JP2015043050A - Optical waveguide and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide capable of readily detecting a positional deviation between a core pattern and a patterned upper clad layer.SOLUTION: An optical waveguide includes on a first clad layer: a first core pattern having a refractive index higher than that of the first clad layer; a second core pattern having a refractive index lower than that of the first core pattern and higher than that of the clad layer; and a patterned second clad layer covering the upper surface and the side surface of the first core pattern.

Description

  The present invention relates to an optical waveguide and a method for manufacturing the same.

  With the increase in information capacity, development of optical interconnection technology that uses optical signals not only for communication fields such as trunk lines and access systems but also for information processing in routers and servers is underway. In particular, as an optical transmission path for using light for short-distance signal transmission between boards in a router or a server device, optical fibers that have a higher degree of freedom in wiring and can be densified than optical fibers. It is desirable to use a waveguide. Among them, an optical waveguide using a polymer material excellent in processability and economy is promising.

In this optical waveguide, as described in Patent Document 1, a core pattern is formed on a lower clad layer, the core pattern is covered with an upper clad layer, and then the upper clad layer is aligned with the core pattern. There is a pattern.
When the core pattern and the upper clad layer are patterned in separate processes, as in the optical waveguide described in Patent Document 1, the upper clad is prevented so as not to cause a defect in optical signal transmission or an optical waveguide mounting. It is required that the layer is formed without deviating from the core pattern.

JP 2012-155035 A

However, in the optical waveguide described in Patent Document 1, both the core pattern and the upper clad layer are made of a highly transmissive resin, and the difference in refractive index is small, so that the core pattern and the upper clad layer are separate members. It was difficult to visually recognize, and it was difficult to measure misalignment between the core pattern and the patterned upper cladding layer.
Therefore, an object of the present invention is to provide an optical waveguide that can easily measure a positional shift between a core pattern and a patterned upper cladding layer.

As a result of intensive studies to solve the above problems, the present inventors have found that the lower cladding layer (referred to as the first cladding layer in the present invention) and the upper cladding layer (in the present invention, the second cladding layer) covering the core pattern. It has been found that by providing another core pattern in which positional correlation is ensured with the clad layer, the positional deviation between the core pattern and the upper clad layer covering the core pattern can be measured. The present invention has been completed based on such knowledge.
That is, the present invention
(1) On the first cladding layer, a first core pattern having a refractive index higher than that of the first cladding layer, a second cladding layer covering an upper surface and a side surface of the first core pattern, and the first cladding layer A second core pattern having a refractive index lower than that of one core pattern and having a refractive index higher than that of the first cladding layer and having a positional correlation with the second cladding layer. Optical waveguide,
(2) The optical waveguide according to (1), wherein the second core pattern and the second cladding layer are formed in the same step.
(3) The optical waveguide according to (1) or (2), wherein the second core pattern and the second cladding layer are formed of the same material.
(4) The optical waveguide according to any one of (1) to (3), wherein a side surface and an upper surface of the second core pattern are covered with a third cladding layer having a refractive index lower than that of the second core pattern.
(5) The optical waveguide according to any one of (1) to (4), wherein a side surface and an upper surface of the second cladding layer are covered with a third cladding layer having a refractive index lower than that of the second core pattern.
(6) The light according to any one of (1) to (5), wherein a fourth cladding layer having a refractive index lower than that of the first core pattern is provided between the first cladding layer and the first core pattern. Waveguide,
(7) The optical waveguide according to (6), wherein the fourth cladding layer is embedded in the second cladding layer,
(8) The optical waveguide according to any one of (1) to (7), wherein an optical path conversion mirror is provided on at least one of the optical axis of the first core pattern and the optical axis of the second core pattern. ,
(9) Step A of forming a first core pattern having a refractive index higher than the refractive index of the first cladding layer on the first cladding layer, and the first core pattern on the first cladding layer. Forming a second core pattern having a lower refractive index and a refractive index higher than that of the first cladding layer, and forming a second cladding layer on the upper and side surfaces of the first core pattern. A method of manufacturing an optical waveguide having step B;
(10) The optical waveguide according to (9), further comprising a step C of forming a fourth cladding layer having a refractive index lower than that of the first core pattern on the first cladding layer before the step B. Method,
(11) The method according to (9) or (10), which includes a step D of forming a third cladding layer having a refractive index lower than that of the second core pattern on a side surface and an upper surface of the second core pattern after the step B. Manufacturing method of optical waveguide,
(12) In the step D, the method for manufacturing an optical waveguide according to (11), wherein the second cladding layer is embedded by the third cladding layer,
(13) The method according to any one of (9) to (12), further including a step E of providing an optical path conversion mirror on at least one of the optical axes of the first core pattern and the second core pattern after the step A. Manufacturing method of optical waveguide,
(14) In the optical waveguide according to any one of (1) to (8), detection light is incident on the first core pattern and the second core pattern, and the first core pattern and the second core pattern are used. A position detection method of an optical waveguide for detecting a positional shift amount in a direction perpendicular to the optical axis of the second cladding layer with respect to the first core pattern and in a substrate plane direction from the mutual positions of the emitted detection lights;
Is to provide.

  ADVANTAGE OF THE INVENTION According to this invention, the optical waveguide which can measure easily the position shift of a core pattern and the patterned upper clad layer which covers this core pattern can be provided.

It is sectional drawing which shows the one aspect | mode of the optical waveguide of this invention. It is sectional drawing which shows another aspect of the optical waveguide of this invention. It is sectional drawing which shows another aspect of the optical waveguide of this invention. It is sectional drawing along the optical axis of the 1st core pattern of the optical waveguide of FIG. It is a top view of the optical waveguide of FIG.

As shown in FIGS. 1 to 5, the optical waveguide according to the embodiment of the present invention has a first core pattern 5 having a refractive index higher than the refractive index of the first cladding layer 1 on the first cladding layer 1. The second cladding layer 2 covering the upper surface and the side surface of the first core pattern 5, and the refractive index lower than that of the first core pattern 5 and the refractive index higher than the refractive index of the first cladding layer 1. The optical waveguide includes the second cladding layer 2 and the second core pattern 6 in which positional correlation is ensured.
The first cladding layer 1 is preferably formed using a first cladding layer forming resin, and the first core pattern 5 is formed using a first core pattern forming resin different from the resin. Preferably, the second clad layer 2 is preferably formed using a second clad layer forming resin different from each of the resins, and the second core pattern forming resin is used for forming the first clad layer. It is preferable to use a resin different from the resin and the first core pattern forming resin, and the second core pattern forming resin is formed using the same resin as the second cladding layer forming resin. preferable.

The second core pattern 6 normally functions as an optical waveguide for inspection for measuring the position of the second cladding layer 2, but can also function as an optical waveguide used for optical transmission as necessary.
It is preferable that the second core pattern 6 and the second cladding layer 2 covering the first core pattern 5 are formed in the same process because their positions can be formed with good correlation.
Further, when the second core pattern 6 and the second cladding layer 2 covering the first core pattern 5 are formed of the same material, transparency is obtained with respect to the light for position detection of the second core pattern 6. It is preferable because it is easily formed.

