JP2014191280A - Optical waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide with suppressed optical propagation loss.SOLUTION: An optical waveguide for transmitting light from a light-emitting element is provided. The optical waveguide at least includes a polymer derived from (meth) acrylic ester monomer (A) and a polymer derived from cyclic ether monomer (B), and both the (meth) acrylic ester monomer (A) and the cyclic ether monomer (B) have a mesogen skeleton or a mesogen-analogous skeleton.

Description

The present invention relates to an optical waveguide used for optical signal transmission.

  With the development of communication technology and the progress of cloud computing, the demand for optical signal transmission between electronic devices is increasing. Short-distance optical signal transmission technology of several meters or less, and even tens of centimeters or less is called optical interconnection, and is film-like from the viewpoint of improving mounting density and compatibility with conventional electrical wiring manufacturing processes. Application of the polymer optical waveguide (optical waveguide film) is mainly studied.

  A self-forming optical waveguide described below has been proposed as a technique for easily performing optical axis alignment, which is one of the problems in optical interconnection. That is, a photosensitive resin having a predetermined composition is filled between opposing optical fibers or between an optical fiber and an optical waveguide film, or between an optical fiber / optical waveguide film and a light receiving and emitting element, and one optical fiber, The light having the (first) photosensitive wavelength of the photosensitive resin is made incident from the optical waveguide film or the light emitting element. Alternatively, light of the same wavelength is also incident simultaneously from the other optical fiber or optical waveguide film. Then, the polymerization reaction of the monomer contained in the photosensitive resin occurs, and accordingly, the refractive index of the polymerized part becomes higher than that of the peripheral part. Light confinement occurs due to a difference in refractive index between the overlapped portion and the peripheral portion, and an optical waveguide core is formed. The above reaction continuously occurs along the light traveling direction, so that an optical waveguide core is finally formed over the entire optical path.

When light is incident simultaneously from both one optical fiber / optical waveguide film and the other optical fiber / optical waveguide film or light emitting element, the optical waveguide core grows from both sides of the photosensitive resin. At this time, even if there is a slight deviation between both optical axes, the cores are coupled with a low loss based on the optical waveguide core forming mechanism. Therefore, the high-precision alignment that is conventionally required between the light emitting / receiving element and the optical fiber is not necessary.

  At the time when the optical waveguide core is formed, the photosensitive resin in the peripheral portion of the core, that is, the region to be the cladding, is in an unreacted state, that is, in a liquid state or a gel state. Therefore, the final product cannot be made as it is. The following two methods have been proposed for stabilizing the clad after the formation of the optical waveguide core.

  In the first method, the optical waveguide core is formed by a difference in refractive index before and after polymerization of a photosensitive resin (Patent Document 1). In general photosensitive resins, the refractive index increases as the free volume decreases due to polymerization. That is, when the monomer is polymerized, a difference in refractive index occurs between the polymerized part and the unpolymerized part. Therefore, if the refractive index difference before and after the polymerization satisfies a predetermined condition, the optical waveguide core is autonomously formed by the polymerization. Thereafter, the unreacted monomer remaining in the periphery of the core is washed and removed to obtain a self-formed optical waveguide having air as a cladding (paragraph [0056]). Instead of air, an inert gas such as nitrogen or argon may be filled (paragraph [0053]). Furthermore, after washing and removing the unreacted monomer, a second photosensitive resin having a refractive index lower than that of the optical waveguide core can be filled, and the whole can be irradiated with light and cured (paragraph [0056]. ).

The second method uses a mixture of two kinds of polymerizable monomers having different polymerization mechanisms and refractive indexes (Patent Documents 1 and 2). That is, the photosensitive resin has a relatively high refractive index and a monomer M ₁ that is polymerized by irradiation with light having a predetermined wavelength λ ₁ , and a refractive index that is relatively low and different from the λ _1. A mixture with a monomer M ₂ that is polymerized by irradiation with light of wavelength λ ₂ is used. There is a relationship of λ ₁ > λ ₂ between the wavelengths λ ₁ and λ ₂ , and since the polymerization mechanisms of the two are different from each other, they are not copolymerized. At this time, when light having a wavelength λ ₁ is emitted from the tip of the optical fiber or the optical waveguide film inserted in the photosensitive resin, the monomer M ₁ is selectively polymerized and the refractive index is increased. Further, as the monomer M ₁ is polymerized, the unreacted monomer M ₁ is consumed at the location, so that a concentration gradient of the unreacted monomer M ₁ occurs with the peripheral portion. In order to compensate for the concentration gradient, the unreacted monomer M ₁ diffuses from the peripheral part to the light irradiation part, and the polymerization of the monomer M ₁ further proceeds. As a result, the refractive index of the light irradiation part further increases. That is, in this method, in addition to the refractive index increases due to polymerization of the monomers M _1, the refractive index increases due to the uneven distribution of the light irradiation portion of the monomer M ₁ is the core is formed by both occur. At that time, the monomer M ₂ having a relatively low refractive index diffuses in a direction opposite to that of the monomer M _{1 in} a complementary manner, and is unevenly distributed in a region other than the light irradiation portion.

Subsequently, by irradiating light of wavelength lambda ₂ throughout the photosensitive resin is cured core periphery. Polymerization of the monomer M ₂ proceeds by irradiation with light having a wavelength λ ₂ . On the other hand, since not all the monomers M ₁ are localized in the core, unreacted monomers M ₁ remain in the periphery of the core before irradiation with light of wavelength λ ₂ . In general, the monomers M ₁ to be polymerized by the wavelength lambda _1, since also polymerized by the irradiation of short-wavelength light than the radiation of the wavelength lambda ₁ of the light, to the irradiation of the subsequent wavelength lambda ₂ of the light it, the photosensitive The entire conductive resin is cured. As a result, the core and the clad of the self-formed optical waveguide are formed without removing or replacing the uncured resin around the core.

Japanese Patent Publication No. 2000-347043 Japanese Patent Publication No. 2004-149579

The second method has been proposed in order to improve the problem in the first method, and has an advantage that there is no need to clean and replace the clad in the first method. However, a new problem has arisen due to the difficulty of forming the core and cladding in a single photosensitive resin.

That is, even if the monomer M ₁ and the monomer M ₂ are selected so that they have the desired refractive index difference, good propagation loss cannot always be obtained. When the compatibility between the monomer M ₁ and the monomer M ₂ or their polymer is low, the domain size in the microphase separation during polymerization becomes large, which causes light scattering. On the other hand, if both the compatibility is too high, the diffusion from the cladding of the monomers M ₁ to the core is not occur sufficiently, it is impossible to obtain a high relative refractive index difference.

