WO2025070157A1 - Optical waveguide, package for housing electronic element, electronic module, and electronic device - Google Patents

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

This disclosure relates to optical waveguides, packages for storing electronic elements, electronic modules, and electronic devices.

A multiplexer is known that combines optical waveguides that guide light of multiple wavelengths and outputs the light in the same direction and at the same location. On the other hand, WO 2017/090333 discloses an optical waveguide that does not combine the optical waveguides, but brings the output end faces of each optical waveguide close to each other and outputs the light in the same direction, thereby essentially multiplexing the light.

(1) The optical waveguide of the present disclosure is
It comprises a cladding having a first surface and a core located within the cladding.
The core comprises a first core extending in a first direction between a first end face and a second end face exposed from the first face, and a second core spaced from the first core in a second direction perpendicular to the first direction and extending between a third end face and a fourth end face exposed from the first face.
The first core has a first straight portion, one end of which is the first end face, and 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 toward the second end face.
The second core has a first curved portion having a curved shape, the distance between the first core becoming smaller as the second core approaches the fourth end face.
In a side view along the second direction, the reduced portion and the first curved portion have an overlapping portion.
(2) In the optical waveguide described in (1) above, the third end face has an area smaller than that of the first end face.
(3) In the optical waveguide according to (1) or (2) above, the second end face has an area smaller than that of the fourth end face.
(4) In the optical waveguide according to 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 straight portion in the first direction.
(5) In the optical waveguide described in any one of (1) to (4) above, 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) In the optical waveguide according to 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 according to any one of (1) to (6) above, the first core has one end which is the second end face and a second linear portion whose width in the second direction is constant.
(8) In the optical waveguide described in any one of (1) to (7) above, 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) In the optical waveguide described in (8) above, the circumferential angle of the first arcuate portion is equal to the circumferential angle of the second arcuate portion.
(10) The optical waveguide described in any one of (1) to (9) above, wherein the core comprises a third core positioned on the opposite side of the second core in the second direction from the first 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 when viewed from the side along the second direction, the second curved portion and the reduced portion have an overlapping portion.
(11) In the optical waveguide according to (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, a distance between a center position of the third end face and a center position of the first end face is different from a distance between a center position of the fifth end face and a center position of the first end face.
(13) The optical waveguide described in (8) above, wherein the core includes a third core located on the opposite side of the second core in the second direction across 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 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 connected to the second curved portion, and a sixth straight portion having one end at the sixth end face and connected to the second curved portion, the second curved portion having a third arc portion connected to the fifth straight portion and a fourth arc portion connected to the sixth straight portion, the radius of curvature of the third arc portion and the radius of curvature of the fourth arc portion are equal, and the second curved portion and the reduced portion have an overlapping portion in a side view along the second direction.
(14) In the optical waveguide according to (13) above, the circumferential angle of the third arcuate portion is equal to the circumferential angle of the fourth arcuate portion.
(15) In the optical waveguide according to (13) or (14) above, the radius of curvature of the first arcuate portion and the radius of curvature of the third arcuate portion are different from each other.
(16) In the optical waveguide according to 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 according to 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) A package for storing an electronic element according to the present disclosure comprises a substrate having a second surface, an optical waveguide according to 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 surface and the third end surface are exposed on a third surface of the wall portion.
(19) An electronic module of the present disclosure comprises a package for storing an electronic element as described in (18) above, an electronic element located in the element mounting area, and a lid body located on the clad 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 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 performs display using light emitted from the electronic module.

1 is an overall perspective view of a light-emitting module having an optical waveguide according to an embodiment of the present invention; FIG. 2 is a plan view of the light-emitting module. FIG. 2B is a cross-sectional view taken along section line AA in FIG. 2A. FIG. 2 is a diagram showing a side view of the optical waveguide module. FIG. 4 is a diagram illustrating the shape of a core. FIG. 11 is a perspective view showing the overall structure of a light-emitting module according to a second embodiment. FIG. 13 is a perspective view showing the overall structure of a light-emitting module according to a third embodiment. FIG. 1 is a perspective view showing an example of AR glasses using a light-emitting module.

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 the cover 40 is excluded from Fig. 2A.
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 cover body 40, and the like.

An optical waveguide module 10, which is a package for housing an electronic element according to this embodiment, includes a substrate 11, a clad 12, a core 13, electrodes 14, and the like.
In the following, as shown in Figures 1, 2A, etc., 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 in the XY plane. The X axis is defined as a first direction, and the Y axis is defined as a second direction. The upward direction perpendicular to the XY plane is defined as the Z axis. In a plan view seen from above along the Z axis, the optical waveguide module 10 of this embodiment is substantially rectangular, but is not limited to this.