  In the optical waveguide according to the embodiment of the present invention, the side surface and the upper surface of the second core pattern 6 may be covered with the third cladding layer 3 having a refractive index lower than that of the second core pattern 6. Thereby, control of the refractive index difference with the 2nd core pattern 6 is also attained, and also the 2nd core pattern 6 can be protected. Further, the third clad layer 3 may cover the second clad layer 2 as shown in FIGS. 1 and 2, or may not be covered as shown in FIG. When the third cladding layer 3 covers the second cladding layer 2, the toughness of the optical waveguide itself can be easily obtained, and the optical waveguide covered with the second cladding layer 2 can be protected. The third cladding layer is preferably formed using a third cladding layer forming resin.

The optical waveguide according to the embodiment of the present invention may have a fourth cladding layer 4 having a refractive index lower than that of the first core pattern 5 between the first cladding layer 1 and the first core pattern 5. .
By providing the fourth cladding layer 4, the height from the surface of the first cladding layer 1 to the center of the first core pattern 5 and the height from the surface of the first cladding layer 1 to the center of the second core pattern 6 are obtained. It becomes possible to adjust. For example, in the case where a plurality of optical fibers and the like are aligned with the optical axis center of the optical waveguide, by providing the fourth cladding layer 4, the height from the optical fiber center to the core center of the first core pattern 5 is increased. Since the height to the core center of the second core pattern 6 can be made uniform, good coupling efficiency can be obtained. The fourth cladding layer is preferably formed using a resin for forming a fourth cladding layer.

  Further, the fourth cladding layer 4 is preferably formed in the same pattern as the first core pattern 5 and embedded in the second cladding layer 2. If the end portion of the fourth cladding layer 4 is not covered by the second cladding layer 2, the outline of the cladding layer covering the periphery of the first core pattern 5 is seen in a plan view as viewed from the direction perpendicular to the first cladding layer forming surface. Looks blurry. On the other hand, by forming the fourth cladding layer 4 so as to be embedded in the second cladding layer 2, the periphery of the first core pattern 5 is covered in a plan view as viewed from the direction perpendicular to the first cladding layer forming surface. Since the cladding layer has a substantially rectangular shape, the outer peripheral position of the cladding layer covering the first core pattern 5 can be easily determined.

An optical path conversion mirror 8 may be provided on at least one of the optical axis of the first core pattern 5 and the optical axis of the second core pattern 6. The optical path conversion mirror 8 is a mechanism capable of optical path conversion of light propagating through the first core pattern 5 or the second core pattern 6 in a direction substantially perpendicular to the first cladding layer forming surface. The light path input / output mirror 8 can input and output light from the substrate plane direction. For this reason, the positional deviation of the second cladding layer 2 is caused by the light output from the optical path conversion mirror 8 on the optical axis of the second core pattern 6, and the positional deviation of the second cladding layer 2 is shifted with respect to the first cladding layer forming surface. Thus, measurement is possible from a substantially vertical direction. One or two or more optical path conversion mirrors 8 may be installed on one core pattern optical axis.
The optical path conversion mirror 8 may be used for transmission of an optical signal in addition to the measurement of positional deviation.

  According to the optical waveguide of the present invention, a light beam for inspection (referred to as detection light) is incident on the first core pattern 5 and the second core pattern 6, and the light beam emitted from the first core pattern 5 and the second core pattern 6. The positional deviation amount of the second cladding layer 2 with respect to the optical axis of the first core pattern 5 in the direction perpendicular to the substrate and in the direction of the substrate plane can be measured. An optical path conversion mirror 8 may be provided in the middle of the first core pattern 5 and the second core pattern 6.

An example of the position calculation method is shown in the following formula (1). Reference is also made to FIG.
(Position displacement between the first core pattern 5 and the second cladding layer 2)
= (Distance dr between core center position M1 of first core pattern 5 and core center position M2 of second core pattern 6 in the substrate plane direction)-(design value di) (1)
However, as shown in FIG. 1, the core center position of the first core pattern 5 is the center of both side surface positions S11 and S12 of the first core pattern 5, and the core center position of the second core pattern 6 is the second center position. It is the center of both side surface positions S21 and S22 of the core pattern 6. The design value di is the distance between the centers of the first core pattern 5 and the second core pattern 6 in design.
Since the core pattern has high brightness and high contrast when the detection light passes, automatic measurement using a photodetector or the like can be easily performed in addition to visual observation.
As described above, the positional deviation amount of the second cladding layer 2 with respect to the optical axis of the first core pattern 5 in the substrate vertical direction and the substrate plane direction can be measured.

In the optical waveguide of the present invention, the first core pattern 5 covered with the third cladding layer 3 can also be formed. As a result, the optical waveguide of the present invention includes the first core pattern 5 covered with the second cladding layer 2 and the second core pattern 6 covered with the third cladding layer 3 on the same first cladding layer 1. Then, the first core pattern 5 covered with the third cladding layer 3 can be formed. That is, optical waveguides having different refractive index differences can be formed on the same first cladding layer.
For this reason, for example, when the light incident on the optical waveguide from a light receiving element such as a laser diode, an optical waveguide, or an optical fiber is light having a large divergence angle, the coupling efficiency can be improved by selecting a combination that easily obtains a high refractive index difference. Can be improved. The first core pattern 5 covered with the third cladding layer 3 corresponds to a combination that easily obtains a high refractive index difference. Further, the first core pattern 5 covered with the third cladding layer 3 can have a larger core diameter than the first core pattern 5 covered with the second cladding layer 2, so that the coupling efficiency is further improved.
When the light emitted from the optical waveguide to the light receiving element such as a photodiode, optical waveguide, or optical fiber is light having a small divergence angle, the coupling efficiency can be improved by selecting a combination that can easily obtain a low refractive index difference. . The first core pattern 5 covered with the second cladding layer 2 corresponds to a combination that can easily obtain a low refractive index difference. Further, since the first core pattern 5 covered with the second cladding layer 2 can have a smaller core diameter than the second core pattern 6, the coupling efficiency is further improved.
In the optical waveguide of the present invention, the above-mentioned selection can be made in the same optical waveguide substrate, and a combination of refractive index differences between them can also be selected.

Below, each member used for the optical waveguide of this invention is demonstrated in detail.
[substrate]
The optical waveguide of the present invention preferably has a substrate 7. The substrate 7 imparts toughness, rigidity, and flexibility to the optical waveguide. Further, the substrate 7 can prevent the optical waveguide from being broken when the optical path conversion mirror 8 is formed. The substrate 7 may be unnecessary. When the substrate 7 is not applied, at least the first cladding layer 1 may be formed and then removed from the first cladding layer 1.
From the above viewpoint, the material of the substrate 7 that can be used for the optical waveguide of the present invention includes, for example, a glass epoxy resin substrate, a ceramic substrate, a glass substrate, a silicon substrate, a plastic substrate, a metal substrate, and a resin layer on each substrate. Examples include a substrate with a resin layer provided, a substrate with a metal layer provided with a metal layer on each substrate, an FR-4 substrate, and an electric wiring board.
If the substrate 7 and the first cladding layer 1 are not adhesive or if the adhesiveness is weak, a substrate with an adhesive layer in which an adhesive layer is provided on the surface of the substrate 7 may be used. Further, the substrate may be subjected to a roughening process, a coupling process, or the like for improving adhesiveness.

  By using a substrate having rigidity and toughness as the substrate 7, it is possible to impart rigidity to the optical waveguide. As the substrate capable of imparting rigidity, it is preferable that the thickness of the substrate 7 is larger when the substrate of the above-described material is used. The thickness is not particularly limited, but if it is 40 μm or more, there is an advantage that the strength as the substrate 7 can be easily obtained, and if it is 2000 μm or less, there is an advantage that a rigid and low-profile optical waveguide can be easily obtained. From the above viewpoint, the thickness of the substrate 7 is preferably in the range of 50 μm to 1000 μm.

