example, 200 μm or more and 300 μm or less. Blue light tends to be scattered slightly more than green light at the curved portions. Therefore, the radius of curvature R2 of the second curved portion 13B2 of the third core 13B is larger than the radius of curvature R1 of the first curved portion 13G2 of the second core 13G, i.e., the curve is gentler, which reduces the scattering of blue light compared to the scattering of green light and reduces light loss. Meanwhile, the light-emitting element 30G tends to generate more heat than the light-emitting element 30B for the same amount of light. By positioning the light-emitting element 30G farther from the center of the optical waveguide module 10 than the light-emitting element 30B, the impact of heat on the optical waveguide module 10 can be reduced to the extent of the impact of the light-emitting element 30G.

[0036] The length L11 of the third straight portion 13G1 on the incident side and the length L12 of the fifth straight portion 13B1 may be equal. Specifically, the lengths L11 and L12 may be, for example, 50 μm or more and 300 μm or less. This allows the blue and green incident light to experience approximately the same loss before entering the first curved portion 13G2 and the second curved portion 13B2, thereby reducing unevenness in the amount of light. Accordingly, the amounts of heat generated by the passage of light through the third straight portion 13G1 and the fifth straight portion 13B1 are also approximately the same, thereby reducing the possibility of uneven distortion of the optical waveguide module 10. Furthermore, because the third straight portion 13G1 and the fifth straight portion 13B1 are parallel straight lines, part of the distortion of the second core 13G and the third core 13B caused by heat along the lines, mainly the distortion component in the Y direction, is canceled out. By setting the length of the third straight portion 13G1 to approximately 50 times the wavelength of the light from the light-emitting element 30G or more, the effects of scattering and reflection of light from the third end face eG1 can be kept away from the first curved portion 13G2. If the length of the third straight portion 13G1 is approximately 300 times the wavelength of the light from the light-emitting element 30G or more, significant light loss may occur. Therefore, the length L11 of the third straight portion 13G1 may be, for example, approximately 50 μm or more and 300 μm or less. The length L12 of the fifth straight portion 13B1 may also be set as described above depending on its relationship with the wavelength of the light from the light-emitting element 30B. Meanwhile, the length L31 of the fourth straight portion 13G3 and the length L32 of the sixth straight portion 13B3 on the output side may be different. Furthermore, the length L33 of the second straight portion 13R3 may be longer than the length L31 but shorter than the length L32. Specifically, the lengths L31, L32, and L33 may be, for example, 50 μm or more and 300 μm or less. In one embodiment, the length of the fourth straight portion 13G3 may be longer than the length of the sixth straight portion 13B3. The path length of the second core 13G is the sum of the length of the fourth straight portion 13G3, the lengths of the third straight portion 13G1, and the first curved portion 13G2. The path length of the third core 13B is the sum of the length of the sixth straight portion 13B3, the length of the fifth straight portion 13B1, and the length of the second curved portion 13B2. The path length of the second core 13G may be longer than the path length of the third core 13B.Note that the positions of the second end face eR2, the fourth end face eG2, and the sixth end face eB2 in the X direction may be aligned regardless of the above. For this reason, the length L31 of the fourth straight portion 13G3 may also be different from the lengths of the first straight portion 13R1, the third straight portion 13G1, or the fifth straight portion 13B1 on the incident side, such as the length of the first straight portion 13R1.

[0037] The first end face eR1, the third end face eG1, and the fifth end face eB1 are located at different positions in the X direction on the incident surface S3. The first end face eR1 is closest to the second end face eR2, and therefore the path length of the first core 13R is short. The third end face eG1 is farther from the output surface S1 than the fifth end face eB1. These positions may be determined based on the difference in heat generation between the light-emitting element 30G, which is a green-emitting LD, and the light-emitting element 30B, which is a blue-emitting LD, among the light-emitting elements 30, or the difference in the radius of curvature between the first curved portion 13G2 and the second curved portion 13B2.

[0038] By defining the shapes of the multiple cores 13 as described above, it becomes possible to emit light of each wavelength from the light-emitting module 1 with higher propagation efficiency and more uniform light intensity than conventionally.

