JP3858460B2 - Optical signal transmission system and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical signal transmission system having an optical waveguide, a structure that improves the coupling efficiency of input / output light even when a surface light emitting element or a surface light receiving element is used, and enables stable optical signal transmission, and a simple structure thereof. It relates to a manufacturing method.
[0002]
[Prior art]
With the advancement of IC technology and LSI technology, these operating speeds and integration scales have improved, and high performance in microprocessors and large capacity of memory chips are rapidly progressing. Under such circumstances, the high-speed and high-density signal wiring and the electrical wiring delay are the bottleneck to the above-mentioned high performance. As a technology that can solve this problem, optical interconnection (optical wiring) has attracted attention.
Optical wiring is considered to be applicable to various layers, such as between equipment devices, between boards in equipment equipment, between chips in boards, etc. For example, for signal transmission over a relatively short distance, such as between chips. An optical signal transmission system using an optical waveguide as a transmission line is effective.
[0003]
Here, when an optical wiring using an optical waveguide is applied to, for example, a transmission path for a multi-chip module (MCM) connecting LSIs, an edge-emitting laser diode (LD) or a light emitting device that is often used conventionally is used. When a diode (LED) is used as a light emitting element on the transmission side, the light emitting element can be disposed in the vicinity of the incident end face of the optical waveguide. However, when a surface emitting laser diode such as a vertical cavity surface emitting laser (VCSEL), which is advantageous for power saving and surface array, is used as a light emitting element, the above arrangement is a structure. It is difficult.
Further, when a photodiode is used as the light receiving element, since it is a surface light receiving element, it is also difficult to dispose it near the exit end face of the optical waveguide.
[0004]
As one of the solutions, as shown in FIG. 12, the light emitting element and the light receiving element are arranged above the optical waveguide, and between the thickness direction of the substrate including the optical waveguide and the in-plane direction of the substrate. There is known an optical signal transmission system configured to bend an optical path using a mirror member.
In FIG. 12, an optical waveguide extending in the in-plane direction is formed on the substrate 31. In this optical waveguide, a core 33 is surrounded by a clad 32 made of a material having a lower refractive index. The clad 32 is formed by dividing it into a lower clad layer 32L and an upper clad layer 32U. On the incident end side and the emission end side of the core 33, an incident side mirror 34 and an emission side mirror 35 having a light reflection surface inclined by, for example, 45 ° from the substrate surface are disposed, and above these, a light emitting element 36 and a light receiving element, respectively. An element 37 is arranged.
[0005]
The light emitting element 36 is mounted on the upper surface of the clad 32 with the light emitting surface facing downward. The light emitted from the light emitting element 36 first travels in the clad 32 in the thickness direction (downward direction) of the substrate, and then is reflected by the incident side mirror 34 and enters the core 33 as indicated by an arrow in the figure. Then, after propagating through the core 33, the light is reflected by the output side mirror 35, travels in the traveling direction in the thickness direction (upward direction) of the substrate, and enters the light receiving element 37. In FIG. 12, the light is drawn so that the light travels straight through the core 33. However, this is merely for the convenience of illustration, and in actuality, light incident within a predetermined critical angle range is shown. Needless to say, it propagates while repeating total reflection at the interface between the clad 33 and the clad 32.
[0006]
The manufacturing process when the optical waveguide of such an optical signal transmission system is formed using a polymer material is roughly as follows.
First, as shown in FIG. 10, a lower clad layer 32L and a core layer having a higher refractive index than the lower clad layer 32L are formed on a substrate 31 made of a material such as silicon or glass by spin coating and heat treatment, for example. The cores 33 are sequentially laminated, and then the core layer is patterned to form the cores 33. This patterning is performed, for example, by dry etching through a metal mask (not shown).