  A first object of the present invention is to provide an optical waveguide with low light propagation loss. Furthermore, the second object of the present invention is to provide an optical waveguide in which the light propagation loss is suppressed to a lower level than before even by a special technique such as a self-forming optical waveguide. The overall performance of the optical circuit including the light receiving / emitting element is not only the light propagation loss inherent to the optical waveguide, but also the total loss including the coupling loss between the optical element and the optical waveguide, and the radiation loss at the optical path conversion unit. Determined by optical insertion loss, defined as the sum of factors.

  The present inventors diligently studied that the core and the clad of the optical waveguide are made of a three-dimensional cross-linked polymer, and that the polymer is derived from a specific (meth) acrylate monomer and a cyclic ether monomer, It has been found that the light propagation loss can be remarkably suppressed.

The present invention includes the following inventions.
(1) An optical waveguide for transmitting light from a light-emitting element, wherein the optical waveguide is composed of a polymer derived from a (meth) acrylate monomer (A ₁ ) and a cyclic ether monomer (B ₁ ). And the (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) both have a mesogenic skeleton or a mesogenic analog skeleton. Optical waveguide.

(2) The optical waveguide according to (1), wherein the optical waveguide further includes a portion derived from a cyclic ether monomer (B ₂ ) having no aromatic ring.

(3) Both the (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) have the same mesogenic skeleton or mesogenic analog skeleton. ) Or the optical waveguide according to (2).

(4) The optical waveguide according to any one of (1) to (3) above, wherein a concentration of the mesogen skeleton or mesogen-related skeleton is higher in the core than in the cladding.

(5) The (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) have a structural unit represented by the following general formula (I), The optical waveguide according to any one of (1) to (4) above.

（上記（I）式において、Ｒ^１、Ｒ^２、Ｒ^３およびＲ^４は任意の有機基であり、ｊおよびｋは０〜４の整数である。Ｒ^３またはＲ^４が複数存在する場合、それらが互いに異なっていてもよい。また、Ｒ^１〜Ｒ^４のうちの少なくとも１つは、末端に（メタ）アクリロイル基または環状エーテル基を有する。）

(In the above formula (I), R ¹ , R ² , R ³ and R ⁴ are arbitrary organic groups, and j and k are integers of 0 to ^{4. When} there are a plurality of R ³ or R ⁴ , They may be different from each other, and at least one of R ^{1 to} R ⁴ has a (meth) acryloyl group or a cyclic ether group at the terminal.

  In the optical waveguide of the present invention, a (meth) acrylic acid ester monomer having a mesogen skeleton or a mesogen-like skeleton and a cyclic ether monomer cooperatively form a high refractive index core. Since the core is formed from the (meth) acrylic acid ester monomer having a high polymerization rate and the cyclic ether monomer having a low polymerization rate, the phase separation at the core / cladding interface due to the rapid polymerization reaction is alleviated, and the optical waveguide Internal light scattering can be kept low. Moreover, it is easy to increase the relative refractive index difference between the core and the clad. As a result, it is possible to obtain an optical waveguide in which the light propagation loss is significantly suppressed as compared with the conventional case. The optical waveguide of the present invention can achieve particularly desirable effects when it is a self-forming optical waveguide.

It is a figure which shows the outline of the optical waveguide evaluation optical system used in the Example.

The optical waveguide of the present invention is a cured resin product containing at least a polymer derived from a (meth) acrylic acid ester monomer (A ₁ ) and a polymer derived from a cyclic ether monomer (B ₁ ). Furthermore, both the (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) have a mesogenic skeleton or a mesogenic analog skeleton.

  In the present specification, the (meth) acrylic acid ester monomer is a generic term for an acrylic acid ester monomer and a methacrylic acid ester monomer. In this specification, the cyclic ether monomer refers to a compound having a cationic polymerizable cyclic ether moiety. Specific examples include compounds having an oxirane moiety such as a glycidyl group and a 3,4-epoxycyclohexyl group, and an oxetanyl group (oxetane-3-yl group). In the present specification, the above cyclic ether moieties may be collectively referred to as a cyclic ether group. The cured resin may have a part derived from a monomer containing both a (meth) acrylic acid ester group and a cyclic ether group.

The mesogenic skeleton refers to a portion having anisotropy that contributes to the formation of an intermediate phase, particularly a liquid crystal phase, based on the definition of IUPAC. In general, it is understood as an organic group having a rigid structure such as an aromatic ring capable of exhibiting liquid crystallinity, and typical mesogenic skeletons include, for example, JP-T-1996-503728, JP-A-1999-323162, It is disclosed in Japanese Patent Application Laid-Open Nos. 2004-331811 and 2009-242572. On the other hand, in the present invention, the mesogen-related skeleton refers to a structure that does not exhibit liquid crystallinity but has molecular orientation similar to the mesogen skeleton. Specifically, among the conventionally known mesogen skeletons, those having an aromatic ring are different from each other only in the position or type of the substituent on the aromatic ring. That is, a structure in which the ring structure of the aromatic ring itself is different from that of the mesogen skeleton or a structure having no bond structure between the aromatic rings that characterizes the mesogen skeleton is not regarded as a mesogen-related skeleton. For example, those that do not contain a single bond between aromatic rings in a biphenyl skeleton or an ester bond in a phenyl benzoate skeleton are not classified as mesogen-related skeletons. In the present invention, the obtained polymer may not exhibit liquid crystallinity at room temperature or in a molten state.

  In the present invention, the mesogenic skeleton and mesogenic analog skeleton preferably have a structure represented by the following general formulas (I) to (III).

（上記（Ｉ）式において、Ｒ^１、Ｒ^２、Ｒ^３およびＲ^４は任意の有機基であり、ｊおよびｋは０〜４の整数である。Ｒ^３またはＲ^４が複数存在する場合、それらが互いに異なっていてもよい。また、Ｒ^１〜Ｒ^４のうちの少なくとも１つは、末端に（メタ）アクリロイル基または環状エーテル基を有する。）

(In the above formula (I), R ¹ , R ² , R ³ and R ⁴ are arbitrary organic groups, and j and k are integers of 0 to ^{4. When} there are a plurality of R ³ or R ⁴ , They may be different from each other, and at least one of R ^{1 to} R ⁴ has a (meth) acryloyl group or a cyclic ether group at the terminal.

