JP2000081519A - Optical waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the adhesiveness of a cladding part to a substrate without sacrificing the superior characteristics of an amorphous fluorine-containing polymer by forming the cladding part from a specified polymer. SOLUTION: The optical waveguide has a cladding part comprising a polymer containing a fluorine-contg. alicyclic structure having a functional group. This functional group is preferably a carboxylic acid group. The polymer is appropriately a polymer obtained by polymerizing a monomer having a fluorine- containing alicyclic structure, preferably perfluoro(2,2-dimethyl-1,3-dioxol) or a polymer having a fluorine-containing alicyclic structure in the principal chain obtained by cyclopolymerizing a fluorine-containing monomer having two or more polymerizable double bonds, preferably a perfluoro(allyl vinyl ether) or perfluoro(butenyl vinyl ether).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide having a cladding portion made of a polymer having a fluorine-containing aliphatic ring structure having a functional group, having a high adhesion to a substrate and a small transmission loss.

[0002]

2. Description of the Related Art It is known that by using an amorphous fluoropolymer as an optical waveguide material, transmission loss can be reduced, moisture absorption can be reduced, and light scattering according to orientation birefringence can be suppressed. Kaihei 4-190202).

However, when this amorphous fluorinated polymer is used for the cladding portion of an optical waveguide, there is a disadvantage that the adhesion to a substrate is low. Therefore, for example, when a layer is formed in the order of a clad and a core on a silicon substrate, and the core is processed into a desired shape to form an optical waveguide, the clad made of an amorphous fluorine-containing polymer is formed on the substrate or the core. Easy to peel from. Also, when the optical waveguide portion is cut out from the substrate after the formation of the optical waveguide, the clad portion is easily peeled off from the substrate.
Furthermore, when this amorphous fluorinated polymer is used for the core portion of an optical waveguide, it is difficult to find a material having a lower refractive index necessary for the cladding of the optical waveguide because the refractive index of the material itself is low. There is also a disadvantage.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and improves the adhesion between the clad portion and the substrate without sacrificing the excellent characteristics of the amorphous fluoropolymer. It is an object to provide an improved optical waveguide.

[0005]

According to the present invention, there is provided an optical waveguide having a core portion provided on a substrate, through which light propagates, and a cladding portion formed around the core portion, wherein the cladding portion is functional. An optical waveguide comprising a fluorine-containing aliphatic ring structure-containing polymer having a group.

The optical waveguide of the present invention has high adhesion between the clad portion and the substrate surface in contact with the clad portion. In addition, the adhesion between the clad and the core can be improved, and the use of a polymer containing a fluorine-containing aliphatic ring structure as the core material can also reduce the occurrence of interface irregularities between the clad and the core. When using a fluorine-containing aliphatic ring structure-containing polymer as the core material, in order to make the refractive index of the core material higher than the refractive index of the cladding material, the fluorine-containing aliphatic ring structure-containing polymer is used as the core material. It is also preferable to compound a compound having a high refractive index.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, an optical waveguide is a basic component of an optical functional device formed on a semiconductor substrate such as a quartz glass substrate or a silicon substrate, and can constitute various passive optical components. The optical waveguide has a structure including a core portion through which light propagates and a clad portion formed around the core portion, and includes an optical fiber. In order for light to propagate through the core, the refractive index of the material of the core needs to be higher than the refractive index of the material of the clad. The propagating light is confined in the waveguide, and the propagating light is controlled by an external field (an external signal). Optical waveguides are classified according to their functions into optical modulators, optical switches, wavelength selectors, optical integrated circuits, and the like.

The optical waveguide generally comprises a clad formed on a substrate, a core formed on the clad, and a clad formed on the core. As a method of forming a clad portion around a core portion on a substrate, a clad portion is formed on a substrate, and after forming a core portion on the clad portion, a part of the core portion is removed by etching, By forming the clad portion on the remaining core portion, a configuration in which the periphery of the core portion is surrounded by the clad portion can be obtained.

The fluorine-containing aliphatic ring structure-containing polymer (hereinafter, also referred to as a fluorine-containing polymer) in the present invention includes a polymer obtained by polymerizing a monomer having a fluorine-containing aliphatic ring structure, A polymer having a fluorinated aliphatic ring structure in the main chain obtained by cyclopolymerization of a fluorinated monomer having one or more polymerizable double bonds is preferred. Having a fluorinated aliphatic ring structure in the main chain means that at least one of the carbon atoms constituting the aliphatic ring is a carbon atom in a carbon chain constituting the main chain,
In addition, it has a structure in which a fluorine atom or a fluorine-containing group is bonded to at least a part of carbon atoms constituting the aliphatic ring.

The material of the cladding in the present invention is a polymer having a fluorine-containing aliphatic ring structure having a functional group (hereinafter also referred to as a fluorine-containing polymer having a functional group). The material of the core is not particularly limited as long as the material has a higher refractive index than the material of the clad. However, as the core material, an amorphous fluoropolymer is preferable from the viewpoint of its physical properties and adhesion to the clad. A particularly preferred core material is a fluorine-containing aliphatic ring structure-containing polymer of the same type as the clad material, which is a material having a high affinity for the clad material and in which interface irregularities between the clad and the core hardly occur. Hereinafter, the present invention will be described by taking, as an example, a case where a polymer having the same fluorine-based aliphatic ring structure as the clad material is used as the core material.