By using the substrate 7 having flexibility and toughness for the substrate 7, flexibility can be imparted to the optical waveguide. Examples of the substrate capable of imparting flexibility include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyphenylene ether, polyether sulfide, polyarylate, liquid crystal polymer, polysulfone, and polyether. Preferred examples include sulfone, polyether ether ketone, polyether imide, polyamide imide, and polyimide.
The thickness of the substrate 7 when the substrate is used is not particularly limited, but if it is 5 μm or more, there is an advantage that the strength as the substrate 7 is easily obtained, and if it is 200 μm or less, low profile and flexibility are obtained. There is an advantage that it is easy. From the above viewpoint, the thickness of the substrate 7 is preferably in the range of 10 μm to 100 μm.

[First cladding layer]
If the refractive index of the first cladding layer 1 used in the optical waveguide of the present invention is lower than that of the first core pattern 5 and the second core pattern 6, the first core pattern 5, the second core pattern 6, and the first cladding layer are used. 1 is preferable because light can propagate at the interface with 1 while repeating total reflection.
The refractive index difference between the first cladding layer 1 and the second core pattern 6 is preferably such that the refractive index difference represented by the following formula (2) is not less than 0.1% and not more than 6.0%. From the viewpoint of the above and from the viewpoint of the ease of controlling the refractive index of the material, it is better if it is 1.0% or more and 6.0% or less, more preferably 2.0% or more and 6.0% or less.
(Refractive index difference) = (n ₁ ² −n ₂ ² ) ^1/2 / (2 × n ₁ ² ) (2)
Here, n ₁ is the refractive index of the high refractive index side layer, and n ₂ is the refractive index of the low refractive index side layer.

  The method for forming the first cladding layer 1 is not particularly limited. For example, the first cladding layer forming resin varnish is applied, or the first cladding layer forming resin film is laminated or pressed with a subject. For example, a method of forming the first cladding layer 1 by laminating the first cladding layer 1 may be used. From the viewpoint of curing after coating or laminating, a thermosetting resin, a photocurable resin, and a combination thereof are preferable.

The thickness of the first cladding layer 1 is not particularly limited, but is preferably 5 μm or more from the viewpoint of light confinement of the second core pattern 6, and is preferably 200 μm or less from the viewpoint of moldability of the resin layer. The thickness is more preferably 10 μm or more and 100 μm or less from the viewpoint of thickness control, and further preferably 10 μm or more and 50 μm or less from the viewpoint of low profile.
The first clad layer 1 may be a single layer or a plurality of layers, and is made of the same material as the second clad layer 2, the third clad layer 3, and the fourth clad layer 4 described later. Or a different material.

[Second cladding layer]
The second clad layer 2 only needs to have a refractive index lower than that of the first core pattern 5, can favorably propagate light propagating through the first core pattern 1, and protect the first core pattern.
The refractive index difference between the second cladding layer 2 and the first core pattern 5 is preferably such that the refractive index difference represented by the above formula (2) is not less than 0.1% and not more than 6.0%. From the viewpoint of safety and the ease of controlling the refractive index of the material, it is better if it is 1.0% or more and 6.0% or less, more preferably 2.0% or more and 6.0% or less.

  The method for forming the second cladding layer 2 is not particularly limited, but the second cladding layer 2 and the second core pattern 6 are respectively formed on part of the surface of the first cladding layer 1 as shown in FIGS. When forming as a pattern, a method similar to the method of forming the first cladding layer 1 can be applied. That is, after the resin for forming the second cladding layer is applied on the surface of the first cladding layer 1 by laminating, laminating, pressing, or the like, photolithography processing for exposing and developing, anisotropic etching (dry etching), or the like is used. Pattern can be formed. Moreover, a pattern can be formed by disposing the varnish or film of the second clad layer forming resin only at a desired location. A photolithographic process is mentioned suitably from the point that a highly accurate position alignment is possible. Further, from the viewpoint of applying photolithography processing, the second cladding layer forming resin is more preferably a photosensitive resin.

The thickness of the second cladding layer 2 is not particularly limited as long as it is a thickness that can cover the first core pattern 5 or the first core pattern 5 and the fourth cladding layer 4. From the viewpoint of light confinement, it is preferable to secure a thickness of at least 5 μm from the side surface of the first core pattern 5 to the side surface of the second cladding layer 2.
The thickness of the second cladding layer 2 formed on the upper surface of the first core pattern 5 is particularly large when the third cladding layer 3 is formed on the second cladding layer 2 as shown in FIGS. There is no limitation. As shown in FIG. 3, when the third cladding layer 3 is not formed on the second cladding layer 2, it is preferable to secure 5 μm or more because the light confinement property is improved. The thickness of the second cladding layer 2 is preferably 200 μm or less from the surface of the first cladding layer 1 from the viewpoint of the resin layer formability. Furthermore, from the viewpoint of photolithography processability, the thickness from the surface of the first cladding layer 1 is more preferably 20 μm or more and 160 μm or less. From the viewpoint of securing appropriate rigidity and strength to the optical waveguide, it is more preferably 50 μm or more and 160 μm or less.
The second cladding layer 2 may be a single layer or a plurality of layers.

[Third cladding layer]
If the refractive index of the third cladding layer 3 is lower than that of the second core pattern 6, the light confinement property of the second core pattern 6 is good, and the refractive index difference between the second core pattern 6 and the third cladding layer 3 is good. This is preferable because control is facilitated and the second core pattern 6 can be protected.
The refractive index difference between the second core pattern 6 and the third cladding layer 3 is preferably such that the refractive index difference represented by the above formula (2) is not less than 0.1% and not more than 6.0%. From the viewpoint of safety and the ease of controlling the refractive index of the material, it is better if it is 1.0% or more and 6.0% or less, more preferably 2.0% or more and 6.0% or less.
If the refractive indexes of the third cladding layer 3 and the first cladding layer 1 are the same, both the upper and lower surfaces and the side surfaces of the second core pattern 6 can be covered with the cladding layer having the same refractive index. Since light can propagate to the approximate center of the pattern 6, it is preferable from the viewpoint of coupling efficiency.

The method for forming the third cladding layer 3 is not particularly limited. For example, when the third cladding layer 3 is formed on the entire surface as in the optical waveguide shown in FIGS. 1 and 2, the third cladding layer is formed. For example, the third clad layer 3 may be formed by applying a resin varnish or laminating a third clad layer forming resin film on a subject using a laminate or a press.
In addition, as shown in FIG. 3, when the second cladding layer 2 is formed as an exposed pattern, after the third cladding layer forming resin is applied on the subject by the above method, laminated, pressed, etc. The pattern can be formed by photolithography processing for exposure and development, anisotropic etching (dry etching), or the like. Moreover, the pattern can be formed by disposing the varnish or film of the third clad layer forming resin only at a desired location. A photolithographic process is mentioned suitably from the point that a highly accurate position alignment is possible. Further, from the viewpoint of applying photolithography processing, the third cladding layer forming resin is more preferably a photosensitive resin.

