WO2002084346A1

WO2002084346A1 - Optical waveguide

Info

Publication number: WO2002084346A1
Application number: PCT/JP2002/003552
Authority: WO
Inventors: Atsushi Watakabe; Jun-Ichi Tayanagi; Katsumi Suzuki
Original assignee: Asahi Glass Company, Limited
Priority date: 2001-04-10
Filing date: 2002-04-09
Publication date: 2002-10-24
Also published as: JPWO2002084346A1

Abstract

An optical waveguide provided on a substrate, characterized in that the materials of the core portion and the clad portion thereof comprise a fluorine-containing crosslinked polymer having a triazine ring, respectively. The optical waveguide has good heat resistance and exhibits reduced propagation loss.

Description

Specification

Optical waveguide

The present invention relates to an optical waveguide using a triazine ring-containing fluoropolymer. <Background technology>

Optical waveguides have been studied in order to respond to recent improvements in the amount and speed of information transmission, and optical waveguide materials with various structures are also being studied. For example, materials having excellent transparency such as acrylate polymers, polycarbonates, and fluorine-containing polyimides are being studied, but materials with further lower propagation loss are desired.

Japanese Patent Application Laid-Open No. HEI 4-190202 discloses that by using an amorphous fluoropolymer as an optical waveguide material, propagation loss can be reduced, the moisture absorption rate can be reduced, and light that follows orientation birefringence can be reduced. It is described that scattering can be suppressed. The fluorinated polymer is a linear polymer, and there is room for further improvement in heat resistance.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an optical waveguide having excellent heat resistance and small propagation loss without sacrificing the excellent characteristics of a fluoropolymer.

The present invention relates to 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 material of the core portion or the clad portion has a triazine ring. An optical waveguide characterized by being a crosslinked fluorine-containing polymer; and 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. The material of the core portion and the cladding portion is a crosslinked fluoropolymer having a triazine ring, and the core portion is An optical waveguide having a higher refractive index than the cladding.

As the optical waveguide of the present invention, the latter optical waveguide is particularly preferable. In this case, in order for the core portion to have a higher refractive index than the cladding portion, it is preferable to use a polymer having a higher refractive index for the core portion than for the cladding portion. Means for changing the refractive index of the fluoropolymer include changing the triazine ring density (the higher the triazine ring density, the higher the refractive index), including halogen atoms other than fluorine atoms or hydrogen atoms (halogen atoms other than fluorine atoms or The higher the number of hydrogen atoms, the higher the refractive index).

Examples of the crosslinked fluorine-containing polymer having a triazine ring include a fluorine-containing polymer obtained by polymerizing a fluorine-containing triazine compound having two or more polymerizable unsaturated groups, and an oligomer including a monomer unit having a cyano group. There is a fluoropolymer obtained by thermal crosslinking, and the latter fluoropolymer is particularly preferred. BEST MODE FOR CARRYING OUT THE INVENTION>

In the present invention, the optical waveguide is a basic component of an optical functional device formed on a semiconductor such as a quartz glass substrate or a silicon substrate, and can constitute various 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. In order for light to propagate through the core, the refractive index of the core material must be higher than the refractive index of the cladding material. The propagating light is confined in the waveguide and propagates in the core. The propagating light can be controlled by an external field (an external signal or a nearby core). Optical waveguides are classified according to their functions into optical modulators, optical switches, wavelength selectors, and optical integrated circuits, and various waveguides can be combined in various ways.

The optical waveguide is usually composed of a clad part in contact with the substrate and a core part in the clad. This optical waveguide usually has a clad layer formed on a substrate, A layer serving as a core portion is formed on this layer, and a part of the layer serving as the core portion is removed by etching or the like to form a portion through which light propagates (that is, a core portion). The portion where the key portion is not formed is formed by a method of further forming a layer serving as a clad portion on the layer serving as a clad portion. The upper and lower layers formed by this method are integrated into a clad portion, and the core portion is surrounded by the upper and lower layers.

The crosslinked fluorine-containing polymer having a triazine ring in the present invention (hereinafter referred to as a fluorine-containing polymer (Q)) contains a triazine ring in the molecule and has at least

A cured product obtained by addition polymerization of a fluorine-containing compound having two polymerizable unsaturated groups (hereinafter referred to as a fluorine-containing polymer (Q-1)) or the cyano group of a fluorine-containing oligomer containing a cyano group is trimerized. A cured product obtained by forming a triazine ring (hereinafter referred to as a fluorine-containing polymer (Q-2)) is preferred. Hereinafter, this addition polymerization or trimerization is also referred to as cross-linking, and forming a polymer cross-linked by cross-linking is also referred to as curing.

The fluoropolymer (Q) is a polymer in which some or all of the hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms, and is 40% or more (preferably 6% or more) of the total of hydrogen atoms and fluorine atoms. Polymers in which 0% or more, particularly 80% or more) are fluorine atoms are preferred. Some of the hydrogen atoms may be replaced by halogen atoms other than fluorine atoms (chlorine atoms and bromine atoms). The halogen atoms are particularly chlorine atoms in view of the thermal stability and chemical stability of the polymer. Atoms are preferred.