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.

The core 13 is located inside the cladding 12 and transmits light. The cladding 12 and the core 13 are optically transparent members, and may be, for example, silicon dioxide, glass such as quartz, or resin. The materials of the cladding 12 and the core 13 may contain the same material, or may be different, for example, the cladding 12 may be resin and the core 13 may be glass. More specifically, the material of the cladding 12 may be silicon dioxide, and the material of the core 13 may be silicon oxynitride (SiON), also known as silicon oxynitride. The refractive index of the core 13 is greater than that of the cladding 12. The difference in refractive index depends on the structure of the core 13, such as the shape, but can be set to, for example, about 0.01 to 2.0. This provides the optical waveguide of this embodiment in which light incident from one end of the core 13 is transmitted along the core 13. In one embodiment, there are three independent cores 13. In one embodiment, the cross-sectional shape of each core 13 perpendicular to the central axis (extension direction) may be rectangular or trapezoidal.

The clad 12 is located on one surface of the flat substrate 11, here the upper surface S2 which is the surface on the +Z side. The upper 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 arranged apart from each other in the Y direction. The end surface on the +X side of the clad 12 is the exit surface S1. The exit surface S1 is the first surface. As shown in FIG. 2C, the second end surface eR2, the fourth end surface eG2, and the 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 exit surface S1, that is, the normal directions of each end surface may be aligned parallel to each other.
In each drawing, for the sake of explanation, the ratios of the width, length and spacing of the core 13 do not necessarily reflect the actual values.

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

As shown in Figures 1 and 2A, the cladding 12 may have a recess C1 on the -X side of the core 13 that opens 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 a wall portion 12W that is connected to the optical waveguide portion 12L and is a sidewall portion that surrounds the recess C1 on three sides, i.e., the ±Y direction and the -X direction. The recess C1 may penetrate the cladding 12 so that a part of the substrate 11 is exposed at the bottom surface.

The substrate 11 may also have an insulating layer on the 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 on 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 may not be a uniform flat surface, and may have internal irregularities. If the material of the insulating layer is the same as that of the clad 12, such as silicon dioxide, the insulating layer may be integral with the clad 12.

The inside of the recess C1 may be an element mounting area 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. Each set of electrodes 14 includes a first electrode 141 connected to an electrode pad 141a and a second electrode 142, as shown in FIG. 2A.

The light-emitting element 30 is located on the electrode pad 141a of the first electrode 141, electrically connected to the electrode pad 141a. A connection terminal (not shown) may be located on the bonding surface side of the light-emitting element 30 with the electrode pad 141a. This connection terminal is bonded to the electrode pad 141a by, for example, a brazing material or a conductive adhesive. The electrode pad 141a may be located on a 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 there is an insulating layer on the substrate 11, the surface of the element mounting portion may be covered with this insulating layer, and the inside 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 substrate 11 on the bottom surface by an insulating material different from that of the bottom surface.

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. The tip of the second electrode 142 may also have an electrode pad for joining the bonding wire W.

Each electrode 14 may extend outside the recess C1 through between the wall 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.

The surface on the +X side of the sidewall surface facing the recess C1, i.e., the surface of the optical waveguide portion 12L, may be the incident surface S3 where the first end surface eR1, the third end surface eG1, and the fifth end surface 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 surface eR1, the third end surface eG1, and the fifth end surface eB1 may face the light emission ends of the three light-emitting elements 30, respectively, or may be the end surfaces where light is incident on the core 13. The core 13 connects the first end surface eR1 and the second end surface eR2, connects the third end surface eG1 and the fourth end surface eG2, and connects the fifth end surface eB1 and the sixth end surface eB2. The center position of the first end surface eR1 and the center position of the second end surface eR2 may be at the same position in the Y direction perpendicular to the X direction and the Z direction.

The first end face eR1, the third end face eG1, and the fifth end face eB1 are positioned at intervals d11, d12 in the Y direction. The intervals d11, d12 can be set to be larger than the width of each light-emitting element 30 in the Y direction so as to reduce the incidence of stray light of the emitted light from each light-emitting element 30 on each end face. In one embodiment, the protrusions 122 of the cladding 12 may be positioned 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 makes it possible to reduce the incidence of stray light from each light-emitting element 30 on the other end faces without making the intervals d11, d12 larger than the width of the light-emitting element 30.

As shown in FIG. 1 etc., 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 output 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 the function of converting the output light from the second end face eR2, the fourth end face eG2, and the sixth end face eB2 into parallel light.

