JP2020194071A - Optical waveguide and rgb light-emitting device - Google Patents

Abstract

To achieve both high propagation efficiency and high allowance for the arrangement of other optical modules for connecting optical paths.SOLUTION: An optical waveguide 101 is an optical waveguide in which a core 10, a cladding 11, and condensing lenses 21, 22, 23 are integrally coupled. The core forms a multiplexing path that connects a plurality of incident end faces 31a, 32a, 33a with one emission end face 41a through a plurality of divided paths 31, 32, 33 having the incident end faces at one ends, a multiplexing part 40 at which the plurality of divided paths meet with each other, and an integrated path 41 having the emission end face at one end. The plurality of condensing lenses are provided corresponding to the plurality of incident end faces. The condensing lenses are respectively arranged opposite to the incident end faces of the core, and the condensing lenses condense rays of light incident from incident end faces 21a, 22a, 23a of the condensing lenses and make the rays of light incident on the incident end faces of the core.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an optical waveguide and an RGB light emitting device including an optical waveguide.

Conventionally, an optical waveguide having a branching / coupling structure of an optical path or the like has been used.
In Patent Document 1, each RGB light is incident on a common waveguide (core) as an optical waveguide that combines three lights of red (R) light, green (G) light, and blue (B) light. , A slanted structure in which the width of the waveguide (core) decreases linearly toward the emission side, or three waveguides (cores) by incidenting each RGB light into a different waveguide (core). ) Are associated with a waveguide associative structure.

Japanese Unexamined Patent Publication No. 2005-070573

However, in the inclined structure, the boundary surface between the core and the clad around the waveguide is inclined, and the light incident on the boundary surface is close to the vertical incident, and light transmission is likely to occur. Therefore, light leakage from the waveguide occurs, and the propagation loss increases.
On the other hand, in the waveguide associative structure, the width of the incident end of each light can be narrowed to reduce the inclination of the waveguide and suppress the light leakage from the waveguide, but the narrower the incident end, the smaller the light leakage from the waveguide. Due to an arrangement error when mounting a module such as a light emitting element that injects light into the optical waveguide, light that does not enter the waveguide tends to be generated, which also causes propagation loss.
As described above, it has been difficult to achieve both high propagation efficiency and high tolerance for arrangement with other optical modules connecting the optical paths in the optical waveguide.

The optical waveguide according to one aspect of the present disclosure is an optical waveguide in which a core, a cladding, and a condenser lens are integrally coupled, and the core is formed between a plurality of incident end faces and one outgoing end face. A condensing lens is formed by forming a condensing waveguide that connects a plurality of dividing paths having an incident end face as one end, a confluent portion in which the plurality of dividing paths meet, and an integrated path having the emitting end face as one end. A plurality of the condensing lenses are provided corresponding to the plurality of incident end faces, and the condensing lenses are respectively arranged to face the incident end faces of the core, and the light incident from the incident end faces of the condensing lens is collected by the condensing lens of the core. It is designed to be focused and incident on the incident end face.

The RGB light emitting device of one aspect of the present disclosure includes the optical waveguide and light source modules for red (R) light, green (G) light, and blue (B) light, and the optical waveguide includes the incident end face. The number of light sources, the number of the dividing paths, and the number of the condensing lenses are set to 3, so that the light from the light source module is incident on each of the condensing lenses, combined by the combined waveguide, and emitted. It is assembled in.

According to the optical waveguide of the present disclosure, it is possible to achieve both high propagation efficiency and high tolerance for arrangement with other optical modules connecting optical paths.

According to the RGB light emitting device of the present disclosure, it is possible to achieve both high propagation efficiency and high tolerance for arrangement with the light source module.

It is a top view of the RGB light emitting device which comprises the optical waveguide which concerns on 1st Embodiment of this disclosure. It is a top view of the RGB light emitting device provided with the optical waveguide according to 1st Embodiment of this disclosure, and is the figure for demonstrating the arrangement error of a light emitting element. It is a top view which shows the optical waveguide model which concerns on a comparative example, and the misalignment direction X. It is a top view which shows the optical waveguide model which concerns on an example of this invention, and the tilt deviation direction θ. It is a graph which shows the change of the propagation efficiency with respect to the position X of a light emitting element. It is a graph which shows the change of the propagation efficiency with respect to the inclination angle θ of a light emitting element. It is a plan view (a) and the sectional view (b) of AA of the RGB light emitting device provided with the optical waveguide according to the second embodiment of the present disclosure. It is a top view of the RGB light emitting device which comprises the optical waveguide which concerns on 3rd Embodiment of this disclosure. It is a top view of the RGB light emitting device which comprises the optical waveguide which concerns on 4th Embodiment of this disclosure. It is a top view of the RGB light emitting device which comprises the optical waveguide which concerns on 5th Embodiment of this disclosure. It is a top view of the RGB light emitting device provided with the optical waveguide according to the sixth embodiment of the present disclosure. It is a top view of the RGB light emitting device which comprises the optical waveguide which concerns on 7th Embodiment of this disclosure. It is a top view of the RGB light emitting device which comprises the optical waveguide which concerns on 8th Embodiment of this disclosure. It is a top view of the RGB light emitting device which comprises the optical waveguide which concerns on 9th Embodiment of this disclosure.