Particularly preferred fluorine-containing polymers (Q) include a fluorine-containing polymer in which all of the hydrogen atoms are replaced by fluorine atoms (hereinafter referred to as a perfluoropolymer) and a hydrogen atom in which all of the hydrogen atoms are replaced by fluorine atoms and chlorine atoms. Substituted (however, the number of chlorine atoms is preferably 30% or less with respect to the sum of fluorine atoms and chlorine atoms) is preferably a fluorine-containing polymer (hereinafter referred to as perhalofluoropolymer). Such a perfluoropolymer or perhalofluoropolymer is particularly preferable as a material for obtaining a waveguide having a low propagation loss. The fluoropolymer (Q) has a carbon atom and a fluorine atom, and optionally has a halogen atom or a hydrogen atom other than a fluorine atom as described above. In addition, it has a nitrogen atom (the nitrogen atom of the tria 'ring) and may optionally have an oxygen atom. Further, the polymer may have a nitrogen atom other than the nitrogen atom in the ring or an atom of any other type, but it is usually preferable that the polymer does not contain such an atom. Known fluorine-containing polymers (Q) can be used. The fluorine-containing polymer (Q) is described in, for example, Japanese Patent Application Laid-Open Nos. 5-33928, 6-340640, 6-340710, and It is described in, for example, Japanese Laid-Open Patent Application No. Hei 7-2608031 and Japanese Patent Application Laid-Open No. 11-110205.

Among the fluoropolymers (Q), the fluoropolymer (Q-1) can be obtained by, for example, addition polymerization of the following fluorinated compound (hereinafter referred to as a triazine ring-containing monomer). Further, a partially polymerized product of a triazine ring-containing monomer can be used as a raw material, and this can be finally polymerized to obtain a fluoropolymer (Q-1).

The fluorine-containing polymer (Q-2) of the fluorine-containing polymer (Q) can be obtained, for example, by trimerizing the cyano group of the fluorine-containing oligomer having a cyano group. Examples of the fluorine-containing oligomer having a cyano group include a homo-oligomer obtained by addition polymerization of a fluorine-containing compound having a cyano group and a polymerizable unsaturated group (hereinafter, referred to as a fluorine-containing monomer having a cyano group), and a fluorine-containing oligomer having a cyano group. Examples include a co-oligomer obtained by addition polymerization of two or more monomers, and a co-oligomer obtained by addition polymerization of a fluorine-containing monomer having a cyano group and another copolymerizable monomer.

Further, a fluorine-containing monomer having a functional group that can be converted to a cyano group (hereinafter, referred to as a precursor group) and a fluorine-containing compound having a polymerizable unsaturated group (hereinafter, referred to as a precursor-group-containing fluorine-containing monomer) is used as a cyano group. A homo-oligomer ゃ co-oligomer as described above is produced in place of the fluorine-containing monomer contained, The precursor group may be converted to a cyano group to produce a fluorine-containing oligomer containing a cyano group.

The fluorine-containing oligomer having a cyano group is preferably an oligomer having a monomer unit represented by the following formula 1 or 2.

Equation 1

-Equation 2

(A) _n -CN

In Formulas 1 and 2, A represents a divalent group represented by one OR ¹ — or one: R ² —, and n represents 0 or 1. R ¹ R ² represents a polyfluoroalkylene group which may have an etheric oxygen atom between carbon atoms. This polyfluoroalkylene group has two or more fluorine atoms, and may have a halogen atom or a hydrogen atom other than a fluorine atom. The number of carbon atoms of the polyfluoroalkylene group is suitably from 1 to 15, and preferably from 2 to 12. The polyfluoroalkylene group may have a halogen atom or a hydrogen atom other than a fluorine atom. Also, etheric oxygen atoms can exist between the carbon atoms of the polyfluoroalkylene group, and the number of oxygen atoms can range from 1 for 4 carbon atoms to 1 for 1 carbon atom. preferable.

As R ¹ and R ² , 50% or more, particularly 70% or more, of the total of the hydrogen atom and the fluorine atom is a fluorine atom, and may have a chlorine atom or a hydrogen atom in addition to the fluorine atom. And a polyfluoroalkylene group having 2 to 12 carbon atoms which may have an etheric oxygen atom. In particular, a perfluoroalkylene group which may have an etheric oxygen atom or a perhalopolyfluoroalkylene group which may have an etheric oxygen atom (however, a halogen atom other than a fluorine atom Is a chlorine atom, and the number of fluorine atoms is 50% or more of the total number of fluorine atoms and chlorine atoms. (Especially 70% or more is preferable)), and when there are 2 to 12 carbon atoms and an etheric oxygen atom, 1 to 4 carbon atoms and 1 to 2 carbon atoms A ratio of one is preferred. In addition, n is preferably 1.

The cyano group-containing fluorine-containing oligomer having one monomer unit represented by the formulas 1 and 2 is obtained by polymerizing the cyano group-containing fluorine-containing monomer represented by the following formulas 3 and 4 together with other monomers as necessary. Is obtained. Further, it is obtained by polymerizing a fluorine-containing monomer containing a precursor group represented by the following formulas 5 and 6, together with another monomer if necessary, and then converting the precursor group in the oligomer to a cyano group. In the following formulas 3 to 6, A, n represents the same meaning as defined above for A, n, _c B is representative of a precursor group

CF ₂ = CF- (A) _n -CN

CH ₂ = CF-(A) „-CN 'Equation 4

CF ₂ = C F- (A) _n -BEquation 5

CH ₂ = CF— (A) _n -B ··· Formula 6 The precursor groups include one COOH, -COX (where X represents a halogen atom), one COOR ³ (where R ³ is a halogen atom) Represents an alkyl group having 4 or less carbon atoms which may have a), — and a monovalent group having a carbonyl group such as CONH ₂ is preferable. These precursor groups, for example, if one COX and one COOR ³ is reacted with NH ₃ - converted into CONH _2, one CONH ₂ groups Torifuruoro acetic anhydride, is reacted with a dehydrating agent such as phosphorus pentoxide Can be converted to CN. Details of such a method for converting a precursor group into a cyano group are described in, for example, JP-A-11-120905.