A lid 40 may be bonded to the clad 12 around the upper part of the recess C1. That is, the lid 40 may cover the element mounting area M to seal the recess C1. In one embodiment, the upper surface position of the light-emitting element 30 bonded to the electrode 14 may be lower in the Z direction than the upper surface position of the clad 12. Therefore, the lid 40 may be flat or have a small recess corresponding to the protrusion 121. If the upper surface position of the light-emitting element 30 is higher than the upper surface position of the clad 12, the lid 40 may have a recess on the lower surface, i.e., the surface on the -Z side. 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 a metal material, the lid 40 may have a plating layer on the surface. Examples of the material 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 sandwiching the conductor between them and joining 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.

The light-emitting element 30 is an electronic element of this embodiment, for example, a laser diode (LD), and each emits 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 may cause red light to be incident on the first end face eR1. The light-emitting element 30G and the light-emitting element 30B are located on both sides of the light-emitting element 30R, and the light-emitting element 30G causes green light to be incident on the third end face eG1, and the light-emitting element 30B causes blue light to be incident on the fifth end face eB1. The positions of the LDs are not limited to the above case and may be changed as appropriate.

The shape of the core 13 in the cladding 12 will now be described in more detail.
FIG. 3 is a diagram illustrating the shape of the core 13. As shown in FIG.

Of the three cores 13, the first core 13R in the center 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.

The first core 13R has a linear shape extending in the X direction. The first core 13R has a first linear portion 13R1 at both ends, which has a constant width in the Y direction (second direction) in a plan view, i.e., in 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 reduced 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, and as the width gradually decreases, the cross-sectional area also gradually decreases.

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 becomes smaller as it 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 becomes smaller as it 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, that is, in a side view seen from the Y direction, the positions of the first curved portion 13G2 and the second curved portion 13B2 have a portion that overlaps with the position of the reduced portion 13R2. The reduced portion 13R2, the first curved portion 13G2, and the second curved portion 13B2 have more light leakage than the straight portion. In a plan view, the inclined portions of the side surfaces of these cores 13 are aligned in the same range in at least a portion of the longitudinal direction, so that light leaking from one core is less likely to enter another core. Therefore, by increasing the proportion of the overlapping portion as much as possible, the above-mentioned effect can be more effectively achieved. The above-mentioned overlapping portion may be, for example, 90% or more, more preferably 95% or more, of the length in the X direction of the first curved portion 13G2 and the second curved portion 13B2.

The distance d21 between the center position of the second end face eR2 and the center position of the sixth end face eB2 may be equal to the distance d22 between the center position of the second end face eR2 and the center position 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 nearly equal distances d21 and d22, the light of the three wavelengths is emitted to approximately the same position and in the same direction with sufficient visual accuracy even if it is not multiplexed into a single optical waveguide (core). Note that when the required resolution is low, the above-mentioned distances may be 10 μm or more. If the distances d21 and d22 are 1 μm or less, the processing accuracy required during manufacturing increases, resulting in increased costs and labor. Furthermore, when the spacing d21, d22 is less than 1 μm, even if the cores do not merge, the light from one core may cross the thin cladding 12 and pass to the adjacent core.

Since the first core 13R is positioned in a straight line in 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 length of the second core 13G and the third core 13B. For example, when the temperature rises, the brightness of a red-emitting LD is more likely to decrease 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 light and green light.

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, about 2 to 8 μm. Furthermore, the width of the 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 above 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 having 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 in the curved portion, where light leakage is greater than in the straight portion, thereby reducing the loss of light. In addition, because the second core 13G and the third core 13B have the same width, the energy density distribution of the passing light becomes symmetrical, and the distribution of heat generation can also be made closer to symmetry. This makes it possible to disperse and alleviate stresses related to deformation, particularly stresses caused by expansion due to temperature rise.

On the other hand, the first end face eR1 has a width w11 in a planar view, and the second end face eR2 has a width w12 in a planar 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 planar view gradually decreases from width w11 to width w12. In one embodiment, the decrease from width w11 to width w12 may be a constant decrease rate. The decrease rate represents the amount of decrease in width in the Y direction per length in the X direction. The line in a planar view of the side of the reduced portion 13R2 may be a tapered shape that is a straight line. In addition, the reduction angle, which is the size of the angle formed by the side of the reduced portion 13R2 with respect to the side of the first straight portion 13R1, may be the same on both the left and right side faces. When the reduction angle is not the same on both the left and right side faces, one of the reduction angles with respect to the first straight portion 13R1 is larger than when the reduction angles are the same on both the left and right side faces. Therefore, there is a tendency for light leakage from the first core 13R to increase as the reduction angle increases. Therefore, by making the reduction angles on both side surfaces of the first straight portion 13R1 the same, the first core 13R can reduce light leakage.