[0007]
Next, as shown in FIG. 11, the entrance side mirror 34 and the exit side mirror 35 are arranged on the entrance end side and the exit end side of the core. The mirrors 34 and 35 are shown in FIG. 11 as having a reflective film deposited on an inclined surface of an appropriate base material having a triangular cross-sectional shape, but this is also a convenient expression. The inclined surface of the base material may be used as the reflective surface as it is without forming a reflective film. Further, when the base material is formed by using the same material layer as that of the core 33, it is possible to leave portions to be the base material at both ends of the core 33 in the stage shown in FIG. .
Further, the upper cladding layer 32U is formed flat on the entire surface of the substrate by, for example, spin coating and heat treatment. The upper clad layer 32U is made of the same material as the lower clad layer 32L, and constitutes the clad 32 surrounding the core 33 in cooperation with the lower clad layer 32L.
Thereafter, if the light emitting element 36 and the light receiving element 37 are mounted on the upper surface of the clad 32 at positions facing the incident side mirror 34 and the outgoing side mirror 35, respectively, the optical signal transmission system shown in FIG. Can be configured.
[0008]
[Problems to be solved by the invention]
However, light from the light emitting element 36 is emitted with a certain divergence angle, and light from the exit end of the core 33 is also emitted with a certain divergence angle. Therefore, in order to increase the light coupling efficiency between the components of the optical signal transmission system, the distance between the light emitting element 36 and the incident side mirror 34 and the distance between the emission side mirror 35 and the light receiving element 37. Must be optimized for the divergence angle.
[0009]
However, even if such optimization is performed on a single waveguide, there is a problem in that the coupling efficiency differs between layers in the stacked optical signal transmission system. This problem will be described with reference to FIG.
FIG. 13 shows an example of an optical signal transmission system in which three-layer optical waveguides are laminated in the thickness direction of the substrate. The components of the first layer, which is the layer immediately above the substrate 41, are the clad 42a, the core 43a, the incident side mirror 44a, and the output side mirror 45a; the components of the second layer above it are the clad 42b, the core 43b, and the incident side. The components of the third layer above the mirror 44b and the exit side mirror 45b are a clad 42c, a core 43c, an entrance side mirror 44c, and an exit side mirror 45c. Further, light emitting elements 46a, 46b, 46c and light receiving elements 47a, 47b, 47c corresponding to these layers are arranged on the upper surface of the clad 42c. Each component of these optical signal transmission systems follows a spatial arrangement that does not interfere with optical coupling in other layers.
[0010]
Here, when the performances of the light emitting elements 46a, 46b, 46c are all the same and have the same light divergence angle, and the performances of the light receiving elements 47a, 47b, 47c are all the same and have the same light receiving sensitivity, The coupling efficiency decreases as the optical path length increases. In other words, even if the light from the light emitting element 46c can efficiently reach the light receiving element 47c through the core 43c in the third layer, the light introduced into the core 43b is reduced in the second layer due to the divergence angle. Therefore, the amount of light incident on the light receiving element 47b is reduced. Such a decrease in coupling efficiency becomes more serious for the first layer having a longer optical path length.
Therefore, the present invention improves the optical coupling efficiency and eliminates the optical path length dependency even when the optical waveguides are laminated, and an optical signal transmission system that enables stable signal transmission, and simple manufacturing thereof. It aims to provide a method.
[0011]
[Means for Solving the Problems]
The optical signal transmission system of the present invention uses the mirror members provided on the incident end side and the emission end side in the optical waveguide extending in the in-plane direction of the substrate, and the light traveling direction in the optical waveguide And a traveling direction of propagating light before and after the optical waveguide, at least of an optical path from the light emitting element to the incident side mirror member or an optical path from the output side mirror member to the light receiving element. On the other hand, a propagation control layer made of a material having a refractive index different from that of the cladding portion of the optical waveguide is interposed in the middle portion, and at least an incident side mirror member or at least a light receiving element is provided at the interface between the propagation control layer and the cladding portion. By giving a shape that can converge the propagating light toward one side, the coupling efficiency is increased.
