JP2000047044A - Optical signal transmission system and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To accurately form a reflection surface for bending an optical path at an entrance stage and an exit stage of an optical waveguide by a method suitable for mass production. SOLUTION: A mirror layer 4 is formed using a material having different etching selectivity or developer solubility from both a core 3 and a clad 2 constituting an optical waveguide. In order to form the mirror layer 4, a lower clad layer, which is the lower half of the clad layer 2, is formed, and after patterning the core 3, the mirror forming layer formed by covering the entire surface of the base is etched. Etching so that an undercut is directly under the mask, or patterning through photolithography and development processing. In any case, the inclination angle θ between the incident-side reflecting surface 5 and the emitting-side reflecting surface 6 can be determined in a self-aligned manner. Both reflecting surfaces may have a half mirror characteristic, and the mirror layer 4 itself may be used as a core of the optical waveguide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an optical signal transmission system having optical path bending means at an entrance stage and an exit stage of an optical waveguide, and a method of manufacturing the optical signal transmission system with high accuracy.

[0002]

2. Description of the Related Art With the advance of IC technology and LSI technology, their operation speed and integration scale have been improved, and high performance of microprocessors and large capacity of memory chips have been rapidly advanced. Under such circumstances, high-speed and high-density signal wiring and electrical wiring delay are bottlenecks in the above-mentioned high performance. Optical interconnection (optical wiring) has attracted attention as a technique that can solve this problem. Optical wiring is considered to be applicable to various layers, such as between equipment devices, between boards in equipment devices, between chips in a board, etc., but for signal transmission over a relatively short distance such as between chips. An optical signal transmission system using an optical waveguide as a transmission path is effective.

Here, a multi-chip module (MCM) for connecting an optical wiring using an optical waveguide, for example, between LSIs
In the case of application to a transmission line for transmission, when an edge emitting type laser diode (LD) or a light emitting diode (LED), which has been widely used, is used as a light emitting element on a transmission side,
This light emitting element can be arranged close to 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 arraying, is used as a light emitting element, such an arrangement is not applicable. It is difficult.
Furthermore, when a photodiode is used as the light receiving element, it is difficult to dispose the photodiode as close as possible to the exit end face of the optical waveguide because it is a surface light receiving element.

As one of the solutions, as shown in FIG. 13, a light emitting element and a light receiving element are arranged above an optical waveguide, and the thickness direction of the base including the optical waveguide and the in-plane direction of the substrate are determined. There is known an optical signal transmission system in which a light path is bent by using a mirror member between the optical signal transmission systems. In FIG. 13, an optical waveguide extending in the in-plane direction is formed on a 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 cladding 32 is formed into a portion below the core 33c and a portion above the core 33c in terms of manufacturing method. A mirror layer 33m is arranged on the incident end side and the output end side of the core 33c. The end face of the mirror layer 33m is formed, for example, by an incident side reflection face 34 inclined by 45 ° with respect to the end face of the core 33c.
The light-emitting element 39 and the light-receiving element 40 are disposed above these.

The light emitting element 39 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 39 is, as shown by the arrow in the figure,
First, the light travels in the cladding 32 in the thickness direction (downward direction) of the substrate, is subsequently reflected by the incident-side reflecting surface 34, enters the core 33c, propagates in the core 33c in the in-plane direction, and then exits. The light is reflected by 35 and travels in the traveling direction in the thickness direction (ascending direction) of the substrate, and enters the light receiving element 40. In addition,
In FIG. 13, light is drawn so as to go straight through the core 33c. However, this is merely for convenience of illustration, and actually, light incident within a predetermined critical angle range is transmitted to the core 33c. It goes without saying that the light propagates while repeating total reflection at the interface with the clad 32.