Examples of the cyano group-containing fluorine-containing monomer represented by Formulas 3 and 4 include the following compounds. Examples of the precursor group-containing fluorine-containing monomers represented by Formulas 5 and 6 include, for example, compounds in which the cyano group of the following compound is the precursor group. CF ₂ = CFO (CF ₂ ) _P CN

CF ₂ = CF (OCF ₂ CF (CF ₃ )) _{q + 1} C

CF ₂ = CF (OCF ₂ CF (CF ₃ )) _r O (CF ₂ ) _S CN

CF ₂ = CF (OCF ₂ CF (CF ₂ C 1)) _t OCF ₂ CF (CF ₃ ) CN

CF ₂ = CF (OCF ₂ CF (CF ₂ C 1)) _u O (CF ₂ ) _V CN

CF ₂ = CFO (CF ₂ ) _w OCF (CF ₃ ) CN

CF ₂ = CF CN

CF ₂ = CF (CF ₂ ) _P CN

CF ₂ = CF (CF ₂ CF (CF ₃ )) _q OCF ₂ CF (CF ₃ ) CN

CF ₂ = CF (CF ₂ CF (CF ₃ )) _r O (CF ₂ ) _S CN

CF ₂ = CF (CF ₂ CF C 1) _t OCF ₂ CF (CF ₃ ) CN

CF ₂ = CF (CF ₂ CFG 1) _u O (CF ₂ ) _V CN

CF ₂ = CF (CF ₂ ) _w OCF (CF ₃ ) CN

CH ₂ = CFCF ₂ 0 (CF (CF ₃ ) CF ₂ 〇) _{q + 1} CF (CF ₃ ) CN

[However, p is an integer of 2 to 12, Q is an integer of 0 to 4, r is an integer of 1 or 2, s is an integer of 1 to 4, t is an integer of 1 to 4, u is 1 or 2, V Represents an integer of 1 to 4, and w represents an integer of 2 to 5. ].

Monomers that can be copolymerized with the fluorinated monomer represented by Formulas 3 to 6 or the fluorinated monomer having a precursor group in place of the cyano group thereof, other than the fluorinated monomer represented by Formulas 3 to 6 Is preferred. The proportion of the monomer units represented by the formulas 1 and 2 in the co-oligomer relative to the total monomer units is not particularly limited, but is suitably 10 mol% or more, and preferably 20 mol% or more. A particularly desirable ratio is 30 mol% or more. If this ratio is low, the crosslink density of the fluoropolymer (Q-2) decreases (the triazine ring content decreases).

The higher the crosslink density of the fluoropolymer (Q-2), the higher the glass transition of the polymer Temperature rises. The glass transition temperature of the fluorine-containing polymer (Q-2) should be 50 ° C or higher, more preferably 75 ° C or higher, and still more preferably 100 ° C or higher, in the operating temperature range of the obtained optical waveguide characteristics. Is preferred from the viewpoint of stability. When the fluorinated polymer (Q-1) is obtained, it can be cured by copolymerization with another monomer at the time of curing (crosslinking by addition polymerization) of the triazine ring-containing monomer as described above. Fluorine-containing monomers are also preferred as the monomers to be copolymerized.

On average, the number of cyano group-containing monomer units in the cyano group-containing fluorine-containing oligomer is 3 or more, particularly preferably 4 or more in one molecule. The upper limit is preferably 500 or less. The preferred number of one unit of a cyano group-containing monomer in the fluorine-containing oligomer having a cyano group is 3 to 100, more preferably 4 to 50, and particularly preferably 5 to 50 in one molecule. Further, the number of all monomer units in this oligomer is preferably 500 or less, more preferably 100 or less. If the number is too large, the solubility of the fluorine-containing oligomer containing a cyano group in a solvent is reduced, and crosslinking is likely to be difficult.

The other fluorinated monomer is not limited as long as it is a fluorinated monomer copolymerizable with a monomer having a cyano group or a precursor group, but the following fluorinated monomers are preferred. Tetrafluoroethylene, black trifluoroethylene, trifluoroethylene, vinylidene fluoride, 1,1-dichloro-2,2-difluoroethylene, pinyl fluoride, hexafluoropropylene, the following fluorine-containing pinyl ethers [X Is an integer from 1 to 12, and y is an integer from 1 to 50. ] And the like.

F (CF ₂ ) _x OCF = CF ₂

CF3CF2CF2O (CF (CF ₃ ) CF ₂₀ ) _y CF = CF ₂

Still other fluorine-containing monomers include perfluorocyclic monomers having a polymerizable unsaturated group in the ring such as perfluoro (2,2-dimethyl-1,3-dioxole), and perfluoro (2-methylidene-1-methyl-1,1). 3—Dioxolan) etc. Perfluorocyclic monomers having a polymerizable unsaturated group between the carbon atom of the ring and the carbon atom of the outer ring, such as perfluoro (butenyl vinyl ether) and perfluoro (arylvinyl ether) When there is a monomer, etc., when the cyano group-containing fluorine-containing oligomer is trimerized to form a triazine ring to form a fluorine-containing polymer (Q-2), the cyano group-containing fluorine-containing oligomer is simply heated to obtain a cyano group. Can be trimerized, but it is preferable to use a catalyst to promote the trimerization reaction more quickly. In addition, ammonia reacts with the cyano group to convert part or all of the cyano group to —C (= NH) —NH ₂ group, and then trimerizes simultaneously with the deammonification reaction to form a triazine ring. A method can also be used. In this method, the trimerization reaction rate is promoted more than the method of simply trimerizing the cyano group as it is.