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 wider than the width w2. The end face width is wider than the size of the emission end of the light-emitting element 30, thereby improving the tolerance against the mounting position deviation of the light-emitting element 30. In addition, the width of the first end face eR1 of the first core 13R is wider than the width of the other end faces, so that the energy density is lowered compared to the amount of incident light. For example, the red light-emitting LD is more likely to have its brightness reduced due to a rise in temperature than other light-emitting LDs, but the energy density can be reduced by using the above configuration. This reduces the possibility that the temperature will rise significantly near the first end face eR1 compared to other parts. Therefore, the possibility that the brightness of the red light-emitting LD will decrease can be reduced.

Each core 13 may have a first straight portion 13R1, a third straight portion 13G1, and a fifth straight 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. Also, each core 13 may have a second straight portion 13R3, a fourth straight portion 13G3, and a sixth straight 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 leakage of light from the core 13. Also, the beam shape of the emitted light can be stabilized by passing the light through the second straight portion 13R3, the fourth straight portion 13G3, and the sixth straight portion 13B3 before emission. The length of each straight portion on the emission side is at least as long as necessary to stabilize the beam shape according to the resolution of the image to be output, and is within a range in which the disadvantage of loss due to being too long is not greater. Therefore, the length of each straight line portion may be determined appropriately according to the above conditions, but may be, for example, 50 μm or more and about 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.

The length of the reduced portion 13R2 may be longer than the length of the first straight portion 13R1 and the length of the second straight 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 straight 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. At this time, if the second end face eR2 becomes too small, the emitted light is likely to diffuse. Compared to the fourth end face eG2 for green light and the sixth end face eB2 for blue light, which are relatively more likely to diffuse than red light, the degree of diffusion of light of each wavelength can be made closer by narrowing the second end face eR2 for red light to a small size.

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. The thickness h of the core 13 may be, for example, 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.

The first curved portion 13G2 of the second core 13G may be a combination of a first arc portion 13G21 and a second arc portion 13G22 having the same radius of curvature R1 and the same circumferential angle T1 (length LG = R1 · T1) and having 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 be a combination of a third arc portion 13B21 and a fourth arc portion 13B22 having the same radius of curvature R2 and the same circumferential angle T2 (length LB = R2 · T2) and having 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 straight 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 the loss of light in the second core 13G and the third core 13B. Furthermore, the first curved portion 13G2 and the second curved portion 13B2 have shapes that are approximately symmetrical with respect to the first core 13R, which makes it easier 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 of the optical waveguide as a whole and makes it difficult for distortion biased to occur in one direction.

The radius of curvature R1 and the radius of curvature R2 may be different from each other. In one embodiment, the radius of curvature R1 may be larger than the radius of curvature R2. Specifically, for example, the radius of curvature R1 may be 3.5 mm or more and 5.0 mm or less. The radius of curvature R2 may be 3.0 mm or more 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, for example, 10.0° or more and 15.0° or less. In one embodiment, the circumferential angle T1 may be smaller than the circumferential angle T2 by about 0.5° or more 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 larger than the length LG. On the other hand, the interval d12 may be smaller than the interval d11. Specifically, the intervals 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 in the curved portion. To compensate for this, 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, so that the scattering of blue light is reduced more than the scattering of green light, and the loss of light is reduced. On the other hand, 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 effect of heat on the optical waveguide module 10 can be reduced to the extent of the effect of the light-emitting element 30G.

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 have the same loss until they enter the first curved portion 13G2 and the second curved portion 13B2, respectively, thereby reducing the unevenness in the amount of light. In addition, the amount of heat generated according to the passage of light through the third straight portion 13G1 and the fifth straight portion 13B1 is also made to be approximately the same, thereby reducing the possibility that the amount of distortion of the optical waveguide module 10 will be uneven. In addition, since 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 according to the heat along the straight lines, mainly the distortion component in the Y direction, is offset. The length of the third straight portion 13G1 is about 50 times or more the wavelength of the light of the light emitting element 30G, so that the influence of scattering or 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 about 300 times or more the wavelength of the light of the light emitting element 30G, the loss of light may be large. Therefore, the length L11 of the third straight portion 13G1 may be, for example, about 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 according to the relationship with the wavelength of the light of the light emitting element 30B.
On the other hand, the length L31 of the fourth straight portion 13G3 on the emission side and the length L32 of the sixth straight portion 13B3 may be different. Furthermore, the length L33 of the second straight portion 13R3 may be longer than the length L31 and 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 and 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 and 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. 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 without following 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.

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 away from the exit surface S1 than the fifth end face eB1. These positions may be determined according to the difference in heat generation between the light-emitting element 30G, which is a green light-emitting LD, and the light-emitting element 30B, which is a blue light-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.