（上記（II）式において、Ｘは単結合、−Ｃ＝Ｃ−基または−ＣＯＯ−基を示す。また、Ｒ^５およびＲ^６は互いに連結していてもよい任意の有機基であり、ｍおよびｎは０〜５の整数である。Ｒ^５またはＲ^６が複数存在する場合、それらが互いに異なっていてもよい。また、Ｒ^５またはＲ^６のうちの少なくとも１つは、末端に（メタ）アクリロイル基または環状エーテル基を有する。）

(In the above formula (II), X represents a single bond, —C═C— group or —COO— group. R ⁵ and R ⁶ are any organic groups which may be linked to each other, m And n is an integer of 0 to ^{5. When a} plurality of R ⁵ or R ⁶ are present, they may be different from each other, and at least one of R ⁵ or R ⁶ is terminal (meta ) It has an acryloyl group or a cyclic ether group.

（上記（III）式において、Ｒ^７およびＲ^８は任意の有機基であり、ｐおよびｑは０〜４の整数である。Ｒ^７またはＲ^８が複数存在する場合、それらが互いに異なっていてもよい。また、Ｒ^７またはＲ^８のうちの少なくとも１つは、末端に（メタ）アクリロイル基または環状エーテル基を有する。）

(In the formula (III), R ⁷ and R ⁸ are arbitrary organic groups, and p and q are integers of 0 to 4. When a plurality of R ⁷ or R ⁸ are present, they are different from each other. Also, at least one of R ^{7 and} R ⁸ has a (meth) acryloyl group or a cyclic ether group at the terminal.

  The mesogen skeleton or mesogen-related skeleton preferably has a fluorene skeleton represented by the above general formula (I).

In the present invention, the (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) preferably have the same mesogenic skeleton or mesogenic analog skeleton. Since these monomers have the mesogen skeleton or the mesogen analog skeleton, they have a higher refractive index than other components in the photosensitive resin composition, and mainly contribute to the formation of the optical waveguide core.

The optical waveguide of the present invention can be produced, for example, by the following method. That is, an optical fiber or an optical waveguide film is contacted or inserted into a photosensitive resin composition containing at least a (meth) acrylic acid ester monomer (A ₁ ) and a cyclic ether monomer (B ₁ ), and a predetermined wavelength λ ₁ Of light. At this time, in order to advance radical polymerization of the (meth) acrylic acid ester monomer (A ₁ ), the photosensitive resin composition contains a photo radical generator that generates radical species by light having a wavelength λ ₁ . There is a need. Further, it preferably contains a photoacid generator that generates a cation species (Lewis acid or Bronsted acid) by light having a wavelength λ ₂ shorter than the wavelength λ ₁ . However, instead of the photoacid generator or in combination with the photoacid generator, a heat latent acid generator that generates the cationic species by heating may be used.

When light having the wavelength of λ ₁ is incident on the photosensitive resin composition, the photo radical generator is cleaved in the light irradiation region, and radical species are generated. Using the radical species as a trigger, the (meth) acrylic acid ester monomer (A ₁ ) is polymerized in the light irradiation region. As a result, the refractive index of the region increases and an optical waveguide core is formed. As the polymerization proceeds, the concentration of the unreacted (meth) acrylate monomer (A ₁ ) decreases in the region. In order to compensate for the generated concentration gradient, the (meth) acrylic acid ester monomer (A ₁ ) in the peripheral region diffuses and moves to the light irradiation region, and polymerization further proceeds. Along with this, the refractive index of the core further increases.

At this time, since the cyclic ether monomer (B ₁ ) does not have radical polymerization activity, it does not participate in the polymerization reaction. However, since the cyclic ether monomer (B ₁ ) has a mesogenic skeleton or a mesogenic analog skeleton in the molecule, like the (meth) acrylic acid ester monomer (A ₁ ), both have high affinity. . Therefore, the diffusion of the cyclic ether monomer (B ₁ ) is also promoted following the diffusion movement of the (meth) acrylic acid ester monomer (A ₁ ). That is, the cyclic ether monomer (B ₁ ) is also localized in the optical waveguide core region where the (meth) acrylic acid ester monomer (A ₁ ) and the polymerization product thereof are unevenly distributed. When the cyclic ether monomer (B ₁ ) having a mesogen skeleton or a mesogen analog skeleton in the molecule is localized in the core, the refractive index of the core is further increased.

Thereafter, the cyclic ether monomer is cationically polymerized by irradiating the entire photosensitive resin composition with light having the wavelength λ ₂ or heating the entire photosensitive resin composition. As a result, not only the core but also the unreacted cyclic ether monomer present in the cladding around the core is polymerized, and the entire resin is stabilized as a three-dimensional crosslinked cured product.

The photosensitive resin composition further includes a cyclic ether monomer (B ₂ ) having no aromatic ring in the molecule in addition to the cyclic ether monomer (B ₁ ) having a mesogen skeleton or a mesogen analog skeleton in the molecule. It is preferable that Since the cyclic ether monomer (B ₂ ) does not have an aromatic ring in the molecule, it has poor affinity with any of the (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ). . For this reason, as the (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) diffuse to the optical waveguide core, they are diffused and localized in the core peripheral region in a complementary manner. Contributes to the formation of cladding. That is, although the cyclic ether monomer (B ₁ ) and the cyclic ether monomer (B ₂ ) are both cationically polymerizable monomers, they diffuse in opposite directions. Further, the cyclic ether monomer (B _2), since in the molecule does not have an aromatic ring, a refractive index of the (meth) acrylic acid ester monomer (A ₁₎ and the cyclic ether monomer (B ₁₎ The refractive index is relatively lower than the refractive index, and contributes to an increase in the relative refractive index difference between the core and the clad formed.

As described above, the polymerization of the (meth) acrylate monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) that are unevenly distributed in the optical waveguide core proceeds in two stages. That is, the (meth) acrylic acid ester monomer (A ₁ ) undergoes radical polymerization by the incidence of light of wavelength λ ₁ from the optical fiber / optical waveguide film. Next, the cyclic ether monomer (B ₁ ) undergoes cationic polymerization by irradiation or heating of the light having the wavelength λ ₂ to the entire photosensitive resin. In general, it is known that cationic polymerization has a slower reaction rate than radical polymerization. In the above, since the cationic polymerization with a slow reaction rate is involved in the formation of the core, the phase separation accompanying the rapid curing of the core region and the generation of the light scattering factor due thereto can be suppressed. Therefore, an optical waveguide with little loss can be obtained. Furthermore, since the monomer (A ₁ ) and the monomer (B ₁ ), both of which have a high refractive index, contribute to the formation of the core cooperatively, the relative refractive index difference between the core and the cladding is increased. be able to.