The catalyst for trimerizing the cyano group includes at least one selected from amines, amidines, compounds having an imidoylamidine structure, acids, tetraphenyltin, transition metal salts of carboxylic acids, and peroxides. Can be used. Further, a blocked amine compound in which part or all of the active hydrogen of ammonia or an amine compound is protected with another functional group can be used as a catalyst.

The use amount of the trimerization catalyst is preferably from 0.01 to 30 parts by mass, more preferably from 0.1 to 30 parts by mass, and more preferably from 0.5 to 30 parts by mass, based on 100 parts by mass of the fluorine-containing oligomer having a cyano group. -10 parts by mass is more preferred.

As the amines, one or more selected from aliphatic amines, amines having an aliphatic ring, amines having an aromatic ring, and the like can be used. In addition, one or more selected from primary amines, secondary amines and tertiary amines can be used. One or more selected from primary amines and secondary amines are preferred because of higher catalytic activity, and primary amines are more preferred. Amines having an aromatic ring are preferred from the viewpoint of improving the heat resistance of the cured product, and aliphatic amines are preferred from the viewpoint of high catalytic activity. Further, in order to reduce the propagation loss of the optical waveguide, it is preferable to use an amine compound having a low boiling point, since it is easy to remove the remaining amine compound simultaneously with curing and by heat treatment after Z or Z or curing. . In order to enhance the compatibility with the fluorinated oligomer having a cyano group, 2- (fluoroalkyl) ethylamine, 3- (fluoroalkyl) propylamine, 4- (fluoroalkyl) aniline, 3-

(Fluoroalkyl) One or more fluorine-based amines such as aniline may be used.

Specific examples of trimerization catalysts such as amines, amidines, compounds having an imidoylamidine structure, blocked amine compounds, acids, tetrafluorophenyltin, transition metal salts of carboxylic acids, and peroxides are disclosed in, for example, There is a trimerization catalyst described in the publication of 1102905.

The fluorinated oligomer containing a cyano group can be used together with other compounds containing a cyano group, and a mixture thereof can be cured by a trimerization reaction of the cyano group to obtain a cured product. As the cyano group-containing compound, a fluorine-containing compound having one or two cyano groups other than the fluorine-containing oligomer having a cyano group is preferable. A preferred fluorinated compound is a perfluoro-alcohol having 1 to 2 cyano groups. When such a cyano group-containing compound is used in combination, the amount used is preferably 100 parts by mass or less, more preferably 1 to 70 parts by mass, based on 100 parts by mass of the cyano group-containing fluorine-containing oligomer. 5 to 50 parts by mass is more preferred.

The fluorine-containing oligomer containing a cyano group is usually cross-linked at a place where an optical waveguide is formed (that is, on the substrate) to obtain a fluorine-containing polymer (Q). However, the present invention is not limited to this, and after forming a partially crosslinked product of a cyano group-containing fluorine-containing oligomer in advance, this partial bridge may be further crosslinked at a place where an optical waveguide is formed to obtain a fluoropolymer (Q). . The partially cross-linked product must be one that can be dissolved in a solvent or one that can be processed with external energy such as heat, and that does not interfere with the formation of the core or clad. In the optical waveguide of the present invention, at least one of the core part and the clad part is made of a fluoropolymer (Q). When the core material is s-fluorinated polymer (Q), any material having a lower refractive index can be used as the cladding material. When the material of the clad portion is a fluorine-containing polymer (Q), any material having a higher refractive index than that of the core portion can be used. In any case, the material other than the fluorine-containing polymer (Q) is preferably a fluorine-containing polymer. In particular, an amorphous perfluoro polymer and a perha polyfluor polymer soluble in a solvent are preferred.

Specifically, for example, a homopolymer / copolymer of a perfluorocyclic monomer having a polymerizable unsaturated group on the ring, a perfluorocyclic ring having a polymerizable unsaturated group between a carbon atom of the ring and a carbon atom of the outer ring. There are homopolymers / copolymers of monomers and cyclized homopolymers / copolymers of cyclopolymerizable polyfluorene-based monomers. In particular, the material for the optical waveguide described in JP-A-2000-81519 is preferable. In addition, various additives may be blended to adjust the refractive index of the fluoropolymer other than the fluoropolymer (Q). For example, a material having a high refractive index can be obtained by mixing a compound having a high refractive index with a fluoropolymer.

A more preferred optical waveguide of the present invention is an optical waveguide in which the core and cladding materials are both made of fluorine-containing polymer (Q). This optical waveguide has a high affinity at the interface between the core and the clad, so that interface irregularities are less likely to occur. Since the core material and the cladding material need to have different refractive indices, the fluorine-containing polymers (Q) need to have different refractive indices. The method for controlling the refractive index is not particularly limited, and examples thereof include the following method.

(Control Method 1) Control the triazine ring density of the fluoropolymer (Q). The higher the triazine ring density, the higher the refractive index. For example, a fluoropolymer (Q-2) obtained from a cyano group-containing fluorine-containing oligomer having a high cyano group content is used as a core material using two kinds of fluorine-containing oligomers having different cyano group contents. An optical waveguide is formed by using a fluorine-containing polymer (Q-2) obtained from a fluorine-containing oligomer having a low cyano group content as a cladding material.