[0039] Second Embodiment In the first embodiment, the light emitting element 30 is sealed by the lid 40 in the recess C1 of the light emitting module 1. However, the entire light emitting module may be sealed in a package.

[0040] 4 is a perspective view showing the overall structure of a light emitting module 1a according to the second embodiment. The light emitting module 1a includes an optical waveguide module 10a, a light emitting element 30, a package 50, and a lid 40a.

[0041] The entire optical waveguide module 10a is located within a recess C5a of a package 50. A lid 40a seals the open upper surface of the recess C5a of the package 50. The package 50 may be made of, for example, ceramic, which has high thermal conductivity.

[0042] The optical waveguide module 10a may have, instead of the recess C1, a step C1a that is one step lower than the upper surface of the cladding 12 over the entire area on the light emitting element 30 side of the incident surface S3, i.e., the -X side.

[0043] The package 50 has a recess C5a large enough to accommodate the optical waveguide module 10a, and a window 51. The window 51 is located in the direction of emission of light from the second end face eR2, the fourth end face eG2, and the sixth end face eB2. The window 51 may be a light-transmitting member that can convert the emission light into parallel light in place of the lens 20. Alternatively, the window 51 may be a member that simply transmits light, and the lens 20 may be located within the package 50 along the emission surface S1, as in the first embodiment.

[0044] The package 50 may have connection electrodes (not shown) exposed on the inner surface of the sidewall. The connection electrodes are electrically connected to the electrodes 14. Electrical wiring is located within the sidewall, connecting the connection electrodes to external electrodes (not shown) located on the outer surface of the package 50. The external electrodes may be located on the outer surface of the sidewall, or on the bottom surface of the package 50. The package 50 may be made of the same material as the substrate 11, or may be made of a different material. That is, the package 50 may be made of silicon, a ceramic material, or an organic resin.

[0045] Third Embodiment Figure 5 is a perspective view showing the overall structure of a light-emitting module 1b according to a third embodiment. In one embodiment, the substrate of the optical waveguide module 10b does not need to extend below the element mounting region M. That is, the light-emitting element 30 may be located directly on the bottom surface of the package 50b. Furthermore, the optical waveguide module 10b may not have a substrate; that is, the bottom surface of the cladding 12 may be in contact with the bottom surface of the package 50b. In this case, electrodes 54 may also be located on the bottom surface of the package 50b, and these electrodes may be connected to wiring within the sidewall or bottom plate of the package 50b. Alternatively, two electrodes of the light-emitting element 30 may be connected to two electrodes located on the sidewall of the package 50b, respectively, by bonding wires or the like.

[0046] Fourth Embodiment FIG. 6 is a perspective view showing an example of AR (Augmented Reality) glasses G, which are an electronic device according to this embodiment, using the light-emitting module 1, the light-emitting module 1a, or the light-emitting module 1b.

[0047] The AR glasses G are also called smart glasses. 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] The control unit 90 has a CPU, RAM, and non-volatile memory, and performs 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.

[0052] 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.

[0053] 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.

[0054] As described above, the optical waveguide of this embodiment includes a clad 12 having an exit surface S1, and a core 13 located within the clad 12. The core 13 includes a first core 13R extending in the X direction between a first end face eR1 and a second end face eR2 exposed from the exit surface S1, and a second core 13G spaced apart from the first core 13R in the Y direction and extending between a third end face eG1 and a fourth end face eG2 exposed from the exit surface S1. The first core 13R has a first linear portion 13R1 whose one end is the first end face eR1 and whose width in the Y direction is constant, and a tapered portion 13R2 connected to the first linear portion 13R1 and whose cross-sectional area in the Y direction decreases toward the second end face eR2. The second core 13G has a curved first curved portion 13G2 whose distance from the first core 13R decreases as it approaches the fourth end face eG2. In a side view along the Y direction, the contracted portion 13R2 and the first curved portion 13G2 overlap. According to this optical waveguide, the first core 13R has a linear shape, and the contracted portion 13R2 is provided midway, thereby reducing loss and improving the accuracy of the emitted light. Meanwhile, the second core 13G has the first curved portion 13G2 midway, bringing the fourth end face eG2 closer to the second end face eR2. In a side view, the first curved portion 13G2 at least partially overlaps with the contracted portion 13R2. This makes it difficult for light leaking from the first curved portion 13G2, where light leakage increases midway through the second core 13G, to enter other first cores 13R, etc. This allows the optical waveguide to appropriately improve the light propagation efficiency while obtaining an appropriate resolution.