By defining the shapes of the multiple cores 13 in this manner, 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 ever before.

[Second embodiment]
In the above-described first embodiment, the structure has been shown in which 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.

FIG. 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.

The entire optical waveguide module 10a is located within the recess C5a of the package 50. The open surface at the top end of the recess C5a of the package 50 is sealed by the lid 40a. The package 50 may be made of, for example, ceramic and have high thermal conductivity.

Instead of the recess C1, the optical waveguide module 10a may have 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.

The package 50 has a recess C5a of a size capable of accommodating the optical waveguide module 10a, and a window portion 51. The window portion 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 portion 51 may be a light-transmitting member capable of converting the emission light into parallel light in place of the lens 20. Alternatively, the window portion 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.

The package 50 may have a connection electrode (not shown) exposed on the inner surface of the side wall. The connection electrode is electrically connected to the electrode 14. Electrical wiring is located within the side wall, and connects the connection electrode to an external electrode (not shown) located on the outer surface side of the package 50. The external electrode may be located on the outer surface of the side wall, 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.

[Third embodiment]
FIG. 5 is a perspective view showing the overall structure of a light-emitting module 1b according to the third embodiment.
In one embodiment, the optical waveguide module 10b may not have a substrate extending below the element mounting region M. That is, the light emitting element 30 may be directly located on the bottom surface of the package 50b. The optical waveguide module 10b may not have a substrate itself, that is, the bottom surface of the clad 12 may be in contact with the bottom surface of the package 50b. In this case, an electrode 54 may also be located on the bottom surface of the package 50b, and the electrode may be connected to wiring in the side wall or bottom plate of the package 50b. Alternatively, two electrodes of the light emitting element 30 and two electrodes located on the side wall of the package 50b may be connected by bonding wires or the like.

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

The AR glasses G are also called smart glasses. The AR glasses G may have a temple T and a display unit 80. The light-emitting module 1 may be located inside the temple T. The temple T may be bendable or non-bendable. If the temple T is bendable, the light-emitting module 1 may not emit light when it is bent.

The display unit 80 may include a scanning mirror 81 and a light guiding unit 82 .
The scanning mirror 81 is a MEMS (Micro-Electro Mechanical Systems) mirror, and 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 guide unit 82. The scanning mirror 81 may be located inside the temple T.

The light guide unit 82 has 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 is optically transparent. For example, the light guide unit 82 may use a wave guide 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 the 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.

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.

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 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.

Note that here, the glass surfaces including the light guide section 82 are shown separately on the left and right, but the AR glass G may have a single glass surface, such as in the case of goggles. The glass surface may also have a large curved surface, particularly in the case of a half-mirror system.

The AR glasses G may also be a head-mounted display that has a band or support for wearing on a person's head instead of temples T.

As described above, the optical waveguide of this embodiment includes the clad 12 having the exit surface S1, and the core 13 located in the clad 12. The core 13 includes the first core 13R extending in the X direction between the first end face eR1 and the second end face eR2 exposed from the exit surface S1, and the second core 13G spaced apart in the Y direction from the first core 13R and extending between the third end face eG1 and the fourth end face eG2 exposed from the exit surface S1. The first core 13R has a first straight portion 13R1 having one end that is the first end face eR1 and a constant width in the Y direction, and a reduced portion 13R2 connected to the first straight portion 13R1 and having a cross-sectional area in the Y direction that decreases as it approaches the second end face eR2. The second core 13G has a first curved portion 13G2 having a curved shape and the distance from the first core 13R becomes smaller as it approaches the fourth end face eG2, and when viewed from the side along the Y direction, the reduced portion 13R2 and the first curved portion 13G2 have an overlapping portion.
According to this optical waveguide, the first core 13R has a linear shape and has a reduced portion 13R2 in the middle, thereby reducing loss and improving the accuracy of the emitted light. On the other hand, the second core 13G has a first curved portion 13G2 in the middle to bring the fourth end face eG2 closer to the second end face eR2, and the first curved portion 13G2 at least partially overlaps with the reduced portion 13R2 in a side view. This makes it difficult for the light leaked at the first curved portion 13G2, where light leakage increases in the middle of the second core 13G, to enter other first cores 13R, etc. This makes it possible for the optical waveguide to obtain an appropriate resolution while appropriately improving the propagation efficiency of light.

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 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 the rise in temperature near the first end face eR1 of the first core 13R.

The second end face eR2 may have a smaller area than the fourth end face eG2. Emitted green light, which has a shorter wavelength, is more likely to diffuse than emitted red light. Therefore, by narrowing the area of the second end face eR2 to match the diffusion of red light to that of green light, the resolution can be easily and appropriately adjusted.