(Control method 2) Control the content of chlorine, bromine and hydrogen atoms in the fluoropolymer (Q). The higher the content of these atoms, the higher the refractive index. For example, a fluorine-containing polymer (Q-2) obtained from a fluorine-containing oligomer containing a chlorine atom containing a chlorine atom is used as a core material and contains no chlorine atom (but no bromine atom or hydrogen atom). An optical waveguide is formed using a fluorine-containing polymer (Q-2) obtained from a fluorine oligomer as a cladding material.

(Control method 3) Control the density of the fluoropolymer (Q). The higher the density, the higher the refractive index. For example, a fluorine-containing polymer (Q-2) obtained from a cyano group-containing fluorine-containing oligomer obtained by copolymerizing the above-mentioned perfluorocyclic monomer or a cyclizable fi-polymerizable gen-based monomer is a cyano group containing no monomer unit of the monomer. The density is lower than that of the fluorine-containing polymer (Q-2) obtained from the fluorine-containing oligomer. Therefore, an optical waveguide is formed by using the high-density one of these two types of fluorine-containing polymer (Q-2) as a core material and the low-density one as a cladding material.

(Control method 4) Compounds having different refractive indices (hereinafter referred to as dopants) are mixed with the fluoropolymer (Q). For example, an optical waveguide is formed using a mixture containing a dopant having a higher refractive index than the fluoropolymer (Q) as a core material and a fluoropolymer (Q) containing no dopant as a cladding material.

The above control methods can be used in combination of two or more. For example, a fluorine-containing polymer (Q-2) obtained from a fluorine-containing oligomer having a high cyano group content and containing chlorine is used as a core material and does not contain chlorine atoms (but also contains bromine atoms and hydrogen atoms). An optical waveguide can be formed using a fluorine-containing polymer (Q-2) obtained from a cyano group-containing fluorine-containing oligomer having a low cyano group content as a cladding material. The dopant in the above control method 4 is a dopant which does not hinder the transparency of the fluoropolymer (Q-2) and absorbs a small amount of light passing through the optical waveguide. Is preferred. As such a dopant, a fluorine-containing compound having high solubility in the fluorine-containing polymer (Q-2) and containing no hydrogen atom bonded to a carbon atom, or a particulate metal oxide is preferable. This dopant preferably has a higher refractive index than the fluorine-containing polymer (Q-2). Therefore, a fluorine-containing compound having an aromatic ring such as a benzene ring or a halogen atom other than a fluorine atom such as a chlorine atom or a bromine atom is preferable. . As such a dopant, a known dopant used for an optical material (for example, an optical fiber) using a fluoropolymer can be used. For example, using the dopants described in JP-A-8-5848, JP-A-11-67030, JP200-81915, etc. sell.

As the particulate metal oxide, a particulate metal oxide formed by hydrolyzing a metal compound having two or more hydrolyzable groups in a fluoropolymer (Q-2) is preferable. The metal atom of the hydrolyzable metal compound is preferably Si, Ti, Zr, Hf, Th or the like, and the hydrolyzable group is preferably a hydrolyzable group such as an alkoxy group or an alkylamino group. The hydrolyzable metal compound may have 2 or less non-hydrolyzable organic groups. The non-hydrolyzable organic group is preferably an organic group having a carbon atom directly bonded to a metal atom, particularly preferably an alkyl group, a polyfluoroalkyl group, an aminoalkyl group, an epoxyalkyl group and the like. Further, the fine particulate metal oxide may be formed using an initial condensate obtained by partially condensing the above hydrolyzable metal compound in advance. Specific examples of the hydrolyzable metal compound include tetraalkoxysilane, alkyltrialkoxysilane, 21- (perfluoroalkyl) ethyltrialkoxysilane, tetraalkoxytitanium, and tetraalkoxyzirconium.

Since the width of the core, the height of the core, and the interval between the mating cores are each usually 0.1 m to several tens im, which are extremely small, the heat treatment during the production of the optical waveguide is very small. As a result, the dopant in the core part may diffuse into the clad part, and a sufficient difference in the refractive index between the core part and the clad part may not be obtained. If this is a concern, do Preferably, one pant is chemically bonded to the fluoropolymer (Q).

For example, using a triazine ring-containing monomer that can be a fluoropolymer (Q-1) and a compound having a copolymerizable unsaturated group as a dopant, a triazine ring-containing monomer and this monomer are copolymerized to form a fluoropolymer (Q-1). Q-1) can be formed. Further, for example, a fluorine-containing polymer (Q-2) can be formed by using a dopant containing a cyano group and carrying out a trimerization reaction together with a fluorine-containing oligomer containing a cyano group to cure and cure. '

Furthermore, a functional group is introduced into the triazine ring-containing monomer or the cyano group-containing fluorine-containing oligomer, and the dopant is similarly chemically combined with the fluorine-containing polymer (Q) using a dopant having a functional group capable of binding to this functional group. Can be combined.

As a method of forming an optical waveguide on a substrate, usually, a layer (1) of a material to be a clad portion is formed on a substrate, and then a layer (2) of a material to be a core portion is formed on the layer (1). Then, a part of the layer (2) is removed by etching to form a core portion, and after etching, a layer (3) of a material to be a clad portion is formed on the layer (2). If each of the above-mentioned curable substances is in a liquid state, each layer may be applied as it is to form a layer of the curable substance. However, usually, a hardened substance is dissolved in a solvent, and a solution adjusted to a desired viscosity is used. After applying the solution, the solvent is removed to form a layer of the curable substance. Thereafter, by curing the curable substance, a layer of a material that is a cured product of the curable substance is formed. The removal and curing of the solvent may be performed continuously.