In such an optical signal transmission system, one of the points is processing of the end face of the mirror layer 33m. Regarding the case where the mirror layer 33m is formed using the same material layer as the core 33c, a number of processes have been considered so far. Such a method has been proposed. For example, FIG. 14 shows a process for forming a light reflecting surface by laser abrasion. First, as shown in FIG. 1A, a lower cladding layer 32a made of an organic polymer material is formed on a substrate 31 made of a material such as silicon or glass by, for example, spin coating and heat treatment.
A core / mirror forming layer 33f made of an organic polymer material having a higher refractive index is laminated.

Next, as shown in FIGS. 1B and 1C, the core / mirror forming layer 33f is patterned by laser abrasion. At this time, the laser
While scanning the beam in the direction in which the light reflecting surface is desired to be inclined, the output is gradually reduced. A desired tilt angle can be set on the light reflecting surface according to a combination of the scanning speed and the beam output. As a result, the core 33c having the vertical end face and the inclined end face, that is, the mirror layer 33m having the incident-side reflecting surface 34 are simultaneously formed adjacently. In addition,
When performing beam irradiation through a mask, the irradiation site may be moved by moving the mask instead of scanning the laser beam. In addition, laser
A method using an ion beam instead of abrasion is also known.

As another method, for example, a method of performing anisotropic dry etching via a photoresist whose shape is devised is described in Japanese Patent Application Laid-Open No. 6-265793. In this method, first, as shown in FIG. 15A, a lower cladding layer 32a and a core / mirror forming layer 32f both made of an organic polymer material are laminated on a substrate 31, and further, a core / mirror forming layer is formed. An etching mask 36 of a photoresist material is formed on the layer 33f. The opening 37 of the etching mask 36 does not expose the underlying core / mirror forming layer 32f on the bottom surface, but has a thickness gradient at a portion where a light reflecting surface is to be formed. This inclination is set according to the etching selectivity between the etching mask 36 and the core / mirror forming layer 33f.

When anisotropic etching is performed in this state using, for example, oxygen plasma, the thin portion of the etching mask 36 is quickly removed by ion sputtering, so that the edge of the etching mask 36 recedes. Then, the opening 37 gradually widens. Along with this, the underlying core / mirror forming layer 33f starts to be sequentially removed from the exposed portion as shown in FIG. 6B, and finally, as shown in FIG. Layer 33 having a core 33c having an inclined end surface, ie, an incident-side reflecting surface 34
and m are simultaneously formed adjacently.

[0010]

However, there is a point to be improved in the above-mentioned conventional method for forming a light reflecting surface.
First, in the method of processing the core / mirror formation layer 33f by laser ablation or ion beam,
Since the processing can be performed only at one place on the substrate, when trying to form the light reflecting surface of many mirror layers,
It takes a lot of time and effort. Meanwhile, etching
In the method using anisotropic dry etching through a mask, processing can be performed at multiple locations on the substrate at one time, but strict conditions such as the thickness of the etching mask, the sensitivity of the photoresist material, and the output of irradiation light are strict. And it is difficult to obtain high accuracy and reproducibility. Therefore, the present invention provides a novel optical signal transmission system having optical path bending means accurately formed at an entrance stage and an output stage of an optical waveguide, and a method for collectively and accurately manufacturing the optical path bending means. Aim.

[0011]

As a result of intensive studies, the present inventors have found that the conventional problem is caused by the simultaneous production of the core and the mirror layer from a common material layer. First, it was considered necessary to configure the mirror layer with a material different from that of the core. Furthermore, since the mirror layer is also in contact with the clad in the optical signal transmission system, it is practically necessary that the constituent material of the mirror layer be different from the clad in consideration of the feasibility in the process. Also, from the process point of view, "different materials"
It is particularly practical to use materials having different etching selectivity or developer solubility. If the difference between these properties is used, the end face of the mirror layer, that is, the light reflecting surface is etched or photolithographically used. It was thought that it could be formed consistently. The present invention is proposed based on the above study results.