[0011] The fluorine-containing aliphatic ring structure-containing polymer used as the core material may have a functional group or may not have a functional group. However, those having a functional group are preferable in that they have excellent adhesion to the clad material. Further, in order to increase the refractive index of the core material, it is preferable to blend a polymer having a higher refractive index than the polymer, for example, a compound (2) described later, with the polymer containing a fluorine-based aliphatic ring structure.

The polymer having a fluorinated aliphatic ring structure in the main chain obtained by polymerizing a monomer having a fluorinated aliphatic ring structure includes perfluoro (2,2-dimethyl-1,
Homopolymerization of a monomer having a fluorinated aliphatic ring structure such as 3-dioxole) or a radical polymerizable monomer such as tetrafluoroethylene, chlorotrifluoroethylene, or perfluoro (methylvinyl ether). Having a fluorinated aliphatic ring structure in the main chain obtained by copolymerization with a monomer
3-18964).

The polymer having a fluorine-containing aliphatic ring structure in the main chain obtained by cyclopolymerization of a fluorine-containing monomer having two or more polymerizable double bonds includes perfluoro (allyl vinyl ether). ) Or perfluoro (butenyl vinyl ether) by cyclopolymerization of a monomer or a monomer such as a radical polymerizable monomer such as tetrafluoroethylene, chlorotrifluoroethylene or perfluoro (methyl vinyl ether). Having a fluorinated aliphatic ring structure in the main chain obtained by copolymerizing
238115).

Further, perfluoro (2,2-dimethyl-
Monomers having a fluorinated aliphatic ring structure such as 1,3-dioxole) and perfluoro (allyl vinyl ether)
A polymer having a fluorine-containing aliphatic ring structure in the main chain can also be obtained by copolymerizing a fluorine-containing monomer having two or more polymerizable double bonds such as perfluoro (butenyl vinyl ether) and the like.

The polymer having a fluorinated aliphatic ring structure has a polymerized unit having a fluorinated aliphatic ring structure in an amount of at least 20 mol% based on all polymerized units of the polymer having a fluorinated aliphatic ring structure.
In particular, those containing 40 mol% or more are preferable in terms of transparency, mechanical properties, and the like. The polymerized unit having a fluorine-based aliphatic ring structure is a unit obtained by polymerizing the monomer having the fluorine-based aliphatic ring structure, and the fluorine-based monomer having two or more polymerizable double bonds. A polymerized unit formed by cyclopolymerization.

The perfluoro compound is preferably used as the polymer having a fluorinated aliphatic ring structure, since the polymer can be transmitted with lower loss. As the fluorine-containing aliphatic ring structure-containing polymer which is a perhalo compound, specifically, the following general formulas (1) to (4)
Those having a polymerized unit selected from the following are exemplified. In addition, the fluorine atom in these fluorine-containing aliphatic ring structure-containing polymers may be partially substituted with a chlorine atom in order to increase the refractive index. Further, as shown in the examples of the monomers described below, the fluorine-containing aliphatic ring structure-containing polymer has the general formula (1)
A polymer having a polymerized unit having a fluorinated aliphatic ring structure other than the polymerized unit selected from (4) to (4) may be used.

[0017]

Embedded image

[In the general formulas (1) to (4), h is 0
An integer from 0 to 5, i is an integer from 0 to 4, j is 0 or 1, h +
i + j is 1 to 6, s is an integer of 0 to 5, t is an integer of 0 to 4, u is 0 or 1, s + t + u is 1 to 6, p, q, r
Are each independently an integer from 0 to 5, p + q + r is from 1 to 6,
R ^{1 to} R ⁷ are each independently a fluorine atom, a chlorine atom, a chlorodifluoromethyl group, a trifluoromethyl group, or a perfluoroalkoxy group having 1 to 3 carbon atoms. ]

As the monomer having a fluorinated aliphatic ring structure in the present invention, a monomer selected from the compounds represented by any of the following formulas (5) to (7) is preferable.

[0020]

Embedded image

[In the general formulas (5) to (7), R ⁸ to
R ¹⁹ is each independently a fluorine atom, a chlorine atom, a chlorodifluoromethyl group, a trifluoromethyl group, a C 1-3 perfluoroalkoxy group, or R ^19
10 and R ¹¹ , R ¹⁴ and R ¹⁵ and R ¹⁸ and R ¹⁹ may be linked to form a ring. ]

Specific examples of the compound represented by any of formulas (5) to (7) include compounds represented by any of formulas (8) to (16).

[0023]

Embedded image

As the fluorine-based monomer having two or more polymerizable double bonds, a compound represented by any of the following formulas (17) to (19) is preferable.

[0025]

CY ¹ Y ² = CY ³ OCY ⁴ Y ⁵ CY ⁶ Y ⁷ CY ⁸ = CY ⁹ Y ¹⁰ (17) CZ ¹ Z ² = CZ ³ OCZ ⁴ Z ⁵ CZ ⁶ = CZ ⁷ Z ⁸ (18) ^{CW 1 W 2 = CW 3 OCW} 4 W 5 OCW 6 = CW 7 W 8 (19)

[In the general formulas (17) to (19), Y
^{1 to} Y ¹⁰ , Z ^{1 to} Z ⁸ and W ^{1 to} W ⁸ are each independently a fluorine atom, a chlorine atom, a chlorodifluoromethyl group, or a trifluoromethyl group. ]

Specific examples of the compound represented by any of the general formulas (17) to (19) include the following compounds.