Furthermore, the length of the reduced portion 13R2 in the X direction may be longer than the length of the first straight portion 13R1 in the X direction. In other words, in the first core 13R, the reduction angle, which is the angle between the side of the reduced portion 13R2 and the side of the first straight portion 13R1, may be relatively small. This allows the optical waveguide to reduce light leakage.

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 position of the second end face eR2 and the center position of the fourth end face eG2 may be 1 μm or more and 10 μm or less. By emitting multiple light beams, particularly light beams of different wavelengths, at intervals of 10 μm or less, the optical waveguide can combine and emit light with visually sufficient 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.

The path length of the first core 13R may be shorter than the path length of the second core 13G. This makes it possible to more effectively reduce the loss of light emitted from the light-emitting element 30R in the optical waveguide and to prevent 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.

The first core 13R may also have a second straight section 13R3 with one end being the second end face eR2 and a constant width in the Y direction. This makes it possible to stabilize the beam shape and intensity distribution of the light reduced by the reduction section 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 in the transverse mode, it is possible to further stabilize the beam shape and intensity distribution of the light.

The second core 13G may have a third straight portion 13G1 having one end at the third end face eG1 and connected to the first curved portion 13G2, and a fourth straight portion 13G3 having one end at the fourth end face eG2 and connected to the first curved portion 13G2. The first curved portion 13G2 may have a first arc portion 13G21 connected to the third straight portion 13G1, and a second arc portion 13G22 connected to the fourth straight 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 manner, the first curved portion 13G2 is a combination of two symmetrical arc-shaped portions, so that the loss of light in the first curved portion 13G2 can be reduced.

Also, the circumferential angle of the first arc portion 13G21 and the circumferential angle of the second arc 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 component, thereby reducing distortion in the second core 13G. Furthermore, the magnitude of the distortion that remains unoffset in the second core 13G will be roughly the same, so the effect of this remaining distortion on the propagation of light passing through the second core 13G can be reduced.

The core 13 may also include a third core 13B located on the opposite side of the second core 13G in the Y direction across the first core 13R and spaced apart from the first core 13R, and extending between a fifth end face eB1 and a sixth end face eB2 located on the emission 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 emission surface S1. In a side view along the Y direction, the second curved portion 13B2 and the reduced portion 13R2 may have an overlapping portion. In this way, when the third core 13B is present, the third core 13B is positioned in a shape and has the same or similar characteristics as the second core 13G with respect to the first core 13R, so that the light propagation efficiency can be easily improved. Therefore, the light emitted by each LD can be emitted with an appropriate resolution.

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 a rise in temperature than the light-emitting elements 30G and 30B, the area of the first end face eR1 may be larger than the area of the third end face eG1 and the area of the fifth end face eB1. This relatively reduces the energy density near the first end face eR1. Therefore, the temperature rise near the first end face eR1 of the first core 13R close to the light-emitting element 30R can be reduced, and the temperature rise can be brought closer to the level of the temperature rise near the third end face eG1 and the fifth end face eB1.

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, taking into account the loss of light in the first curved portion 13G2 and the second curved portion 13B2, the distances d11 and d21 may be different. Furthermore, taking into account the difference in the amount 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.

The second curved portion 13B2 of the third core 13B may have a third arc portion 13B21 that connects to the fifth straight portion 13B1 and a fourth arc portion 13B22 that connects to the sixth straight 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, by making the second curved portion 13B2 a combination of two symmetrical arc-shaped portions, it is possible to reduce light loss in the second curved portion 13B2.

Also, the circumferential angle of the third arc portion 13B21 and the circumferential angle of the fourth arc portion 13B22 may be equal. This partially cancels out the stresses due to thermal deformation in the third arc portion 13B21 and the fourth arc portion 13B22, reducing the distortion of the third core 13B. Furthermore, the magnitude of the 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 portion 13B21 and the fourth arc portion 13B22, so the effect of the distortion remaining in the third core 13B on the propagation of light passing through the third core 13B can be reduced.

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

The path length of the fifth straight portion 13B1 and the path length of 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.

Furthermore, the planar width of the cross section perpendicular to the extension direction of the second core 13G and the planar width of the cross section perpendicular to the extension direction of the third core 13B may each be constant. The core 13 may have increased light leakage in curved portions and portions where the width changes. In other words, compared to the first core 13R which is straight but has a reduced portion 13R2, the width may be constant so that the amount of light leakage due to the curvature of the second core 13G and third core 13B which have curved portions can be reduced as much as possible.

Moreover, 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-mentioned waveguide located on the 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. A first end face eR1 and a third end face eG1 may be exposed on an 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.