The thickness of the third cladding layer 3 is not particularly limited, but the thickness from the upper surface of the second core pattern 6 to the surface of the third cladding layer 3 is 5 μm or more from the viewpoint of light confinement of the second core pattern 6. It is preferable. Furthermore, the thickness from the surface of the first cladding layer 1 is preferably 200 μm or less from the viewpoint of the resin layer formability. Further, from the viewpoint of photolithography processability, the thickness from the surface of the first cladding layer 1 is more preferably 20 μm or more and 160 μm or less. From the viewpoint of securing appropriate rigidity and strength to the optical waveguide, it is more preferably 50 μm or more and 160 μm or less.
The third clad layer 3 may be a single layer or a plurality of layers, and is made of the same material as the first clad layer 1, the second clad layer 2, and the fourth clad layer 4, respectively. May be different materials.

[Fourth cladding layer]
If the refractive index of the fourth cladding layer 4 is lower than that of the first core pattern 5, it is preferable because light can propagate while repeating total reflection at the interface between the first core pattern 5 and the fourth cladding layer 4.
The refractive index difference between the fourth cladding layer 4 and the first core pattern 5 is such that the refractive index difference represented by the above formula (2) is not less than 0.1% and not more than 6.0%. From the viewpoint of the above and from the viewpoint of the ease of controlling the refractive index of the material, it is better if it is 1.0% or more and 6.0% or less, more preferably 2.0% or more and 6.0% or less.
If the refractive indexes of the fourth cladding layer 4 and the second cladding layer 2 are the same, the upper and lower surfaces and the side surfaces of the first core pattern 5 can be covered with the cladding layer having the same refractive index. Since light can propagate to the approximate center of the pattern 5, it is preferable from the viewpoint of coupling efficiency.

  The method of forming the fourth cladding layer 4 is not particularly limited. However, as shown in FIG. 1, when forming a pattern so as to be embedded in the second cladding layer 2, a resin for forming the fourth cladding layer is used. After patterning on the surface of the first clad layer 1 by the same method as described above by coating, laminating, pressing, etc., a pattern is formed using photolithography processing that exposes and develops, anisotropic etching (dry etching), etc. can do. Moreover, the pattern can be formed by disposing the varnish or film of the fourth clad layer forming resin only at a desired location. A photolithographic process is mentioned suitably from the point that a highly accurate position alignment is possible. Further, from the viewpoint of applying photolithography processing, the fourth cladding layer forming resin is more preferably a photosensitive resin.

The thickness of the fourth cladding layer is not particularly limited, but is preferably 5 μm or more from the viewpoint of light confinement of the first core pattern 5, and is preferably 200 μm or less from the viewpoint of moldability of the resin layer. Further, it is more preferably 5 μm or more and 100 μm or less from the viewpoint of thickness control, and further preferably 10 μm or more and 50 μm or less from the viewpoint of low profile.
The fourth cladding layer 4 may be a single layer or a plurality of layers, and may be the same material as the first cladding layer 1, the second cladding layer 2, and the third cladding layer 3. It may be a material.

[First core pattern]
The first core pattern 5 used in the optical waveguide of the present invention has a higher refractive index than any of the first cladding layer 1, the second cladding layer 2, and the fourth cladding layer 4, and the main part where light propagates It is.
From the above viewpoint, it is only necessary that the detection light and the wavelength of the optical signal propagate to have a transparency that does not adversely affect the light propagation.
When the first core pattern 5 is formed as a pattern on a part of the surface of the first cladding layer 1 or the fourth cladding layer 4, a method similar to the method of forming the second cladding layer or the fourth cladding layer can be applied. . That is, the first core pattern forming resin is applied on the surface of the first clad layer 1 by laminating, laminating, pressing, etc., and then exposed and developed by photolithography, anisotropic etching (dry etching), or the like. Pattern can be formed. Moreover, a pattern can be formed by arranging a varnish or a film of the first core pattern forming resin only at a desired location. A photolithographic process is mentioned suitably from the point that a highly accurate position alignment is possible. Further, from the viewpoint of applying photolithography processing, the first core pattern forming resin is more preferably a photosensitive resin.

  The thickness of the first core pattern 5 is not particularly limited. However, when the thickness of the first core pattern 5 after formation is 10 μm or more, in the coupling with the light emitting / receiving element, the optical fiber, or the optical waveguide after the optical waveguide is formed. There is an advantage that the alignment tolerance can be expanded, and when it is 160 μm or less, there is an advantage that the coupling efficiency is improved in coupling with the light emitting / receiving element, the optical fiber or the optical waveguide after the optical device is formed. From the above viewpoint, the thickness of the first core pattern 5 is preferably in the range of 30 μm to 150 μm.

[Second core pattern]
The second core pattern 6 has a higher refractive index than the first clad layer 1 and the fourth clad layer 4 and is a part where light propagates. It is only necessary that the detection light propagating from the above viewpoint has transparency that does not adversely affect the detection of light. When the second core pattern 6 is used for propagation of an optical signal, the second core pattern 6 is preferably transparent to such an extent that the propagation of light does not hinder the optical signal to be used.
The material, formation method, and thickness of the second core pattern are preferably the same as those of the first core pattern 5 described above. When performing the same process using the same material as the second clad layer 2, it is preferable that the second clad layer 2 has the same formation method and the same thickness.

[Optical path conversion mirror]
An optical path conversion mirror 8 may be provided on at least one of the optical axis of the first core pattern 5 and the optical axis of the second core pattern 6. The optical path conversion mirror 8 is not particularly limited as long as it is a mechanism capable of optical path conversion of light propagating through the first core pattern 5 or the second core pattern 6 in a direction substantially perpendicular to the first cladding layer forming surface. The optical path of the outgoing optical path may be changed to 45 ° to 135 °, more preferably 75 ° to 105 °, and still more preferably 87 ° to 93 ° with respect to the optical path.
Further, the direction of the optical path after the conversion is a surface on which the substrate 7 is disposed on the first cladding layer 1 even in a direction away from the surface on which the first core pattern 5 and the like are disposed on the first cladding layer 1 (referred to as an upward direction). It may be a direction away from (referred to as downward direction). When the optical path is converted downward toward the first cladding layer 1 and passes through the substrate 7, it is preferable that the substrate 7 has transparency capable of transmitting the wavelength of the detection light. .
FIG. 4 is a cross-sectional view of the optical waveguide shown in FIG. 1 cut out along the optical axis of the first core pattern 5. As shown in FIG. 4, the optical path conversion mirror 8 may be an air reflection mirror in which an inclined surface of approximately 45 ° is formed on the optical axis of the first core pattern 5 or the optical axis of the second core pattern 6. . A reflective metal layer may be disposed on the inclined surface to form a metal reflection mirror.

The manufacturing method of the optical waveguide of the present invention will be described in detail below.
In step A, a first core pattern 5 having a refractive index higher than the refractive index of the first cladding layer 1 is formed on the first cladding layer 1 formed on at least a part of the substrate surface.
These cladding layers and core patterns are preferably formed using a resin, and the method of laminating the resins is not particularly limited. For example, the first core pattern forming resin is formed on the first cladding layer 1. The method of apply | coating a varnish and the method of laminating | stacking the film of 1st core pattern formation resin on the 1st clad layer 1 are mentioned. As a method for applying the varnish, a spin coater, a die coater, a comma coater, a curtain coater, a gravure coater, or the like can be used. The varnish may be formed by previously diluting with a solvent or the like and then applying the varnish by the above method or the like and drying the solvent.
As a method for laminating the resin film, it can be laminated by appropriately applying pressure, temperature or the like using a roll laminator, a vacuum roll laminator, a flat plate laminator, a vacuum flat plate laminator, a normal pressure press, a vacuum press or the like.

