JP5321077B2 - Optical waveguide and optical waveguide module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide and an optical waveguide module in which transmission loss of light is reduced when light is transmitted between the optical waveguide and such external elements as a light emitting element and a light receiving element. <P>SOLUTION: The optical waveguide 3 includes an upper clad layer 33, a lower clad layer 31 and a core layer 32 which is sandwiched between the upper clad layer 33 and the lower clad layer 31, and is extended in a prescribed direction. The optical waveguide 3 has a pair of end faces intersecting with the extended direction are tilted. The tilted faces are composed of the end face of the upper clad layer 33, the end face of the core layer 32 and the end face of the lower clad layer 31, and is tilted out from the upper clad layer 33 side to the lower clad layer 31 side. The angle between the tilted faces and the optical axis (axis along the extended direction of the optical waveguide 3) in the core layer 32 is approximately 45 degrees. The thickness of the central part in the extended direction of the core layer 32 and the thickness of the end part of the core layer 32 are different from each other. Further, the optical waveguide 3 is a film having flexibility. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an optical waveguide and an optical waveguide module.

  Conventionally, in the field of communication and the like, a film-like optical waveguide is sometimes used. For example, the light emitting element and the optical connector are connected by a film-like optical waveguide.

Japanese Patent Laid-Open No. 10-300961

  In such an optical waveguide, it is required to reduce light propagation loss when light is propagated between light emitting elements and external elements such as light receiving elements. However, it is difficult for conventional optical waveguides to meet such demands.

  An object of the present invention is to provide an optical waveguide and an optical waveguide module capable of reducing a propagation loss of light between a light emitting element and an external element such as a light receiving element.

  As a result of the study by the present inventors, it is possible to reduce the propagation loss of light between the light emitting element and the external element such as the light receiving element by making the thickness of the core layer different between the end and the center I understood. Conventionally, an optical waveguide is manufactured by applying a composition constituting a cladding layer on a substrate, applying a composition constituting a core layer on the composition, and laminating the cladding layer and the core layer. (See Patent Document 1). Therefore, in the conventional optical waveguide, the thickness of the core layer is uniform, and the thickness of the core layer cannot be different between the end portion and the central portion.

According to the present invention, the upper cladding layer and lower cladding layer, said upper cladding layer, wherein a lower clad layer and the core sandwiched between layers, in the optical waveguide extending along the predetermined direction, the light guide The waveguide includes a photosensitive resin film in which the upper cladding layer, the core layer, and the lower cladding layer are formed, and the upper cladding layer, the lower cladding layer, or the core layer irradiates the photosensitive resin film with light. The one end surface intersecting with the extending direction of the optical waveguide is an inclined surface inclined from the upper cladding layer side toward the lower cladding layer side, and the thickness in the extending direction center of the end portion of the core layer is different to the thickness of one end portion of the inclined surface side, before Symbol upper cladding layer and the lower Rudd layer is one area one of the non-irradiated region irradiated region and the light is irradiated with light to the film plane of said photosensitive resin film is not irradiated, the core layer is the photosensitive resin is any other region of the non-irradiated region irradiated region and the light is irradiated with light to the film plane of the film is not irradiated, the upper cladding layer optical waveguide extending direction along the side surface of the There is provided an optical waveguide in which a side surface along the optical waveguide extending direction of the core layer and a side surface along the optical waveguide extending direction of the lower cladding layer constitute the film surface of the photosensitive film.

According to the present invention, by making the thickness of the core layer different between the end portion and the central portion, it is possible to reduce the light propagation loss between the light emitting element and the external element such as the light receiving element.
For example, if the thickness of the end portion of the core layer is made thinner than the center portion and the light receiving element is disposed on the end side, the light propagating in the core layer can be narrowed down and reliably incident on the light receiving element.
On the other hand, if the thickness of the end portion of the core layer is made thicker than the center portion and the light emitting element is arranged on the end side, light generated from the light emitting element can be reliably guided into the core layer. In the core layer, light can be narrowed and propagated.

  Furthermore, for example, if the thickness of the end of the core layer is increased so as to penetrate the lower cladding layer, light can be more reliably propagated between the external optical element and the core layer.

  In addition, according to the present invention, it is possible to provide an optical waveguide module that includes a light emitting element, a light receiving element, and an optical waveguide connecting the light emitting element and the light receiving element, and the optical waveguide is the above-described optical waveguide.

  According to the present invention, there are provided an optical waveguide and an optical waveguide module capable of reducing the propagation loss of light when light is propagated between external elements such as a light emitting element and a light receiving element.

It is a perspective view which shows the optical waveguide concerning 1st embodiment of this invention. It is a top view which shows the film concerning 1st embodiment. It is a figure which shows the manufacturing process of a film. It is a figure which shows the manufacturing process of a film. It is a figure which shows the dicing process of a film. It is a figure which shows the optical waveguide module in 1st embodiment. It is a schematic diagram which shows the installation state of an optical waveguide. It is a perspective view which shows the optical waveguide module concerning 2nd embodiment of this invention. It is a figure which shows the optical waveguide in 2nd embodiment. It is a figure which shows the figure and film which show the optical waveguide concerning 3rd embodiment of this invention. It is a figure which shows the optical waveguide concerning the modification of this invention. It is a figure which shows the propagation loss of the optical waveguide in the Example of this invention. It is a figure which shows the optical waveguide in the Example of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.
(First embodiment)
(Optical waveguide)
First, the outline of the optical waveguide 3 of the present embodiment will be described with reference to FIG.
The optical waveguide 3 of the present embodiment includes an upper clad layer 33 and a lower clad layer 31, an upper clad layer 33, and a core layer 32 sandwiched between the lower clad layer 31, and extends along a predetermined direction. Is.
In the optical waveguide 3, a pair of end surfaces (film end surfaces) intersecting the extending direction are inclined surfaces. This inclined surface is constituted by the end surface of the upper cladding layer 33, the end surface of the core layer 32, and the end surface of the lower cladding layer 31, and is inclined outward from the upper cladding layer 33 side toward the lower cladding layer 31 side. The angle formed by this inclined surface and the optical axis in the core layer 32 (axis along the extending direction of the optical waveguide 3) is about 45 degrees.
Further, the thickness of the central portion of the core layer 32 in the extending direction is different from the thickness of the end portion of the core layer 32. Further, the optical waveguide 3 is a flexible film.

Next, the optical waveguide 3 of this embodiment will be described in detail.
As shown in FIG. 1, the optical waveguide 3 includes an upper clad layer 33 extending in one direction when viewed from the film surface side, a core layer 32 extending in one direction together with the upper clad layer 33, and one with the core layer 32. It has a lower cladding layer 31 extending in the direction. When viewed from the film surface side, an upper clad layer 33, a core layer 32, and a lower clad layer 31 are laminated.
The lower cladding layer 31 extends in one direction, and its thickness (thickness along the height direction of the optical waveguide 3) increases from one end to the other end.
Similarly, the upper clad layer 33 extends in one direction, and its thickness (thickness along the height direction of the optical waveguide 3) increases from one end to the other end.
On the other hand, in the core layer 32, the thickness at the center portion in the extending direction of the core layer 32 (thickness along the height direction of the optical waveguide 3) and the thickness of the end portion are different. Specifically, in the present embodiment, the thickness of the core layer 32 gradually decreases from one end side toward the other end side. That is, the thickness of the core layer 32 gradually changes when viewed from the front side (film surface side), and the thickness continuously decreases from one end side toward the other end side. The upper surface and the lower surface of the core layer 32 are configured by inclined surfaces inclined from one end side of the core layer 32 toward the other side.

Here, the thickness A along the height direction from the lower surface of the lower cladding layer 31 to the upper surface of the upper cladding layer 33, and the width of the optical waveguide 3 orthogonal to the height direction of the optical waveguide 3 and orthogonal to the extending direction. A / B, which is a ratio to the dimension B, is preferably 2 or more.
Among these, A / B is preferably 5 or more from the viewpoint of manufacturability of the optical waveguide 3, and A / B is preferably 10 or less.
The width dimension B corresponds to the film thickness of the optical waveguide 3.