By forming a self-forming optical waveguide using the photosensitive resin composition, a core and a clad are autonomously formed inside the resin. As a result, the concentration of the site derived from the (meth) acrylic acid ester monomer (A ₁ ) and the concentration of the site derived from the cyclic ether monomer (B ₁ ) are both higher than the cladding in the core. A cured resin is obtained.

That is, the concentration of the mesogen skeleton or mesogen analog skeleton in the cured product is higher in the core than in the clad. At this time, the degree of change of the density and the manner of change can be variously changed according to conditions. That is, it depends on the type and ratio of the monomer used, and the light irradiation conditions. By utilizing this fact, a step index type optical waveguide in which the concentration of the portion changes stepwise at the interface between the core and the cladding may be formed, or the concentration gradually decreases from the core toward the cladding. A graded index type optical waveguide may be formed. In the present invention, as long as the average value of the sum of the concentrations of the mesogen skeleton and the mesogen-related skeleton in the core is substantially higher than the average value in the clad, the manner of changing them is not particularly limited.

As the (meth) acrylic acid ester monomer (A ₁ ), various compounds including commercially available products can be used. Specifically, o-phenylphenol (meth) acrylate, 2,3′-dihydroxybiphenyl di (meth) acrylate, 1-hydroxynaphthalene (meth) acrylate, 2,3-hydroxynaphthalene di (meth) acrylate, 9, 9-bis (4-hydroxyphenyl) fluorene di (meth) acrylate, epoxy acrylate of 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxystilbene, 4-hydroxybenzoic acid-4′-hydroxy Examples include, but are not limited to, phenyl epoxy acrylates, and ethylene oxide (EO) -modified, propylene oxide (PO) -modified, or epichlorohydrin (ECH) -modified compounds.

In addition to the (meth) acrylic acid ester monomer (A ₁ ) having a mesogenic skeleton or a mesogenic analog skeleton in the molecule, a (meth) acrylic acid ester monomer having a single aromatic ring or no aromatic ring (A ₂ ) may be used in combination. Specific examples of such compounds include benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and tribromophenyl. Examples include (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and the like, but are not limited thereto.

On the other hand, as the cyclic ether monomer (B ₁ ), specifically, o-phenylphenol glycidyl ether, 4,4′-bis (glycidyloxy) -1,1′-biphenyl, 2,2′-bis (glycidyl) Oxy) -1,1′-biphenyl, bis (glycidyloxy) naphthalene, 9,9-bis [4- (glycidyloxy) phenyl] fluorene, 4,4′-bis [(3,4-epoxycyclohexyl) methoxymethyl ] -1,1′-biphenyl, 4,4′-bis [3- (ethyloxetane-3-yl) methoxy] -1,1′-biphenyl, 2,2′-bis [3- (ethyloxetane-3) -Yl) methoxy] -1,1'-biphenyl, bis [3- (ethyloxetane-3-yl) methoxy] naphthalene and their EO, PO or ECH modifications A compound etc. are mentioned, However, It is not limited to these. Further, among the epoxy monomer having a mesogen skeleton disclosed in JP2009-242572A and the aromatic skeleton-containing alicyclic epoxy compound disclosed in JP2009-179568A, a mesogen skeleton or An alicyclic epoxy monomer having a mesogen-like skeleton can also be suitably used.

Further, as the cyclic ether monomer (B ₂ ), specifically, 2-ethylhexyl glycidyl ether, glycerol diglycidyl ether, diethylene glycol diglycidyl ether, 1,2-cyclohexanecarboxylic acid diglycidyl, 1,4-cyclohexanedimethanol di Glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, poly (ethylene glycol) diglycidyl ether, 1,3-bis (3-glycidoxy Propyl) -1,1,3,3-tetramethyldisiloxane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexyl) ) Adipate, bis [2- (3,4-epoxycyclohexyl) ethyl] tetramethyldisiloxane, 3-ethyl-3-hydroxymethyloxetane, 2-ethylhexyloxetane, ethylene glycol bis (3-ethyl-3-oxetanylmethyl) Examples thereof include, but are not limited to, ether, diethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, poly (ethylene glycol) bis (3-ethyl-3-oxetanylmethyl) ether, and the like.

On the other hand, as the photo radical generator, a known one can be used. Specific examples include carbonyl compounds such as benzoin ethyl ether, benzophenone and diethoxyacetophenone; acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide. Alkylaryl borates such as tetrabutylammonium triphenylbutylborate and tetrabutylammonium trinaphthylbutylborate; diaryliodonium salts such as diphenyliodonium hexafluorophosphate; triazine compounds such as tris (trichloromethyl) triazine; 3,3 ′ -Di (tert-butylperoxycarbonyl) -4,4'-di (methoxycarbonyl) benzophenone, tert-butylperoxycarbonyl Organic peroxides such as benzoate; bisimidazole derivatives such as 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,1′-bisimidazole; . The photo radical generator is preferably added in an amount of 0.05 to 10% by mass, more preferably 0.1 to 5.0% by mass, based on the photosensitive resin composition.

Examples of the photoacid generator include diaryl iodonium salts such as diphenyliodonium hexafluorophosphate, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroantimonate, and diphenyliodonium tetrakis (pentafluorophenyl) borate; triphenylsulfonium hexa Triarylsulfonium salts such as fluorophosphate, triphenylsulfonium hexafluoroantimonate, (4-phenylthiophenyl) diphenylsulfonium hexafluorophosphate; sulfonic acid ester, imidosulfonate, dialkyl-4-hydroxysulfonium salt, arylsulfone Acid-p-nitrobenzyl ester, silanol-aluminum Umm complexes, and the like. The photoacid generator is preferably added in an amount of 0.05 to 10% by mass, more preferably 0.1 to 5.0% by mass, based on the photosensitive resin composition.

Thermal latent acid generators that can be used in place of or together with the photoacid generator include, for example, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, (4-phenylthiophenyl) diphenylsulfonium Triarylsulfonium salts such as hexafluorophosphate; trialkylsulfonium such as 1- (2-butenyl) tetrahydrothiophenium hexafluoroantimonate, 1- (3-methyl-2-butenyl) tetrahydrothiophenium hexafluoroantimonate Examples include salts. Of these, triarylsulfonium salts also function as a photoacid generator. The thermal latent acid generator is preferably added in an amount of 0.05 to 10% by mass, more preferably 0.1 to 5.0% by mass, based on the photosensitive resin composition.