[0055] The third end face eG1 may have a smaller area than the first end face eR1. If the luminance of the light-emitting element 30R is more likely to decrease due to a rise in temperature than that of the light-emitting element 30G, the area of ​​the first end face eR1 may be increased to relatively reduce the energy density. This allows the optical waveguide to reduce a rise in temperature near the first end face eR1 of the first core 13R.

[0056] The second end face eR2 may have a smaller area than the fourth end face eG2. Green light, which has a shorter wavelength, is more easily diffused than red light. Therefore, by narrowing the area of ​​the second end face eR2 and adjusting the diffusion of red light to match that of green light, the resolution can be easily and appropriately adjusted.

[0057] Furthermore, the length of the reduced portion 13R2 in the X direction may be longer than the length of the first linear portion 13R1 in the X direction. That is, in the first core 13R, the reduced angle, which is the angle formed by the side surface of the reduced portion 13R2 with respect to the side surface of the first linear portion 13R1, may be relatively small. This allows the optical waveguide to reduce light leakage.

[0058] Furthermore, the X direction, which is the normal direction of the second end face eR2, may be the same as the normal direction of the fourth end face eG2. The distance between the center positions of the second end face eR2 and the fourth end face eG2 may be 1 μm or more and 10 μm or less. By emitting multiple light beams, particularly light beams with different wavelengths, at intervals of 10 μm or less, the optical waveguide can combine and emit the light beams with sufficient visual resolution. Furthermore, by emitting multiple light beams at intervals of 1 μm or more, the possibility of light from one optical waveguide transferring to another optical waveguide can be reduced.

[0059] Furthermore, the path length of the first core 13R may be shorter than the path length of the second core 13G. This more effectively reduces the loss of light emitted from the light emitting element 30R in the optical waveguide, and prevents the amount of incident light from increasing more than necessary. Therefore, the optical waveguide can reduce the effects of heat generation from the light emitting element 30R.

[0060] The first core 13R may also have a second straight portion 13R3 whose one end is the second end face eR2 and whose width in the Y direction is constant. This stabilizes the beam shape and intensity distribution of the light reduced by the reduction portion 13R2, thereby reducing the diffusion of the light emitted from the second end face eR2. In particular, when the light passing through the first core 13R is a multi-mode light in the transverse mode, the beam shape and intensity distribution of the light can be further stabilized.

[0061] The second core 13G may have a third linear portion 13G1 having one end at the third end face eG1 and connecting to the first curved portion 13G2, and a fourth linear portion 13G3 having one end at the fourth end face eG2 and connecting to the first curved portion 13G2. The first curved portion 13G2 may have a first arc portion 13G21 connecting to the third linear portion 13G1 and a second arc portion 13G22 connecting to the fourth linear portion 13G3. The radius of curvature of the first arc portion 13G21 and the radius of curvature of the second arc portion 13G22 may be equal. In this way, by forming the first curved portion 13G2 as a combination of two symmetrical arc-shaped portions, light loss at the first curved portion 13G2 can be reduced.

[0062] The circumferential angle of the first arc-shaped portion 13G21 and the circumferential angle of the second arc-shaped portion 13G22 may be equal. This makes it easier for the stresses caused by thermal deformation in both portions to be partially offset, particularly in the Y direction, thereby reducing distortion in the second core 13G. Furthermore, the magnitude of the distortion that remains unoffset in the second core 13G is also approximately the same, thereby reducing the effect of this remaining distortion on the propagation of light passing through the second core 13G.

[0063] The core 13 may also include a third core 13B located on the opposite side of the second core 13G in the Y direction, separated from the first core 13R, and extending between a fifth end face eB1 and a sixth end face eB2 located at the exit surface S1. The third core 13B may have a curved shape and a second curved portion 13B2 whose distance from the first core 13R decreases as it approaches the exit surface S1. In a side view along the Y direction, the second curved portion 13B2 and the reduced portion 13R2 may overlap. In this way, when the third core 13B is included, the third core 13B can be positioned relative to the first core 13R and shaped to have the same or similar characteristics as the second core 13G, thereby easily improving light propagation efficiency. This allows light emitted by each LD to be emitted with appropriate resolution.