[0012]
As the structure of the optical signal transmission system, what is considered to be easy to achieve especially from the viewpoint of the manufacturing process is that the interface between the propagation control layer and the cladding part is at least one of the incident side mirror member and the output side mirror member. In this structure, the refractive index of the propagation control layer is made larger than the refractive index of the cladding part. This is because such a convex surface can be formed by selectively removing the surface layer portion of the cladding.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The optical signal transmission system according to the present invention has an optical path from a light emitting element to an incident side mirror member, an optical path from an output side mirror member to the light receiving element, or a refraction of a propagation control layer interposed in the middle of both optical paths. By combining the effect of the rate and the effect of the interface shape between the propagation control layer and the cladding part, the convergence of the propagation light in the thickness direction of the substrate including the cladding part is improved. The propagation control layer may be interposed in any one of the above optical paths, and the coupling efficiency is improved to some extent by using only one of them. However, it is self-evident that the coupling efficiency of the entire system can be improved when it is interposed in both optical paths. In the most general thin film formation process on the substrate, the thin film is laminated on the entire surface of the substrate unless patterning is performed. Therefore, if the propagation control layer is laminated on the entire surface of the cladding portion, this layer is formed. Inevitably intervened on both optical paths.
[0014]
The propagation control layer may be interposed anywhere in the optical path as long as it can directly contact and form an interface with clad portions having different refractive indexes. Therefore, the propagation control layer does not necessarily need to form the outermost layer portion of the substrate.
The shape of the interface at the portion overlapping the optical path varies depending on the refractive index relationship between the propagation control layer and the cladding portion. That is, when the refractive index of the propagation control layer is larger than the refractive index of the cladding part, the interface is convex toward the incident side mirror, the output side mirror, or both. On the contrary, when the refractive index of the propagation control layer is smaller than the refractive index of the cladding part, the interface is convex toward the light emitting element, the light receiving element, or both.
[0015]
By the way, the conditions required for the clad part and the core part constituting the optical waveguide and the propagation control layer provided in the present invention are high transparency, low waveguide loss, and little change in refractive index and volume over time. And excellent heat resistance in consideration of solder mounting of the light emitting / receiving element. As materials satisfying these conditions, quartz is known for inorganic materials, and ultraviolet curable resins such as epoxy and acrylic materials for organic materials, and polymer materials such as polyimide are known. In particular, the polymer material has advantages that the cost is low, it can be manufactured by a low-temperature process, and it is easy to cope with an increase in area.
[0016]
When the interface between the propagation control layer and the cladding part is convex toward at least one of the incident side mirror and the emission side mirror, the concave part may be formed on the surface layer part of the cladding part by some method.
As a method for forming such a concave surface portion, a method of removing the surface layer portion of the cladding portion by isotropic etching and a method of combining selective exposure and development can be considered.
When isotropic etching is performed, an etching mask having an opening is formed on at least one of the upper surface of the incident side mirror member or the outgoing side mirror member on the surface of the clad portion, and the etching mask is exposed in the opening. The surface layer portion of the cladding portion is removed. Isotropic etching can be typically performed by wet etching using an appropriate etching solution or dry etching mainly based on radical reaction.
[0017]
On the other hand, in order to form the concave surface portion by selective exposure and development, it is assumed that the clad portion is made of a photosensitive material typified by a photoresist. Moreover, considering that the site of the photochemical reaction due to exposure is limited to the surface layer portion of the cladding portion, it is particularly preferable in practice to use a positive photosensitive material whose molecular weight is reduced in the exposed portion.
[0018]
【Example】
Hereinafter, specific examples of the present invention will be described.
[0019]
Example 1
Here, a configuration of an optical signal transmission system having a propagation control layer having a refractive index higher than that of the cladding part, and the interface between the cladding part and the propagation control layer being convex toward the entrance side mirror and the exit side mirror An example will be described with reference to FIG.
In FIG. 1, an optical waveguide extending in the in-plane direction is formed on a substrate 1. This optical waveguide has a core 3 surrounded by a clad 2 made of a material having a lower refractive index. The clad 2 is formed by being divided into a lower clad layer 2L and an upper clad layer 2U. On the incident end side and the emission end side of the core 3, an incident side mirror 4 and an emission side mirror 5 having a light reflecting surface inclined by, for example, 45 ° from the substrate surface are arranged.