Wherein the, mesogenic skeleton or mesogenic analogue backbone (meth) acrylic acid ester monomer (A _1), or having one aromatic ring, having no aromatic ring (meth) acrylic acid ester monomer (A _2), and The preferred blending mass of the cyclic ether monomer (B ₁ ) having a mesogenic skeleton or a mesogen-related skeleton and the cyclic ether monomer (B ₂ ) having no aromatic ring varies depending on the combination of the monomer used and the photoradical / acid generator, Generally, the following should be done. That is,
(Meth) acrylic acid ester monomer (A ₁ ) 10-50 parts by mass,
(Meth) acrylic acid ester monomer (A ₂ ) 0 to 20 parts by mass,
10-50 parts by mass of cyclic ether monomer (B ₁ ),
10-80 parts by mass of cyclic ether monomer (B ₂ ),
Preferably,
(Meth) acrylic acid ester monomer (A ₁ ) 20 to 40 parts by mass,
(Meth) acrylic acid ester monomer (A ₂ ) 0 to 10 parts by mass,
20-40 parts by mass of cyclic ether monomer (B ₁ ),
20-60 parts by mass of cyclic ether monomer (B ₂ ),
More preferably. The monomers (A ₁ ), (A ₂ ), (B ₁ ) and (B ₂ ) may be a mixture of a plurality of compounds.

  In addition to the above components, a non-reactive low molecular weight compound may be used in combination as a plasticizer, and a thermoplastic polymer or the like may be included as a binder.

  As an optical fiber / optical waveguide film for entering light for self-forming an optical waveguide core into the photosensitive resin composition, a step index type optical fiber in which the refractive index between the core and the clad changes stepwise An optical waveguide film may be used, or a graded index optical fiber / optical waveguide film in which the refractive index continuously changes may be used.

  Further, either single mode or multimode optical fiber / optical waveguide film may be used. The core diameter or mode field diameter in the single mode optical fiber / optical waveguide film is about 10 μm or less, and the core diameter or mode field diameter in the multimode optical fiber / optical waveguide film is about several tens to several hundreds μm. The core diameter or mode field diameter of the optical waveguide formed in the photosensitive resin composition by the optical fiber / optical waveguide film is substantially the same as or slightly larger than that of the optical fiber / optical waveguide film.

The light source for self-forming the optical waveguide core is not particularly limited as long as it can generate light having a wavelength λ ₁ that can excite the photo radical generator. For example, a high-pressure mercury lamp, a metal halide lamp, a light emitting diode (LED), a semiconductor laser, a solid laser, or the like can be used. Furthermore, a light-emitting element such as a surface-emitting semiconductor laser (VCSEL: Vertical Cavity Surface Emitting Laser) mounted on a wiring board or a device in which the optical waveguide of the present invention is incorporated is used as a light source for directly forming a self-forming optical waveguide. May be.

On the other hand, as a light source for curing the surrounding clad after the optical waveguide core is formed in the photosensitive resin, any light source having a wavelength λ ₂ that can excite the photoacid generator can be used. There is no particular limitation. Specifically, various light sources similar to the above can be used. What is necessary is just to irradiate so that the light from arbitrary light sources may reach | attain the said whole clad. In addition, when using a thermal latent acid generator instead of the photoacid generator, or when using the photoacid generator and the thermal latent acid generator in combination, the photosensitive resin is prepared using a known heat source. What is necessary is just to heat and harden.

  The optical waveguide produced as described above has a mode in which the concentration of the mesogen skeleton or mesogen analog skeleton is higher in the core than in the clad. The fact that the mesogen skeleton or mesogen-related skeleton is actually unevenly distributed in the core can be confirmed, for example, by the following method.

First, a region (P _core ) containing a relatively large amount of _core and a region (P _clad ) containing a relatively large amount of cladding are sampled from the cured resin product on which the optical waveguide is formed. The position and shape of the core in the optical waveguide can be confirmed by making light incident from one end face and observing the near-field pattern of the emitted light from the other end as in the conventional optical waveguide film.

In addition, when the clad surrounding the core can be observed from the outside with an optical microscope or the like, the range and shape of the internal core may be directly confirmed through the transparent clad. If the position and range of the core can be specified, the P _core and P _clad are _separated from the optical waveguide accordingly. For example, it can be individually sampled by excimer laser processing or mechanical drilling.

  Examples of a method for analyzing the collected sample include a method for identifying and quantifying unreacted monomers remaining in the sample. Generally, a small amount of unreacted monomer remains in the cured resin obtained by photopolymerization or thermal polymerization. This is because the diffusion of the monomer is limited by the increase in the crosslinking density accompanying the progress of the polymerization reaction, and as a result, the isolated monomer cannot participate in the polymerization reaction. Generally, several percent to 20% of the raw material monomer remains in the resin cured product without being polymerized.

The unreacted monomer can be identified and quantified by, for example, GC-MS (gas chromatograph mass spectrometry) after solvent extraction of the unreacted monomer from the resin cured product. The concentration of unreacted monomer identified and quantified by the above method relatively reflects the amount of polymerization sites derived from the corresponding monomer. That is, if the concentration of the unreacted monomer (A ₁ ) or monomer (B ₁ ) having a mesogen skeleton or a mesogen-related skeleton is higher in the P _core than the P _clad , the monomer is polymerized and incorporated into the polymer chain It can be judged that the concentration of the mesogenic skeleton or the mesogen-related skeleton in the _core is higher in P _core than in P _clad .

On the other hand, the mesogenic skeleton or mesogenic analog skeleton contained in the samples P _core and P _clad may be directly identified and quantified by reactive pyrolysis GC-MS. For example, the mesogenic skeleton or mesogenic analog skeleton contained in the P _core or P _clad is cleaved from the polymer chain by a reaction thermal decomposition method using an organic alkali reagent such as tetramethylammonium hydroxide or a supercritical methanol decomposition method. In addition, a method for identification and quantification by GC-MS or the like can be used.

  In the above description, the optical waveguide of the present invention has been described only when it is manufactured by a self-forming method. However, the optical waveguide of the present invention is not limited to the case where it is a self-forming optical waveguide. For example, even when the optical waveguide is manufactured by a so-called soft lithography method, the light propagation loss can be reduced by the present invention.