[0064] Furthermore, the area of ​​the third end face eG1 and the area of ​​the fifth end face eB1 may both be smaller than the area of ​​the first end face eR1. Therefore, if the luminance of the light-emitting element 30R is more likely to decrease due to temperature increases than the light-emitting elements 30G and 30B, the area of ​​the first end face eR1 may be larger than the areas of the third end face eG1 and the fifth end face eB1. This relatively reduces the energy density near the first end face eR1. Therefore, the temperature increase near the first end face eR1 of the first core 13R close to the light-emitting element 30R can be reduced, and the temperature increase can be brought closer to the level near the third end face eG1 and the fifth end face eB1.

[0065] Furthermore, the distance d11 between the center position of the third end face eG1 and the center position of the first end face eR1 may be different from the distance d21 between the center position of the fifth end face eB1 and the center position of the first end face eR1. By determining an appropriate relationship between the radius of curvature and the angle of circumference in consideration of factors such as light loss at the first curved portion 13G2 and the second curved portion 13B2, the distances d11 and d21 may be different. Furthermore, in consideration of differences in the amounts of heat generated by the light emitting element 30G and the light emitting element 30B, the distances from the first core 13R, which is the center of these optical waveguides, may be made different.

[0066] Furthermore, the second curved portion 13B2 of the third core 13B may have a third arc portion 13B21 connected to the fifth linear portion 13B1 and a fourth arc portion 13B22 connected to the sixth linear portion 13B3. The radius of curvature of the third arc portion 13B21 and the radius of curvature of the fourth arc portion 13B22 may be equal. In this way, the second curved portion 13B2 is a combination of two symmetrical arc-shaped portions, thereby reducing light loss in the second curved portion 13B2.

[0067] The circumferential angle of the third arc-shaped portion 13B21 and the circumferential angle of the fourth arc-shaped portion 13B22 may be equal. This partially cancels out stresses due to thermal deformation in the third arc-shaped portion 13B21 and the fourth arc-shaped portion 13B22, thereby reducing distortion of the third core 13B. Furthermore, the magnitude of distortion remaining in the third core 13B due to the stresses not canceled out in the third core 13B is also approximately the same in the third arc-shaped portion 13B21 and the fourth arc-shaped portion 13B22, thereby reducing the effect of distortion remaining in the third core 13B on the propagation of light passing through the third core 13B.

[0068] The radius of curvature R1 of the first arc-shaped portion 13G21 and the radius of curvature R2 of the third arc-shaped portion 13B21 may be different from each other. By varying the radius of curvature depending on the wavelength of light incident on the third end face eG1 and the fifth end face eB1, for example, the difference in the degree of leakage of blue light and green light, the amount of light leakage can be appropriately adjusted.

[0069] The path lengths of the fifth straight portion 13B1 and the sixth straight portion 13B3 may be different from the path length of the first straight portion 13R1. The lengths of the fifth straight portion 13B1 and the sixth straight portion 13B3 can be appropriately adjusted depending on the path length of the second curved portion 13B2 and / or the difference in the amount of heat generated by the light-emitting element 30.

[0070] Furthermore, the width in a plan view of a cross section perpendicular to the extension direction of the second core 13G and the width in a plan view of a cross section perpendicular to the extension direction of the third core 13B may each be constant. Light leakage may increase in the curved portions and portions where the width changes in the core 13. That is, compared to the first core 13R, which is linear but has a tapered portion 13R2, the widths of the second core 13G and the third core 13B, which have curved portions, may be constant so as to minimize the amount of light leakage due to the curvature.

[0071] Furthermore, the optical waveguide module 10, which is a package for housing an electronic element according to this embodiment, may include a substrate 11 having an upper surface S2, the above-described waveguide located on this upper surface S2, and an electrode 14 located in an element mounting region M above the upper surface S2. The cladding 12 has a wall portion 12W surrounding the element mounting region M. The first end face eR1 and the third end face eG1 may be exposed on the incident surface S3 of the wall portion 12W. By using such an optical waveguide module 10, the light-emitting element 30 is connected to the electrode 14 in the element mounting region M, making it possible to emit light from the light-emitting element 30 to the outside with higher propagation efficiency.