Next, the first core pattern 5 is formed. There is no limitation in particular as a method of forming a 1st core pattern, It can form by the various method mentioned above. Below, the example of the formation method formed by photolithography process is demonstrated in detail.
On the resin layer made of the first core pattern forming resin formed as described above, a mask resist having a desired shape of the first core pattern 5 is formed, and after the first core pattern 5 is formed by etching, A method of removing the mask resist is mentioned. In addition, the first core pattern is formed through the mask with actinic rays capable of curing the resin through a quartz mask or a film mask on which the shape of the first core pattern 5 is drawn using the photosensitive first core pattern forming resin. There is a method of forming the first core pattern 5 by etching after irradiating the forming resin.
As an etching method, either dry etching or wet etching may be used. Preferable examples of the etchant used in the case of wet etching include various solvents that can remove the uncured first core pattern forming resin, various alkaline aqueous solutions, and mixed solutions thereof.

  In step B, a second core pattern 6 having a refractive index lower than that of the first core pattern 5 and having a refractive index higher than that of the first cladding layer 1 is formed on the first cladding layer 1. At the same time, the second cladding layer 2 is formed on the upper and side surfaces of the first core pattern 5. These core patterns are preferably formed using a resin, and the pattern can be formed by the same method as in step A described above. It is preferable to form the second cladding layer 2 and the second core pattern 6 from the same process and the same material because the positional correlation between the second cladding layer 2 and the second core pattern 6 is easily secured.

Prior to step B, step C may be performed. In the step C performed before the step B, the fourth cladding layer 4 having a refractive index lower than that of the first core pattern 5 is formed on the first cladding layer 1. The fourth clad layer 4 is further preferably placed so as to be buried by the second clad layer 2 in the subsequent process B.
The fourth cladding layer 4 is preferably formed using a resin for forming the fourth cladding layer, and can be formed by the same method as in step A described above.

Step D may be performed after Step B. In step D performed after step B, the third cladding layer 3 having a refractive index lower than that of the second core pattern 2 is formed on the side surface and the upper surface of the second core pattern 2. In step D, the second cladding layer 2 is preferably embedded by the third cladding layer 3. The third cladding layer is preferably formed using a third cladding layer forming resin.
As shown in FIGS. 1 and 2, the third cladding layer 3 includes a first core pattern 5 formed on the surface of the first cladding layer 1 and covered with the second cladding layer 2, and a second core pattern 6. May be formed so as to cover both. Further, the third cladding layer 3 may be patterned in accordance with the second core pattern 6 as shown in FIG.
In either case, it can be formed by the same method as that for the first cladding layer 1 described above.
As shown in FIGS. 1 and 2, when patterning is not performed, after the third clad layer forming resin is disposed, the third clad layer 3 may be appropriately cured. As shown in FIG. 3, when patterning in accordance with the second core pattern 6, the same method as that for the second cladding layer 2 described above can be applied.

In the method for manufacturing an optical waveguide of the present invention, after the step A, the optical waveguide conversion mirror 8 may be provided on the optical axis of at least one of the first core pattern 5 and the second core pattern 6. Good. The process E may be after the process A, and may be after the process B, after the process C, and after the process D. When the optical path conversion mirror 8 is formed on the end face of the first core pattern 5, the process A is good, and when the optical path conversion mirror 8 is formed on the end face of the second core pattern 6, the process B is followed. Good. The method for forming the optical path conversion mirror 8 is not particularly limited, and examples thereof include a method of forming an inclined surface for the optical path conversion mirror 8 by using laser ablation or cutting such as a dicing saw. If the optical path conversion mirrors 8 are formed on the optical axes of the first core pattern 5 and the second core pattern 6 in the same process, a plurality of optical path conversion mirrors 8 can be efficiently formed, and their positional correlation is secured. It is preferable because it is easy.
Further, the reflective metal layer may be formed on the inclined surface using cutting or the like. The method for forming the reflective metal layer is not particularly limited, and examples thereof include vapor deposition, sputtering, and plating. As the type of the reflective metal layer, various metals such as Au, Ag, Cu, Al, Cu, Ni, Ti, and alloys thereof are preferably used.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.
Example 1
<Preparation of resin films for forming first and third cladding layers>
[Production of (A) (meth) acrylic polymer (base polymer)]
46 parts by mass of propylene glycol monomethyl ether acetate and 23 parts by mass of methyl lactate were weighed in a flask equipped with a stirrer, a cooling pipe, a gas introduction pipe, a dropping funnel, and a thermometer, and stirred while introducing nitrogen gas. . The liquid temperature was raised to 65 ° C., 47 parts by weight of methyl methacrylate, 33 parts by weight of butyl acrylate, 16 parts by weight of 2-hydroxyethyl methacrylate, 14 parts by weight of methacrylic acid, 2,2′-azobis (2,4-dimethylvaleronitrile ) A mixture of 3 parts by mass, 46 parts by mass of propylene glycol monomethyl ether acetate and 23 parts by mass of methyl lactate was added dropwise over 3 hours, followed by stirring at 65 ° C. for 3 hours, and further stirring at 95 ° C. for 1 hour. A) A (meth) acrylic polymer solution (solid content: 45% by mass) was obtained.

[Measurement of weight average molecular weight]
(A) The result of having measured the weight average molecular weight (standard polystyrene conversion) of (meth) acrylic polymer using GPC ("SD-8022", "DP-8020", and "RI-8020" by Tosoh Corp.). 3.9 × 10 4. As the column, “Gelpack GL-A150-S” and “Gelpack GL-A160-S” manufactured by Hitachi Chemical Co., Ltd. were used.

[Measurement of acid value]
As a result of measuring the acid value of (A) (meth) acrylic polymer, it was 79 mgKOH / g. The acid value was calculated from the amount of 0.1 mol / L potassium hydroxide aqueous solution required to neutralize the (A) (meth) acrylic polymer solution. At this time, the point at which the phenolphthalein added as an indicator changed color from colorless to pink was defined as the neutralization point.

[Preparation of resin varnish for forming first and third cladding layers]
As a base polymer, 84 parts by mass (solid content 38 parts by mass) of the (A) (meth) acrylic polymer solution (solid content 45% by mass), (B) urethane (meth) acrylate having a polyester skeleton as a photocuring component ( Shin-Nakamura Chemical Co., Ltd. “U-200AX”) 33 parts by mass, and urethane (meth) acrylate having a polypropylene glycol skeleton (Shin-Nakamura Chemical Co., Ltd. “UA-4200”) 15 parts by mass, (C ) As a thermosetting component, a polyfunctional block isocyanate solution (solid content 75% by mass) obtained by protecting isocyanurate type trimer of hexamethylene diisocyanate with methyl ethyl ketone oxime (“Sumijour BL3175” manufactured by Sumika Bayer Urethane Co., Ltd.) 20 1 part by mass (solid content 15 parts by mass), (D) 1- [4- 2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (“Irgacure 2959” manufactured by BASF Japan Ltd.), 1 part by weight, bis (2,4,6-trimethylbenzoyl) 1 part by mass of phenylphosphine oxide (“Irgacure 819” manufactured by BASF Japan Ltd.) and 23 parts by mass of propylene glycol monomethyl ether acetate as an organic solvent for dilution were mixed with stirring. After pressure filtration using a polyflon filter having a pore size of 2 μm (“PF020” manufactured by Advantech Toyo Co., Ltd.), degassing was performed under reduced pressure to obtain a resin varnish for forming a cladding layer.