The viscosity of the solution can be adjusted by adjusting the concentration of the curable substance, partially crosslinking the curable substance in the solution, and the like. Removal of the solvent after coating is usually carried out by evaporating and removing the solvent by heating, but removal by reduced pressure can also be carried out. As a coating method, a spin coating method, a diving method, a potting method, a die coating method, a spray coating method, a curtain coating method, or the like is employed, and the spin coating method is particularly preferable.

When forming the above layers by curing the material, the upper layer is usually formed after the lower layer curable substance is sufficiently hardened. This method suppresses interface flatness and interface irregularities between layers. Is preferred. However, in some cases, the upper layer can be formed in a partially cured state of the lower layer curable substance. At this time, the lower layer is preferably cured to such an extent that it does not easily dissolve in the solvent of the solution applied thereon. This method can improve the adhesion between the layers. In the present invention, by using a curable substance such as a triazine ring-containing monomer or a cyano group-containing fluoropolymer, the influence of the solvent for forming the upper layer and the influence of heat on the lower layer during layering can be reduced. This makes it easy to form an optical waveguide, and a good optical waveguide can be obtained.

The concentration of the triazine ring-containing monomer or the cyano group-containing fluorinated oligomer in the coating solution is not particularly limited, but is suitably 0.1 to 80% by mass, and preferably 1 to 50% by mass. The solvent is not particularly limited as long as it can dissolve the triazine ring-containing monomer and the cyano group-containing fluorinated oligomer, but since they are fluorinated compounds, the fluorinated solvent has high solubility. More preferred. The boiling point of the solvent is suitably from 20 to 350 ° C, preferably from 40 to 300 ° C. The solvent may be a mixed solvent of two or more solvents.

Examples of the solvent include polyfluoroaromatic hydrocarbons such as perfluorobenzene, borofluorotrialkylamines such as monofluorotributylamine, dichloropentafluoropropane, 1H-perfluorohexane, Fluorooctane), (perfluorooctyl) Polyfluoroaliphatic hydrocarbons such as ethylene, polyfluoroalicyclic hydrocarbons such as perfluorodecalin, polyfluorocyclic ethers such as perfluoro (2-butyltetrahydrofuran), 2,2 Polyfluoro alcohols such as 1,3,3,4-alkyl, and alkyl polyfluoroalkyl ethers such as methyl perfluorobutyl ether and ethyl perfluoro octyl ether.

The optical waveguide of the present invention has heat stable mechanical properties and optical properties by using a three-dimensionally cross-linked fluoropolymer for the core material and the clad material. Ma Further, the adhesion between the substrate and the clad portion can be improved. In addition, when a fluorine-containing polymer cross-linked three-dimensionally is used for both the core and the clad, the adhesion at the interface between the two parts is increased, and interface irregularity is less likely to occur.

Various functional compounds can be blended in the core portion and the clad portion of the optical waveguide of the present invention, whereby various functions can be added to the optical waveguide. For example, a fluorescent functional organic dye (for example, a rhodamine-based dye having a light amplification function) can be blended. It is preferable that such a functional compound is fixed in the cladding material or the core material. ^ The three-dimensionally cross-linked fluorine-containing polymer having a triazine ring has this function by containing a triazine ring. It is effective for fixing a sex compound.

Examples of devices using the optical waveguide of the present invention include a directional coupler, an optical modulator, an optical switch, a wavelength selector, and an optical integrated circuit. Since the refractive index of the fluoropolymer in the present invention can be controlled to 1.4 or more, a 45-degree reflection structure capable of bending light 90 degrees at an extremely short distance can be employed. Therefore, optical surface mounting technology used when mounting optical devices on printed wiring boards, etc. (Uchida, Masuda: Optical surface mounting technology / ^7- optical SMT, IEICE 199 Fall National Conference 4, C-189), etc., and these substrates are applied to high-speed electronic circuit components and optical signal propagation systems such as high-speed optical LAN, subscriber optical communication, and optical switching information processing. It can be applied to a system that uses both, a package equipped with an opto-electronic hybrid integrated circuit, and an opto-electronic print that enables engineering and electrical connection with a printed wiring board. When the optical waveguide and the waveguide type optical device of the present invention are used for these applications, a higher-performance substrate having a low loss value can be formed.

Since the fluoropolymer of the present invention has a bridge structure, it has a high glass transition temperature (T g). The high T g and low water absorption make it possible to construct a highly reliable system with high environmental resistance.