[0028]

[Of 5] _{CF 2 = CFOCCl 2 CF 2 CF} = CF 2, CF 2 = CFOCF 2 CF 2 CCl = CF 2, CF 2 = CFOCF 2 CF 2 CF = CF 2, CF 2 = CFOCF 2 CFClCF = CF 2, CF ₂ = CFOCF ₂ CF ₂ CF = CFCl, CF ₂ = CFOCF ₂ CF (CF ₃ ) CF = CF ₂ , CF ₂ = CFOCF ₂ CF (CF ₃ ) CCl = CF ₂ , CF ₂ = CFOCF ₂ CF = CF _{2 , CF 2 = CFOCF (CF 3} ) CF = CF 2, CF 2 = CFOCF 2 OCF = CF 2, CF 2 = CClOCF 2 OCCl = CF 2, CF 2 = CFOCCl 2 OCF = CF 2, CF 2 = CFOC (CF _{3) 2} OCF = CF _2.

The functional groups of the functional group-containing fluoropolymer in the present invention are not particularly limited, and include carboxylic acid groups, sulfonic acid groups, groups having an ester bond, alkenyl groups,
Examples include a hydrolyzable silyl group, a hydroxyl group, a maleimide group, an amino group, a cyano group, and an isocyanate group. As the functional group, a carboxylic acid group is particularly preferable from the viewpoint that adhesion to a substrate such as a silicon substrate is good and transparency is not hindered. The number of functional groups in the functional group-containing fluoropolymer is 0.001 per 1 g of the functional group-containing fluoropolymer.
To 1 mmol, preferably 0.01 to 1 mmol, more preferably 0.01 to 0.2 mmol. A fluorine-containing polymer having no functional group may be used together with the functional-group-containing fluorine-containing polymer.

As a method for producing the above-mentioned fluorine-containing polymer having a functional group, there are a method of producing a fluorine-containing polymer and then introducing a functional group into the fluorine-containing polymer, or a method capable of forming the above-mentioned fluorine-containing polymer. A method of producing a fluorine-based polymer having a functional group by allowing a compound having a functional group and reacting with the monomer during the polymerization of the monomer to be present. After producing a fluorine-based polymer having a group capable of being converted into a functional group instead of a functional group (hereinafter referred to as a precursor functional group), the precursor functional group is converted into a functional group to obtain a desired functional group-containing fluorine-based polymer. Polymers can also be produced. Examples of the precursor functional group include an alkoxycarbonyl group, and this alkoxycarbonyl group is converted to a carboxylic acid group by hydrolysis. The following method is preferred as a method for producing the functional group-containing fluoropolymer.

1) A monomer capable of forming a fluorine-based polymer is polymerized in the presence of a polymerization initiator or a chain transfer agent having a functional group or a precursor functional group to form a fluorine-containing polymer having a functional group or a precursor functional group. A method of manufacturing coalescence. The precursor functional group of the precursor functional group-containing fluoropolymer is then converted into a functional group. For example, a fluorine-based polymer having a carboxylic acid group, a sulfonic acid group, an alkoxycarbonyl group, or the like can be produced using a polymerization initiator or a chain transfer agent having the group. The fluorinated polymer having an alkoxycarbonyl group is then hydrolyzed to be converted to a carboxylic acid group fluorinated polymer. 2) A fluorine-containing aliphatic ring structure-containing polymer having a functional group or a precursor functional group by subjecting a polymer having a fluorine-containing aliphatic ring structure to high-temperature treatment in the presence of oxygen to oxidatively decompose a side chain or a terminal of the polymer. How to manufacture. It is considered that a fluorocarbonyl group is generated by oxidative decomposition, and the fluorinated polymer can be converted into a carboxylic acid group-containing fluoropolymer by reacting the fluorinated polymer with water after oxidative decomposition. Further, the fluorinated polymer can be converted into an alkoxycarbonyl group-containing fluorinated polymer by reacting the fluorinated polymer with an alkanol after oxidative decomposition, and further hydrolyzed to be converted into a carboxylic acid group-containing fluorinated polymer.

3) A method for producing a fluoropolymer having a functional group or a precursor functional group by copolymerizing a monomer capable of forming a fluoropolymer and a monomer having a functional group or a precursor functional group . The precursor functional group of the precursor functional group-containing fluoropolymer is then converted into a functional group. For example, an alkoxycarbonyl group-containing monomer such as methyl perfluoro (5-oxa-6-hexanoate) is copolymerized to produce a precursor functional group-containing fluoropolymer, which is then hydrolyzed to form a carboxylic acid group-containing fluoropolymer. Convert to polymer. 4) A method of converting the functional group of the functional group-containing fluoropolymer obtained by the above methods 1) to 3) into another functional group by a known or well-known method.

The material forming the core portion in the optical waveguide of the present invention is preferably a material having a core portion having a higher refractive index than the cladding portion, and a "compound having a higher refractive index than a fluoropolymer" (hereinafter, referred to as "compound"). A mixture of the compound (2)) and a fluoropolymer is preferred. As the compound (2), a substance having a low molecular weight can be used as long as it can increase the refractive index of the fluorine-based polymer containing the compound (2) more than the refractive index of the fluorine-based polymer alone without substantially increasing light scattering. Compounds, oligomers,
Any of polymers may be used. As the compound (2), a substance having a refractive index higher than that of the fluoropolymer by 0.001 or more is preferable.