That is, in the optical signal transmission system according to the present invention, the optical path bending means provided at the entrance stage and the exit stage of the optical waveguide extending in the in-plane direction of the substrate may include a clad portion and a core portion constituting the optical waveguide. And a different material, and the end face thereof is opposed to the end face of the core at a predetermined angle.

In order to manufacture such an optical signal transmission system, a core portion having a higher refractive index is formed on the lower cladding layer by patterning, and the entire surface of the base is made of a material layer different from the core portion and the lower cladding layer. Forming a material layer for forming an optical path bending means by coating with an optical path bending means, and patterning the material layer to provide an end face facing the end face of the core portion at a predetermined angle as a light reflecting surface. Is formed, and finally the entire surface of the substrate is covered with an upper cladding layer.

Here, when the material layer is formed by using a material having etching selectivity to both the core portion and the lower cladding layer, the material layer faces the end face of the core portion on the material layer. An optical path bending means is formed by forming an etching mask having a pattern edge at a position and etching the material layer so as to cause an undercut immediately below the etching mask. When the material layer is formed using a photosensitive material having a different developer solubility for both the core and the lower clad layer, the material layer is formed using a selective exposure and development processing photosensitive material layer, The optical path bending means can be formed through the selective exposure and the development processing. All of these methods are different from the conventional methods using laser abrasion or ion beam, and can process a large number of light reflecting surfaces in a substrate surface at a time, and are excellent in productivity. In addition, the precision and reproducibility are superior to the etching through the etching mask having the inclined film thickness.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an optical signal transmission system according to the present invention, a material layer different from both a core portion and a clad portion is used as an optical path bending means. The end surface of this material layer functions as a light reflecting surface as long as it has sufficiently high smoothness. However, a metal thin film or a dielectric thin film may be applied as necessary. This deposition can be, for example, evaporation, sputtering,
This can be done by ion plating.

The light reflecting surface has a half mirror characteristic,
When the transparency of the material layer itself is sufficiently high and the refractive index is higher than that of the clad, the material layer itself can also be a core part of the optical waveguide. In this case, since the light reflecting surface functions as a beam splitter, light propagating in a single direction can be split into a straight traveling direction and another direction. Also, if a similar light reflection layer is formed at the exit end of the mirror layer, the light is also branched into the straight direction and the other direction, so that the light repeatedly travels straight and reflected inside the base while repeating. It can be propagated vertically and horizontally. This is advantageous in that the possibility of design and the degree of freedom of an optical signal transmission system in which a plurality of optical waveguides are stacked in the thickness direction of the base are greatly increased.

The performance required for the cladding and core constituting the optical waveguide of the present invention is that transparency is high, waveguide loss is small, refractive index and volume change with time are small, light emission and light reception. Excellent heat resistance in consideration of solder mounting of the element. When the optical path bending means is also used as the core part, the same performance is required for the material layer for forming the optical path bending means. The requirements regarding need not be met in particular. However, in any case, examples of the material constituting the clad portion, the core portion, and the optical path bending means include quartz as an inorganic material, ultraviolet curable resin such as epoxy or acrylic as an organic material, and a polymer material such as polyimide. be able to. In particular, a polymer material has advantages such as low cost, production by a low-temperature process, and easy adaptation to a large area.

In the method of the present invention for manufacturing such an optical signal transmission system, the light reflecting surface which is the end face of the optical path bending means is formed by etching or photolithography. In the present invention, since the end face of the core portion has already been formed at this time, only the light reflection surface may be formed alone, and accordingly,
It makes it easier to apply self-aligned processes. When the optical path bending means is formed using a material having etching selectivity with respect to the core, the etching is performed so as to cause an undercut immediately below the etching mask. Such etching can be performed isotropically by wet etching using an etching solution or dry etching using radicals in plasma as main etching species. Alternatively, when the optical path bending means has a certain kind of crystallinity or molecular orientation, anisotropic etching can be advanced by using a specific etching solution to automatically generate an inclined surface. it can.