[0020]
A high refractive index propagation control layer 6 is laminated on the cladding 2. Convex surface portions are formed at the interface between the clad 2 and the high refractive index propagation control layer 6 toward the entrance side mirror 4 and the exit side mirror 5, respectively. These convex surface portions are concave surface portions, that is, the incident side concave surface portion 7 and the emission side concave surface portion 8 when the surface of the clad 2 is considered as a reference. Further, on the surface of the high refractive index propagation control layer 6, a light emitting element 9 is disposed at a portion corresponding to the incident side concave surface portion 7, and a light receiving element 10 is disposed at a portion corresponding to the emission side concave surface portion 8. ing.
[0021]
The light emitting element 9 is mounted on the upper surface of the high refractive index propagation control layer 6 with the light emitting surface facing downward. The light emitted from the light emitting element 9 propagates in the high refractive index propagation control layer 6 with a constant divergence angle as indicated by an arrow in the figure, but is refracted when it reaches the incident-side concave surface portion 7. Then, it propagates in the clad 2 as propagating light converged substantially in parallel. The propagating light is reflected by the incident side mirror 4 and enters the core 3, propagates through the core 3, is reflected by the output side mirror 5, and propagates again through the cladding 2 in the thickness direction (upward direction) of the substrate. . During this time, the propagating light is slightly diverged, but is refracted when it reaches the exit-side concave surface portion 8, propagates through the high refractive index propagation control layer 6 while being converged, and enters the light receiving element 10.
[0022]
In FIG. 1, the light is drawn so as to travel straight through the core 3. However, this is merely for the convenience of illustration, and actually light incident within a predetermined critical angle range is shown. Needless to say, it propagates while repeating total reflection at the interface between 3 and clad 2.
As described above, according to the optical signal transmission system described above, since the propagation light is converged at the front stage and the rear stage of the optical waveguide, the coupling efficiency between the light emitting element 9 and the optical waveguide, and the coupling between the optical waveguide and the light receiving element 10 is achieved. Efficiency has been improved.
[0023]
Example 2
Here, a configuration example of a laminated optical signal transmission system in which a structure in which a concave surface portion is provided at the interface between a high refractive index propagation control layer and a cladding portion is laminated in three stages will be described with reference to FIG.
FIG. 2 is an example of an optical signal transmission system in which three-layer optical waveguides are stacked in the thickness direction of the substrate. The components of the first layer, which is the layer immediately above the substrate 11 side, are the cladding 12a, the core 13a, the incident side mirror 14a, the output side mirror 15a, and the high refractive index propagation control layer 16a; The clad 12b, the core 13b, the incident side mirror 14b, the output side mirror 15b, and the high refractive index propagation control layer 16b; the third layer components thereon are the clad 12c, the core 13c, the incident side mirror 14c, and the output side mirror 15c. And a high refractive index propagation control layer 16c.
[0024]
In each layer, incident-side concave surface portions 17a, 17b, and 17c and output-side concave surface portions 18a, 18b, and 18c are formed at the interfaces between the claddings 12a, 12b, and 12c and the high refractive index propagation control layers 16a, 16b, and 16c, respectively. Has been. In the example shown in FIG. 2, all the formation patterns of the concave portions in each layer are made common to facilitate the production.
Further, light emitting elements 19a, 19b, 19c and light receiving elements 20a, 20b, 20c corresponding to these layers are arranged on the upper surface of the uppermost high refractive index propagation control layer 16c. Each component of these optical signal transmission systems follows a spatial arrangement that does not interfere with optical coupling in other layers.