Furthermore, the light-emitting module 1, which is an electronic module of this embodiment, includes the above-mentioned optical waveguide module 10, a light-emitting element 30 which is an electronic element located in the element mounting area M, and a lid 40 which is located on the cladding 12 and covers the element mounting area 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 a higher propagation efficiency than in the past. Therefore, the light emitting module 1 can reduce power consumption and obtain a higher brightness of emitted light compared to the amount of heat while reducing the amount of heat generated.

Moreover, the AR glasses G, which are the electronic device of this embodiment, may include the above-mentioned light-emitting module 1 and a display unit 80. The electronic element may be a light-emitting element, and the display unit 80 may perform display using light emitted from the light-emitting module 1.
Such AR glasses G can be made smaller, lighter, and more affordable by including a light-emitting module 1 that is small, has high light-emitting efficiency, and can reduce heat generation. This reduces the burden on the wearer when wearing the glasses, and also makes it easier to improve the glasses' fashionability.

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

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

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 faces, but this is not limited to the above. The incident end faces may be oriented in different directions. With regard to the second core 13G and the third core 13B, incidence from end faces located on the ±Y side, which is the lateral surface of the optical waveguide section 12L, or incidence from inclined end faces is also possible. 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.

In the above, the first curved portion 13G2 and the second curved portion 13B2 are described as having two arcuate portions directly connected to each other, but this is not limited to the above. A straight line portion may be located between the arcuate portions.

Furthermore, at least any 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 portion of the first curved portion 13G2 and the second curved portion 13B2 may be another 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.

In addition, while the optical waveguide has been described above as having three cores, this is not limited to this. The number of cores may be any other number greater than or equal to two. In the case of four or more cores, optical waveguides having multiple cores that transmit light of the same wavelength, optical waveguides having a core that transmits infrared rays, etc. are possible. 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 cores, for example, and may have a larger radius of curvature.

In addition, even if 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 to determine which core transmits which wavelength of light according to the combination of wavelengths to be transmitted. Furthermore, it is sufficient to appropriately determine the length of the reduced portion 13R2, the radius of curvature R1 and the angle of circumference T1 of the first curved portion 13G2, and the radius of curvature R2 and the angle of circumference T2 of the second curved portion 13B2 according to the wavelength of light to be transmitted.

In addition, when the core transmits three wavelengths of light, namely 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.

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

In addition, the tapered shape of the reduction portion 13R2 has been described as having a constant planar width reduction and a straight side shape in plan view, but 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 straight portion 13R1 and the second straight portion 13R3. In this case, it is preferable that there are no parts where the rate of reduction in width relative to the distance in the X direction is significantly large. Furthermore, regardless of the description of the above embodiment, the reduction portion 13R2 may have a tapered shape with a variable thickness h.

In the above, an electronic module has been described in which light emitted by a light-emitting element is input from the first end face eR1, the third end face eG1, and the fifth end face eB1, respectively, and is output to approximately the same position, but this is not limited to the above. For example, the electronic element may have a light-receiving element, and the light input from the second end face eR2, the fourth end face eG2, and the sixth end face eB2 may be received by the light-receiving element. Furthermore, light may include electromagnetic waves other than visible light, such as infrared rays, as long as the light has a wavelength that can be transmitted by an optical waveguide. Accordingly, a temperature measuring element for measuring temperature may also be included in the electronic element.

In the above, the electronic device equipped with the light-emitting module having the optical waveguide has been described using AR glasses, which are smart glasses including a head-mounted display, as an example, but the electronic device may also be used in other electronic devices, such as a head-up display and a projector.
In addition, the specific configurations, structures, positional relationships, materials, and the like shown in the above embodiments can be appropriately modified 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 its equivalents.

This disclosure can be used in optical waveguides, packages for storing electronic elements, electronic modules, and electronic devices.

Reference Signs List 1, 1a, 1b Light emitting module 10, 10a, 10b Optical waveguide module 11, 11b Substrate 12 Cladding 12L Optical waveguide section 12W Wall section 121, 122 Projection section 13 Core 13R First core 13G Second core 13B Third core 13R1 First straight section 13R3 Second straight section 13G1 Third straight section 13G3 Fourth straight section 13B1 Fifth straight section 13B3 Sixth straight section 13G2 First curved section 13B2 Second curved section 13G21 First arc section 13G22 Second arc section 13B21 Third arc section 13B22 Fourth arc section 13R2 Reduced section 14 Electrode 141 First electrode 142 Second electrode 141a Electrode pad 20 Lenses 30, 30R, 30G, 30B Light emitting element 40, 40a Lid 50, 50b Package 51 Window 54 Electrode 80 Display 81 Scanning mirror 82 Light guiding section 90 Control section C1, C5a Recess C1a Step 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 Top surface S3 Incident surfaces T1, T2 Circumferential angle W Bonding wires w11, w12, w2 Width