(Manufacturing method of the optical waveguide 3)
Next, a method for manufacturing the optical waveguide 3 will be described with reference to FIGS.
First, as shown in FIG. 2, a film 34 is prepared.
The film 34 is configured such that the clad layers 341 and the core layers 342 are alternately arranged when viewed from the surface side. A plurality of clad layers 341 and a plurality of core layers 342 are formed. The core layer 342 becomes the core layer 32 of the optical waveguide 3, and the cladding layer 341 becomes the upper cladding layer 33 and the lower cladding layer 31 of the optical waveguide 3.
The thickness of the film 34 is about 50 to 500 μm, and this thickness corresponds to the width dimension B of the optical waveguide 3.

Here, an example is given and demonstrated about the manufacturing method of such a film 34. FIG.
First, a composition as a raw material for the film 34 is prepared.
This composition is a photosensitive resin composition, for example, (A) a cyclic olefin resin and (B) a monomer having a cyclic ether group and an oligomer having a cyclic ether group that have a refractive index different from that of (A). And (C) a photoacid generator.
(A) Cyclic olefin resin The cyclic olefin resin of (A) is added in order to ensure the film moldability of the photosensitive resin composition, and serves as a base polymer.
Here, the cyclic olefin resin may be unsubstituted, or hydrogen may be substituted with another group. Examples of the cyclic olefin resin include norbornene resins and benzocyclobutene resins.
Especially, it is preferable to use norbornene-type resin from viewpoints, such as heat resistance and transparency.

As norbornene resin, for example,
(1) addition (co) polymer of norbornene type monomer obtained by addition (co) polymerization of norbornene type monomer,
(2) an addition copolymer of a norbornene monomer and ethylene or α-olefins,
(3) an addition polymer such as an addition copolymer of a norbornene-type monomer and a non-conjugated diene and, if necessary, another monomer;
(4) a ring-opening (co) polymer of a norbornene-type monomer, and a resin obtained by hydrogenating the (co) polymer if necessary,
(5) a ring-opening copolymer of a norbornene-type monomer and ethylene or α-olefins, and a resin obtained by hydrogenating the (co) polymer if necessary,
(6) Ring-opening copolymers such as norbornene-type monomers and non-conjugated dienes, or other monomers, and polymers obtained by hydrogenating the (co) polymers as necessary. Examples of these polymers include random copolymers, block copolymers, and alternating copolymers.

  These norbornene resins include, for example, ring-opening metathesis polymerization (ROMP), combination of ROMP and hydrogenation reaction, polymerization by radical or cation, polymerization using cationic palladium polymerization initiator, other polymerization initiators ( For example, it can be obtained by any known polymerization method such as polymerization using a polymerization initiator of nickel or another transition metal).

Among these, as the norbornene-based resin, an addition (co) polymer is preferable. Addition (co) polymers are also preferred because they are rich in transparency, heat resistance and flexibility.
Among these, the norbornene-based resin preferably includes a norbornene repeating unit having a substituent containing a polymerizable group and a norbornene repeating unit having a substituent containing an aryl group.

  As the repeating unit of norbornene having a substituent containing a polymerizable group, the repeating unit of norbornene having a substituent containing an epoxy group, the repeating unit of norbornene having a substituent containing a (meth) acryl group, and an alkoxysilyl group At least one of the repeating units of norbornene having a substituent containing is preferable. These polymerizable groups are preferable because of their high reactivity among various polymerizable groups.

  Moreover, if the thing containing 2 or more types of norbornene repeating units containing such a polymeric group is used, both flexibility and heat resistance can be achieved.

  On the other hand, by including a norbornene repeating unit having a substituent containing an aryl group, the aryl group has extremely high hydrophobicity, so that dimensional change due to water absorption can be prevented more reliably.

  Furthermore, the norbornene-based polymer preferably contains an alkylnorbornene repeating unit. The alkyl group may be linear or branched.

  By including the repeating unit of alkyl norbornene, the norbornene-based polymer has high flexibility, and thus can provide high flexibility (flexibility).

  A norbornene-based polymer containing an alkylnorbornene repeating unit is also preferable because of its excellent transmittance with respect to light in a specific wavelength region (particularly, a wavelength region near 850 nm).

The norbornene-based resin as described above preferably has a leaving group. Here, the leaving group is a group that is released by the action of an acid.
Specifically, those having at least one of an —O— structure, an —Si—aryl structure, and an —O—Si— structure in the molecular structure are preferable. Such an acid leaving group is released relatively easily by the action of a cation.
Specifically, it is preferable to use the following norbornene resin. The compound represented by (1) can be obtained, for example, by reacting hexylnorbornene (HxNB) with diphenylmethylnorbornene methoxysilane under a Ni catalyst.

(R7 represents an alkyl group having 1 to 10 carbon atoms, i is an integer of _0~3, p ₅ / _q 5 is 20 or less)

((B) Monomer having a cyclic ether group, oligomer having a cyclic ether group)
Next, the component (B) will be described.
(B) is at least one of a monomer having a cyclic ether group and an oligomer having a cyclic ether group. The component (B) may be any component that has a refractive index different from that of the resin (A) and is compatible with the resin (A). The refractive index difference between the component (B) and the resin (A) is preferably 0.01 or more.
The refractive index of the component (B) may be higher than that of the resin (A), but the component (B) preferably has a lower refractive index than that of the resin (A).

The monomer having a cyclic ether group (B) and the oligomer having a cyclic ether group are polymerized by ring-opening in the presence of an acid. Considering the diffusibility of the monomer and oligomer, the molecular weight (weight average molecular weight) of the monomer and the molecular weight (weight average molecular weight) of the oligomer are preferably 100 or more and 400 or less, respectively.
(B) has, for example, an oxetanyl group or an epoxy group. Such a cyclic ether group is preferable because it is easily opened by an acid.

  As the monomer having an oxetanyl group and the oligomer having an oxetanyl group, for example, Formula (2) or Formula (3) can be used. By using these, there is an advantage that transparency is excellent in the vicinity of a wavelength of 850 nm and that both flexibility and heat resistance are possible. These may be used alone or in combination. Examples of the formula (2) and the formula (3) include Toa Gosei Co., Ltd., DOX, CAS # 18934-00-4, Toa Gosei Co., Ltd. CHOX, CAS # 483303-25-9, and the like.

Examples of the monomer having an epoxy group and the oligomer having an epoxy group include the following. The monomer and oligomer having an epoxy group are polymerized by ring-opening in the presence of an acid.
As an epoxy group-containing monomer and an epoxy group-containing oligomer, epoxy norbornene (ProNB's EpNB), γ-glycidoxypropyltrimethoxysilane (Toray Dow Corning Silicone's Z-6040), 2- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane (E0327 manufactured by Tokyo Chemical Industry Co., Ltd.) can be used.
Furthermore, 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate (Delcel Chemical Co., Celoxide 2021P), 1,2-epoxy-4-vinylcyclohexane (Daicel Chemical Co., Celoxide 2000), 1,2: 8,9 diepoxy limonene (Delcel Chemical Co., Celoxide 3000) can be used.
The component (B) is preferably 1 part by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the component (A). Of these, 2 parts by weight or more and 20 parts by weight or less are preferable. Thereby, the refractive index modulation between the core and the clad is possible, and there is an effect that both flexibility and heat resistance can be achieved.

((C) Photoacid generator)
Any photoacid generator may be used as long as it absorbs light energy to generate Bronsted acid or Lewis acid. For example, triphenylsulfonium trifluoromethanesulfonate, tris (4-t-butylphenyl) sulfonium- Sulfonium salts such as trifluoromethanesulfonate, diazonium salts such as p-nitrophenyldiazonium hexafluorophosphate, ammonium salts, phosphonium salts, diphenyliodonium trifluoromethanesulfonate, iodonium salts such as (triccumyl) iodonium-tetrakis (pentafluorophenyl) borate, Quinonediazides, diazomethanes such as bis (phenylsulfonyl) diazomethane, 1-phenyl-1- (4-methylphenyl) sulfonyl Sulfonic esters such as oxy-1-benzoylmethane and N-hydroxynaphthalimide-trifluoromethanesulfonate, disulfones such as diphenyldisulfone, tris (2,4,6-trichloromethyl) -s-triazine, 2- ( And compounds such as triazines such as 3.4-methylenedioxyphenyl) -4,6-bis- (trichloromethyl) -s-triazine. These photoacid generators can be used alone or in combination.