[0025]
In such a configuration, the light from the light emitting element 19a passes through the three incident-side concave portions 17c, 17b, and 17a and the three layers of the claddings 12c, 12b, and 12a, and the path is bent by the incident-side mirror 14a. The light-receiving element 20a passes through the core 13a of the optical waveguide, is reflected by the exit-side mirror 15a, passes through the three exit-side concave portions 18a, 18b, and 18c, and the three clads 12a, 12b, and 12c. The
Similarly, light from the light emitting element 19b passes through the two incident-side concave surface portions 17c and 17b in the front stage of the second-layer optical waveguide, and passes through the two output-side concave surface portions 18b and 18c in the subsequent stage. .
The light from the light emitting element 19c passes through one incident-side concave surface portion 17c at the front stage of the third-layer optical waveguide, and passes through one emission-side concave surface portion 18c at the subsequent stage.
That is, the light introduced into the optical waveguide in a deeper layer from the surface of the substrate passes through a large number of concave portions at the front and rear stages of the optical waveguide, and the propagation light is converged each time. Therefore, the conventional dependence of the coupling efficiency on the optical path length is eliminated, and good coupling efficiency is achieved in any depth layer.
[0026]
In the example shown in FIG. 2, since the formation pattern of the concave portion in each layer is made common in consideration of the ease of manufacture, some layers are shielded by the mirror of the upper layer so that the light is completely converged. A concave portion that does not contribute is also provided. Therefore, the formation pattern of the concave portion may be changed for each layer so that the concave portion of the portion that does not contribute to light convergence is not formed from the beginning.
On the other hand, the propagating light passing through the optical waveguide located deep from the surface of the substrate passes through several concave portions of the same shape. Needless to say, it is possible to reduce the number of concave portions to be passed by optimizing the refractive index of the high refractive index propagation control layer and the curvature of the concave portion for each layer.
[0027]
Example 3
Here, a manufacturing process in the case where a polymer material is used as a constituent material of the optical waveguide and high refractive index propagation control layer 6 of the optical signal transmission system shown in FIG. Description will be made with reference to FIG.
First, as shown in FIG. 3, on the substrate 1 made of a material such as silicon or glass, the lower clad layer 2L and the lower clad layer 2L have a refractive index higher than that of the lower clad layer 2L through, for example, polymethylmethacrylate spin coating and heat treatment. A high core layer was laminated in this order, and then the core layer was patterned to form the core 3. This patterning is performed, for example, by dry etching through a metal mask (not shown).
[0028]
Next, as shown in FIG. 4, the entrance side mirror 4 and the exit side mirror 5 were formed on the entrance end side and the exit end side of the core. The two mirrors 4 and 5 are shown in FIG. 4 as having a reflective film deposited on an inclined surface of an appropriate base material having a triangular cross-sectional shape, but this is also a convenient expression. The inclined surface of the base material may be used as the reflective surface as it is without forming a reflective film. Further, when the base material is formed using the same material layer as that of the core 3, it is possible to leave portions to be the base material at both ends of the core 3 in the stage shown in FIG.
Further, the upper clad layer 2U is formed flat on the entire surface of the substrate through, for example, spin coating and heat treatment. The upper clad layer 2U is made of the same material as the lower clad layer 2L, and constitutes the clad 2 surrounding the core 3 in cooperation with the lower clad layer 2L.
[0029]
Next, as shown in FIG. 4, an etching mask 21 made of a metal material such as Al or Ti is formed on the upper surface of the clad 2. The etching mask 21 is provided with an opening 22 above the incident side mirror 4 and the emission side mirror 5.
Next, isotropic etching using, for example, oxygen plasma is performed to remove the surface layer portion of the clad 2 exposed inside the opening 22, and as shown in FIG. A side concave surface portion 8 was formed.
Next, as shown in FIG. 6, after the etching mask 21 is peeled off, a polymer material having a refractive index higher than that of polymethyl methacrylate constituting the cladding 2 is spin-coated on the entire surface of the substrate, and this is subjected to heat treatment. Was cured to form the high refractive index propagation control layer 6 flat.