[First Embodiment]
First, the optical waveguide of the first embodiment of the present disclosure and the RGB light emitting device including the optical waveguide will be described.
As shown in FIG. 1, the RGB light emitting device 101 of the present embodiment includes an optical waveguide 201, a red (R) light emitting element 301, a green (G) light emitting element 302, and a blue (B) light emitting element 303. And an emission optical system 401.
The light emitting elements 301, 302, and 303 correspond to the light source module. Laser diodes and the like are applied as the light emitting elements 301, 302, and 303.

The optical waveguide 201 is a mass in which the core 10, the clad 11, and the three condensing lenses 21, 22, and 23 are integrally coupled. At this time, the optical waveguide 201 may be, for example, glass such as quartz, resin, or the like. In the optical waveguide 201, the materials constituting the core 10 and the clad 11 may both be glass or resin, or one may be glass and the other may be resin. In this case, the refractive indexes of the core 10 and the clad 11 are different, and the core 10 preferably has a higher refractive index than the clad 11. This difference in refractive index is used to totally reflect light. That is, if a path is made of a material having a high refractive index and the surrounding area is surrounded by a material having a low refractive index, the light can be confined in the path having a high refractive index.
The core 10 includes a plurality of dividing paths 31 (32, 33) having an incident end surface 31a (32a, 33a) as one end between the plurality of incident end faces 31a, 32a, 33a and one exit end surface 41a, and the plurality of said. A junction waveguide is formed which connects the junction 40 where the division paths 31, 32, and 33 of the above meet with each other and the integration path 41 having the exit end surface 41a as one end.

A plurality of condenser lenses 21, 22, and 23 are provided corresponding to the plurality of incident end faces 31a, 32a, 33a.
Condensing lenses 21, 22, and 23 are arranged to face the incident end faces 31a, 32a, and 33a of the core 10, respectively. The optical axes of the condenser lenses 21, 22, and 23 are arranged on the central axes of the incident end faces 31a, 32a, and 33a.
Light (red (R) light, green (G) light, blue (B) light) emitted from the light emitting elements 301, 302, 303 and incident from the incident end faces 21a, 22a, 23a of the condenser lens is collected by the condenser lens. 21, 22, 23 are designed to collect and incident light on the incident end faces 31a, 32a, 33a of the core 10.
The RGB light 402 is emitted from the emission end face 41a due to the combined wave by the core 10.
The condenser lens 21, 22, 23 is, for example, a plano-convex lens in which the incident end faces 21a, 22a, 23a are formed in a plane and the exit end faces 21b, 22b, 23b are formed in a convex surface.
The optical waveguide 201 and the light emitting elements 301, 302, 303 are assembled so that the optical axes of the condenser lenses 21, 22, and 23 coincide with the center of the light emitting portion of the light emitting elements 301, 302, 303.

Further, in the combined waveguide by the core 10, the widths of the incident end faces 31a, 32a, 33a of the core 10 are wider than the width of the exit end faces 41a of the core 10. Then, it has a section in which the width of the waveguide gradually decreases from the incident end faces 31a, 32a, 33a toward the exit end face 41a. In the present embodiment, the sections where the waveguide width gradually decreases are divided paths 31, 32, 33.

Further, the combined waveguide by the core 10 passes through an S-shaped curved portion from the incident end faces 31a, 33a of the core 10 with respect to a part of the plurality of dividing paths 31, 32, 33, that is, the dividing paths 31, 33 on both sides. We are meeting at the combined wave section 40. In order to reduce the curvature of the curved portion, almost the entire portion of the dividing paths 31 and 33 is formed as an S-shaped curved portion.