On the other hand, the inclined surface can be formed by photolithography depending on the fact that the exposure light goes to some extent below the edge of the light-shielding film of the photomask by diffraction and the sensitivity of the material layer for forming the optical path bending means. This is because a distribution of the amount of absorbed light occurs in the thickness direction of the layer, and the progress of the resist reaction is different between the surface layer portion and the deep portion. The photosensitive characteristics of the material layer may be either positive type or negative type.

When the etching or photolithography alone does not provide a sufficient inclination of the processed surface to become a light reflecting surface, the optical path bending means after patterning is contracted by heating to set the inclination angle of the light reflecting surface to a desired angle. Adjusting to a value is effective. When heat shrinkage is assumed, it is extremely advantageous to use an organic polymer material as the material layer for forming the optical path bending means. For example, if the material layer is a polyimide layer, volume shrinkage can be caused by heating at a temperature on the order of 300 ° C. The inclination angle can be appropriately set according to the positional relationship between the light reflecting surface of the light path bending means and the light reflecting surface of the light emitting element, the light receiving element, or another light path bending means laminated in the thickness direction of the base. . However, in order to prevent unnecessary coupling to other optical waveguides and generation of noise, it is preferable that light propagating in the thickness direction of the base is perpendicular to the in-plane direction of the base. It is particularly preferable that the inclination angle of the surface is 45 ° or near it.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described.

Embodiment 1 Here, the most basic configuration of the optical signal transmission system of the present invention 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. In this optical waveguide, a ridge-shaped core 3 is surrounded by a clad 2 made of a material having a lower refractive index. A mirror layer 4 is disposed on the incident end side and the output end side of the core 3. The end faces of the mirror layer 4 are, for example, an incident-side reflecting surface 5 and an outgoing-side reflecting surface 6 having an inclination angle θ of 45 °.

On the cladding 2, the incident-side reflecting surface 5 is provided.
The light-emitting element 9 is disposed at a position facing the light-receiving element 10, and the light-receiving element 10 is disposed at a position facing the light-emitting side reflection surface 6.
The light emitting element 9 is mounted on the clad 2 with the light emitting surface facing downward, and the light emitted from this element propagates vertically in the clad 2 as shown by the arrow in the figure, and the incident side reflecting surface 5 The light is then incident on the core 3 and propagates horizontally in the core 3, is reflected on the emission-side reflecting surface 6, propagates vertically again in the clad 2, and is incident on the light receiving element 10. In FIG. 1, light is drawn so as to go straight through the core 3, but this is merely for convenience of illustration, and actually, light incident within a predetermined critical angle It goes without saying that the light propagates while repeating total reflection at the interface between the cladding 3 and the cladding 2.

Embodiment 2 Here, a configuration example of a laminated optical signal transmission system in which a light reflecting surface has a half mirror characteristic and a mirror layer itself also functions as a core portion of an optical waveguide will be described. This will be described with reference to FIG. FIG. 2 is an example of an optical signal transmission system in which two layers of optical waveguides are stacked in the thickness direction of a base. The components of the first layer immediately above the substrate 11 are the first layer clad 12, the first layer core 13, and the first layer mirror layer 14, and the second layer components thereon are the second layer core. 16, second mirror layer 17 and second clad layer 18
It is.

First mirror layer 14 and second mirror layer 17
Has a higher refractive index than the first-layer clad 12 and the second-layer clad 18 and is formed in a ridge shape similarly to the first-layer core 13 and the second-layer core 16. Can function as In addition, both end surfaces of the reflecting surface 15 have an inclination angle of 45 ° as an example.
It has been. This reflection surface 15 is a half mirror,
Half of the incident light is split in the straight direction and half is split in the orthogonal direction by reflection. Such beam splitting and waveguiding by the mirror layers occur in various parts of the optical signal transmission system, thereby enabling optical coupling between different layers.