  The content of the photoacid generator is preferably 0.01 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the component (A). Especially, 0.02 weight part or more and 0.2 weight part or less are preferable. Thereby, there exists an effect of a reactive improvement.

The photosensitive resin composition may contain additives such as a sensitizer in addition to the above components (A), (B), and (C).
The sensitizer increases the sensitivity of the photoacid generator to light and is suitable for reducing the time and energy required for activation (reaction or decomposition) of the photoacid generator and for activating the photoacid generator. It has a function of changing the wavelength of light to a wavelength.
Such a sensitizer is appropriately selected according to the sensitivity of the photoacid generator and the peak wavelength of absorption of the sensitizer, and is not particularly limited. For example, 9,10-dibutoxyanthracene (CAS No. 76275) is selected. -14-4) anthracenes, xanthones, anthraquinones, phenanthrenes, chrysene, benzpyrenes, fluoranthenes, rubrenes, pyrenes, indanthrines, thioxanthen-9-one (Thioxanthen-9-ones) are used alone or as a mixture.

Specific examples of the sensitizer include 2-isopropyl-9H-thioxanthen-9-one, 4-isopropyl-9H-thioxanthen-9-one, 1-chloro-4-propoxythioxanthone, phenothiazine, and these Of the mixture.
The content of the sensitizer in the photosensitive resin composition is preferably 0.01% by weight or more, more preferably 0.5% by weight or more, and further preferably 1% by weight or more. preferable. In addition, it is preferable that an upper limit is 5 weight% or less.

Next, a method for producing the film 34 using the photosensitive resin composition as described above will be described.
Here, the photosensitive resin composition whose component (B) has a refractive index lower than (A) cyclic olefin resin is used.

First, as shown in FIG. 3A, the photosensitive resin composition is dissolved in a solvent to form the varnish 20, and this varnish 20 is applied onto the substrate S.
Examples of the solvent for adjusting the photosensitive resin composition to varnish include, for example, diethyl ether, diisopropyl ether, 1,2-dimethoxyethane (DME), 1,4-dioxane, tetrahydrofuran (THF), tetrahydropyran (THP), Ether solvents such as anisole, diethylene glycol dimethyl ether (diglyme), diethylene glycol ethyl ether (carbitol), cellosolv solvents such as methyl cellosolve, ethyl cellosolve, phenyl cellosolve, aliphatic hydrocarbon solvents such as hexane, pentane, heptane, cyclohexane , Toluene, xylene, benzene, mesitylene and other aromatic hydrocarbon solvents, pyridine, pyrazine, furan, pyrrole, thiophene, methylpyrrolidone and other aromatic heterocyclic compounds Amide solvents such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), halogen compound solvents such as dichloromethane, chloroform and 1,2-dichloroethane, ethyl acetate, methyl acetate, ethyl formate, etc. Ester solvents, various organic solvents such as sulfur compound solvents such as dimethyl sulfoxide (DMSO) and sulfolane, or mixed solvents containing them.

Next, after apply | coating the varnish 20 on the base material S, it is made to dry and a solvent is evaporated (desolvent). As a result, as shown in FIG. 3B, the varnish 20 becomes a film 340A for forming an optical waveguide.
Here, examples of the method for applying the varnish 20 include a doctor blade method, a spin coating method, a dipping method, a table coating method, a spray method, an applicator method, a curtain coating method, and a die coating method. It is not limited.

Next, light (for example, ultraviolet rays) is selectively applied to the film 340A.
As shown in FIG. 4A, a mask M in which an opening is formed is disposed above the film 340A. The film 340A is irradiated with light through the opening of the mask M.
In the film 340 </ b> A, in the region irradiated with light, an acid is generated from the photoacid generator. The component (B) is polymerized by the generated acid.
In the region not irradiated with light, no acid is generated from the photoacid generator, so that component (B) is not polymerized. In the irradiated part, since the component (B) is polymerized to become a polymer, the amount of the component (B) is reduced. Thereby, the component (B) of an unirradiated part diffuses to an irradiated part, and thereby a refractive index difference occurs between the irradiated part and the unirradiated part.
Here, when the component (B) has a lower refractive index than the cyclic olefin resin, the component (B) of the unirradiated part diffuses into the irradiated part, and the refractive index of the unirradiated part increases. The refractive index of the irradiated part is lowered.
In addition, the refractive index difference between the polymer obtained by polymerizing the component (B) and the monomer having a cyclic ether group is about 0 or more and 0.001 or less, and the refractive indexes are considered to be substantially the same.

Further, when a cyclic olefin resin having a leaving group is used as (A), the following action occurs.
In the portion irradiated with light, the leaving group of the cyclic olefin resin is eliminated by the acid generated from the photoacid generator. In the case of a leaving group such as a -Si-aryl structure, a -Si-diphenyl structure, and a -O-Si-diphenyl structure, the refractive index of the resin decreases due to the leaving. For this reason, the refractive index of the irradiated portion is lowered.

  Thus, when the photosensitive resin composition of this embodiment is used, it is possible to start superposition | polymerization of a component (B) with the acid generate | occur | produced from a photo-acid generator.

  Next, the film 340A is heated. In this heating step, the component (B) of the irradiated portion irradiated with light is further polymerized. On the other hand, in this heating step, the component (B) in the unirradiated part is volatilized. Thereby, in an unirradiated part, a component (B) decreases and it becomes a refractive index close | similar to cyclic olefin resin.

In this film 340 </ b> A, as shown in FIG. 4B, the region irradiated with light becomes the cladding layer 341, and the non-irradiated region becomes the core layer 342. The refractive index of the core layer 342 is higher than the refractive index of the cladding layer 341, and the structure concentration derived from the (B) in the core layer 342 is different from the structure concentration derived from the (B) in the cladding layer 341. . Specifically, the structure concentration derived from (B) in the core layer 342 is lower than the structure concentration derived from (B) in the cladding layer 341.
The cladding layer 341 has a refractive index lower than that of the core layer 342, and the refractive index difference between the cladding layer 341 and the core layer 342 is, for example, 0.01 or more.
The film 34 will be obtained by the above process.
Note that the film 340 </ b> A may be formed using a material in which a region irradiated with light becomes a core layer and a non-irradiated region becomes a cladding layer.

Next, the film 34 is diced to obtain the optical waveguide 3.
For example, as shown by a dotted line in FIG. 2, the clad layer 341 is cut along the extending direction of the clad layer 341 with a dicing blade (step 1), and further in the extending direction of the clad layer 341 and the core layer 342. The plurality of clad layers 341 and the plurality of core layers 342 are cut so as to intersect at 45 degrees (step 2).
By step 2, an inclined surface is formed on one end surface of the optical waveguide 3.
Then, in order to form the inclined surface of the other end surface of the optical waveguide 3, the other end portion of the cut film is cut by a dicing blade (step 3). In step 3, as in step 2, the plurality of cladding layers 341 and the plurality of core layers 342 may be cut so as to intersect at 45 degrees with respect to the extending direction of the cladding layer 341 and the core layer 342.
Here, as shown in FIG. 5, the dicing blade D used for the dicing in the steps 1 to 3 has a disk shape (columnar shape) and a blade edge is flat. The cutting edge and the surface of the film 34 are arranged in parallel. This dicing blade has a V-shaped cutting edge.
Moreover, there is no restriction | limiting in particular in the order which implements the process 1 and the process 2, After performing the process 1, you may implement the process 2, You may implement the process 1 after implementing the process 2.
Thereafter, the cut film 34 is peeled off from the substrate S to form an optical waveguide 3.
When manufacturing the optical waveguide 3, as shown by the inclined dotted line in FIG. 2, the film 34 is diced to form one inclined surface, and then the film 34 is further diced to the other of the optical waveguides. An inclined surface may be formed. In this case, a plurality of optical waveguides 3 having different waveguide lengths can be obtained. Also, as shown by the slanted dotted line in FIG. 2, after the film 34 is diced to form one inclined surface, the film 34 is peeled off, the diced portions are rearranged, diced again, and put together at once. The other inclined surface of the plurality of optical waveguides 3 may be formed. In this way, a plurality of optical waveguides 3 having the same waveguide length can be obtained.