[Preparation of resin films for forming first and third cladding layers]
The first and third clad layer forming resin varnishes obtained above are coated on a non-treated surface of a PET film (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd., thickness 50 μm) as a support film. (Multicoater TM-MC, manufactured by Hirano Techseed Co., Ltd.), dried at 100 ° C. for 20 minutes, and then subjected to surface release treatment PET film (“Purex A31” manufactured by Teijin DuPont Films Ltd.), A thickness of 25 μm) was pasted to obtain resin films for forming the first and third cladding layers.
At this time, the thickness of the resin layer formed from the first and third clad layer forming resin varnishes can be arbitrarily adjusted by adjusting the gap of the coating machine, and the thickness after drying will be described later. .

[Measurement of refractive index]
The 50 μm resin film obtained above with the protective film peeled off is vacuum-pressurized laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.) on a silicon substrate (size: 60 × 20 mm, thickness: 0.6 mm). After vacuuming to 500 Pa or less, lamination was performed under conditions of a pressure of 0.4 MPa, a temperature of 50 ° C., and a pressurization time of 30 seconds. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated with 2000 mJ / cm ² with an ultraviolet exposure machine (ExM-1172, manufactured by Oak Manufacturing Co., Ltd.), the support film was peeled off, and further heated at 160 ° C. for 1 hour to measure the refractive index. A sample was prepared. The refractive index of the sample at a wavelength of 830 nm was measured using a prism-coupled refractometer (manufactured by Metricon, trade name: Model 2020). The refractive index of the cured resin layer was 1.496.

<Preparation of Resin Film for Forming First Core Pattern>
(A) As a base polymer, 26 parts by mass of a phenoxy resin (trade name: Phenotote YP-70, manufactured by Toto Kasei Co., Ltd.), and (B) 9,9-bis [4- (2- Acrylyloxyethoxy) phenyl] fluorene (trade name: A-BPEF, Shin-Nakamura Chemical Co., Ltd.) 36 parts by mass, and bisphenol A type epoxy acrylate (trade name: EA-1020, Shin-Nakamura Chemical Co., Ltd.) ) 36 parts by mass, (C) As a photopolymerization initiator, 1 part by mass of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (trade name: Irgacure 819, manufactured by BASF Japan Ltd.), and 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (trade name: Irgacure 2959, ASF Japan Co., Ltd.) 1 part by weight, core layer-forming resin in the same manner and conditions as the above-mentioned preparation of the clad layer-forming resin varnish except that 40 parts by weight of propylene glycol monomethyl ether acetate was used as the organic solvent A varnish was prepared. Thereafter, pressure filtration and degassing under reduced pressure were performed in the same manner and conditions as described above.
The resin varnish for forming a core layer obtained above is the same as the above production example on the non-treated surface of a PET film (trade name: Cosmo Shine A1517, manufactured by Toyobo Co., Ltd., thickness: 16 μm) as a support film. Then, a release PET film (trade name: Purex A31, Teijin DuPont Films Co., Ltd., thickness: 25 μm) is applied as a protective film so that the release surface is on the resin side, and the core layer A forming resin film was obtained.
At this time, the thickness of the resin layer formed from the resin varnish for forming the core layer can be arbitrarily adjusted by adjusting the gap of the coating machine, and the thickness after drying will be described later.

[Measurement of refractive index]
When the refractive index of the cured resin layer was measured by the same method as described above, the refractive index was 1.577.

<Preparation of resin film for forming second core pattern, second and fourth cladding layers>
[Second Core Pattern, Base Polymer for Forming Second and Fourth Cladding Layers; Production of (Meth) acrylic Polymer (P-1)]
In a flask equipped with a stirrer, a cooling pipe, a gas introduction pipe, a dropping funnel, and a thermometer, 42 parts by mass of propylene glycol monomethyl ether acetate and 21 parts by mass of methyl lactate were weighed and stirred while introducing nitrogen gas. . The liquid temperature was raised to 65 ° C., 14.5 parts by mass of N-cyclohexylmaleimide, 20 parts by mass of benzyl acrylate, 39 parts by mass of o-phenylphenol 1.5EO acrylate, 14 parts by mass of 2-hydroxyethyl methacrylate, 12. After dropping a mixture of 5 parts by mass, 4 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile), 37 parts by mass of propylene glycol monomethyl ether acetate, and 21 parts by mass of methyl lactate over 3 hours, 65 ° C. For 3 hours, and further continued stirring at 95 ° C. for 1 hour to obtain a (meth) acrylic polymer (P-1) solution (solid content: 45 mass%).
As a result of measuring the acid value and the weight average molecular weight of the P-1 solution by the same method as described above, they were 80 mg KOH / g and 32,000, respectively.

[Preparation of resin varnish for forming second core pattern, second and fourth cladding layers]
(A) As an alkali-soluble (meth) acrylic polymer containing a maleimide skeleton in the main chain, 60 parts by mass of the P-1 solution (solid content 45% by mass), (B) as a polymerizable compound, ethoxylated bisphenol A diacrylate ( Hitachi Chemical Co., Ltd., trade name: FANCLIL FA-324A ("FANCLIL" is a registered trademark)) 15 parts by mass and ethoxylated bisphenol A diacrylate (Hitachi Chemical Co., Ltd., trade name: FANCLIL FA- 321A) 15 parts by mass, phenol biphenylene type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: NC-3000, epoxy equivalent 275 g / eq) 10 parts by mass, (C) 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one (manufactured by BASF Japan Ltd.) Product name: Irgacure 2959) 1 part by weight, 1 part by weight of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (manufactured by BASF Japan Ltd., trade name: Irgacure 819) was weighed in a wide-mouthed plastic bottle, Using a stirrer, the core part-forming resin varnish was prepared by stirring for 6 hours under the conditions of a temperature of 25 ° C. and a rotation speed of 400 min−1. Thereafter, using a polyflon filter having a pore size of 2 μm (product name: PF020, manufactured by Toyo Roshi Kaisha, Ltd.) and a membrane filter having a pore size of 0.5 μm (product name: J050A, manufactured by Toyo Roshi Kaisha, Ltd.), a temperature of 25 ° C., Pressure filtration was performed under the condition of a pressure of 0.4 MPa. Subsequently, using a vacuum pump and a bell jar, vacuum degassing was performed for 15 minutes under the condition of a reduced pressure of 50 mmHg to obtain a resin varnish for forming a second core pattern, second and fourth cladding layers.

[Preparation of resin film for forming second core pattern, second and fourth cladding layers]
The second core pattern, the second and fourth clad layer forming resin varnishes are coated on a non-treated surface of a PET film (manufactured by Toyobo Co., Ltd., trade name: A1517, thickness 16 μm) (Hirano Tech Seed Co., Ltd.) It is applied using a multi-coater (trade name: TM-MC), dried at 100 ° C. for 20 minutes, and then a release PET film (manufactured by Teijin DuPont Films, trade name: Purex A31, thickness) as a protective film. 25 μm) was applied to obtain a resin film for forming a second core pattern, second and fourth cladding layers. At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coating machine, and the thickness after drying will be described later.