[0072] Furthermore, a light-emitting module 1, which is an electronic module of this embodiment, includes the above-described optical waveguide module 10, a light-emitting element 30, which is an electronic element located in the element mounting region M, and a lid 40 located on the cladding 12 and covering the element mounting region M. The electrode 14 may include a first electrode 141 and a second electrode 142. The light-emitting element 30 may include a light-emitting element 30R connected to the first electrode 141 and a light-emitting element 30G connected to the second electrode 142. Such a light-emitting module 1 can emit light with higher propagation efficiency than conventional modules. Therefore, the light-emitting module 1 can reduce power consumption and obtain higher emitted light brightness relative to the heat generation while reducing heat generation.

[0073] Furthermore, the AR glasses G, which are the electronic device of this embodiment, may include the above-described light-emitting module 1 and a display unit 80. The electronic element may be a light-emitting element, and the display unit 80 may display information using light emitted from the light-emitting module 1. By including a light-emitting module 1 that is small, has high light-emitting efficiency, and can reduce heat generation, such AR glasses G can be made smaller, lighter, and more affordable. This reduces the burden on the wearer when wearing the glasses and also makes them more fashionable.

[0074] The above embodiment is merely an example, and various modifications are possible. For example, although the above description assumes that the circumferential angles T1 and T2 of the second core 13G and the third core 13B are different, they do not necessarily have to be different. They may have the same circumferential angle depending on the required length of each core and the intervals d11 and d12.

[0075] On the other hand, the radius of curvature R2 of the first arc-shaped portion 13G21 and the second arc-shaped portion 13G22 may be the same as the radius of curvature R1 of the third arc-shaped portion 13B21 and the fourth arc-shaped portion 13B22.

[0076] In the above embodiment, the first end face eR1, the third end face eG1, and the fifth end face eB1 on the incident side are described as parallel surfaces, but this is not limited to this. The incident end faces may be oriented in different directions. With regard to the second core 13G and the third core 13B, light can be incident from end faces located on the ±Y sides, which are lateral surfaces of the optical waveguide section 12L, or from inclined end faces. In this case, the circumferential angles of the first arc portion 13G21 and the second arc portion 13G22 may be different from each other, and the circumferential angles of the third arc portion 13B21 and the fourth arc portion 13B22 may be different from each other.

[0077] In the above description, the two arcuate portions of the first curved portion 13G2 and the second curved portion 13B2 are directly connected to each other, but this is not limiting. A straight line portion may be located between the arcuate portions.

[0078] Furthermore, at least one of the first arc portion 13G21, the second arc portion 13G22, the third arc portion 13B21, and the fourth arc portion 13B22 may not be a simple arc. As long as there are no discontinuous bends, each of the first curved portion 13G2 and the second curved portion 13B2 may be a different type of curve. Furthermore, the first arc portion 13G21 and the second arc portion 13G22 may have different lengths, and the third arc portion 13B21 and the fourth arc portion 13B22 may have different lengths.

[0079] Furthermore, although the optical waveguide has been described above as having three cores, this is not limited thereto. The number of cores may be two or more. In the case of four or more cores, an optical waveguide having multiple cores that transmit light of the same wavelength, or an optical waveguide having a core that transmits infrared light, may be considered. In this case, the fourth core may be aligned in the same plane as the other cores on the opposite side of the first core 13R with respect to the outer second core 13G or third core 13B in the above three-core configuration, and may have a larger radius of curvature.

[0080] Furthermore, even when the optical waveguide has three cores, these three cores do not necessarily have to transmit light of three wavelengths: red light, green light, and blue light. In this case, it is sufficient that which core transmits which wavelength of light depending on the combination of wavelengths to be transmitted. Furthermore, it is sufficient that the length of the contracted portion 13R2, the radius of curvature R1 and the inclined angle T1 of the first curved portion 13G2, and the radius of curvature R2 and the inclined angle T2 of the second curved portion 13B2 are each appropriately determined depending on the wavelength of the light to be transmitted.