As the low molecular weight compound, for example, there is a halogenated aromatic hydrocarbon which does not contain a hydrogen atom bonded to a carbon atom. In particular, halogenated aromatic hydrocarbons containing only a fluorine atom as a halogen atom and halogenated aromatic hydrocarbons containing a fluorine atom and another halogen atom are preferable in view of compatibility with the fluorine-based polymer.

Examples of the halogenated aromatic hydrocarbon include, for example, a compound represented by the formula Φ-Z _b [Φ is a b-valent perfluoroaromatic ring residue, Z is a halogen atom other than fluorine, —Rf, —C
ORf, -ORf, or -CN. Here, Rf is a perfluoroalkyl group, a perhalopolyfluoroalkyl group, or monovalent Φ. b is an integer of 0 or more. ] The compound represented by these. The aromatic ring includes a benzene ring and a naphthalene ring. The perfluoroalkyl group or perhalopolyfluoroalkyl group as Rf preferably has 5 or less carbon atoms. As a halogen atom other than fluorine, a chlorine atom or a bromine atom is preferable.

Specific compounds include, for example, 1,3-
Dibromotetrafluorobenzene, 1,4-dibromotetrafluorobenzene, 2-bromotetrafluorobenzotrifluoride, chloropentafluorobenzene, bromopentafluorobenzene, iodopentafluorobenzene, decafluorobenzophenone, perfluoroacetophenone, perfluorobiphenyl, chlorohepta Examples include fluoronaphthalene and bromoheptafluoronaphthalene.

As the oligomer, a homopolymerized oligomer of a fluorine-containing monomer such as tetrafluoroethylene, chlorotrifluoroethylene, dichlorodifluoroethylene, hexafluoropropylene, or perfluoro (alkyl vinyl ether), or two or more of these monomers may be used. And copolymer oligomers. In addition, -CF ₂ CF (CF ₃ )
O- or _{- (CF 2) n O- (} n is an integer of 1 to 3) such as perfluoropolyether having structural units of can be used.

As the compound (2) or a precursor thereof, a compound represented by the general formula R ^a _m MR ^b _4-m (where m is an integer of 0 to 3 and R ^a is a non-hydrolyzable organic compound having 1 to 14 carbon atoms) Group [where m is 2
Or in the case of 3, a plurality of R ^a may be the same or different from each other], R ^b is a hydrolyzable group, M is Si,
Ti, Zr, Hf or Th. Or a partially hydrolyzed condensate of this compound (both are collectively referred to as compound a). It is considered that the compound a, which is a compound capable of hydrolysis and condensation, becomes a final hydrolysis condensation product in the fluoropolymer. In the process of forming the optical waveguide, there is usually a heat treatment step at the time of forming the core portion, and it is considered that this heating turns the compound a into a final hydrolyzed condensate. A fluorine-based polymer containing this hydrolyzed condensate is preferable as the core material in the present invention. As the compound a, one kind represented by the above general formula may be used.
More than one species may be used in combination.

Examples of the hydrolyzable group include an alkoxy group, an alkoxyalkoxy group, an acyloxy group, an aryloxy group, an aminoxy group, a carbamoyl group, a ketoxime group, an isocyanate group and a halogen atom. Preferably, it is a group obtained by removing a hydrogen atom from a hydroxyl group of a monohydric alcohol such as an alkoxy group and an alkoxyalkoxy group. Particularly, an alkoxy group is preferable, and its carbon number is 4
Or less, particularly preferably 1 or 2 pieces.

[0040] It is preferred that at least one of the non-hydrolyzable organic group R ^a in the compound a is an organic group having a functional group. When ^a non-hydrolyzable organic group having no functional group is present in ^Ra , the organic group is usually an alkyl group. As the functional group, for example, an amino group, an epoxy group,
Examples include a glycidoxy group, a mercapto group, and an isocyanate group.

In the optical waveguide, the width of the core portion, the height of the core portion, and the distance between adjacent core portions are each usually 0.1 μm to 0.1 μm.
Since it is several tens of μm and extremely small, the compound (2) in the core part diffuses into the clad part due to the heat treatment during the production of the optical waveguide, and a sufficient difference in the refractive index between the core part and the clad part may not be obtained. is there.

In this case, the fluoropolymer and the compound (2)
It is preferable to employ a mixture in which the fluoropolymer is a functional group-containing fluoropolymer and the compound (2) has a functional group capable of reacting with the functional group of the functional group-containing fluoropolymer. By reacting both functional groups to bond the compound (2) to the fluoropolymer, diffusion of the compound (2) due to heating can be suppressed. The functional group-containing fluorine-containing polymer and the fluorine-containing polymer having no functional group may be used in combination. The compound (2) having a functional group capable of reacting with the functional group of the functional-group-containing fluorine-containing polymer and the functional group-containing fluorine-containing polymer The compound (2) having no functional group capable of reacting with the functional group of the fluoropolymer may be used in combination. Examples of such a compound (2) include the above-mentioned halogenated aromatic hydrocarbons and oligomers having the above functional groups.