The optical waveguide by the soft lithography method can be produced by a method disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-58530. In that case, a photo / thermosetting resin composition mainly containing a (meth) acrylic acid ester monomer (A ₁ ) and a cyclic ether monomer (B ₁ ) is used as a core material, and as a cladding material, A photo / thermosetting resin composition containing a cyclic ether monomer (B ₂ ) may be used.

  Japanese Unexamined Patent Application Publication No. 2008-58530 discloses a method comprising the following six steps. First, in the first step, a uniform layer made of the core material is applied to the entire surface of a base material having an underclad layer. Thereafter, in the second step, a mold provided with a concave groove for shaping the core shape is disposed on the surface of the core material layer. The mold is made of a resin-made sheet such as cycloolefin polymer or silicone, and has flexibility. In the third step, the mold is pressed from the end of the substrate with a roller or the like, and laminated on the entire surface of the core material layer while eliminating bubbles. As a result, the concave groove is filled with the core material, and excess core material existing in other regions is eliminated. Next, in a fourth step, the core material is cured while maintaining the concave groove shape of the mold by irradiating light from the upper surface of the laminated mold or the lower surface of the substrate. In the fifth step, when the mold is released from the cured core material layer, a core layer formed with a desired core shape is formed. In the sixth step, the core layer is coated with the clad material (over clad formation), and cured by light or heat to obtain an embedded optical waveguide.

At this time, in order to obtain an optical waveguide in which the light propagation loss is kept low, either of the following two methods may be used. In the first method, the (meth) acrylate monomer (A ₁ ) contained in the core material is polymerized by light having a wavelength λ ₁ , and the cyclic ether monomer (B ₁ ) is converted to a wavelength λ ₂ (λ ₂ A photoradical generator and a photoacid generator each having sensitivity in the wavelength region are added so as to be polymerized by light of <λ ₁ ). Alternatively, the (meth) acrylic acid ester monomer (A ₁ ) contained in the core material is polymerized by light of wavelength λ ₁ and the cyclic ether monomer (B ₁ ) is polymerized by heat. A photo radical generator and a heat latent acid generator having sensitivity are added in advance.

Using such a core material composition, light of wavelength λ ₁ is irradiated in the fourth step. By irradiating the light of the wavelength lambda _1, among the monomers contained in the core material composition, only (meth) acrylic acid ester monomer (A ₁₎ are polymerized. At that time, by optimizing the kind and composition ratio of the (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ), even if the monomer (B ₁ ) is unreacted, the gold It is preferable to use a composition that has good mold releasability and loses fluidity to such an extent that the core shape can be maintained after release. After irradiation of the wavelength lambda ₁ of the light, and releasing the mold, performing the formation of the over cladding is the sixth step. At that time, an appropriate standing time is provided before the clad is cured. At this time, the unreacted cyclic ether monomer (B ₁ ) contained in the core diffuses into the uncured overclad material. Thereafter, if the overcladding material is cured by light or heat, in addition to the cyclic ether monomer (B ₁ ), other components such as the cyclic ether monomer (B ₂ ) in the cladding material are also polymerized and cured. An optical waveguide is obtained. According to the first method, the concentration of the site derived from the (meth) acrylate monomer (A ₁ ) decreases stepwise from the core toward the clad, and the site derived from the cyclic ether monomer (B ₁ ) As a result, an optical waveguide in which the concentration of is gradually decreased from the core toward the clad can be obtained.

In the second method, the (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) contained in the core material are polymerized by light having the same wavelength λ _1. A radical generator and the photoacid generator are selected in advance. Using such a core material composition, light of wavelength λ ₁ is irradiated in the fourth step. By appropriately controlling the irradiation energy of light, a part of the monomer (A ₁ ) and a part of the monomer (B ₁ ) are not sufficiently polymerized, and a so-called semi-cured state can be obtained. .

The mold is released from the semi-cured core material layer thus obtained. Thereafter, in the formation of the over clad as the sixth step, an appropriate standing time is provided before the clad is cured. At this time, the unreacted monomer (A ₁ ) and the monomer (B ₁ ) contained in the core diffuse into the uncured overclad material. Thereafter, if the overclad material is cured by light or heat, in addition to the monomers (A ₁ ) and (B ₁ ), other components such as the cyclic ether monomer (B ₂ ) in the cladding material are also polymerized and cured. The target optical waveguide is obtained. According to the second method, the concentration of the site derived from the (meth) acrylate monomer (A ₁ ) and the concentration of the site derived from the cyclic ether monomer (B ₁ ) are both gradually increased from the core toward the clad. A reduced optical waveguide is obtained.

In both the first method and the second method, at least a part of the cyclic ether monomer (B ₁ ) among the monomers contained in the core material composition is diffused in the cladding material. . Therefore, it is possible to copolymerize with the cyclic ether monomer (B ₂ ) contained in the clad material composition, suppress the generation of light scattering factors at the core / cladding interface, and form a strong three-dimensional crosslinked structure. it can. Moreover, since both the monomer (A ₁ ) and the monomer (B ₁ ) have a mesogenic skeleton or a mesogenic analog skeleton, the electronic and steric affinity between them is high. Therefore, even when the above-described process is adopted, the monomer (A ₁ ) or the monomer (B ₁ ) is not excessively diffused into the cladding region. Therefore, it is possible to obtain an optical waveguide in which the light propagation loss is suppressed to a lower level than in the past.

The optical waveguide thus produced can be used as an optical wiring in a substrate on which various optical elements are mounted, for example. Further, when the optical waveguide is manufactured by a self-forming method, it can be used as an optical via for coupling the optical fiber / optical waveguide film and the light emitting element or the light receiving element with low loss in the optical wiring substrate. . Moreover, you may use in order to couple | bond optical fiber / optical waveguide films.

Furthermore, if a mirror that reflects at least part of the light incident from the light source is arranged in the middle of the optical path of the light source for forming the optical waveguide core, the optical waveguide core that can change the optical path by the mirror portion is autonomously provided. Can be formed. By adopting such a method, it is possible to easily realize an optical multiplexer, an optical demultiplexer, or the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

  The chemical names and structures of the monomers used in the examples are shown below. The monomer (B-1) is 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxy-trans-stilbene as a starting material, and is a reference example (paragraph) of JP2009-242572A. [0068]). The monomer (B-2) uses p-hydroxybenzoic acid and hydroquinone as starting materials, and literature (Cosimo Carfagna et al., Macromol. Chem. Phys., Vol. 201, pp. 2631-2638 (2000)). Was synthesized in accordance with the method disclosed in US Pat.