Thereafter, on the surface of the high refractive index propagation control layer 6, the light emitting element 9 is mounted above the incident side concave surface portion 7 and the light receiving element 10 is mounted above the output side concave surface portion 8, as shown in FIG. An optical signal transmission system was fabricated.
[0030]
Example 4
Here, referring to FIG. 7 and FIG. 8, a photosensitive polymer material is used as the constituent material of the clad 2 and the incident side concave surface portion 7 and the emission side concave surface portion 8 are formed by photolithography and development processing. While explaining.
First, as shown in FIG. 7, the processes up to the formation of the upper cladding layer 2U were performed in the same manner as in Example 3 described above. However, the lower cladding layer 2L and the upper cladding layer 2U were formed using positive photosensitive polyimide.
Next, a part of the upper cladding layer 2L was selectively exposed using, for example, g-line through the photomask PM. In this photomask PM, a light shielding layer made of, for example, a Cr film is formed on a transparent mask substrate 23 with a predetermined pattern, and the exposure light hν is irradiated to the upper part of the incident side mirror 4 and the emission side mirror 5. An opening 25 is provided for this purpose. The exposure at this time may be contact exposure or proximity exposure. However, since the entire thickness of the clad 2 must not be exposed, the exposure amount was set carefully.
[0031]
Next, when development was performed using an alkaline developer, the exposed portion that had been reduced in molecular weight by the photochemical reaction was dissolved, and the incident-side concave surface portion 7 and the emission-side intaglio portion 8 were formed as shown in FIG. It was. The formation of the high refractive index propagation control layer 6 and the mounting of the light emitting element 9 and the light receiving element 10 were performed in the same manner as in Example 3.
[0032]
Example 5
Here, an optical signal transmission system in which a propagation control layer having a refractive index lower than that of the cladding is provided and the interface between the cladding and the propagation control layer is convex toward the light emitting element and the light receiving element will be described with reference to FIG. To do.
In FIG. 9, an optical waveguide extending in the in-plane direction is formed on the substrate 1. In this optical waveguide, the core 3 is surrounded by a clad 26 made of a material having a lower refractive index. The clad 26 is formed by being divided into a lower clad layer 26L and an upper clad layer 26U. Similar to the first embodiment, the entrance side mirror 4 and the exit side mirror 5 are arranged on the entrance end side and the exit end side of the core 3.
[0033]
A low refractive index propagation control layer 27 is laminated on the clad 26, and the light emitting element 9 faces the surface of the low refractive index propagation control layer 27 above the incident side mirror 4 with the light emitting surface facing downward. In addition, the light receiving element 10 is mounted above the emission side mirror 5 with the light receiving surface facing downward.
The interface between the clad 2 and the high refractive index propagation control layer 6 is convex toward the light emitting element 9 and the light receiving element 10, respectively. That is, the incident side convex surface portion 28 and the emission side convex surface portion 29 are formed.
[0034]
In such a configuration, the light emitted from the light emitting element 9 propagates through the low refractive index propagation control layer 27 with a constant divergence angle as indicated by an arrow in the figure, but reaches the incident-side convex surface portion 28. Then, it is refracted and propagates through the clad 26 as propagating light converged substantially in parallel. The propagating light is reflected by the incident side mirror 4 and enters the core 3, propagates through the core 3, is reflected by the output side mirror 5, and propagates again through the clad 26 in the thickness direction (upward direction) of the substrate. . During this time, the propagating light is slightly diverged, but is refracted when it reaches the output convex surface 29, propagates through the low refractive index propagation control layer 27 while being converged, and enters the light receiving element 10.
As described above, according to the optical signal transmission system described above, since the propagation light is converged at the front stage and the rear stage of the optical waveguide, the coupling efficiency between the light emitting element 9 and the optical waveguide, and the coupling between the optical waveguide and the light receiving element 10 is achieved. Efficiency has been improved.