[Measurement of refractive index]
When the refractive index of the cured resin layer was measured by the same method as described above, the refractive index was 1.555.

<Example of Fabrication of Optical Waveguide in FIG. 1>
[Formation of the first cladding layer]
A 100 mm × 100 mm polyimide film (Polyimide: Toray DuPont Co., Ltd., Kapton (registered trademark) EN, thickness: 25 μm) was used as the substrate 1, and the 15 μm-thick first cladding layer obtained above was formed on one surface. After the protective film of the forming resin film is peeled off, a vacuum pressure laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.) is used to evacuate to 500 Pa or less, and then the pressure is 0.4 MPa, the temperature is 90 ° C., and the pressure is increased. Lamination was performed by thermocompression bonding under a pressure time of 30 seconds. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated at 3000 mJ / cm 2 from the support film side of the first clad layer-forming resin film using an ultraviolet exposure machine (ExM-1172, manufactured by Oak Manufacturing Co., Ltd.). Thereafter, the support film was peeled off, dried and cured at 170 ° C. for 1 hour, and the first cladding layer 1 was formed.

[Formation of fourth cladding layer]
After peeling off the protective film of the 10 μm-thick resin film for forming the fourth clad layer obtained above on the first clad layer 1 formation surface obtained above, a vacuum pressure laminator (manufactured by Meiki Seisakusho Co., Ltd.) , MVLP-500), and evacuated to 500 Pa or less, and then thermocompression bonded under the conditions of a pressure of 0.4 MPa, a temperature of 65 ° C., and a pressurization time of 30 seconds to laminate. Subsequently, the resin film for forming the first cladding layer is formed through a negative photomask having an opening (100 mm × 0.08 mm) by using an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.). Ultraviolet rays (wavelength 365 nm) were irradiated from the support film side at 2000 mJ / cm 2. Thereafter, the support film is peeled off, the developer (1% aqueous potassium carbonate solution) is used to remove the uncured fourth clad layer forming resin, followed by washing with water, followed by heat drying and curing at 160 ° C. for 1 hour. Then, the patterned fourth cladding layer 4 was formed.

[Formation of first core pattern]
Next, the 50 μm-thick first core pattern forming resin film obtained above was peeled off from the surface of the fourth clad layer 4 formed above, and then the roll laminator (Hitachi Chemical Technoplant Co., Ltd.) was peeled off. ), HLM-1500), the pressure of 0.4 MPa, the temperature of 50 ° C., and the lamination speed of 0.2 m / min are laminated, and then the above-mentioned vacuum pressure laminator (manufactured by Meiki Seisakusho, MVLP-500) ), And vacuum-pressurized to 500 Pa or less, followed by thermocompression bonding under conditions of a pressure of 0.4 MPa, a temperature of 70 ° C., and a pressurization time of 30 seconds.

  Subsequently, a negative photomask having an opening of 90 mm × 40 μm is aligned so that the opening is on the fourth cladding layer 4, and ultraviolet rays (wavelengths) are used from the support film side using the ultraviolet exposure machine. 365 nm) at 0.8 J / cm @ 2 and then post-exposure heating at 80 DEG C. for 5 minutes. Thereafter, the PET film as the support film was peeled off and etched using a developer (propylene glycol monomethyl ether acetate / N, N-dimethylacetamide = 8/2, mass ratio). Then, it wash | cleaned using the washing | cleaning liquid (isopropanol), and heat-dried at 100 degreeC for 10 minute (s), and the 1st core pattern 5 was formed. The thickness of the obtained first core pattern on the fourth cladding layer 4 was 40 μm and the width was 40 μm.

[Formation of second cladding layer and second core pattern]
After the 60 μm-thick second clad layer and the protective film for the second core pattern forming resin film obtained above are peeled off from the surface on which the first core pattern 5 is obtained as described above, a vacuum pressure laminator (Co., Ltd. ) Using a MVLP-500 manufactured by Meiki Seisakusho, vacuuming was performed to 500 Pa or less, and then thermocompression bonding was performed under the conditions of a pressure of 0.4 MPa, a temperature of 65 ° C., and a pressurization time of 30 seconds for lamination. Subsequently, using a UV exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.), through a negative photomask having openings (A: 95 mm × 0.1 mm and B: 90 mm × 60 μm), The opening A was aligned so as to enclose the previously formed fourth clad layer 4 and irradiated with ultraviolet rays (wavelength 365 nm) at 2500 mJ / cm 2 from the support film side. Thereafter, the support film is peeled off, the developer (1% aqueous potassium carbonate solution) is used to remove the uncured resin for forming the second cladding layer, followed by washing with water, followed by heat drying and curing at 160 ° C. for 1 hour. Then, the patterned second cladding layer 2 and second core pattern 6 were formed. The obtained second core pattern 6 had a thickness of 60 μm and a width of 60 μm. The fourth cladding layer 4 and the first core pattern 5 were embedded in the second cladding layer 2 having a width of 0.1 mm.

[Formation of third cladding layer]
After peeling off the protective film of the third clad layer-forming resin film having a thickness of 75 μm obtained above from the side where the second clad layer 2 and the second core pattern 6 are formed, a vacuum pressure laminator (named machine) Using a MVLP-500) manufactured by Seisakusho, vacuuming was performed to 500 Pa or less, and then thermocompression bonding was performed under the conditions of a pressure of 0.4 MPa, a temperature of 90 ° C., and a pressurization time of 30 seconds for lamination. Subsequently, ultraviolet rays (wavelength 365 nm) were irradiated at 3000 mJ / cm 2 from the support film side of the third clad layer forming resin film using an ultraviolet exposure machine (EXM-1172, manufactured by Oak Manufacturing Co., Ltd.). Then, the support film was peeled off, dried and cured at 170 ° C. for 1 hour, and the third cladding layer 3 was formed to obtain an optical waveguide.

[Production of optical path conversion mirror]
A dicing saw (DAC552, Inc.) provided with a dicing blade having an inclined surface of 45 ° from the surface on which the third cladding layer 3 is formed at a position 1 cm from one end of the first core pattern 5 of the optical waveguide obtained above. The optical path conversion mirror 8 was simultaneously formed on the first core pattern 5 and the second core pattern 6 using a disco) (see FIGS. 4 and 5, FIG. 5 is a plan view of FIG. 4 viewed from a direction substantially perpendicular to the substrate plane). It is a figure.)
Further, using a dicing saw (DAC552, manufactured by DISCO Corporation) having a rectangular dicing blade, the optical path conversion mirror is simultaneously cut into the first core pattern 5 and the second core pattern 6 at a position 5 cm to smooth the end face. Went.