Embodiment 3 In this embodiment, a method for forming the incident side reflection surface 5 in the optical signal transmission system shown in FIG. 1 will be described with reference to FIGS. Such an example will be described with reference to FIGS. Although only the incident-side reflecting surface 5 is described here, the forming process of the emitting-side reflecting surface 6 is exactly the same and can be formed simultaneously. First, a lower cladding layer 2a and a lower cladding layer 2a are formed on a substrate 1 made of a material such as silicon or glass through spin coating and heat treatment of, for example, polymethyl methacrylate.
A core layer (not shown) having a higher refractive index was laminated in this order, and then the core layer was patterned to form a core 3. This patterning is performed by, for example, dry etching through a metal mask (not shown).
FIG. 3 shows a state in which the steps up to this point have been completed.

Next, as shown in FIG. 4, a mirror forming layer 4f made of, for example, a polyimide resin was flatly spin-coated on the entire surface of the substrate. Further, an etching mask 7 having a pattern edge was formed at a position facing the end of the core 3. This etching mask 7
For example, it can be formed using a metal film such as Al or Ti.

Next, the mirror forming layer 4f was etched using an etchant capable of etching only the mirror forming layer 4f without eroding the core 3 and the clad 2. As a result, as shown in FIG.
The portion of f that covers the core 3 was removed, and an undercut was formed immediately below the pattern edge of the etching mask 7 to form the incident-side reflecting surface 5 facing the core 3. The distance between the core 3 and the incident-side reflecting surface 5 can be adjusted according to the horizontal distance between the pattern edge of the etching mask 7 and the end face of the core 3, and the horizontal distance is wide. As the position increases, the position of the incident-side reflecting surface 5 formed becomes farther from the end face of the core 3. The formation of the incident-side reflecting surface 5 in the present invention is thus self-aligned, and can be performed with extremely high accuracy and reproducibility.

Next, as shown in FIG.
After the mask 7 was peeled off, the upper clad layer 2b was formed flat on the entire surface of the substrate through, for example, spin coating of polymethyl methacrylate and heat treatment. The upper cladding layer 2b is made of the same material as the lower cladding layer 2a, and forms the cladding 2 surrounding the core 3 in cooperation with the lower cladding layer 2a. Thereafter, as shown in FIG. 7, the light-emitting element 9 is mounted on the surface of the upper cladding layer 2b at a position facing the incident-side reflecting surface 5, and further on the emitting end (not shown). The light receiving element 10 was mounted at a position opposing the optical signal 6, and the optical signal transmission system as shown in FIG. 1 was completed.

Incidentally, the inclination angle of the incident-side reflecting surface formed by the above-mentioned etching can be adjusted by heating and shrinking the mirror layer 4. That is, as shown in FIG. 8, when the undercut immediately below the pattern edge of the etching mask 7 is small and the incident-side reflecting surface 5a having a larger inclination angle than the desired value is obtained, the mirror forming layer 4f
Depending on the constituent material, it can be heated and shrunk, and the tilt angle can be adjusted to a desired value as shown in FIG. Thereafter, as shown in FIG. 10, the surface of the base may be flattened with the upper cladding layer 2b. Note that the above-described heating is performed to prevent contamination and burn-in by the metal constituting the etching mask 7.
It is desirable to carry out after removing.

Embodiment 4 Here, a method of forming the mirror forming layer 4f using a photosensitive polymer material and forming the incident side reflection surface 5 by photolithography and development processing will be described with reference to FIGS. I will explain it. First, as shown in FIG.
The steps up to the formation of the mirror forming layer 4f were performed in the same manner as in Example 3 described above. However, the constituent material of the mirror forming layer 4f used here is a negative photosensitive resin. Next, a part of the mirror forming layer 4f is, for example, g
It was selectively exposed using a line. This photo mask PM
Is a light-shielding film 22 made of, for example, a Cr film formed on a transparent mask substrate 21 in a predetermined pattern. The light-shielding film 22 covers portions other than the region where the mirror layer 4 is to be formed. The exposure at this time may be contact exposure or proximity exposure.