[0035]
As the method for forming the incident side convex surface portion 28 and the emission side convex surface portion 29, for example, a method in which a member formed into a convex lens shape using the same constituent material as that of the cladding 26 is attached to the upper surface of the flat upper cladding layer 26U. , A method of performing direct shape processing on the cladding surface by laser ablation, a concave surface portion is formed in the low refractive index propagation control layer 27 by isotropic etching or photolithography, and the cladding 26 and A method of embedding the same material is possible.
[0036]
As described above, the present invention has been described based on five examples. However, the present invention is not limited to these examples. For example, a method for processing an optical waveguide or a mirror member, the number of laminated optical waveguides, and a convex surface. Details, such as the arrangement of the portions and the concave portions, can be appropriately changed, selected, and combined.
[0037]
【The invention's effect】
As is clear from the above description, according to the present invention, a surface light-emitting element or a surface light-receiving element that is difficult to mount in the vicinity of the end face of the optical waveguide is used, and as a result, light is propagated in the thickness direction of the substrate. Even in the optical signal transmission system that needs to be transmitted, the propagation light can be converged by controlling the refractive index and interface shape of the material layer interposed in the thickness direction. Therefore, the coupling efficiency of input / output light between each component in the system is improved, and stable optical signal transmission is possible. As a result, the dependency of the coupling efficiency on the optical path length is eliminated, so that the performance and reliability of the stacked optical signal transmission system are also improved. Since the interface shape can be formed in a self-aligned manner by isotropic etching or photolithography, the optical signal transmission system can be easily manufactured.
Therefore, the present invention provides indirect support for increasing the speed and density of signal wiring in various electronic devices, and its industrial value is extremely large.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a configuration example of an optical signal transmission system according to the present invention.
FIG. 2 is a schematic cross-sectional view showing a configuration example of an optical signal transmission system according to the present invention in which a plurality of optical waveguides are stacked.
3 is a schematic cross-sectional view showing a state in which an optical waveguide having an entrance side mirror and an exit side mirror is formed in the manufacturing method of the optical signal transmission system of FIG. 1; FIG.
4 is a schematic cross-sectional view showing a state in which an etching mask is patterned on the clad of FIG. 3;
5 is a schematic cross-sectional view showing a state where an incident-side concave surface portion and an output-side concave surface portion are formed by etching a surface layer portion of a clad through the etching mask of FIG. 4;
6 is a schematic cross-sectional view showing a state in which a high refractive index propagation control layer is laminated on the upper surface of the clad in FIG. 5;
FIG. 7 is a schematic cross-sectional view showing a state in which selective exposure is performed through a photomask on a clad made of a positive photosensitive polymer material in another example of the method for manufacturing an optical signal transmission system of the present invention. is there.
8 is a schematic cross-sectional view showing a state in which the clad layer in FIG. 7 is developed to form an incident-side concave surface portion and an output-side concave surface portion.
FIG. 9 is a schematic cross-sectional view showing another configuration example of the optical signal transmission system of the present invention in which a convex portion is provided on the surface of a clad and a low refractive index propagation control layer is laminated thereon.
FIG. 10 is a schematic cross-sectional view showing a state in which a core is patterned on a lower cladding layer in a conventional method of manufacturing an optical signal transmission system.
11 is a schematic cross-sectional view showing a state where an input side mirror and an output side mirror are arranged at the input / output ends of the core shown in FIG. 10 and an optical waveguide is completed by stacking an upper clad layer.
12 is a schematic cross-sectional view showing a configuration example of a conventional optical signal transmission system configured by combining a light emitting element and a light receiving element with the optical waveguide of FIG.