Claims (20)

a cladding having a first surface;
a core located within the cladding;
Equipped with
The core is
a first core extending in a first direction between a first end surface and a second end surface exposed from the first surface;
a second core that is spaced apart from the first core in a second direction perpendicular to the first direction and extends between a third end surface and a fourth end surface exposed from the first surface;
Equipped with
The first core is
a first linear portion having one end which is the first end surface and has a constant width in the second direction;
a reduced portion connected to the first linear portion, the reduced portion having a cross-sectional area in the second direction decreasing toward the second end surface;
having
the second core has a first curved portion having a curved shape and a distance between the first core and the first curved portion decreasing toward the fourth end surface,
In a side view along the second direction, the reduced portion and the first curved portion have an overlapping portion.
Optical waveguide. The optical waveguide of claim 1, wherein the third end face has a smaller area than the first end face. The optical waveguide according to claim 1 or 2, wherein the second end face has a smaller area than the fourth end face. The optical waveguide according to any one of claims 1 to 3, wherein the length of the reduced portion in the first direction is longer than the length of the first straight portion in the first direction. a normal direction of the second end face is the same as a normal direction of the fourth end face,
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;
The optical waveguide according to any one of claims 1 to 4. The 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. The optical waveguide according to any one of claims 1 to 6, wherein the first core has a second straight portion whose one end is the second end face and whose width in the second direction is constant. The second core is
a third straight portion, one end of which is the third end surface and which is connected to the first curved portion;
a fourth straight portion, one end of which is the fourth end surface and which is connected to the first curved portion;
having
The first curved portion has a first arc portion connected to the third straight portion and a second arc portion connected to the fourth straight portion,
The radius of curvature of the first arc portion is equal to the radius of curvature of the second arc portion.
The optical waveguide according to any one of claims 1 to 7. The optical waveguide of claim 8, wherein the circumferential angle of the first arc portion is equal to the circumferential angle of the second arc portion. 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 surface and a sixth end surface located on the first surface,
the third core has a curved shape and a second curved portion whose distance from the first core becomes smaller as the third core approaches the first surface,
In a side view along the second direction, the second curved portion and the reduced portion have an overlapping portion.
The optical waveguide according to any one of claims 1 to 9. The optical waveguide of claim 10, wherein 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. 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. 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 surface and a sixth end surface located on the first surface,
The third core is
a second curved portion having a curved shape, the distance between the second curved portion and the first core decreasing as the second curved portion approaches the first surface;
a fifth straight portion, one end of which is the fifth end surface and which is connected to the second curved portion;
a sixth straight portion, one end of which is the sixth end surface and which is connected to the second curved portion;
having
The second curved portion has a third arc portion connected to the fifth straight portion and a fourth arc portion connected to the sixth straight portion,
The radius of curvature of the third arc portion is equal to the radius of curvature of the fourth arc portion,
In a side view along the second direction, the second curved portion and the reduced portion have an overlapping portion.
9. The optical waveguide according to claim 8. The optical waveguide of claim 13, wherein the circumferential angle of the third arc portion is equal to the circumferential angle of the fourth arc portion. The optical waveguide according to claim 13 or 14, wherein the radius of curvature of the first arc portion and the radius of curvature of the third arc portion are different from each other. The optical waveguide according to any one of claims 13 to 15, wherein the path length of the fifth straight section and the path length of the sixth straight section are different from the path length of the first straight section. The optical waveguide according to any one of claims 10 to 12, wherein the width of the cross section perpendicular to the extension direction of the second core and the width of the cross section perpendicular to the extension direction of the third core are each constant. a substrate having a second surface;
The optical waveguide according to any one of claims 1 to 17, located on the second surface;
an electrode located in an element mounting area on the upper side of the second surface;
Equipped with
The cladding is
A wall portion surrounding the element mounting area is provided,
the first end surface and the third end surface are exposed on a third surface of the wall portion;
A package for storing electronic elements. The electronic device storage package according to claim 18 ;
an electronic element located in the element mounting area;
a lid located on the clad and covering the element mounting area;
Equipped with
The electrodes include a first electrode and a second electrode,
The electronic element includes a first electronic element connected to the first electrode and a second electronic element connected to the second electrode.
Electronic module. 20. An electronic module according to claim 19;
A display unit;
Equipped with
the electronic element is a light-emitting element,
The display unit performs display using light emitted from the electronic module.
Electronic devices.

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