In the present embodiment, the photosensitive resin composition as described above is used as the material of the film 34, but is not limited thereto.
For example, you may use the photosensitive resin composition of another composition which is disclosed by Unexamined-Japanese-Patent No. 2006-323318. This photosensitive resin composition contains a light-induced heat-developable material (PITDM) composed of a polymer and an additive (including at least a monomer, a promoter and a catalyst precursor), and is irradiated with light and heated. In the polymer, a material that causes a monomer reaction is used.
As the polymer, the norbornene-based resin as described above can be used.
A monomer is a compound that reacts in an irradiated region by light irradiation to form a reactant, and the presence of this reactant can cause a difference in refractive index between the irradiated region and an unirradiated region of light. . Examples include norbornene monomers, acrylic acid (methacrylic acid) monomers, epoxy monomers, and styrene monomers.

The catalyst precursor is a substance capable of initiating the above-described monomer reaction (for example, polymerization reaction, crosslinking reaction), and is a substance whose activation temperature is changed by the action of a promoter activated by light irradiation.
As the catalyst precursor (procatalyst), any compound may be used as long as the activation temperature changes (increases or decreases) with light irradiation, but particularly with light irradiation. Those having a lower activation temperature are preferred. As a result, the core layer can be formed by heat treatment at a relatively low temperature, and it is possible to prevent deterioration of the characteristics (optical transmission performance) of the optical waveguide due to unnecessary heat being applied to the other layers.

  In the state where the activation temperature is lowered (active latent state), the catalyst precursor has an activation temperature lower by about 10 to 80 ° C. (preferably about 10 to 50 ° C.) than the original activation temperature. Is preferred. Thereby, the refractive index difference between the core layer and the clad layer can be surely generated.

Such a catalyst precursor includes (mainly) one containing at least one of Pd (OAc) ₂ (P (i-Pr) ₃ ) ₂ and Pd (OAc) ₂ (P (Cy) ₃ ) _2. Is preferred.
Hereinafter, Pd (OAc) ₂ (P (i-Pr) ₃ ) ₂ may be abbreviated as “Pd545”, and Pd (OAc) ₂ (P (Cy) ₃ ) ₂ may be abbreviated as “Pd785”. .
Ac is acetate, Pr is propyl, and Cy represents cyclohexyl.

  The cocatalyst is a substance that can be activated by irradiation with light to change the activation temperature of the catalyst precursor (procatalyst) (the temperature at which the monomer reacts). As this cocatalyst (cocatalyst), any compound can be used as long as its molecular structure is changed (reacted or decomposed) by light irradiation and activated. Containing a compound (photoinitiator) that decomposes upon irradiation with a proton and generates a cation of a proton or other cation and a weakly coordinating anion (WCA) that can be substituted for the leaving group of the catalyst precursor (mainly) ) Are preferably used.

Examples of the weakly coordinating anion include tetrakis (pentafluorophenyl) borate ion (FABA ⁻ ) and hexafluoroantimonate ion (SbF ₆ ⁻ ).

  Examples of the promoter (photoacid generator or photobase generator) include tetrakis (pentafluorophenyl) borate and hexafluoroantimonate, tetrakis (pentafluorophenyl) gallate, and aluminates. , Antimonates, other borates, gallates, carboranes, halocarboranes.

Furthermore, as a material of the film 34, the photosensitive resin composition disclosed in JP-A-2005-70556, JP-A-2006-22317, JP-A-2006-152016, and JP-A-2007-31555 is used. can do. Specifically, an epoxy resin and a photocuring initiator are included.
Moreover, the composition containing the polysilane compound disclosed by Unexamined-Japanese-Patent No. 2004-12635, Unexamined-Japanese-Patent No. 2004-333883, and Unexamined-Japanese-Patent No. 2006-299066 can be used. For example, a composition containing a polysilane compound, a double bond-containing silicone compound, and an organic peroxide can be used. In this composition, a double bond-containing silicone compound is included as a silicone compound. Light is irradiated to make the irradiated region a cladding layer and the unirradiated region a core layer. At this time, in the irradiated region, the Si—Si bond of polysilane is cut to form a Si—O—Si bond, the refractive index is lowered, and an addition polymerization reaction due to a double bond occurs. As a result, a difference in refractive index between the core layer and the cladding layer occurs.

(Optical waveguide module)
The optical waveguide 3 obtained by the above manufacturing method can be used as the optical waveguide module 2 as shown in FIG.
FIG. 6A is a cross-sectional view of the optical waveguide module 2, and FIG. 6B is a plan view of the optical waveguide module 2. FIG. 6C is a plan view showing the support member 23 of the optical waveguide module 2.
The optical waveguide module 2 includes a light emitting element 21, a light receiving element 22, an optical waveguide 3 that connects the light emitting element 21 and the light receiving element 22, and a pair of support members 23.
The light emitting element 21 is a surface light emitting element.
The support member 23 accommodates the light emitting element 21 or the light receiving element 22 and supports the optical waveguide 3.
The support member 23 has a rectangular parallelepiped box shape with an open top surface, a bottom surface portion 231 on which the light emitting element 21 or the light receiving element 22 is installed, and side wall portions (walls) erected on each side of the bottom surface portion 231. Part) 232.
The pair of support members 23 are arranged to face each other with a predetermined distance. A slit 232 </ b> A is formed at the upper end portion of the side wall portion 232 facing the side wall portion 232 of the other support member 23 among the side wall portions 232 of the one support member 23. Similarly, a slit 232 </ b> A is formed at the upper end portion of the side wall portion 232 facing the side wall portion 232 of the one support member 23 among the side wall portions 232 of the other support member 23.
The end of the optical waveguide 3, specifically, the end of the lower clad layer 31 is fitted into the slit 232 </ b> A.
The tip of the end of the optical waveguide 3 supported by the support member 23 is located immediately above the light emitting region of the light emitting element 21 or the light receiving region of the light receiving element 22.
Of the end portions of the optical waveguide 3, the end portion with the thicker core layer 32 is disposed on the light emitting element 21, and the end portion with the thinner core layer 32 is disposed on the light receiving element 22. The

  The light generated in the light emitting element 21 passes through the lower cladding layer 31, is reflected by the inclined surface, and propagates through the core layer 32. Thereafter, the light is reflected by the other inclined surface of the optical waveguide 3, bent, and enters the light receiving element 22 through the lower cladding layer 31.

Such an optical waveguide module 2 is installed inside an optical device or the like. At this time, as shown in FIG. 1 and FIG. 6A, the upper clad layer 33 of the optical waveguide 1 may be installed so as not to bend toward the lower clad layer 31 side. ), The upper cladding layer 33 of the optical waveguide 3 may be bent toward the lower cladding layer 31 side. When a sufficient height cannot be secured in the installation space, the upper clad layer 33 of the optical waveguide 3 can be bent and installed on the lower clad layer 31 side. FIG. 7A is a side view of the optical waveguide 3 viewed from the inclined surface side.
Further, as shown in the schematic diagram of FIG. 7B, the optical waveguide 3 may be arranged in a curved U-shape, for example. The optical waveguide 3 is curved and arranged so that the pair of ends of the optical waveguide 3 face each other. FIG. 7B is a plan view of the optical waveguide 3 viewed from the upper clad layer 33 side.
In addition, as a raw material of the support member 23, ceramics, an organic material, etc. can be used.

Next, the effect of this embodiment is demonstrated.
The propagation loss of light can be reduced by making the thickness of the core layer 32 different between the end portion and the center portion. If the thickness of the end portion of the core layer 32 is made thicker than the central portion and the light emitting element 21 is arranged on the end side as in the present embodiment, the light generated from the light emitting element 21 is spread. It becomes possible to guide into the inside reliably.
On the other hand, if the thickness of the end portion of the core layer 32 is made thinner than the center portion and the light receiving element 22 is disposed on the end side, the light propagating in the core layer 32 can be narrowed down and incident on the light receiving element. .
In the present embodiment, the thickness of the core layer 32 gradually changes when viewed from the front side (film surface side), and the thickness is continuously reduced from one end side toward the other end side. It has become. Thereby, irregular reflection of light in the core layer 32 can be prevented, and light propagation loss can be reduced.