The compound a having a functional group capable of reacting with the functional group of the functional group-containing fluoropolymer is a compound a in which m is 1 to 3, and at least one of ^Ra is a functional group-containing fluoropolymer. A compound that is a non-hydrolyzable organic group having a functional group capable of reacting with the functional group of the polymer (hereinafter, referred to as compound b) is preferable. This compound b may be a partially hydrolyzed condensate as defined for the compound a. More preferably, compound b is used together with compound a.

A combination in which the functional group of the functional group-containing fluoropolymer is a carboxylic acid group and the functional group of the compound b is an amino group is preferred. When compound a and compound b are used in combination, compound a is preferably a combination having three or more hydrolyzable groups, and compound b is preferably a combination having two hydrolyzable groups.

Compound a and compound b because of high transparency
Are preferably silane compounds. Compound a
Preferred are tetraalkoxysilanes, monoalkyl trialkoxysilanes, fluoroalkylalkoxysilanes, aromatic alkoxysilanes, and partially hydrolyzed condensates of these compounds. The compound b is preferably an alkoxysilane compound having an amino group-containing non-hydrolyzable organic group, an alkoxysilane compound having a glycidoxy group-containing non-hydrolyzable organic group, or a partially hydrolyzed condensate of these compounds.

Tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, etc. Monoalkyltrialkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, etc., and fluoroalkylalkoxylanes Examples include trifluoromethyltrimethoxysilane, trifluoropropyltrimethoxysilane, pentafluorobutyltrimethoxysilane, nonafluorohexyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluoro Decylmethyldimethoxysilane, heptadecafluoroundecyltrimethoxysilane and the like; Such as emissions are preferred.

Examples of the alkoxysilane compound having an amino group-containing non-hydrolyzable organic group include aminoalkylalkoxysilanes such as 3-aminopropylmethyldiethoxysilane and 3-aminopropyltriethoxysilane;
Preferred are aminoarylalkoxysilanes such as aminophenyltrimethoxysilane, aminophenyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. Examples of the alkoxysilane compound having a glycidoxy group-containing non-hydrolyzable organic group include 3
Glycidoxyalkylalkoxysilanes such as -glycidoxypropyltrimethoxysilane and 3-glycidoxypropylmethyldimethoxysilane are preferred.

The ratio of the compound (a), compound (b) or the total amount of the compounds (a) and (b) to the total amount of the fluorine-containing polymer, the functional group-containing fluorine-containing polymer or both is 100 parts by weight of the former and 1 to 100 parts by weight of the latter. Preferably by weight,
More preferably, it is 5 to 50 parts by weight.

As a method of forming a core portion and a clad portion on a substrate, a clad portion is coated on a substrate, a core portion is coated, and then a part of the core portion is etched.
Next, a method of coating a clad portion on the core portion after the etching may be mentioned. Coating methods include spin coating, dipping, potting, die coating,
A spray coating method or the like is employed, and a spin coating method is particularly preferable.

When the core is coated, for example, in the case of a combination of a functional group-containing fluoropolymer and the compound b, it is preferable to use a solution in which the mixture is dissolved in a solvent.
The method for preparing this solution is not particularly limited as long as a uniform solution is obtained, and the following methods (a) to (c) are exemplified.

(A) A method in which a solution of the compound b and a solution of the functional group-containing fluoropolymer are separately prepared in advance, and the two solutions are mixed. In this case, the method of preparing the solution of the compound b includes a method of directly preparing the solution in a solvent compatible with the solution of the functional group-containing fluoropolymer, or a method of preparing the solution in the solvent incompatible with the solution of the polymer. A solution of a compatible solvent may be obtained by a known solvent substitution method. The latter is used when the hydrolysis-condensation reaction of the compound b does not proceed sufficiently in a solvent compatible with the polymer solution or when it is difficult to control the degree of polymerization of the partially hydrolyzed condensate. (B) A method of dissolving a non-condensed compound b in a solution of a functional group-containing fluoropolymer prepared in advance and performing a partial hydrolysis condensation reaction of the compound b in the solution. (C) A method in which a solution of the compound b is prepared in advance, and a functional group-containing fluoropolymer is added and dissolved therein.

Functional group-containing fluoropolymer resin and compound b
May be reacted at the time of preparing the solution, or may be reacted at the time of coating film formation at the time of coating. It is preferable that a partial reaction be carried out during the solution preparation, because the compatibility between the functional group-containing fluoropolymer resin and the compound b is improved. The solution may be prepared while heating in order to react during the preparation of the solution.

The condensation reaction of the compound a and the compound b can be performed by a known or known method. For example, there is a method in which compound a or compound b is subjected to a hydrolytic condensation reaction by adding water in the presence of a solvent and a catalyst. In this case, heating may be performed if necessary. As the catalyst, inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid, and organic acids such as formic acid, oxalic acid and acetic acid can be used.

Usually, the molecular weight of the partially hydrolyzed condensate is preferably in the range of 500 to 10,000 in terms of polystyrene-equivalent weight average molecular weight, because it is compatible with the fluorine-based polymer or the functional group-containing fluorine-based polymer and the solubility in a solvent. It is preferable from the viewpoint of properties. Next, if necessary, water present in the system may be removed by distillation or the like, and the catalyst may be removed with an ion exchange resin or the like. As a solvent used in the above solution preparation, a mixture of an aprotic fluorinated solvent and a protic fluorinated solvent is preferable.