Generally, when two optical waveguides having the same phase velocity are arranged close to each other, the guided light propagating through one optical waveguide gradually shifts to the other optical waveguide. Such a basic structure An element consisting of a component is called a directional coupler. The directional coupler produced using the optical waveguide of the present invention exhibits a low to very low coupling loss value similarly to the substrate, and the fluorine-containing polymer has low water absorption and high Tg. It shows very high reliability because of its characteristics. Similarly, excellent characteristics are exhibited in a waveguide-type optical device such as an optical switch / wavelength selection device or an optical modulator using the directional coupler in a multi-stage or parallel combination. Above all, low birefringence improves wavelength division accuracy in wavelength selectors (for example, AWGs (Arrayed-Waveguide G ratings)) used as main components of recent wavelength division multiplexing (WDM) communication systems. The use of the optical waveguide of the present invention makes it possible to obtain high wavelength accuracy. In addition, by changing the molar ratio of the triazine structure, a large difference in refractive index can be obtained, so that miniaturization and high integration are possible. On the other hand, a thermo-optical switch (hereinafter referred to as a TO switch) is a waveguide type optical device that makes use of the large temperature dependence of the refractive index as an application example of a plastic optical waveguide that has attracted attention in recent years. In the case of quartz, a Mach-Zehnder (MZ) type, which uses the phase difference even in thermo-optic switches, is generally used, but in the case of polymers, simple digital switches are possible by using large thermo-optical constants. is there. In the case of the digital switch comprising the optical waveguide of the present invention, since it can be configured only with a simple branching structure, it can be miniaturized and highly integrated, and is very suitable for mass production and cost reduction of waveguide components. It is a waveguide type optical device useful for. In addition, the characteristics of the fluorine-containing polymer of the present invention, such as low birefringence, low water absorption, and high Tg, can greatly contribute to high performance and high reliability of the T〇 switch. ' Example

Examples of the synthesis of triazine ring-containing monomers and fluorine-containing oligomers containing a cyano group and examples of manufacturing optical waveguides using these materials are shown below, but the present invention is not limited to these examples. Abbreviations of the used raw materials and the like are as follows. DIPDC: diisopropyl propyl perylene xydicarbonate

PBPO: perfluorobutanol peroxide

MPOH: Methyl perfluoro (5-oxa-6-heptenoate) [CF ₂ = CFOCF ₂ CF ₂ CF ₂ COOCH3]

PPVE: Perfluoro (propyl vinyl ether) [CF ₂ = CFOCF ₂ CF

CTFE: Black mouth trifluoroethylene

PDD: perfluoro (2,2-dimethyl-1'3-dioxole)

225 CB: 1,3-dichloro-1,1,1,2,2,3-pentachlorofluoropropane PFP: 2,2,3,3,3-dichlorofluoropropanol

MTBE: t-butyl methyl ether

PFO: Perfluoro (n-octane)

MPFBE: Methyl (perfluoro-n-butyl) ether

OTA: n-year-old kutylamine.

Example 1 (Synthesis example 1)

61 g (0.2 mol) of MPOH and DIP DC4 were added to an autoclave having an internal volume of 100 cc, cooled with liquid nitrogen, deaerated, and reacted at 60 ° C for 10 hours. Low-boiling components were distilled off from the reaction solution under reduced pressure, and the residue was dried under vacuum to obtain 45 g of a single polymer of MPOH (13-mer). Next, one C〇〇CH ₃ group was reacted with ammonia in the same manner as in the example described in JP-A-11-102905 to convert it into an amide group, and then reacted with trifluoroacetic anhydride / pyridine. Thus, the amide group was converted to a cyano group to obtain a fluorine-containing oligomer containing a cyano group.

Example 2 (Synthesis example 2)

A polymerization molar ratio of MPOH: PPVE = was obtained in exactly the same manner except that a mixture of 31 g (0.1 mol) of MP〇H and 27 g (0.1 mol) of PPVE was used instead of 61 g of MPOH in Synthesis Example 1. A 1: 1 copolymer (degree of polymerization 10) was obtained. Then this One COO CH ₃ group of the polymer was converted to a cyano group in the same manner as in Synthesis Example 1 to obtain a fluorine-containing oligomer containing a cyano group.

Example 3 (Solution preparation example 1)

After mixing 10 g of the fluorinated oligomer having a cyano group obtained in Synthesis Example 1 with 0.3 g of OTA, 10 g of PFO was added to form a uniform solution.

The mixture was filtered through a TFE membrane filter 1 to prepare an oligomer melt 1.

Example 4 (Solution preparation example 2)

After mixing 10 g of the cyano group-containing fluorinated oligomer obtained in Synthesis Example 2 with 0.3 g and adding 10 g of PF to make a uniform solution, the P TFE having a pore diameter of 0.5 β m was obtained. The mixture was filtered through a membrane filter to prepare an oligomer solution 2.

Example 5 (Synthesis example 3)

In a 200 cc autoclave, 25 g of MPOH (0.08 mol), 2 g of CTFE (0.02 mol), and 2 g of DI PDC (0.01 mol) are charged to the autoclave and the temperature is 60 ° C. Heating and stirring were performed for 10 hours. During this period, CTFE and MPOH were continuously fed so that the input amounts became equimolar and the polymerization pressure in the system became constant. Polymerization mole ratio MPOH: CTFE = 1: Thus, a copolymer (degree of polymerization: 20) was obtained. The _CO〇CH ₃ group of the obtained polymer was converted to a cyano group in the same manner as in Synthesis Example 1 to obtain a fluorine-containing oligomer containing a cyano group.

Example 6 (Synthesis example 4)

In a 100 cc autoclave, 1 g (0.1 mol) of MPOH3, 27 g (0.1 mol) of PVEVE, and a 5% halo% solution of PBPO (solvent: 22'5 cb) 17 · g was added, cooled with liquid nitrogen, deaerated, and reacted at 40 ° C for 5 hours. Low-boiling components were distilled off from the reaction solution under reduced pressure, and the residue was vacuum-dried to obtain a copolymer (polymerization degree: 7) having a polymerization molar ratio of MPOH: PPVE = 1: 1. Then, into a Shiano based an COOCH ₃ group in the same manner as in Synthesis Example 1 to obtain a Shiano fluorine-containing oligomer.