In the present embodiment, the thickness A along the height direction from the lower surface of the lower cladding layer 31 to the upper surface of the upper cladding layer 33 is orthogonal to the height direction of the optical waveguide 3 and orthogonal to the extending direction of the optical waveguide 1. A / B, which is a ratio to the width dimension B of the optical waveguide 1 to be set, is 2 or more.
Thereby, various installation forms can be taken.
For example, as shown in FIG. 7B, the optical waveguide 3 can be arranged in a U-shape when viewed in plan view from the upper cladding layer side. Thereby, it can install also in a narrow installation space, for example, an optical waveguide can be installed in the corner | angular part of cases, such as an optical apparatus.
Furthermore, as shown in FIG. 7A, the optical waveguide 3 can be bent and installed.
Thereby, for example, the optical waveguide 3 can be installed even in a place where the height dimension of the installation space is low.
As described above, depending on the installation location, the optical waveguide 3 may be arranged in a straight state without being bent.
Thus, according to this embodiment, an optical waveguide that can take various installation forms can be provided. Thereby, it can respond to space saving of installation space.
Furthermore, since the width dimension B of the optical waveguide 3 is a dimension corresponding to the film thickness of the optical waveguide 3, it can be installed even if the installation space is narrow.

Furthermore, in this embodiment, A / B, which is the ratio of the height dimension A of the optical waveguide 3 and the width dimension B of the optical waveguide 1, is 10 or less.
Thereby, for example, when the optical waveguide 3 is arranged without being bent as shown in FIG. 1, it is possible to prevent the optical waveguide 3 from being bent. Therefore, it is possible to reliably suppress the occurrence of light propagation loss.

In this embodiment, the slit 232 </ b> A is formed in the support member 23 for supporting the optical waveguide 3. Thereby, it becomes easy to install the optical waveguide 3.
In particular, the optical waveguide 3 has a thickness A along the height direction from the lower surface of the lower cladding layer 31 to the upper surface of the upper cladding layer 33, and the direction in which the optical waveguide 3 extends while being orthogonal to the height direction of the optical waveguide 3. A / B, which is a ratio to the width dimension B of the optical waveguide 3 orthogonal to the above, is 2 or more.
Thereby, for example, the optical waveguide 3 can be inserted into the slit 232 </ b> A while holding the upper clad 33, so that the optical waveguide 3 can be easily installed.

Furthermore, in this embodiment, the photosensitive resin composition is applied onto the substrate S to form a film 34, and the film 34 is selectively irradiated with light to form a core layer and a cladding layer. Yes.
Since the thickness distribution of the core layer can be adjusted by setting the shape of the mask arranged on the film 34 to a desired shape, the thickness of the core layer 32 is different from the end portion and the center portion relatively easily. The optical waveguide 3 can be obtained.

Further, as disclosed in Patent Document 1, conventionally, when manufacturing an optical waveguide, a V-shaped dicing blade has been used.
The V-shaped cutting edge is easily worn, and the worn state of the cutting edge has a great influence on the shape of the dicing surface (the shape of the inclined end surface of the optical waveguide). On the other hand, in this embodiment, since a dicing blade having a flat blade edge is used, such a problem does not occur.

Furthermore, when manufacturing an optical waveguide, when dicing a film for each waveguide, it is necessary to use a dicing blade having a flat blade edge. Therefore, a dicing blade for forming a V-shaped groove and a dicing blade for dicing a film for each waveguide must be used. In this case, since the dicing blade must be replaced, it takes time.
On the other hand, in this embodiment, the same blade is used as the dicing blade for forming the inclined surface of the optical waveguide 3 and the dicing blade for dicing (dividing into pieces) the film 34 for each optical waveguide 3. Can be used. Therefore, labor is not required for manufacturing.

(Second embodiment)
A second embodiment of the present invention will be described with reference to FIG.
Here, the structure of the support member 43 of the optical waveguide module 4 is different from that of the above embodiment. Other points are the same as in the above embodiment.
The optical waveguide module 4 includes a light emitting element 21, a light receiving element 22, an optical waveguide 3 that connects the light emitting element 21 and the light receiving element 22, and a pair of support members 43.
The support member 43 has a rectangular parallelepiped box shape with an open top surface, a bottom surface portion 431 on which the light emitting element 21 or the light receiving element 22 is installed, and side wall portions 432 ( Wall).

The pair of support members 43 are opposed to each other with a predetermined distance. A slit 432 </ b> A is formed in the upper end portion of the side wall portion 432 facing the side wall portion 432 of the other support member 43 among the side wall portions of the one support member 43. Similarly, a slit 432 </ b> A is formed at the upper end portion of the side wall portion 432 that faces the side wall portion 432 of one support member 23 among the side wall portions 432 of the other support member 43.
The end of the optical waveguide 3, specifically, the end of the lower clad layer 31 is fitted into the slit 432 </ b> A.

  Further, a notch 432B is formed at the upper end portion of the side wall portion 432 facing the side wall portion 432 where the slit 432A of the support member 43 is formed. Specifically, a notch 432 </ b> B is formed at the inner upper edge of the upper end of the side wall part 432. The end tip of the optical waveguide 3 is installed in the notch 432B, and a contact surface with which the end tip of the optical waveguide 3 abuts is formed by the notch 432B.

When the optical waveguide 3 is installed on the support member 43, the end of the end of the optical waveguide 3, specifically, the end of the lower cladding layer 31 is cut along the thickness direction so that the contact surface is cut. It is preferable to form the abutting flat surface 311 (see FIGS. 8 and 9).
The end portion of the optical waveguide 3 supported by the support member 43 is located immediately above the light emitting region of the light emitting element 21 or the light receiving region of the light receiving element 22.

  According to such this embodiment, the same effect as 1st embodiment can be produced, and the following effect can be produced.

  By forming a contact surface on the support member 43 and further forming a flat surface 311 on the optical waveguide 3, the optical waveguide 3 can be easily installed.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 10A, the optical waveguide 6 of this embodiment includes a core layer 62 sandwiched between an upper cladding layer 63 and a lower cladding layer 61, the upper cladding layer 63, and the lower cladding layer 61. And extending along one direction. The optical waveguide 6 is a film having flexibility.
In the optical waveguide 6, a pair of end surfaces intersecting the extending direction are inclined surfaces. This inclined surface is constituted by the end surface of the upper cladding layer 63, the end surface of the core layer 62, and the end surface of the lower cladding layer 61, and is inclined outward from the upper cladding layer 63 side toward the lower cladding layer 61 side. The angle formed by this inclined surface and the optical axis in the core layer 62 is 45 degrees.

  The thickness of each of the upper cladding layer 63 and the lower cladding layer 61 is uniform along the extending direction.

The thickness of the core layer 62 at the center in the extending direction is different from the thickness of the end. Specifically, the core layer 62 extends along the clad layers 61 and 63, and one end thereof is bent toward the lower clad layer 61 side. The one end extends through the lower cladding layer 61. As a result, the thickness of the core layer 62 at the center in the extending direction is different from the thickness of the end of the core layer 62. Here, the thickness of the end portion of the core layer 62 is the thickness H from the lower surface of the core layer at one end portion of the core layer to the boundary line between the core layer 62 and the upper cladding layer 63 in the inclined surface. Say.
The width W (width along the extending direction of each cladding layer) of the portion 621 (one end portion) of the core layer 62 passing through the lower cladding layer 61 is from the upper cladding layer 63 side to the lower cladding layer 61. Uniform to the side.
Further, the ratio between the width B and the thickness A of the optical waveguide is the same as that in the above embodiment.