As shown in FIG. 2, an arrangement error of the light emitting elements 301, 302, 303 with respect to the optical waveguide 201 may occur. For example, as in the light emitting element 302 of FIG. 2, a positional shift may occur in a direction perpendicular to the optical axis. Further, for example, as in the light emitting element 303 of FIG. 2, the optical axis may be tilted and displaced.
However, even if there is an arrangement error of the light emitting elements 301, 302, 303 as described above, the light from the light emitting elements 301, 302, 303 is emitted from the incident end faces 31a, due to the light condensing action of the condensing lenses 21, 22, 23. The light is collected on the 32a and 33a and introduced into the dividing paths 31, 32 and 33, respectively. That is, due to the presence of the condenser lenses 21, 22, 23, the propagation loss is small, and the arrangement tolerance of the light emitting elements 301, 302, 303 for connecting the optical path between the light emitting elements 301, 302, 303 and the core 10 is large. ..

Here, a simulation result comparing the propagation efficiencies of the optical waveguide model of the comparative example shown in FIG. 3 and the optical waveguide model of the present invention example shown in FIG. 4 will be disclosed. Further, FIG. 3 shows the direction X of the positional deviation, FIG. 4 shows the direction θ of the tilt deviation, FIG. 5 shows the change in the propagation efficiency with respect to the position X, and FIG. 6 shows the change in the propagation efficiency with respect to the tilt angle θ.
As shown in FIG. 5, a decrease in propagation efficiency is observed at a position X of ± several μm in both the comparative example and the example of the present invention, but in the example of the present invention, the decrease in propagation efficiency is suppressed as compared with the comparative example.
As shown in FIG. 6, in the comparative example, a decrease in propagation efficiency was observed when there was a non-zero inclination angle θ, but in the example of the present invention, no decrease in propagation efficiency was observed over a range of ± 10 °.
As described above, according to the present optical waveguide 201, both high propagation efficiency and high tolerance for arrangement of the light emitting elements 301, 302, and 303 can be achieved at the same time. The RGB light emitting device 101 can combine the lights (R, G, B) of the light emitting elements 301, 302, and 303 and emit them with high efficiency with little propagation loss.

[Second Embodiment]
Next, the RGB light emitting device 102 of the second embodiment and the optical waveguide 202 included therein will be described with reference to FIG. 7. This embodiment is a partial modification of the first embodiment, and the corresponding portion of the modified portion will be described with the same reference numerals.
In the present embodiment, a part of the side surface of the core 10 is exposed to the outside from the clad (in this case, the solid clad which is a component of the optical waveguide). For example, as shown in FIG. 7B, the partition paths 31, 32, and 33 are laminated on the clad 11, and the lateral and upper portions are open. The semi-embedded type may be used.
Therefore, the lateral and upper clad layers become ambient air. Since air having a high refractive index becomes a clad layer, light leakage from the core 10 is less likely to occur and propagation efficiency is improved. For example, it is possible to arrange the incident end faces 31a and 33a on both sides farther from the central incident end face 32a.
Such a structure may be applied to the entire core 10, but may be applied to at least the dividing paths 31, 32, 33.

[Third Embodiment]
Next, the RGB light emitting device 103 of the third embodiment and the optical waveguide 203 included in the RGB light emitting device 103 will be described with reference to FIG. This embodiment is a partial modification of the first embodiment, and the corresponding portion of the modified portion will be described with the same reference numerals.
In the present embodiment, the condenser lenses 21, 22, and 23 have a biconvex shape in which the incident end faces 21a, 22a, 23a and the exit end faces 21b, 22b, 23b are convex.
By making the condensing lenses 21, 22, and 23 biconvex, the condensing force can be increased, and leakage to the incident end faces 31a, 32a, 33a can be further suppressed.

[Fourth Embodiment]
Next, the RGB light emitting device 104 of the fourth embodiment and the optical waveguide 204 included in the RGB light emitting device 104 will be described with reference to FIG. This embodiment is a partial modification of the first embodiment, and the corresponding portion of the modified portion will be described with the same reference numerals.
In the present embodiment, the incident end faces 31a, 32a, 33a of the core 10 are formed on a convex surface having a light collecting action.
By making the incident end faces 31a, 32a, 33a into a convex lens, the reflection on the incident end faces 31a, 32a, 33a is reduced as compared with the case where the incident end faces 31a, 32a, 33a are made flat. Therefore, the light reflection loss can be reduced. At the same time, it is possible to increase the light-collecting power and make it difficult for light to leak.