[0081] In addition, when the cores transmit light of three wavelengths, i.e., red light, green light, and blue light, the positions of the second core 13G and the third core 13B may be interchanged. Also, red light does not necessarily have to be incident on the central linear first core 13R.

[0082] Although the reduced portion 13R2 has been described as having a double-tapered shape, i.e., a shape in which the angles formed by both side surfaces of the reduced portion 13R2 relative to both side surfaces of the first linear portion 13R1 of the first core 13R are equal, this is not limited thereto. The slopes of both side surfaces may be different. For example, the reduced portion 13R2 may have a single-tapered shape in which one side surface is connected to the side surfaces of the first linear portion 13R1 and the second linear portion 13R3 in the same plane, and only the other side surface is inclined to reduce its width.

[0083] Although the tapered shape of the reduced portion 13R2 has been described as a shape in which the width in plan view decreases at a constant rate and the side shape in plan view is linear, this is not limited to this. The side shape in plan view may be curved, or the corners may be rounded near the connection with at least one of the first linear portion 13R1 and the second linear portion 13R3. In this case, it is preferable that there is no portion where the rate of decrease in width relative to the distance in the X direction is significantly large. Furthermore, regardless of the description of the above embodiment, the reduced portion 13R2 may have a tapered shape in which the thickness h changes.

[0084] Although the above description has been given of an electronic module in which light emitted by a light-emitting element is input through the first end face eR1, the third end face eG1, and the fifth end face eB1 and output to approximately the same position, this is not limiting. For example, the electronic element may include a light-receiving element that receives light input through the second end face eR2, the fourth end face eG2, and the sixth end face eB2. Furthermore, light may also include electromagnetic waves other than visible light, such as infrared light, as long as the light has a wavelength that can be transmitted through an optical waveguide. Accordingly, a temperature measuring element for measuring temperature may also be included in the electronic element.

[0085] In addition, although the above description has been given using AR glasses, which are smart glasses including a head-mounted display, as an example of an electronic device equipped with a light-emitting module having an optical waveguide, the present invention may also be used in other electronic devices. Examples of other electronic devices include head-up displays and projectors. 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.

[0086] The present disclosure can be used in optical waveguides, packages for housing electronic elements, electronic modules, and electronic devices.

[0087] 1, 1a, 1b Light-emitting module 10, 10a, 10b Optical waveguide module 11, 11b Substrate 12 Cladding 12L Optical waveguide portion 12W Wall portion 121, 122 Protrusion 13 Core 13R First core 13G Second core 13B Third core 13R1 First straight portion 13R3 Second straight portion 13G1 Third straight portion 13G3 Fourth straight portion 13B1 Fifth straight portion 13B3 Sixth straight portion 13G2 First curved portion 13B2 Second curved portion 13G21 First arc portion 13G22 Second arc portion 13B21 Third arc portion 13B22 Fourth arc portion 13R2 Reduced portion 14 Electrode 141 First electrode 142 Second electrode 141a Electrode pad 20 Lens 30, 30R, 30G, 30B Light emitting element 40, 40a Lid 50, 50b Package 51 Window 54 Electrode 80 Display section 81 Scanning mirror 82 Light guiding section 90 Control section C1, C5a Recess C1a Step section eR1 First end face eR2 Second end face eG1 Third end face eG2 Fourth end face eB1 Fifth end face eB2 Sixth end face G AR glass h Thickness LG, LB, L11, L12, L31, L32 Length M Element mounting area R1, R2 Radius of curvature S1 Emission surface S2 Upper surface S3 Incident surface T1, T2 Circumferential angle W Bonding wire w11, w12, w2 Width

Claims

1. An optical waveguide comprising: a clad having a first surface; and a core located within the clad, wherein the core comprises: a first core extending in a first direction between a first end surface and a second end surface exposed from the first surface; and a second core spaced from the first core in a second direction perpendicular to the first direction, extending between a third end surface and a fourth end surface exposed from the first surface, wherein the first core has: a first straight portion having one end which is the first end surface and which has a constant width in the second direction; and a reduced portion connected to the first straight portion, the cross-sectional area in the second direction decreasing as it approaches the second end surface; and the second core has a first curved portion which is curved and the distance from the first core to the fourth end surface decreases, and wherein the reduced portion and the first curved portion have an overlapping portion in a side view along the second direction.