In FIG. 10A, one end of the optical waveguide 6 is shown, but the other end may have the same configuration, and on the other end side, as in the first embodiment. In addition, the core layer may extend along the clad layers 61 and 63 without being bent.
The optical waveguide 6 having such a structure can be manufactured using a film 64 as shown in FIG. The material of the film 64 is the same as that of the above embodiment, and the manufacturing method thereof is the same as that of the above embodiment. However, the shape of the mask may be set according to the shape of the core layer.
That is, the film 64 has a plurality of core layers 642 and cladding layers 641 arranged alternately. The core layer 642 has a first region 642A extending together with the cladding layer 641, and a second region 642B bent from the first region 642A into the cladding layer 641. As shown by the dotted line in FIG. 10B, the optical waveguide 6 can be obtained by cutting the film 64 with the same dicing blade as in the first embodiment.

Such an optical waveguide 6 can be used as an optical module by using the support members 23 and 43 shown in the first embodiment and the second embodiment.
When the support member 43 is used, it is preferable to form a flat surface 311 similar to the optical waveguide 3 of the above embodiment on the optical waveguide 6.
According to this embodiment, the same effects as those of the above-described embodiment can be obtained, and the following effects can be obtained.
For example, since the end portion of the core layer 62 is bent toward the lower cladding layer 61 side, light is reliably incident on the optical element disposed in the vicinity of the end portion of the core layer 62 or from the optical element. Light can be reliably incident on the core layer 62.

In FIG. 10A, the width W (width along the extending direction of each cladding layer) of the portion 621 (one end portion) of the core layer 62 that penetrates the lower cladding layer 61 is the upper portion. Although uniform from the clad layer side to the lower clad layer side, it is not limited to this. For example, as shown in FIG. 11 (A), the width W (width along the extending direction of each cladding layer) of the portion 621 (one end) passing through the lower cladding layer 61 of the core layer 62. May be wider from the upper surface side of the lower cladding toward the lower surface side.
Thereby, for example, by arranging the light emitting element below the portion 621 of the core layer 62, the light of the light emitting element can be reliably incident on the core layer 62.
In FIG. 11A, one end portion of the optical waveguide is shown, but the other end portion may have the same configuration, and on the other end side, as in the first embodiment. The core layer may extend along each cladding layer without bending.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, the core layer may have a shape as shown in FIG. In FIG. 11B, the core layer 52 extends along each of the cladding layers 51 and 53, and one end thereof is bent toward the lower cladding layer 51 and penetrates the lower cladding layer 51. It is extended. Thereby, the thickness in the center part of the extending direction of the core layer 52 and the thickness of the end of the core layer 52 are different. Here, the thickness of the end portion of the core layer 52 means the thickness H from the lower surface of the core layer at one end portion of the core layer to the boundary line between the core layer and the upper clad layer in the inclined surface. Further, the core layer 52 has a thickness from one end side to the other end side.
More specifically, the core layer 52 is thicker toward one end side in a region extending in a predetermined direction along the cladding layers 51 and 53 of the core layer 52. More specifically, the core layer 52 includes a first region 521 having a uniform thickness of the core layer 52 and a second region that is connected to the first region 521 and gradually increases in thickness toward the end. A region 522 and a third region 523 connected to the second region 522 and having a uniform thickness are provided.
The second region 522 is formed so as to gradually increase in thickness as viewed from the film surface side of the optical waveguide 5.
The third region 523 is thicker than the first region 521.
However, the central positions of the thicknesses of the first region 521, the second region 522, and the third region 523 of the core layer 52 are substantially the same position, and the inclined surface is 45 degrees with respect to the optical axis of the core layer 52. Inclined.
The clad layers 51 and 53 each have a thickness that is reduced according to the spread of the core layer, and the entire thickness of the optical waveguide 5 is uniform.

In such an optical waveguide 5, for example, by arranging the light emitting element below one end of the core layer 52, the light of the light emitting element can surely enter the core layer 52.
In addition, by setting the center positions of the thicknesses of the first region 521, the second region 522, and the third region 523 of the core layer 52 to be substantially the same position, the inclination of the inclined surface with respect to the optical axis is accurately 45 degrees. can do.
Such an optical waveguide 5 can be used as an optical module by using the support members 23 and 43 shown in the first embodiment and the second embodiment. When the support member 43 is used, it is preferable to form a flat surface 311 similar to the optical waveguide 3 on the optical waveguide film shown in FIG.

Further, in each of the above embodiments, the light emitting element and the light receiving element are arranged below the lower cladding layer. However, the present invention is not limited to this, and the light guide is arranged upside down, and the light emitting element and the light receiving element are arranged above the light guide. You may arrange.
In each of the above embodiments, the optical waveguide has a pair of inclined surfaces. However, the present invention is not limited to this, and only one end surface of the pair of end surfaces may be an inclined surface. For example, when the light emitting element is disposed on the end side where the inclined surface is formed and an optical fiber or the like is connected to the other end surface side, only one end surface may be disposed as the inclined surface.

Furthermore, in the said embodiment, although the supporting members 23 and 43 were made into the rectangular parallelepiped shape, it is not restricted to this, For example, it is good also as a column shape with the upper surface opened. In this case, a wall portion surrounding the light receiving element or the light emitting element is provided, and a slit or a cutout may be formed in the wall portion.
The notch is preferably formed at a position facing the slit.

In each of the above embodiments, the optical waveguides 3 and 6 have the upper clad layers 33 and 63 and the lower clad layers 31 and 61 as clad layers. A clad layer may be provided on the side. When a sufficient installation space for the optical waveguide can be secured, the light confinement effect can be enhanced by disposing the cladding layers on the sides of the core layer. In addition, also when it has a clad layer in the side of the core layers 32 and 62, it is preferable that the thickness of an optical waveguide is 500 micrometers or less.
Furthermore, in the first embodiment, the thickness of the core layer 32 is continuously reduced from one end side toward the other end side. However, the thickness is not limited to this, and the thickness of the core layer 32 is stepwise. It is good also as a structure which becomes thin. For example, the core layer includes a first region having a uniform thickness and extending together with the cladding layer, and a second region having a thickness smaller than the first region and a uniform thickness. It is good also as a simple structure.

Next, examples of the present invention will be described.
EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
(Preparation example)
(1) Preparation of film for forming optical waveguide
<Synthesis of hexyl norbornene (HxNB) / diphenylmethylnorbornene methoxysilane (diPhNB) copolymer>
HxNB (CAS number: 22094-83-3) (9.63 g, 0.054 mol), diPhNB (CAS number: 376634-34-3) (40.37 g, 0.126 mol), 1- Hexene (4.54 g, 0.054 mol) and toluene (150 g) were mixed in a 500 mL sealam bottle in a dry box, and further stirred while heating to 80 ° C. in an oil bath to obtain a solution. (Pd1446) (1.04 × 10 ⁻² g, 7.20 × 10 ⁻⁶ mol) and N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate (abbreviation: DANFABA) (2 .30 × 10 ⁻² g, 2.88 × 10 ⁻⁵ mol) were added in the form of a concentrated dichloromethane solution (0.1 mL), respectively. The mixture after addition was stirred with a magnetic stirrer at 80 ° C. for 2 hours. Thereafter, the reaction mixture (toluene solution) was transferred to a larger beaker, and methanol (1 L) as a poor solvent was added dropwise thereto to precipitate a fibrous white solid. The precipitated solid was filtered and vacuum dried in an oven at 60 ° C. to obtain a product having a dry mass of 19.0 g (yield 38%). When the molecular weight of the obtained product was measured by gel permeation chromatography (GPC: THF solvent, polystyrene conversion), the mass average molecular weight (Mw) was 118,000, and the number average molecular weight (Mn) was 60,000. there were. The obtained product was measured by 1H-NMR and identified to be a HxNB / diPhNB-based copolymer (x = 0.32, y = 0.68, n = 5) represented by the following structural formula. When the refractive index of this copolymer was measured by the prism coupling method, the TE mode was 1.5695 and the TM mode was 1.5681 at a wavelength of 633 nm.