FIG. 13 is a schematic cross-sectional view showing a configuration example of a conventional optical signal transmission system in which a plurality of optical waveguides are stacked.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2, 12a, 12b, 12c, 26 ... Cladding 2L, 26L ... Lower clad layer 2U, 26L ... Upper clad layer 3, 13a, 13b, 13 ... Core 4, 14a, 14b, 14c ... Incident side mirror 5, 15a, 15b, 15c ... exit side mirror 6, 16a, 16b, 16c ... high refractive index propagation control layer 7, 17a, 17b, 17c ... incident side concave surface portion 18, 18a, 18b, 18c ... exit side concave surface portion 9, 19a , 19b, 19c ... Light emitting element 20, 20a, 20b, 20c ... Light receiving element 21 ... Etching mask 27 ... Low refractive index propagation control layer 28 ... Incident side convex surface part 29 ... Output side convex surface part PM ... Photomask

Claims (10)

An optical waveguide comprising a core portion and a clad portion surrounding the core portion, and extending in an in-plane direction of the substrate on the substrate;
A light emitting element for making light incident in the thickness direction of the substrate including the cladding,
An incident side mirror member for bending the light traveling direction from the light emitting element to be incident on the optical waveguide;
An exit-side mirror member that bends the traveling direction of light emitted from the optical waveguide in the thickness direction of the substrate including the clad portion;
An optical signal transmission system comprising a light receiving element for receiving reflected light from the exit side mirror member,
A propagation control layer made of a material having a refractive index different from that of the cladding portion is provided at least in the middle of the optical path from the light emitting element to the incident side mirror member and / or the optical path from the emission side mirror member to the light receiving element. An optical signal transmission system comprising an intervening shape and an interface between the propagation control layer and the clad portion capable of converging propagation light toward the reflection-side mirror member and / or the light receiving element. The propagation control layer made of a material having a higher refractive index than the cladding part is interposed in the middle of the optical path from the light emitting element to the incident side mirror member, and the propagation control layer and the cladding part overlapping the optical path The optical signal transmission system according to claim 1, wherein an interface with the projection is convex toward the incident side mirror member. The propagation control layer made of a material having a higher refractive index than the cladding part is interposed in the middle of the optical path from the output side mirror member to the light receiving element, and the propagation control layer and the cladding part overlapping the optical path The optical signal transmission system according to claim 1, wherein an interface with the projection is convex toward the output side mirror member. The propagation control layer made of a material having a refractive index smaller than that of the clad part is interposed in the middle of the optical path from the light emitting element to the incident side mirror member, and the propagation control layer and the clad part overlapping the optical path The optical signal transmission system according to claim 1, wherein an interface of the optical signal is convex toward the light emitting element. The propagation control layer made of a material having a refractive index smaller than that of the cladding part is interposed in the middle part of the optical path from the output side mirror member to the light receiving element, and the propagation control layer and the cladding part overlapping the optical path The optical signal transmission system according to claim 1, wherein an interface between the light receiving element and the light receiving element is convex toward the light receiving element. The optical signal transmission system according to claim 1, wherein the core part, the clad part, and the propagation control layer are all made of a polymer material. An optical waveguide extending on the substrate in the in-plane direction of the substrate, and disposed on the incident end side and the exit end side of the optical waveguide, respectively, and between the thickness direction of the substrate and the in-plane direction of the substrate A first step of forming an entrance side mirror member and an exit side mirror member for bending
A second step of forming a concave portion by selectively removing the surface layer portion of the cladding portion of the optical waveguide above the incident side mirror member and / or the emission side mirror member;
A third step of laminating a propagation control layer made of a material having a refractive index larger than that of the cladding part on the entire surface of the base;
And a fourth step of disposing a light emitting element that emits light toward the incident side mirror and a light receiving element that receives light from the output side mirror on the propagation control layer. A method for manufacturing an optical signal transmission system. In the second step, an etching mask having an opening above the entrance-side mirror member and / or the exit-side mirror member is formed on the surface of the clad portion, and a surface layer of the clad portion exposed in the opening 8. The method of manufacturing an optical signal transmission system according to claim 7, wherein the concave surface portion is formed by isotropically etching the portion. In the first step, the cladding portion of the optical waveguide is formed using a photosensitive material,
8. The method of manufacturing an optical signal transmission system according to claim 7, wherein in the second step, the concave surface portion is formed by performing selective exposure and development processing through a photomask. 8. The method of manufacturing an optical signal transmission system according to claim 7, wherein both the optical waveguide and the propagation control layer are formed using a polymer material.

Images