The aprotic fluorinated solvent is a fluorinated solvent which does not dissociate and generate protons under ordinary reaction conditions, and any known or well-known one can be used. Perfluorodecalin, perfluorocyclohexane, perfluorohexane, perfluorooctane, 1H, 1H, 1
H, 2H, 2H-perfluorooctane, 1H, 1H,
Fluorinated aliphatic hydrocarbons such as 1H, 2H, 2H-perfluorodecane, perfluorotripentylamine,
Examples thereof include fluorinated alkylamines such as perfluorotributylamine and perfluorotripropylamine, and fluorinated cyclic ethers such as perfluoro (2-butyltetrahydrofuran). These may be used in combination of two or more.

The protic fluorinated solvent is a fluorinated solvent which is easily dissociated to generate protons, and a known or well-known solvent can be used. CF ₃ CH ₂ OH, F (CF ₂ )
₂ CH ₂ OH, F (CF ₂ ) ₄ CH ₂ CH ₂ OH, F
(CF ₂ ) ₆ CH ₂ CH ₂ OH, F (CF ₂ ) ₂ CH ₂
CH ₂ CH ₂ OH, F (CF ₂ ) ₄ CH ₂ CH ₂ CH ₂
Fluorine-containing alcohols such as OH are preferably exemplified. These may be used in combination of two or more.

In the process of forming the optical waveguide, there is usually a heating process at the time of forming the core portion. For example, when using a solution or dispersion obtained by dissolving or dispersing a mixture of a fluoropolymer and a compound a or a compound b or a reaction product thereof in a solvent, applying the solution or dispersion to a predetermined portion to remove the solvent Remove,
Thereafter, heating is performed to form a core portion. By this heating, the compound a and the compound b become final hydrolyzed condensation products.
The hydrolysis-condensation product may be bonded to a fluorine-containing aliphatic ring structure-containing polymer. In particular, when the functional group-containing fluorine-based polymer and the compound b are used, it is considered that a core composed of a material in which the functional group-containing fluorine-based polymer and the hydrolysis condensation product of the compound b are bonded is generated. .

In the optical waveguide of the present invention, the adhesion between the substrate and the cladding material can be enhanced by using a polymer having a functional group-containing fluoroaliphatic ring structure as the cladding material. Further, when a fluorine-containing aliphatic ring structure-containing polymer having a functional group is used as the core material, the affinity with the clad material is increased due to the increased affinity with the clad material, and the clad / core gap is increased. Interface irregularities are less likely to occur. Further, by using a compound having a functional group capable of reacting with the functional group together with a fluorine-containing aliphatic ring structure-containing polymer having a functional group as a compound for increasing the refractive index as the core material, the cladding portion of the compound is obtained. Can be suppressed.

Various functional compounds can be blended in the clad portion and the core portion of the optical waveguide of the present invention, whereby various functions can be added to the waveguide. For example, a fluorescent functional organic dye (for example, a rhodamine-based dye having a light amplification function) can be blended. Such a functional compound is preferably fixed in a clad material or a core material.
The fluorine-containing aliphatic ring structure-containing polymer having the above functional group is effective for fixing the functional compound. For example, a rhodamine-based dye has an amino group and can be fixed by bonding to a polymer having a carboxylic acid group.

[0060]

EXAMPLES Example 1 (Synthesis Example) 35 g of perfluoro (butenyl vinyl ether), 150 g of ion-exchanged water, 20 g of methanol, and ((CH ₃ ) ₂ C as a polymerization initiator)
(HOCOO) ₂ 90 mg was placed in a pressure-resistant glass autoclave having an internal volume of 200 cc, and the system was replaced with nitrogen three times. Then, suspension polymerization was carried out at 40 ° C. for 22 hours to obtain a polymer (hereinafter referred to as polymer A). 28 g were obtained.

The intrinsic viscosity [η] of the polymer A is 0.2 at 30 ° C. in perfluoro (2-butyltetrahydrofuran).
dl / g. Further, the polymer A was heated at 300 ° C. in air.
, And then immersed in water to obtain a polymer (hereinafter, referred to as polymer B). A peak attributed to a carboxylic acid group was confirmed in the IR spectrum of polymer B, and the amount of the carboxylic acid group was 0.03 mmol / g polymer B. The light transmittance was as high as 95% or more.

Example 2 (Synthesis Example) 40 g of perfluoro (butenyl vinyl ether) and methyl perfluoro (5
-Oxa-6-heptenoate), 1.6 g of ion-exchanged water and ((CH ₃ ) ₂ CH as a polymerization initiator
90 mg of OCOO) ₂ was placed in a pressure-resistant glass autoclave having an internal volume of 200 cc, and the system was purged with nitrogen three times, followed by suspension polymerization at 40 ° C. for 24 hours to obtain a polymer (hereinafter, referred to as “polymer”).
30 g of polymer C) was obtained.

The intrinsic viscosity [η] of the polymer C is 0.3 at 30 ° C. in perfluoro (2-butyltetrahydrofuran).
It was 4 dl / g. After heat-treating the polymer C in air at 300 ° C. for 3 hours, it was immersed in water to obtain a polymer (hereinafter referred to as polymer D). A peak attributed to a carboxylic acid group was confirmed in the IR spectrum of the polymer D, and the amount of the carboxylic acid group was 0.03 mmol / g.