<Preparation of varnish for optical waveguide formation>
Under yellow light, the HxNB / diPhNB copolymer was dissolved in mesitylene to prepare a 10% by mass copolymer solution (30 g). Separately, in a 100 mL glass bottle, HxNB (42.03 g, 0.24 mol) and bis-norbornenemethoxydimethylsilane (SiX, CAS number: 376609-87-9) (7.97 g, 0.026 The monomer antioxidant solution was obtained by adding two kinds of antioxidants [Irganox 1076 (0.5 g) and Irgafos 168 (0.125 g), manufactured by Ciba)]. To 30.0 g of the above copolymer solution, 3.0 g of the above monomer antioxidant solution and Pd (PCy ₃ ) ₂ (OAc) ₂ (Pd785) (4.95 × 10 ⁻⁴ g per 0.1 mL of methylene chloride) 6.29 × 10 ⁻⁷ mol) and a photoacid generator [RHODORSIL (registered trademark) PHOTOINITIATOR 2074 (CAS number: 178233-72-2)] having an absorption maximum wavelength of 220 nm (per 0.1 mL of methylene chloride, 2.55 × 10 ⁻³ g, 2.51 × 10 ⁻⁶ mol) was added and dissolved uniformly, and then filtered through a filter having a pore diameter of 0.2 μm to prepare a varnish for forming an optical waveguide.

<Production of film for forming optical waveguide>
A film for forming an optical waveguide was produced in the same manner as in the above embodiment. On a 250 μm thick polyethylene terephthalate (PET) film, 10 g of optical waveguide forming varnish is poured and spread with a doctor blade so as to have a substantially constant thickness to form a coating film of the optical waveguide forming varnish. (Thickness before drying 70 μm). The obtained coating film was placed on a hot plate together with the PET film and heated at 50 ° C. for 45 minutes to evaporate toluene, thereby obtaining a dry coating film having a thickness of 50 μm. The obtained dried coating film was irradiated with ultraviolet light having a wavelength of less than 300 nm or 365 nm or less using a high-pressure mercury lamp or metal halide lamp through a photomask having an opening pattern corresponding to the cladding layers 31 and 33 (see FIG. 13). (Irradiation amount 500 mJ / cm ² ). The film after irradiation was placed in an oven, and was first subjected to heat treatment at 50 ° C. for 30 minutes, then at 85 ° C. for 30 minutes, and then at 150 ° C. for 60 minutes. At the time of heating for 10 minutes at the first 50 ° C., the waveguide pattern in the coating film could be visually confirmed. After the heat treatment, the coating film was peeled off from the PET film to obtain a film for forming an optical waveguide (see FIG. 13).

(2) Preparation of clad film material
<Synthesis of Decyl Norbornene (DeNB) / Methyl Glycidyl Ether Norbornene (AGENB) Copolymer>
DeNB (CAS number: 22094-85-5) (16.4 g, 0.07 mol), AGENB (CAS number: 3188-75-8) (5.41 g, 0.03 mol) and toluene ( 58.0 g) was put into a 500 mL sealam bottle in a dry box and mixed, and further stirred while heating to 80 ° C. in an oil bath to obtain a solution. To this solution was added a toluene solution (5 g) of (η ⁶ -toluene) Ni (C ₆ F ₅ ) ₂ (0.69 g, 0.0014 mol). The mixture after addition was stirred with a magnetic stirrer at room temperature for 4 hours. To the mixture was added toluene (87.0 g) and stirred vigorously. Thereafter, the reaction mixture (toluene solution) was transferred to a larger beaker and methanol (1 L), which is a poor solvent, was added dropwise thereto to precipitate a fibrous white solid. The solid content was collected by filtration and vacuum dried in an oven at 60 ° C. to obtain a product having a dry mass of 17.00 g (yield 87%). When the molecular weight of the obtained product was measured by GPC (THF solvent, polystyrene conversion), Mw was 75,000 and Mn was 30,000. The obtained product was measured by 1H-NMR and identified as a DeNB / AGENB-based copolymer (x = 0.77, y = 0.23, n = 10) represented by the following structural formula. When the refractive index of the copolymer was measured by the prism coupling method, the TE mode was 1.5153 and the TM mode was 1.5151 at a wavelength of 633 nm.

<Preparation of varnish for clad layer formation>
Under yellow light, 10 g of the copolymer was dissolved in dehydrated toluene to prepare a 20 mass% copolymer solution (50 g). To this solution, two kinds of antioxidants [Irganox 1076 (0.01 g) and Irgafos 168 (0.0025 g) manufactured by Ciba) and a second photoacid generator having a maximum absorption wavelength of 335 nm (trade name, manufactured by Toyo Ink Manufacturing Co., Ltd.) “TAG-382”) (0.2 g) was added and dissolved uniformly, and then filtered through a filter having a pore diameter of 0.2 μm to prepare a varnish for forming a cladding layer.

<Production of clad film material>
10 g of clad varnish was poured onto a 100 μm-thick PET film placed on a horizontal base, and spread with a doctor blade so as to have a substantially constant thickness to form a clad varnish coating (before drying) Thickness: 30 μm). This coating film was put into a dryer together with a PET film and heated at 50 ° C. for 15 minutes to evaporate toluene to obtain a dried coating film having a thickness of 20 μm. Thereafter, the dried coating film was peeled from the PET film to obtain a clad film material.

(3) Production of optical waveguide The clad film material (size: 20 × 20 cm) is disposed so as to sandwich the optical waveguide-forming film (size: 20 × 20 cm) obtained in (1). A layer laminated film was obtained. The obtained three-layer laminated film was put into a laminator set at 120 ° C. and thermocompression bonded under a pressure of 0.2 MPa for 5 minutes. Thereafter, the three-layer laminated film was returned to room temperature and normal pressure, and a PET film having a thickness of 100 μm was disposed between this and the high-pressure mercury lamp as a wavelength cut filter for shielding a wavelength of 300 nm or less. Next, ultraviolet light was irradiated from a high-pressure mercury lamp through a wavelength cut filter (irradiation amount: 100 mJ / cm ² ). The three-layer laminate after irradiation is immediately put into a dryer without being left (leaving time 0 minutes) and heated at 150 ° C. for 30 minutes to cure the clad film material (cladding layer formation). (1) The adhesion strength enhancement between the film for forming an optical waveguide obtained in the above and the clad film material was completed, and a laminated film having a thickness of 90 μm (corresponding to the width dimension (film thickness) of the optical waveguide: B) was obtained.

(Evaluation)
The obtained three-layer laminated film dicing was provided with a lower cladding layer, a core layer, and an upper cladding layer, and an optical waveguide having a pair of cladding layers on the sides of the core layer. Unlike this embodiment, this optical waveguide has no inclined surface on the end face and no mirror on the end face.
The light generated from the laser diode is input from one end of the core layer through the optical fiber, the output from the other end is measured, and the length of the core layer is cut into several lengths. It measured by the cutback method which measures an output. The total optical loss in each length of the core layer is expressed by the following formula.
Total optical loss (dB) =-10 log (Pn / P0)
Where Pn is the output measured at the other end of each of the core layers of length P1, P2,... Pn, and P0 is the end of the optical fiber prior to coupling the optical fiber to one end of the core layer. It is the measurement output of the light source in.
Next, the total light loss is plotted as in FIG. The regression line of this data is represented by the following equation.
y = mx + n
In the above equation, m represents a light propagation loss, and n represents a coupling loss. The propagation loss of the waveguide of Example 1 was 0.07 dB / cm.