Example 7 (Solution preparation example 3) After dissolving 10 g of the cyano group-containing fluorinated oligomer obtained in Synthesis Example 3 and 0.3 g of zinc perfluorocarbonate [(C ₇ F ₁₅ COO) ₂ Zn] in 10 g of MTBE, 30 g of MPFBE was further dissolved. Solution 3 was prepared.

Example 8 (Solution preparation example 4)

The cyano group-containing fluorinated oligomer obtained in Synthesis Example 4 was dissolved in 225 CB so as to have a concentration of 30% by mass, and ammonia was blown therein by bubbling until the cyano group disappeared and was converted to an amidine group. After the completion of the reaction, 225 cb and the remaining ammonia were removed under reduced pressure at room temperature, and the obtained polymer was dissolved again in PFP so as to be 50% by weight, and then filtered through a PTFE membrane filter having a pore size of 0.5 m. Polymer solution 4 was prepared.

Example 9 (Synthesis example 5)

In a 100 cc autoclave, add 62 g (0.2 mol) of MPOH and 17 g of a 5% by mass solution of PBP II (solvent: 225 cb), cool with liquid nitrogen and deaerate, then use 40 for 5 hours. Reacted. Low boiling components were distilled off from the reaction solution under reduced pressure, followed by vacuum drying to obtain a homopolymer of MPOH (degree of polymerization: 7). Next, one CO〇CH ₃ group was converted to a cyano group in the same manner as in Synthesis Example 1 to obtain a fluorine-containing oligomer having a cyano group.

Example 10 (Synthesis example 6)

A polymerization molar ratio of MP OH: PDD = was obtained in exactly the same manner except that a mixture of 18 g (0.06 mol) of MPOH and 34 g (0.14 mol) of PDD was used instead of 61 g of MPOH in Synthesis Example 1. A 1: 1 copolymer (degree of polymerization 25) was obtained. Then, into a Shiano based an COOCH ₃ group in the same manner as in Synthesis Example 1 to obtain a Shiano group-containing fluorocarbon oligomers.

Example 1 1 (Solution preparation example 5)

Solution 5 was prepared in exactly the same manner and with the same composition as in Solution Preparation Example 4, except that the oligosaccharide obtained in Synthesis Example 5 was used. Example 1 2 (Solution preparation example 6)

Except that the oligomer obtained in Synthesis Example 6 was used, a solution 6 was prepared in exactly the same manner and with the same composition as in Solution Preparation Example 4.

Example 13 (Example 1)

Solution 2 is applied on a silicon substrate by spin coating, and the temperature is 80 ° C for 30 minutes.

Heating was performed at 00 ° C for 15 minutes, at 150 ° C for 15 minutes, and at 300 at 60 minutes to form a clad portion (lower clad portion) having a thickness of 10 m, and a solution 2 coated substrate was obtained. The solution 2 coated substrate was pressurized and heated by 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 100-100.

Solution 1 is spin-coated on a substrate coated with solution 2 except for the cross-cut test, and the temperature is 80 ° C for 30 minutes, 100 ° C for 15 minutes, 150 ° C for 15 minutes, 300 ° C For 60 minutes to form a 5 im thick core. 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 was removed by wet etching, and a clad portion (upper clad portion) was formed thereon by using solution 2 in the same manner as in the formation of the lower clad portion to obtain an optical waveguide. In this optical waveguide, the refractive indices of the cladding and the core were 1.36 and 1.385, respectively. When the propagation loss of the optical waveguide was measured using a light source of a semiconductor laser in this optical waveguide, it was 0.4 dB / cm or less for light with a wavelength of 650 nm and a wavelength of 650 nm.

It was 0.5 dB / cm for light at 1300 nm and 0.6 dB / cm for light at 1550 nm, and was an optical waveguide that could transmit light from visible light to ultraviolet light well. When this waveguide was heated at 150 ° C for 24 hours, the performance as an optical waveguide was measured again, and there was almost no change in the performance.

Examples 14, 15 (Examples 2, 3)

In exactly the same way as in Example 1, the waveguides shown in Table 1 were created using solutions 3 to 6. did. The performance change of this waveguide as a waveguide after heating at 150 ° C for 24 hours was measured, but almost no performance change was observed.

(table 1 )

The optical waveguide of the present invention can transmit light from ultraviolet light to near-infrared light with extremely low loss, and has extremely strong adhesion to a substrate. In addition, the heat resistance of the optical waveguide is extremely high because it is composed of a polymer having high heat resistance, and the stability of the polymer is high during the heat treatment for producing the optical waveguide.

Claims

The scope of the claims

1. 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 material of the core portion or the clad portion has a triazine ring. An optical waveguide, which is a crosslinked fluoropolymer.

2. 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 core portion and the clad portion each have a triazine ring. An optical waveguide comprising a crosslinked fluorine-containing polymer and a core portion having a higher refractive index than a cladding portion.

3. The optical waveguide according to claim 2, wherein the fluoropolymer in the core is a fluoropolymer having a high triazine ring density and a low refractive index compared to the fluoropolymer in the clad.

4. The fluorine-containing polymer in the core portion contains halogen atoms or hydrogen atoms other than fluorine atoms, and the fluorine-containing polymer in the cladding portion contains neither halogen atoms nor hydrogen atoms other than fluorine atoms. 3. The optical waveguide according to claim 2, wherein the polymer has a higher refractive index than the fluorine-containing polymer in the clad portion.

5. The optical waveguide according to claim 1, 2, 3 or 4, wherein the crosslinked fluorine-containing polymer having a triazine ring is a fluorine-containing polymer obtained by thermally crosslinking an oligomer containing a monomer unit having a cyano group. .