[Fifth Embodiment]
Next, the RGB light emitting device 105 of the fifth embodiment and the optical waveguide 205 included in the RGB light emitting device 105 will be described with reference to FIG. This embodiment is a partial modification of the first embodiment, and the corresponding portion of the modified portion will be described with the same reference numerals.
In the present embodiment, a condensing lens 42 for a converging portion that collects light from each of the plurality of dividing paths 31, 32, and 33 and causes the light to enter the integrated path 41 is built in the optical waveguide 205.
By installing the condensing lens 42 in the confluence 40, it is possible to increase the condensing power in the condensing portion 40 and reduce the loss due to light leakage in the confluence 40 and the integrated path 41. ..

[Sixth Embodiment]
Next, the RGB light emitting device 106 of the sixth embodiment and the optical waveguide 206 included in the RGB light emitting device 106 will be described with reference to FIG. This embodiment is a partial modification of the first embodiment, and the corresponding portion of the modified portion will be described with the same reference numerals.
In the present embodiment, the condenser lenses 21, 22, and 23 are diffractive lenses.
By using a diffractive lens as the condenser lens 21, 22, 23, the waveguide can be made thinner and the distance can be shortened.

[7th Embodiment]
Next, the RGB light emitting device 107 of the seventh embodiment and the optical waveguide 207 included in the RGB light emitting device 107 will be described with reference to FIG. This embodiment is a partial modification of the first embodiment, and the corresponding portion of the modified portion will be described with the same reference numerals.
In the present embodiment, the optical axes 21c, 22c, and 23c of the plurality of condenser lenses 21, 22, and 23 are inclined to each other. The inclination is such that when the optical axes 21c, 22c, 23c are extended to the exit side, the optical axes 21c, 22c, 23c approach each other at the combine 40 from the inside of the condenser lenses 21, 22, 23. Is. The optical axes 21c, 22c, and 23c may pass through the combine 40. The optical axes 21c, 22c, and 23c may pass through the central axis of the waveguide in the combine 40. The optical axes 21c, 22c, and 23c may intersect each other on the central axis of the waveguide in the combine 40.
Further, each of the mounting surfaces of the light emitting elements 301, 302, and 303 is formed substantially perpendicular to the corresponding optical axes 21c, 22c, and 23c.
Therefore, the central axes of the light emitting elements 301 and 303 on both sides are arranged so as to face the combine 40, and the optical axes 21c, 22c, and 23c can also be in the same direction.
Therefore, the curved portions of the dividing paths 31, 32, and 33 can be reduced one by one, and the reduction of the curved portions can reduce the loss due to light leakage.
The light emitting elements 301 and 303 may not be tilted, but only the condensing lenses 21 and 23 may be tilted and arranged so that the light from the light emitting elements 301 and 303 is focused on the incident end faces 31a and 33a. In that case, the condenser lenses 21 and 23 may have a biconvex shape.
Further, in the present embodiment, the curved portions of the dividing paths 31, 32, and 33 are set to one place, but as in the first embodiment, the S-shaped curved portion having two curved portions is implemented. You may. Even in that case, the S-shaped curved portion can be gently formed.

[8th Embodiment]
Next, the RGB light emitting device 108 of the eighth embodiment and the optical waveguide 208 included in the RGB light emitting device 108 will be described with reference to FIG. This embodiment is a partial modification of the first embodiment, and the corresponding portion of the modified portion will be described with the same reference numerals.
In the present embodiment, the refractive index of the core 10 is lower in the exit end face 41a than in the combine 40, and has a section in which the refractive index gradually decreases from the combine 40 toward the exit end face 41a. In the present embodiment, almost the entire integrated road 41 is the section thereof.
By setting the refractive index of the core 10 on the emission end surface 41a to be lower, the propagated light is easily emitted in the single mode, and the propagation efficiency of the emitted light is improved.
The number of propagation modes increases as the NA (numerical aperture) increases, but the NA increases as the difference in refractive index between the core layer (widden path) and the clad layer (periphery) increases, so the refractive index of the core 10 is reduced. , The number of propagation modes decreases, and when it is below a certain value, it becomes a single mode.

[9th Embodiment]
Next, the RGB light emitting device 109 of the ninth embodiment and the optical waveguide 209 included in the RGB light emitting device 109 will be described with reference to FIG. This embodiment is a partial modification of the first embodiment, and the corresponding portion of the modified portion will be described with the same reference numerals.
In the present embodiment, the waveguide width of the core 10 is narrower at the exit end surface 41a than at the combine 40. For example, the wave junction 40 has a waveguide width of 10 μm or more, and the emission end face 41a has a waveguide width of less than 10 μm.
Then, the waveguide width of the core 10 has a section in which the width of the waveguide gradually decreases from the combine 40 to the exit end surface 41a. In the present embodiment, almost the entire integrated road 41 is the section thereof.
By narrowing the waveguide width of the emission end surface 41a, the propagated light can be emitted in a single mode, and the propagation efficiency of the emitted light is improved.
The number of propagation modes also depends on the core diameter, and as the waveguide width is reduced, the single mode becomes available below a certain value.