On the other hand, monomer (A-1) and monomer (A-2) were synthesized from monomer (B-1) and monomer (B-2), respectively, according to the method described in JP2011-213996A. As other monomers, commercially available products were used as they were. The structural formula is omitted for commercial products. In the following, the monomers (A-6), (A-7), (A-8), (B-6), and (B-7) do not have a mesogenic skeleton or a mesogenic analog skeleton. They are classified into (meth) acrylic acid ester monomers (A ₁ ) and cyclic ether monomers (B ₁ ), respectively.

<(Meth) acrylic acid ester monomer (A ₁ )>
Monomer (A-1)
4,4′-bis (3-acryloxy-2-hydroxypropoxy) -3,3 ′, 5,5′-tetramethyl-trans-stilbene

モノマー（Ａ−２）
４−（３−アクリロキシ−２−ヒドロキシプロポキシ）安息香酸−４−（３−アクリロキシ−２−ヒドロキシプロポキシ）フェニル

Monomer (A-2)
4- (3-Acryloxy-2-hydroxypropoxy) benzoic acid-4- (3-acryloxy-2-hydroxypropoxy) phenyl

モノマー（Ａ−３）
２−（２−アクリロキシエチルオキシ）ビフェニル （日本蒸溜工業（株）製、ＨＲＤ−０１）
モノマー（Ａ−４）
９，９−ビス［４−（２−アクリロイルオキシエトキシ）フェニル］フルオレン （新中村化学工業（株）製、ＮＫエステルＡ−ＢＰＥＦ）
モノマー（Ａ−５）
２−（１−ナフトキシ）エチルアクリレート （日本蒸溜工業（株）製、ＨＲＤ−０２）
モノマー（Ａ−６）
ＥＯ変性ビスフェノールＡジアクリレート （日本化薬（株）製、カヤラッドＲ−５５１）
モノマー（Ａ−７）
２−フェノキシエチルアクリレート （東京化成工業（株）製）
モノマー（Ａ−８）
トリシクロデカンジメタノール ジアクリレート （新中村化学工業（株）製、Ａ−ＤＣＰ）

Monomer (A-3)
2- (2-Acryloxyethyloxy) biphenyl (manufactured by Nippon Distillation Co., Ltd., HRD-01)
Monomer (A-4)
9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-BPEF)
Monomer (A-5)
2- (1-Naphoxy) ethyl acrylate (manufactured by Nippon Distillation Co., Ltd., HRD-02)
Monomer (A-6)
EO-modified bisphenol A diacrylate (Nippon Kayaku Co., Ltd., Kayarad R-551)
Monomer (A-7)
2-phenoxyethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.)
Monomer (A-8)
Tricyclodecane dimethanol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-DCP)

<Cyclic ether monomer (B ₁ )>
Monomer (B-1)
4,4′-Diglycidyloxy-3,3 ′, 5,5′-tetramethyl-trans-stilbene

モノマー（Ｂ−２）
４−（グリシジルオキシ）安息香酸−４−（グリシジルオキシ）フェニル

Monomer (B-2)
4- (Glycidyloxy) benzoic acid-4- (glycidyloxy) phenyl

モノマー（Ｂ−３）
ｏ−フェニルフェノールグリシジルエーエル （三光（株）製、ＯＰＰ−Ｇ）
モノマー（Ｂ−４）
ＥＯ変性９，９−ビス［４−（２−グリシジルオキシ）フェニル］フルオレン （大阪ガスケミカル（株）製、オグソールＥＧ−２５０）
モノマー（Ｂ−５）
α−ナフチルグリシジルエーテル （和光純薬工業（株）製）
モノマー（Ｂ−６）
ビスフェノールＡジグリシジルエーテル （シグマ・アルドリッチ社製）
モノマー（Ｂ−７）
フェニルグリシジルエーテル （シグマ・アルドリッチ社製）

Monomer (B-3)
o-Phenylphenol glycidyl AEL (manufactured by Sanko Co., Ltd., OPP-G)
Monomer (B-4)
EO-modified 9,9-bis [4- (2-glycidyloxy) phenyl] fluorene (Ossol EG-250, manufactured by Osaka Gas Chemical Co., Ltd.)
Monomer (B-5)
α-Naphthyl glycidyl ether (Wako Pure Chemical Industries, Ltd.)
Monomer (B-6)
Bisphenol A diglycidyl ether (manufactured by Sigma-Aldrich)
Monomer (B-7)
Phenyl glycidyl ether (manufactured by Sigma-Aldrich)

<Cyclic ether monomers _(B 2)>
Monomer (B-8)
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (manufactured by Sigma-Aldrich)
Monomer (B-9)
Bis (3,4-epoxycyclohexylmethyl) adipate (manufactured by Gabriel Performance Products, Inc., GPE-228)
Monomer (B-10)
1,2-epoxy-4- (2-methyloxiranyl) -1-methylcyclohexane (manufactured by Daicel Corporation, Celoxide 3000)
Monomer (B-11)
3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane (manufactured by Toagosei Co., Ltd., OXT-221)

[Example 1]
(Production of self-forming optical waveguide)
Using the optical system of FIG. 1, a self-forming optical waveguide was formed for the photosensitive resin composition shown in Table 1. Furthermore, the optical insertion loss of the formed optical waveguide was measured simultaneously.

The photosensitive resin composition was prepared by the following procedure. First, as (meth) acrylic acid ester monomer _{(A 1),} monomer (A-1) 2.2 g, a cyclic ether monomers _{(B 1),} the monomer (B-1) 1.8 g, a cyclic ether monomers _{(B 2} ), 4.0 g of monomer (B-8) and 2.0 g of monomer (B-10) are mixed, and as a photo radical generator, 0.1 g of Irgacure 819 (manufactured by BASF Germany), photo acid generator As above, 0.2 g of triarylsulfonium hexafluoroantimonate (manufactured by Sigma-Aldrich) was added to obtain the photosensitive resin composition. The obtained resin composition was dropped so as to completely cover the front ends of the optical fibers (14, 15) and the gaps between them to form an optical waveguide. As the optical fiber, a graded index type multimode quartz fiber (core diameter 50 μm, clad diameter 125 μm) was used. The optical fiber is fitted so as to face the V-groove portion of a glass plate (not shown) having a linear V-groove having a width of about 220 μm and a depth of about 190 μm formed on the surface. The optical axes of the optical fibers were matched.