Next, when development was carried out using an alkali developing solution, only the exposed portions insolubilized by the photochemical crosslinking reaction remained as the mirror layer 4, and the incident side reflection surface 5 was formed as shown in FIG. Was done. This incident side reflection surface 5 is
The light slightly enters the inside of the pattern edge of the light-shielding film 22, which is due to the effect of diffracted light generated at the pattern edge. When the thickness of the mirror forming layer 4f is large, it is effective to perform oblique exposure in order to expose a deep portion of the mirror forming layer 4f with a sufficient amount of light. Thereafter, the upper cladding layer 2b is formed in the same manner as in the third embodiment, and the light emitting element 9 and the light receiving element 10 are mounted on the upper cladding layer 2b, and the optical signal transmission as shown in FIG. Completed the system.

When a positive photosensitive resin is used as a constituent material of the mirror forming layer 4f, a photomask PM having a pattern of a light shielding film 22 complementary to that shown in FIG. 11 is used. By performing the exposure, the same mirror layer 4 can be formed. At this time, a desired inclination angle can be given to the incident side reflection surface 5 by performing the exposure under such a condition that the light absorption amount increases in the surface portion of the mirror forming layer 4f and decreases in the deep portion. Further, when the inclination angle of the incident side reflection surface 5 obtained after the photolithography and development processing becomes larger than a target value, the inclination angle is adjusted by heat shrinkage as described in the third embodiment. May be.

Although the present invention has been described based on the four embodiments, the present invention is not limited to these embodiments, and the constituent materials of the optical waveguide and the mirror forming layer, and the processing methods thereof are described. Details such as the number of stacked optical waveguides can be appropriately changed, selected, and combined.

[0035]

As is apparent from the above description, according to the present invention, the light reflecting surface of the optical path bending means can be formed with excellent accuracy and reproducibility. For this reason, it becomes possible to manufacture an optical signal transmission system which needs to propagate light in a thickness direction of a base in a part of an optical path using a surface light emitting element or a surface light receiving element with high productivity. Therefore, the present invention is an indirect support for high-speed and high-density signal wiring in various electronic devices, and its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one configuration example of an optical signal transmission system of the present invention.

FIG. 2 is a schematic cross-sectional view showing one configuration example of an optical signal transmission system of the present invention in which a plurality of optical waveguides are stacked.

FIG. 3 is a schematic cross-sectional view showing a state where a core is patterned on a lower cladding layer in the method of manufacturing the optical signal transmission system of FIG.

FIG. 4 is a plan view of the entire surface of the substrate shown in FIG.
FIG. 4 is a schematic cross-sectional view showing a state in which an etching mask almost covering a mirror forming region is formed.

FIG. 5 is a schematic cross-sectional view showing a state where a mirror forming layer of FIG. 4 is etched.

FIG. 6 is a schematic cross-sectional view showing a state where the etching mask of FIG. 5 is removed.

FIG. 7 is a schematic cross-sectional view showing a state in which the surface of the substrate of FIG. 6 is flattened by an upper clad layer to complete an optical waveguide.

FIG. 8 is a schematic cross-sectional view showing a state where undercut is small in etching of a mirror forming layer.

FIG. 9 is a schematic cross-sectional view showing a state where the mirror layer of FIG. 8 is contracted by heating.

FIG. 10 is a schematic cross-sectional view showing a state in which the surface of the substrate of FIG. 9 is flattened by an upper cladding layer to complete an optical waveguide.

FIG. 11 is a schematic cross-sectional view showing a state in which selective exposure is performed on a mirror forming layer having photosensitivity via a photomask.

12 is a schematic cross-sectional view showing a state in which the mirror layer of FIG. 11 is developed to form a mirror layer.

FIG. 13 is a schematic cross-sectional view showing one configuration example of a conventional optical signal transmission system.