Example 3 (Synthesis Example) Polymer B was immersed in dichloropentafluoropropane / 1-propanol in the presence of sodium borohydride, refluxed for 5 hours, and then washed and dried to obtain a polymer. (Hereinafter referred to as polymer E)
I got In the IR spectrum of the polymer E, a peak attributed to a hydroxyl group was confirmed.

Example 4 (Example) 10 g of polymer B was dissolved in 90 g of perfluorotributylamine to prepare a polymer B solution (hereinafter referred to as B1 solution). 10 g of polymer A, 70 g of perfluorotributylamine, 1H,
A composition comprising 15 g of 1H-pentafluoropropanol, 0.05 g of 3-aminopropylmethyldiethoxysilane and 1.0 g of tetramethoxysilane (hereinafter referred to as A1
Liquid).

The B1 solution was applied on a silicon substrate by a spin coating method, and heated at a temperature of 250 ° C. for 60 minutes to form a clad portion (lower clad portion) having a thickness of 10 μm, thereby obtaining a B1 solution coated substrate. The substrate coated with the B1 liquid was heated under pressure by a pressure cooker tester, and then subjected to JIS K5400, 6.1.
A cross-cut test was performed according to the method specified in No. 4. As a result, the remaining number after 100 hours was 100/100.

The A1 solution was spin-coated on the substrate coated with the B1 solution other than those subjected to the grid test, and heated at a temperature of 250 ° C. for 60 minutes to form a 5 μm core portion. Next, resist coating, pre-baking, exposure, development, and after-baking were performed to obtain a patterned resist layer. The core not protected by the resist layer was removed by dry etching. The remaining resist is removed by wet etching,
A clad portion (upper clad portion) was formed thereon in the same manner as in the formation of the lower clad portion by using the B1 liquid to obtain an optical waveguide.

In this optical waveguide, the refractive indices of the cladding and the core were 1.340 and 1.345, respectively. When the propagation loss of the optical waveguide was measured using a light source of a semiconductor laser for this optical waveguide, 0.1 dB / cm or less for light having a wavelength of 650 nm and 0.1 dB / cm for light having a wavelength of 1300 nm.
11 dB / cm, 0.17 dB with light at a wavelength of 1550 nm
/ Cm, and was an optical waveguide capable of transmitting light from visible light to ultraviolet light satisfactorily.

Example 5 (Example) From 10 g of polymer D, 70 g of perfluorotributylamine, 15 g of 1H, 1H-pentafluoropropanol, 0.15 g of 3-aminopropylmethyldiethoxysilane and 3.0 g of tetramethoxysilane Composition (hereinafter referred to as D1 solution)
Was prepared.

Example 4 except that solution D1 was used instead of solution A1
An optical waveguide was obtained in the same manner as described above. In this optical waveguide,
The refractive indices of the cladding portion and the core portion are 1.340, respectively.
1.348. When the propagation loss of the optical waveguide was measured using a light source of a semiconductor laser in this optical waveguide portion,
0.1 dB / cm or less for light of wavelength 650 nm, wavelength 13
0.10 dB / cm with light of 00 nm, wavelength 1550 nm
Was 0.17 dB / cm, and the optical waveguide was capable of transmitting light from visible light to ultraviolet light.

Example 6 (Example) Phenyltrimethoxysilane and CF ₃ (CF ₂ ) ₅ CH ₂ C in a reaction vessel
H ₂ Si (OCH ₃ ) ₃ was dissolved in methanol at a molar ratio of 1: 1, and after adding nitric acid and water, the mixture was reacted at room temperature for 72 hours. Next, the nitric acid was removed by passing the reaction solution through an ion-exchange resin tower.
Substitution with H, 1H-pentafluoropropanol yielded a solution of the partially hydrolyzed condensate. A composition comprising 5 g of this solution having a solid concentration of 60% by weight, 10 g of polymer B, 85 g of perfluorotributylamine and 0.05 g of 3-aminopropylmethyldiethoxysilane (hereinafter referred to as B3 solution) was prepared.

Example 4 except that solution B3 was used instead of solution A1
An optical waveguide was obtained in the same manner as described above. In this optical waveguide,
The refractive indices of the cladding portion and the core portion are 1.340, respectively.
1.352. When the propagation loss of the optical waveguide was measured using a light source of a semiconductor laser in this optical waveguide portion,
0.1 dB / cm or less for light of wavelength 650 nm, wavelength 13
0.10 dB / cm with light of 00 nm, wavelength 1550 nm
Was 0.15 dB / cm, and was an optical waveguide that could transmit light from visible light to ultraviolet light well.

Example 7 (Example) A composition comprising 10 g of polymer D, 70 g of perfluorotributylamine, 15 g of 1H, 1H-pentafluoropropanol, and 3.0 g of 3-aminopropylmethyldiethoxysilane (hereinafter, referred to as "the following")
D3 solution) was prepared.

Example 4 except that solution D3 was used instead of solution A1
An optical waveguide was obtained in the same manner as described above. In this optical waveguide,
The refractive indices of the cladding portion and the core portion are 1.340, respectively.
1.346. When the propagation loss of the optical waveguide was measured using a light source of a semiconductor laser in this optical waveguide portion,
0.1 dB / cm or less for light of wavelength 650 nm, wavelength 13
0.10 dB / cm with light of 00 nm, wavelength 1550 nm
Was 0.18 dB / cm, and was an optical waveguide that could transmit light from visible light to ultraviolet light well.