Although the embodiments of the present disclosure have been described above, the embodiments are shown as examples, and can be implemented in various other embodiments, and the components are omitted as long as the gist of the invention is not deviated. , Can be replaced or changed.
In addition to the illustrated combinations, the combinations of the first to ninth embodiments can be appropriately combined within a consistent range.

10 Core 11 Clad 21, 22, 23 Condensing lens 21a, 22a, 23a Incident end face 21b, 22b, 23b Exit end face 21c, 22c, 23c Optical axis 31, 32, 33 Dividing path 31a, 32a, 33a Incident end face 40 Part 41 Integrated path 41a Emission end face 42 Condensing part Condensing lens 101 RGB light emitting device (first embodiment)
102 RGB light emitting device (second embodiment)
103 RGB light emitting device (third embodiment)
104 RGB light emitting device (fourth embodiment)
105 RGB light emitting device (fifth embodiment)
106 RGB light emitting device (sixth embodiment)
107 RGB light emitting device (7th embodiment)
108 RGB light emitting device (8th embodiment)
109 RGB light emitting device (9th embodiment)
201 Optical waveguide (first embodiment)
202 Optical waveguide (second embodiment)
203 Optical waveguide (third embodiment)
204 Optical waveguide (4th embodiment)
205 Optical waveguide (fifth embodiment)
206 Optical waveguide (sixth embodiment)
207 Optical waveguide (7th embodiment)
208 Optical waveguide (8th embodiment)
209 Optical waveguide (9th embodiment)
301, 302, 303 Light emitting element 402 RGB light

Claims (12)

An optical waveguide in which a core, a cladding, and a condenser lens are integrally coupled.
The core has a plurality of dividing paths having the incident end face as one end, a confluent portion in which the plurality of dividing paths meet, and the emitting end face as one end between the plurality of incident end faces and one exit end face. Form a combined waveguide that connects to the integrated path
A plurality of the condenser lenses are provided corresponding to the plurality of incident end faces.
Each of the condenser lenses is arranged to face the incident end face of the core, and the light incident from the incident end face of the condenser lens is focused and incident on the incident end face of the core by the condenser lens. Waveguide. The optical waveguide according to claim 1, wherein the combined waveguide has a section in which the width of the incident end face of the core is wider than the width of the exit end face of the core and the width of the waveguide gradually decreases from the incident end face toward the exit end face. .. The optical beam according to claim 1 or 2, wherein the combined waveguide is associated with the combined wave portion through an S-shaped curved portion from the incident end face of the core for a part of the plurality of divided paths. Waveguide. The optical waveguide according to any one of claims 1 to 3, wherein a part of the side surface of the core is exposed to the outside from the clad with respect to at least the plurality of dividing paths. The optical waveguide according to any one of claims 1 to 4, wherein the incident end surface of the core is formed on a convex surface having a light collecting action. The optical waveguide according to any one of claims 1 to 5, wherein a converging lens that collects light from each of the plurality of divided paths and causes the light to be incident on the integrated path is constructed. The optical waveguide according to any one of claims 1 to 6, wherein the condenser lens has a biconvex shape having both convex surfaces. The optical waveguide according to any one of claims 1 to 6, wherein the condensing lens is a diffractive lens. The optical axes of the plurality of the condenser lenses are inclined to each other, and the inclination is such that when each optical axis is extended to the exit side, the optical axes approach each other at the junction from the inside of the condenser lens. The optical waveguide according to any one of claims 1 to 8. Any one of claims 1 to 9, wherein the refractive index of the core is lower than that of the confluence portion at the exit end surface of the core, and has a section gradually decreasing from the confluence portion toward the emission end surface of the core. The optical waveguide according to. Any one of claims 1 to 10, wherein the waveguide width of the core is narrower at the exit end surface of the core than the combine portion, and has a section gradually decreasing from the combine portion toward the emission end surface of the core. The optical waveguide according to 1. The optical waveguide according to any one of claims 1 to 11 and each light source module for red (R) light, green (G) light, and blue (B) light are provided.
In the optical waveguide, the number of incident end faces of the core, the number of dividing paths and the number of condensing lenses are each set to 3.
An RGB light emitting device assembled so that light from the light source module is incident on each of the condenser lenses, and is combined and emitted by the combined waveguide.

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