FIGS. 14A and 14B show a manufacturing process of a conventional optical signal transmission system in which a reflection surface is formed by laser abrasion; FIG. 14A shows a state in which a mirror forming layer is formed; FIG. 3C is a schematic cross-sectional view illustrating a state in which the formation of the incident-side reflection surface has been completed.

FIG. 15A shows a state in which an etching mask having a one-sided tapered opening is formed on a mirror forming layer in a manufacturing process of a conventional optical signal transfer system in which a reflecting surface is formed by etching, and FIG. FIG. 4 is a schematic cross-sectional view showing a state in which the incident-side reflecting surface is being formed, and FIG.

[Explanation of symbols]

1, 11 substrate 2 clad 2a lower clad layer 2b upper clad layer 3 core 4, 4s mirror layer 5, 5a incident-side reflecting surface 6 outgoing-side reflecting surface 7 etching mask 9 light-emitting element DESCRIPTION OF SYMBOLS 10 ... Light receiving element 12 ... 1st layer clad 13 ... 1st layer core 14 ...
First-layer mirror 15 Reflecting surface 16 Second-layer core 17
… Second layer mirror layer 18… Second layer clad 19… Light receiving element PM… Photomask

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 10/02

Claims (8)

[Claims] An optical waveguide comprising a core portion and a cladding portion surrounding the core portion, the optical waveguide extending on the substrate in an in-plane direction of the substrate; and a thickness direction of a base including the cladding portion. A light emitting element for injecting light, an optical path bending means on an incident side for bending a traveling direction of light from the light emitting element and injecting the light into the optical waveguide, and a cladding for a traveling direction of light emitted from the optical waveguide. An optical path bending means on the emission side that bends in the thickness direction of the base including the portion, and a light receiving element for receiving light reflected by the optical path bending means on the emission side, wherein the optical path bending is performed. The means is made of a material layer different from the core portion and the clad portion, and the end surface of the material layer is a light reflecting surface facing the end surface of the core at a predetermined inclination angle. Koshin Transmission system. 2. The optical waveguide according to claim 1, wherein the light reflecting surface has a half mirror characteristic, and the material layer itself also functions as a core of the optical waveguide by being surrounded by the cladding. 2. The optical signal transmission system according to 1. 3. The optical signal transmission system according to claim 1, wherein the core, the clad, and the material layer are all made of a polymer material. 4. A first step of forming a core portion having a higher refractive index on the lower clad layer by patterning, and etching or developing the entire surface of the substrate with respect to both the core portion and the lower clad layer. A second step of coating with a material layer for forming an optical path bending means having a different liquid solubility, and patterning the material layer so that an end face facing the end face of the core at a predetermined angle is a light reflecting surface. A third step of forming an optical path bending means, and a fourth step of forming a buried optical waveguide by covering the entire surface of the substrate with an upper cladding layer. Production method. 5. The method for manufacturing an optical signal transmission system according to claim 4, wherein after the third step is completed, the inclination angle of the light reflecting surface is adjusted by heating and contracting the optical path bending means. . 6. In the third step, a material layer for forming the optical path bending means is formed using a material having etching selectivity to both the core portion and the lower clad layer, and the material layer is formed. Etching having a pattern edge at a position facing the end face of the core portion on
5. The method according to claim 4, wherein the optical path bending means is formed by forming a mask and etching the material layer so as to cause an undercut immediately below the etching mask, and thereafter removing the etching mask. A method for manufacturing the optical signal transmission system according to claim 5. 7. In the third step, a material layer for forming the optical path bending means is formed by using a photosensitive material having a different solubility in a developing solution for both the core portion and the lower clad layer. The method for manufacturing an optical signal transmission system according to claim 4, wherein the optical path bending means is formed through exposure and development processing. 8. The optical signal transmission system according to claim 4, wherein said lower cladding layer, said core portion, said upper cladding layer, and said optical path bending means are all formed of a polymer material. Method.