(Processing example)
The laminated film produced in (3) above was attached to a dicing film, and dicing was performed in the same manner as in the above embodiment. Specifically, a dicing saw (DAD321 manufactured by Disco Corporation, blade: NBC-ZH-226J manufactured by Disco Inc .: the cutting edge is a laminated film so as to be 45 degrees with respect to the center line of the core layer 32 indicated by the one-dot chain line in FIG. The laminated film was cut on both sides (straight lines aa ′ and cc ′ in FIG. 13). In FIG. 13, the clad film material is not shown. The above-mentioned dicing saw was used so as to be parallel to the center of the core layer 32, and the clad layer was cut (straight lines ac and bd in FIG. 13) to obtain a strip-shaped optical waveguide 3. In this optical waveguide 3, the waveguide width ab (thickness A) is 180 μm, the thickness hi of one end of the core layer 32 is 100 μm, and the thickness jk of the other end of the core layer 32 is 50 μm. there were.
In addition, the thickness A along the height direction from the lower surface of the lower cladding layer 31 to the upper surface of the upper cladding layer 33 and the optical waveguide orthogonal to the extending direction and orthogonal to the extending direction. The A / B, which is the width dimension and the ratio to the dimension B corresponding to the film thickness of the optical waveguide 3, was 2.
In FIG. 13, the laminated film shows only one core layer and a pair of clad layers arranged so as to sandwich the core layer, but as shown in FIG. 2, a plurality of core layers, The clad layers are alternately arranged. Then, a plurality of optical waveguides 3 are obtained by dicing as in the above embodiment.
(Measurement example)
The light of the laser diode was input through the optical fiber from the lower clad layer 31 side of the obtained optical waveguide 3 with the inclined surface, and reflected by the inclined surface indicated by aa ′. Thereafter, the light propagated through the core layer 32 and was reflected by the inclined surface indicated by cc ′. The intensity of the reflected light was measured with a photodiode on the c′-d plane, and the total light loss represented by the following formula was obtained.
Total optical loss (dB) =-10 log (P1 / P0)
In the above formula, P1 is the output measured at the end of the optical waveguide on the light output side, and P0 is the measurement of the light source at the end of the optical fiber before coupling the optical fiber to the end of the optical waveguide on the light input side. Is the output. The loss at the pair of end faces (inclined surfaces) of the optical waveguide was calculated by subtracting the loss at the straight line portion from the total optical loss obtained. The loss at the pair of end faces (inclined surfaces) of the waveguide film of Example 1 was 2 dB, which was favorable.

(Example 2)
A strip-shaped optical waveguide was obtained in the same manner as in Example 1. However, the waveguide width ab in this optical waveguide was 900 μm, the thickness hi of one end of the core layer 32 was 100 μm, and the thickness jk of the other end of the core layer 32 was 50 μm. The other points are the same as those in the first embodiment.
Further, the thickness A along the height direction from the lower surface of the lower clad layer 31 to the upper surface of the upper clad layer 33 and the optical waveguide 3 orthogonal to the height direction of the optical waveguide 3 and orthogonal to the extending direction. A / B, which is the ratio of the width B to the dimension B corresponding to the film thickness of the optical waveguide 3, was 10.

(Evaluation)
As in Example 1, the light generated from the laser diode is input from one end of the core layer through the optical fiber, the output from the other end is measured, and the length of the core layer is cut into several stages. Then, the propagation loss of the core layer was measured by the cutback method for measuring the optical output for each length. The propagation loss of the optical waveguide film of Example 2 was 0.07 dB / cm.

(Measurement example)
The light of the laser diode was input through the optical fiber from the lower clad layer 31 side of the obtained optical waveguide 3 with the inclined surface, and reflected by the inclined surface indicated by aa ′. Thereafter, the light propagated through the core layer 32 and was reflected by the inclined surface indicated by cc ′. The intensity of the reflected light was measured with a photodiode on the c′-d plane, and the total light loss represented by the following formula was obtained.
Total optical loss (dB) =-10 log (P1 / P0)
In the above formula, P1 is the output measured at the end of the optical waveguide on the light output side, and P0 is the measurement of the light source at the end of the optical fiber before coupling the optical fiber to the end of the optical waveguide on the light input side. Is the output. The loss at the pair of end faces (inclined surfaces) of the optical waveguide was calculated by subtracting the loss at the straight line portion from the total optical loss obtained. The loss at the pair of end faces (inclined surfaces) of the waveguide of Example 1 was 2 dB, which was favorable.
Further, when a light emitting element and a light receiving element are arranged with respect to the optical waveguides of Examples 1 and 2, light propagation loss occurs when light is propagated between the light emitting element and an external element such as the light receiving element. It was found that can be reliably reduced. As a result, it was confirmed that the optical waveguides of Examples 1 and 2 were very excellent.

2 Optical waveguide module 3 Optical waveguide 4 Optical waveguide module 5 Optical waveguide 6 Optical waveguide 20 Varnish 21 Light emitting element 22 Light receiving element 23 Support member 31 Lower clad layer 32 Core layer 33 Upper clad layer 34 Film 43 Support members 51 and 53 Cladding layer 52 Core layer 61 Lower clad layer 62 Core layer 63 Upper clad layer 64 Film 231 Bottom surface portion 232A Slit 232 Side wall portion 311 Flat surface 340A Film 341 Cladding layer 342 Core layer 431 Bottom surface portion 432A Slit 432B Notch 432 Side wall portion 521 First region 522 Second region 523 Third region 621 Part 641 Clad layer 642 Core layer 642A First region 642B Second region D Dicing blade M Mask S Base material

Claims (10)

An upper cladding layer and a lower cladding layer;
In the optical waveguide comprising a core layer sandwiched between the upper clad layer and the lower clad layer, and extending along a predetermined direction,
The optical waveguide includes a photosensitive resin film in which the upper cladding layer, the core layer, and the lower cladding layer are formed,
The upper clad layer, the lower clad layer or the core layer is formed by irradiating light to the photosensitive resin film,
One end surface intersecting with the extending direction of the optical waveguide is an inclined surface inclined from the upper cladding layer side toward the lower cladding layer side,
The thickness at the central portion in the extending direction of the core layer is different from the thickness of one end portion on the inclined surface side among the end portions of the core layer ,
Before SL upper cladding layer and said lower clad layer is the one area one of the non-irradiated regions to the irradiated region and the light is irradiated with light to the film plane of said photosensitive resin film is not irradiated, The core layer is the other region of the irradiated region irradiated with light on the film surface of the photosensitive resin film and the unirradiated region not irradiated with light ,
The side surface of the upper cladding layer along the optical waveguide extending direction, the side surface of the core layer along the optical waveguide extending direction, and the side surface of the lower cladding layer along the optical waveguide extending direction are films of the photosensitive film. An optical waveguide that forms a surface. The optical waveguide according to claim 1,
A pair of end faces intersecting with the extending direction are inclined surfaces inclined from the upper cladding layer side toward the lower cladding layer side,
The thickness of the said core layer is an optical waveguide which becomes thin toward the other edge part side from the said one edge part side of the said core layer. The optical waveguide according to claim 1,
The inclined surface is inclined outward from the upper cladding layer side toward the lower cladding layer side,
The core layer extends along each of the cladding layers, and the one end is bent toward the lower cladding layer and extends through the lower cladding layer. The optical waveguide according to claim 3,
In the region of the core layer that extends in the predetermined direction along the cladding layer, the optical thickness of the core layer increases from the other end side of the core layer toward the one end side. Waveguide. The optical waveguide according to claim 3,
An optical waveguide in which a width of the one end portion of the core layer along the extending direction of each clad layer increases from the upper surface side of the lower clad layer toward the lower surface side. The optical waveguide according to claim 1,
The optical waveguide is a film-shaped optical waveguide. A light emitting element;
A light receiving element;
An optical waveguide connecting the light emitting element and the light receiving element,
An optical waveguide module, wherein the optical waveguide is the optical waveguide according to claim 1. The optical waveguide module according to claim 7, wherein
The optical waveguide is supported by a support member, and one end of the optical waveguide is disposed on the light emitting element, and the other end is disposed on the light receiving element.
An optical waveguide module in which a slit for fitting the optical waveguide is formed in the support member. The optical waveguide module according to claim 8, wherein
The support member has a pair of opposingly arranged wall portions, and a first support member in which the light emitting element is installed between the pair of wall portions;
A second support member having a pair of opposed wall portions, and the light receiving element is installed between the pair of wall portions;
The first support member supports one end of the optical waveguide, and the second support member supports the other end of the optical waveguide,
Of the wall portions of the first support member, one wall portion disposed on the tip end side of the optical waveguide is formed with a contact surface with which the tip end of the optical waveguide abuts, and the other wall. In the part, the slit is formed,
Of the wall portions of the second support member, one wall portion disposed on the distal end side of the end portion of the optical waveguide is formed with an abutting surface on which the end end portion of the optical waveguide abuts, and the other wall An optical waveguide module in which the slit is formed in the part. The optical waveguide module according to claim 9, wherein
The optical waveguide has a flat surface that contacts the contact surface of the first support member or the contact surface of the second support member at the tip of the end where the inclined surface is formed. Optical waveguide module.

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