  In the optical system of FIG. 1, an LED (light emitting diode) having a wavelength of 405 nm is used as a light source (11) for forming a self-forming optical waveguide, and light oscillated from the light source is incident on two optical fibers. It was introduced into a 1 × 2 optical coupler (12, 13) having a branching ratio of 50/50. The light from the LED is transmitted through two optical couplers and then incident on the photosensitive resin composition (1) through the optical fibers (14, 15). The separation distance between the facing optical fibers was 5.0 mm. After forming the optical waveguide core with the light of the LED, the entire photosensitive resin composition was uniformly irradiated with ultraviolet light (not shown) from a high-pressure mercury lamp to completely cure the core and the clad. .

(Measurement of optical insertion loss)
A surface emitting laser (VCSEL) having a wavelength of 850 nm was used as the light source (16) for simultaneously measuring the optical insertion loss of the formed optical waveguide. The light from the VCSEL enters one of the optical couplers (12) and enters the photosensitive resin (1) through the same multimode optical fiber (14) as described above. The incident light from the VCSEL propagates through the formed optical waveguide core and is coupled to the other optical fiber (15) facing each other. The light emitted from the VCSEL coupled to the opposing optical fiber enters the photodetector (17) through the other optical coupler (13). The light insertion loss was calculated by comparing the light intensity measured by the photodetector with the light intensity emitted from the end face of the optical fiber (14). The results are also shown in Table 1.

(Composition analysis of optical waveguide)
The concentration of the mesogen skeleton and / or mesogen analog skeleton in the core and clad of the obtained optical waveguide was identified and quantified by the following procedure.

The resin cured product formed on the glass substrate with the V-groove was polished to the same height as the surface of the glass substrate to remove excess resin cured product. Next, all of the cured resin remaining in the V-groove was scraped out to obtain a cured resin sample (P _core ) including a core and a clad. The cured resin sample (P _core ) includes not only the core but also the clad, but relatively more cores than the cured resin sample (P _clad ) described later.

On the other hand, a cured resin sample (P _clad ) from which the core of the optical waveguide was removed was separately prepared by the following method. That is, after the excess resin cured product was removed by polishing in the same manner as described above, the core of the resin cured product remaining inside the V-groove was selectively removed by cutting. First, as a result of observing the core shape from the upper surface of the V-grooved glass substrate with an optical microscope, the average diameter of the formed core was 65 μm. The cured resin was cut to a thickness of about 100 μm, and the resin containing the core was removed. Thereafter, the cured resin remaining in the V-groove substrate was scraped off to obtain a cured resin sample (P _clad ) consisting of only the _clad .

The samples (P _core ) and (P _clad ) prepared in this way were each analyzed by a reactive pyrolysis GC-MS method. 30 μg of each sample was weighed, and about 2 μL of a 25% methanol solution of tetramethylammonium hydroxide was added as an organic alkali reagent. The measurement sample thus obtained was analyzed by reactive pyrolysis GC-MS. The temperature in the pyrolysis furnace was 400 ° C. A predetermined amount of methyl stearate was added to the measurement sample as an internal standard.

  In the obtained pyrogram, by comparing the peak area derived from the internal standard substance and the peak area of the degradation product derived from the mesogen skeleton or mesogen-related skeleton, a degradable organism derived from the mesogen skeleton or mesogen-related skeleton Concentration (per unit mass of analysis sample) was calculated. The results are shown in Table 1.

[Examples 2 to 12, Comparative Examples 1 to 6]
A photosensitive resin composition was prepared in the same manner as in Example 1 except that the compositions shown in Tables 1 and 2 were used as the photosensitive resin composition, and the optical insertion loss was measured. The results are also shown in Table 1 and Table 2.

In the optical waveguides of Examples 1 to 12, as a constituent component of the photosensitive resin, a (meth) acrylic acid ester monomer (A ₁ ) having a mesogen skeleton or a mesogen-related skeleton and a cyclic ether monomer (B ₁ ) are used in combination. Yes. Therefore, it is considered that phase separation does not occur even after polymerization and curing by light irradiation, and sufficient localization of the monomer (A ₁ ) and the monomer (B ₁ ) to the core occurs. As a result, a good optical insertion loss was obtained.

On the other hand, in Comparative Examples 1 to 6, since both or one of the (meth) acrylic acid ester monomer and the cyclic ether monomer does not have a mesogen skeleton or a mesogen-related skeleton, a sufficient monomer at the time of light incidence from the quartz fiber Therefore, the relative refractive index difference between the core and the clad cannot be increased. Or even if the localization of a monomer arises, since it originates only in the (meth) acrylic acid ester monomer, the light scattering accompanying microphase separation tends to occur. Therefore, it is considered that the optical insertion loss has deteriorated.

These optical insertion loss values are the total of the loss components inherent to the optical waveguide evaluation optical system, such as the optical propagation loss inherent to the optical waveguide, as well as the optical coupling loss at the interface between the optical fiber and the self-forming optical waveguide. It is. Since the loss component inherent to the optical system is substantially the same in each example and comparative example, the magnitude of the value of the optical insertion loss shown in Table 1 and Table 2 is the material composition of each example and comparative example. Reflects the inherent light propagation loss.

(1) Photosensitive resin (11) LED
(12), (13) Optical coupler (14), (15) Multimode optical fiber (16) 850 nm surface emitting laser (17) Photo detector

Claims (5)

An optical waveguide for transmitting light from a light-emitting element, the optical waveguide comprising a polymer derived from a (meth) acrylate monomer (A ₁ ) and a polymerization derived from a cyclic ether monomer (B ₁ ) And the (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) both have a mesogenic skeleton or a mesogenic analog skeleton. . The optical waveguide according to claim 1, wherein the optical waveguide further includes a portion derived from a cyclic ether monomer (B ₂ ) having no aromatic ring. The (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) both have the same mesogenic skeleton or mesogenic analog skeleton. The optical waveguide described.   The optical waveguide according to claim 1, wherein a concentration of the mesogen skeleton or a mesogen-related skeleton is higher in the core than in the clad. The (meth) acrylic acid ester monomer (A ₁ ) and the cyclic ether monomer (B ₁ ) have a structural unit represented by the following general formula (I), The optical waveguide in any one of -4.

(In the above formula (I), R ¹ , R ² , R ³ and R ⁴ are arbitrary organic groups, and j and k are integers of 0 to ^{4. When} there are a plurality of R ³ or R ⁴ , They may be different from each other, and at least one of R ^{1 to} R ⁴ has a (meth) acryloyl group or a cyclic ether group at the terminal.

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