[Measurement of misalignment between first core pattern and second cladding layer]
Detection light (white light) is incident from the end face of the optical waveguide obtained above, and is output from the optical path conversion mirror 8 provided on the optical axis of the first core pattern 5 toward the first cladding layer 1. The amount of deviation from the design value with respect to the light output in the direction of the first cladding layer 1 from the optical path conversion mirror 8 provided on the optical axis of the second core pattern 6 was 5.0 μm. Moreover, the deviation | shift amount of 1st core pattern center height and 2nd core pattern center height was 0.1 micrometer. In addition, the position of the output light was visually recognized satisfactorily.
Next, in the same manner as described above, the optical waveguide is viewed from the cross-sectional direction, the detection light is incident from the optical path conversion mirror 8, and the amount of deviation from the design values of the first core pattern 5 and the second core pattern 6 is determined from the end face direction. It was 5.0 μm when measured. Moreover, the deviation | shift amount of 1st core pattern center height and 2nd core pattern center height was 0.1 micrometer. In addition, the position of the output light was visually recognized satisfactorily.
When the optical waveguide was visually confirmed from the cross-sectional direction using incident light and the positional deviation from the design value between the center of the second cladding layer 2 and the center of the first core pattern 5 was confirmed, it was 5.0 μm in the same manner. Further, the deviation amount between the center height of the first core pattern and the center height of the second core pattern was also 0.1 μm. It was difficult to visually recognize the positional deviation from the design value between the center of the second cladding layer 2 and the center of the first core pattern 5 from the cross-sectional direction, and it took a long time to measure.

Example 2
In Example 1, an optical waveguide was formed by the same method except that the fourth cladding layer was not formed, and the optical path conversion mirror 8 and end face processing were performed.
[Measurement of misalignment between first core pattern and second cladding layer]
Detection light (white light) is incident from the end face of the optical waveguide obtained above, and is output from the optical path conversion mirror 8 provided on the optical axis of the first core pattern 5 toward the first cladding layer 1. The amount of deviation from the design value with respect to the light output in the direction of the first cladding layer 1 from the optical path conversion mirror 8 provided on the optical axis of the second core pattern 6 was 4.5 μm. In addition, the position of the output light was visually recognized satisfactorily.
Next, in the same manner as described above, the optical waveguide is viewed from the cross-sectional direction, the detection light is incident from the optical path conversion mirror 8, and the amount of deviation from the design values of the first core pattern 5 and the second core pattern 6 is determined from the end face direction. It was 4.5 μm when measured. In addition, the position of the output light was visually recognized satisfactorily.
When the optical waveguide was visually confirmed from the cross-sectional direction using incident light and the positional deviation from the design value between the center of the second cladding layer 2 and the center of the first core pattern 5 was confirmed, it was 4.5 μm. It was difficult to visually recognize the positional deviation from the design value between the center of the second cladding layer 2 and the center of the first core pattern 5 from the cross-sectional direction, and it took a long time to measure.

Example 3
In Example 2, after forming the resin layer for forming the third cladding layer, the third cladding layer is passed through a negative photomask having an opening of 100 mm × 0.1 μm at the position including the second core pattern 6. Ultraviolet rays (wavelength 365 nm) were irradiated at 350 mJ / cm 2 from the support film side of the forming resin film. Thereafter, the support film is peeled off, the uncured resin for forming the third cladding layer is removed using a developer (1% aqueous potassium carbonate solution), then washed with water, and further washed with the above-described ultraviolet exposure machine. An optical waveguide was formed by the same method except that the third cladding layer 3 was patterned by irradiation with 0.0 J / cm 2, heating and drying at 170 ° C. for 1 hour, and patterning the third cladding layer 3, and the optical path conversion mirror 8 and end face processing were performed.
[Measurement of misalignment between first core pattern and second cladding layer]
Detection light (white light) is incident from the end face of the optical waveguide obtained above, and is output from the optical path conversion mirror 8 provided on the optical axis of the first core pattern 5 toward the first cladding layer 1. The amount of deviation from the design value with respect to the light output in the direction of the first cladding layer 1 from the optical path conversion mirror 8 provided on the optical axis of the second core pattern 6 was measured and found to be 3.5 μm. In addition, the position of the output light was visually recognized satisfactorily.
Next, in the same manner as described above, the optical waveguide is viewed from the cross-sectional direction, the detection light is incident from the optical path conversion mirror 8, and the amount of deviation from the design values of the first core pattern 5 and the second core pattern 6 is determined from the end face direction. It was 3.5 μm when measured. In addition, the position of the output light was visually recognized satisfactorily.
When the optical waveguide was visually recognized from the cross-sectional direction using incident light and the positional deviation from the design value between the center of the second cladding layer 2 and the center of the first core pattern 5 was confirmed, it was 3.5 μm. The positional deviation from the design value between the center of the second cladding layer 2 and the center of the first core pattern 5 from the cross-sectional direction is somewhat difficult to see and takes time to measure.

  The optical waveguide of the present invention uses a second core pattern in which a positional correlation is ensured with the second cladding layer covering the first core pattern, and a positional deviation of the second cladding layer is achieved. Can be easily measured, and can be applied to a wide range of fields such as various optical devices, interconnection, and illumination.

  DESCRIPTION OF SYMBOLS 1 ... 1st clad layer, 2 ... 2nd clad layer, 3 ... 3rd clad layer, 4 ... 4th clad layer, 5 ... 1st core pattern, 6 ... 2nd core pattern, 7 ... Substrate, 8 ... Optical path conversion mirror

Claims (14)

On the first cladding layer,
A first core pattern having a refractive index higher than that of the first cladding layer;
A second cladding layer covering an upper surface and a side surface of the first core pattern;
A second core pattern having a refractive index lower than that of the first core pattern and having a refractive index higher than that of the first cladding layer, and having a positional correlation with the second cladding layer;
An optical waveguide.   The optical waveguide according to claim 1, wherein the second core pattern and the second cladding layer are formed in the same process.   The optical waveguide according to claim 1, wherein the second core pattern and the second cladding layer are formed of the same material.   4. The optical waveguide according to claim 1, wherein a side surface and an upper surface of the second core pattern are covered with a third cladding layer having a refractive index lower than that of the second core pattern.   5. The optical waveguide according to claim 1, wherein a side surface and an upper surface of the second cladding layer are covered with a third cladding layer having a refractive index lower than that of the second core pattern.   The optical waveguide according to claim 1, further comprising a fourth clad layer having a refractive index lower than that of the first core pattern between the first clad layer and the first core pattern.   The optical waveguide according to claim 6, wherein the fourth cladding layer is embedded in the second cladding layer.   The optical waveguide according to claim 1, wherein an optical path conversion mirror is provided on at least one of the optical axis of the first core pattern and the optical axis of the second core pattern. Forming a first core pattern having a refractive index higher than the refractive index of the first cladding layer on the first cladding layer; and
On the first cladding layer, a second core pattern having a refractive index lower than that of the first core pattern and having a refractive index higher than that of the first cladding layer is formed. And a step B of forming a second cladding layer on an upper surface and a side surface of the core pattern.   The method of manufacturing an optical waveguide according to claim 9, further comprising a step C of forming a fourth clad layer having a refractive index lower than that of the first core pattern on the first clad layer before the step B.   11. The optical waveguide manufacturing method according to claim 9, further comprising a step D of forming a third cladding layer having a refractive index lower than that of the second core pattern on a side surface and an upper surface of the second core pattern after the step B. Method.   The method of manufacturing an optical waveguide according to claim 11, wherein in the step D, the second cladding layer is embedded by the third cladding layer.   The optical waveguide manufacturing according to any one of claims 9 to 12, further comprising a step E of providing an optical path conversion mirror on an optical axis of at least one of the first core pattern and the second core pattern after the step A. Method.   9. The detection light according to claim 1, wherein detection light is incident on the first core pattern and the second core pattern and is emitted from the first core pattern and the second core pattern. The position detection method of the optical waveguide which detects the amount of position shift in the direction perpendicular to the optical axis of the second clad layer with respect to the first core pattern and the substrate plane direction from each other position.