2. The optical waveguide according to claim 1, wherein said third end face has an area smaller than that of said first end face.

3. The optical waveguide according to claim 1 or 2, wherein the second end face has an area smaller than that of the fourth end face.

4. An optical waveguide according to any one of claims 1 to 3, wherein the length of said tapered portion in said first direction is longer than the length of said first straight portion in said first direction.

5. An optical waveguide according to any one of claims 1 to 4, wherein a normal direction of the second end face is the same as a normal direction of the fourth end face, and a distance between a center position of the second end face and a center position of the fourth end face is 1 μm or more and 10 μm or less.

6. An optical waveguide according to any one of claims 1 to 5, wherein the path length of the first core is shorter than the path length of the second core.

7. An optical waveguide according to any one of claims 1 to 6, wherein the first core has one end which is the second end face and a second linear portion having a constant width in the second direction.

8. An optical waveguide as claimed in any one of claims 1 to 7, wherein the second core has: a third straight portion having one end which is the third end face and which connects to the first curved portion; and a fourth straight portion having one end which is the fourth end face and which connects to the first curved portion; the first curved portion has a first arc portion which connects to the third straight portion and a second arc portion which connects to the fourth straight portion; and the radius of curvature of the first arc portion and the radius of curvature of the second arc portion are equal.

9. The optical waveguide according to claim 8, wherein the circumferential angle of said first arcuate portion is equal to the circumferential angle of said second arcuate portion.

10. An optical waveguide as claimed in any one of claims 1 to 9, wherein the core comprises a third core positioned on the opposite side of the first core in the second direction from the second core, extending between a fifth end face and a sixth end face positioned on the first surface, the third core having a curved shape and a second curved portion whose distance to the first core becomes smaller as it approaches the first surface, and the second curved portion and the reduced portion have an overlapping portion in a side view along the second direction.

11. The optical waveguide according to claim 10, wherein the area of ​​said third end face and the area of ​​said fifth end face are both smaller than the area of ​​said first end face.

12. The optical waveguide according to claim 10 or 11, wherein the distance between the center position of the third end face and the center position of the first end face is different from the distance between the center position of the fifth end face and the center position of the first end face.

13. The optical waveguide as claimed in claim 8, wherein the core comprises a third core located on the opposite side of the second core in the second direction to the first core, the third core extending between a fifth end face and a sixth end face located on the first surface, the third core having a curved shape and a distance from the first core decreasing as it approaches the first surface, a fifth straight portion having one end at the fifth end surface and connecting to the second curved portion, and a sixth straight portion having one end at the sixth end surface and connecting to the second curved portion, the second curved portion having a third arc portion connecting to the fifth straight portion and a fourth arc portion connecting to the sixth straight portion, the radius of curvature of the third arc portion and the radius of curvature of the fourth arc portion being equal, and the second curved portion and the reduced portion having an overlapping portion in a side view along the second direction.

14. The optical waveguide according to claim 13, wherein the circumferential angle of said third arc portion is equal to the circumferential angle of said fourth arc portion.

15. The optical waveguide according to claim 13 or 14, wherein the radius of curvature of said first arc portion and the radius of curvature of said third arc portion are different from each other.

16. An optical waveguide according to any one of claims 13 to 15, wherein the path length of the fifth straight portion and the path length of the sixth straight portion are different from the path length of the first straight portion.

17. An optical waveguide according to any one of claims 10 to 12, wherein the width of a cross section perpendicular to the extension direction of the second core and the width of a cross section perpendicular to the extension direction of the third core are each constant.

18. A package for housing an electronic element comprising: a substrate having a second surface; an optical waveguide according to any one of claims 1 to 17 located on said second surface; and an electrode located in an element mounting area above said second surface, wherein said cladding has a wall portion surrounding said element mounting area, and said first end face and said third end face are exposed on a third surface of said wall portion.

19. An electronic module comprising: a package for housing an electronic element as defined in claim 18; an electronic element located in the element mounting area; and a lid located on the cladding and covering the element mounting area, wherein the electrodes include a first electrode and a second electrode, and the electronic element includes a first electronic element connected to the first electrode and a second electronic element connected to the second electrode.

20. An electronic device comprising: the electronic module according to claim 19; 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.

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