Example 8 (Example) 18 g of polymer E, 180 g of perfluorotributylamine and chlorotrifluoroethylene oligomer 2 having a carboxylic acid group end
g (hereinafter referred to as E1 solution) was prepared.

Example 4 except that E1 solution was used instead of A1 solution
An optical waveguide was obtained in the same manner as described above. In this optical waveguide,
The refractive indices of the cladding portion and the core portion are 1.340, respectively.
1.354. When the propagation loss of the optical waveguide was measured using a light source of a semiconductor laser in this optical waveguide portion,
0.1 dB / cm or less for light of wavelength 650 nm, wavelength 13
0.11 dB / cm with light of 00 nm, wavelength 1550 nm
Was 0.20 dB / cm, and was an optical waveguide that could transmit light from visible light to ultraviolet light well.

Example 9 (Comparative Example) A polymer A solution (hereinafter referred to as A2 solution) was prepared by dissolving 10 g of polymer A in 90 g of perfluorotributylamine. A1 solution is applied on a silicon substrate by spin coating, and the temperature is 250 ° C.
For 60 minutes to form a thin film having a thickness of 10 μm. This thin film was heated under pressure with a pressure cooker tester, and then subjected to a grid test according to the method specified in JIS K5400, 6.14. As a result, the remaining number after 100 hours was 0/100.

[0078]

The optical waveguide of the present invention can transmit light from ultraviolet light to near-infrared light with very low loss, and has extremely strong adhesion to a substrate. Also during the heat treatment for producing the optical waveguide, by suppressing the compound (2) in the core from diffusing into the clad, a sufficient difference in the refractive index between the core and the clad can be ensured.

Claims (10)

[Claims] An optical waveguide provided on a substrate and having a core portion through which light propagates and a clad portion formed around the core portion, wherein the clad portion is a functional group-containing fluorinated aliphatic ring. An optical waveguide comprising a structure-containing polymer. 2. The optical waveguide according to claim 1, wherein the functional group in the functional group-containing fluoroaliphatic ring structure-containing polymer is a carboxylic acid group. 3. The functional group-containing fluoroaliphatic ring structure-containing polymer has a number of functional groups of 0.001 to 1 mmol per 1 g of the functional group-containing fluoroaliphatic ring structure-containing polymer. Or the optical waveguide according to 2. 4. A polymer comprising a fluorine-containing aliphatic ring structure-containing polymer formed by cyclopolymerization of a fluorine-containing monomer having two or more polymerizable double bonds, and a fluorine-containing aliphatic ring structure. The optical waveguide according to claim 1, 2 or 3, wherein the monomer is a polymer having at least one type of polymerization unit selected from polymerization units formed by polymerization. 5. The fluoromonomer having two or more polymerizable double bonds is perfluoro (allyl vinyl ether) or perfluoro (butenyl vinyl ether), and the fluoroaliphatic ring structure-containing monomer is perfluoro (2 , 2-
The optical waveguide according to claim 4, wherein the optical waveguide is dimethyl-1,3-dioxole). 6. The method according to claim 1, wherein the core portion is formed of a mixture of a polymer having a fluorine-based aliphatic ring structure and a compound having a higher refractive index than the polymer, and is made of a material having a higher refractive index than the material of the cladding portion. Item 2. An optical waveguide according to item 1. 7. The optical waveguide according to claim 6, wherein the core is a core formed by heating a mixture of a fluorine-containing aliphatic ring structure-containing polymer and the following compound a in the process of forming the optical waveguide. Compound a: a general formula R ^a _m MR ^b _4-m (where m is an integer of 0 to 3 and R ^a is a non-hydrolyzable organic group having 1 to 14 carbon atoms, provided that m is 2 or 3 In this case, a plurality of R ^a may be the same or different from each other], R ^b is a hydrolyzable group, M is a compound represented by Si, Ti, Zr, Hf or Th), or a compound of the compound Partial hydrolysis condensate. 8. The core portion is formed from a mixture of a polymer having a functional group-containing fluorinated aliphatic ring structure and a compound having a functional group capable of reacting with the functional group of the polymer or a reaction product thereof. 2. The optical waveguide according to claim 1, wherein the optical waveguide is made of a material having a higher refractive index than the material of the clad portion. 9. The core part is formed by heating a mixture of a functional group-containing polymer having a fluorinated aliphatic ring structure and the following compound b or a reaction product thereof in the process of forming an optical waveguide. An optical waveguide according to claim 8. Compound b: In the general formula _{^{R a m MR b 4-m}} ( wherein, m is an integer of from 0 to 3, R ^a is a non-hydrolyzable organic group with the proviso 1 to 14 carbon atoms, m is 2 or 3 A plurality of R ^a may be the same or different from each other], R ^b is a hydrolyzable group, M is Si, Ti, Zr, Hf or Th) and a functional group-containing fluorine-containing fatty acid A compound having ^a functional group capable of reacting with a functional group of a group-ring-structure-containing polymer at Ra, or a partially hydrolyzed condensate of the compound. 10. A compound b wherein m is 1 or 2, and M is S
The photoconductor according to claim 9, wherein i and at least one of ^Ra is a non-hydrolyzable organic group having a functional group capable of reacting with a functional group of the functional group-containing polymer having a fluoroaliphatic ring structure. Wave path.