JP5034638B2 - Varnish containing optical doping material and optical waveguide amplifier using the same - Google Patents

Description

  The present invention relates to a varnish suitable as an optical waveguide material of an optical waveguide amplifier, and an optical waveguide amplifier using the varnish.

  2. Description of the Related Art Conventionally, an optical waveguide amplifier (optical amplifier) that relays and amplifies the intensity of an optical signal that is attenuated in the transmission process is known as a technique that enables long-distance transmission of an optical signal. This optical waveguide amplifier generally has an optical waveguide (core portion) made of silica glass or polymer doped with a rare earth metal (core part), and the signal light whose intensity is attenuated passes through the optical waveguide. In this case, the light is amplified by light corresponding to the wavelength of the signal light emitted from the rare earth metal excited by the excitation light (pump light) having energy larger than that of the signal light. The rare earth metal is composed of praseodymium (Pr, 1.3 μm band), erbium (Er, 1.55-1.61 μm band), thulium (Tm, 1.45 and 1.65 μm) depending on the wavelength of the optical signal to be amplified. Obi) etc. are used.

In recent years, development for reducing the size and weight of the optical waveguide amplifier has been actively conducted. For example, a complex (complex) in which an organic compound is coordinated to a rare earth metal is added to a polymer at a high concentration. In order to improve the signal light amplification effect, the optical waveguide length necessary for amplification is shortened (see Patent Documents 1 to 5).
JP 2000-208551 A JP 2003-258340 A JP 2005-064025 A WO 06/004187 pamphlet JP 2006-222403 A

  By the way, a fluorinated polyimide having excellent heat resistance and moisture resistance and having very high transparency in an optical communication wavelength band (1.3 to 1.6 μm) is known as an optical waveguide material.

  However, when a conventionally known rare earth metal complex is dispersed in a precursor of fluorinated polyimide, it immediately gels, making it difficult to form a thin film. It could not be used as a material.

  In view of the above, an object of the present invention is to provide a varnish of a fluorinated polyimide precursor to which a rare earth metal is added at a high concentration, and an optical waveguide amplifier using the varnish.

  In order to solve the above problems, the applicant treated the complex of rare earth metal in advance with a carboxylic acid compound and added it to the fluorinated polyimide precursor, so that the rare earth metal was added at a high concentration and transparent. Succeeded in producing a varnish from which a thin film can be obtained, leading to the present invention.

  That is, the present invention is characterized by the following items (1) to (13).

  (1) A varnish comprising: a composite obtained by reacting a rare earth metal salt and a metal alkoxide; and a carboxylic acid compound mixed in an organic solvent; and a fluorinated polyimide precursor. .

  (2) The varnish according to (1), wherein the rare earth metal is a lanthanide.

  (3) The varnish according to (1), wherein the rare earth metal is at least one selected from the group consisting of praseodymium (Pr), neodymium (Nd), erbium (Er), and thulium (Tm).

  (4) The varnish according to any one of (1) to (3), wherein the carboxylic acid compound has a pKa value (in water, 25 ° C) of 1.5 or less.

  (5) The varnish according to any one of (1) to (4), wherein the carboxylic acid compound has a boiling point of less than 300 ° C.

  (6) The varnish according to any one of (1) to (5), wherein the carboxylic acid compound has a boiling point equal to or lower than the boiling point of the organic solvent.

  (7) The varnish according to any one of (1) to (6), wherein the carboxylic acid compound does not contain an aliphatic C—H bond in the structure.

  (8) The varnish according to any one of (1) to (7), wherein the carboxylic acid compound is a halide.

（式中、Ｘは０〜５の整数）
で表されるカルボン酸化合物である上記（１）〜（８）のいずれかに記載のワニス。 (9) The carboxylic acid compound is represented by the following general formula (I)

(Where X is an integer from 0 to 5)
The varnish in any one of said (1)-(8) which is a carboxylic acid compound represented by these.

  (10) The varnish according to any one of (1) to (9), wherein the light doping material is formed by blending 50 to 400 mol of the carboxylic acid compound with respect to 1 mol of the rare earth metal.

  (11) An optical waveguide amplifier including at least an optical waveguide formed using the varnish according to any one of (1) to (10).

  (12) The optical waveguide amplifier according to (11), wherein the concentration of the rare earth metal in the core portion of the optical waveguide is 0.01 wt% to 20 wt%.

  (13) An optical doping material for an optical waveguide amplifier obtained by mixing a complex obtained by reacting a rare earth metal salt with a metal alkoxide and a carboxylic acid compound in an organic solvent.

  According to the present invention, it is possible to provide a varnish of a fluorinated polyimide precursor in which a rare earth metal is added at a high concentration and capable of producing a transparent thin film. An optical waveguide amplifier having excellent amplification efficiency can be provided.

  The varnish of the present invention includes a photodoping material obtained by mixing a complex obtained by reacting a rare earth metal salt and a metal alkoxide, and a carboxylic acid compound in an organic solvent, and a fluorinated polyimide precursor. The varnish is characterized by this, and according to this, it becomes possible to disperse the rare earth metal uniformly and at a high concentration in the fluorinated polyimide precursor.

  Hereinafter, each component will be described in detail.

<Composite>
The composite has a structure in which oxygen of a metal alkoxide is coordinated with a rare earth metal, and can be obtained, for example, by blending a salt of the rare earth metal and a metal alkoxide in a solvent and refluxing. .

  Further, the rare earth metal salt is not particularly limited, and for example, rare earth metal nitrates, sulfates, carbonates, chlorides, formates, oxalates, acetates, and the like can be used. Acetate is preferred. The rare earth metals are lanthanides (lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), Terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu)), scandium and yttrium. In the present invention, praseodymium (Pr ), Neodymium (Nd), erbium (Er) and thulium (Tm) are useful and preferred. The rare earth metal salt is preferably dehydrated at 110 to 120 ° C. for about 1 to 2 hours.

  Further, the metal alkoxide is not particularly limited, but is preferably a group 3B (barium, aluminum, gallium, indium, thallium), a group 4A (titanium, zirconium, hafnium) or a group 5A (vanadium, niobium) on the periodic table. Tantalum) and one or more alkoxides having 1 to 5 carbon atoms bonded to each other, more preferably aluminum, gallium, titanium, zirconium, niobium or tantalum, methoxide, ethoxide, propoxide, isopropoxide, A combination of one or more alkoxide groups such as butoxide. Moreover, the said metal alkoxide may be individual or may be used together 2 or more types.

  Further, the compounding ratio when the rare earth metal salt and the metal alkoxide are reacted may be appropriately determined according to the valence of the rare earth metal, and is not particularly limited. For example, an erbium salt and an aluminum alkoxide are used. In such a case, each of them is blended so that aluminum is 3 mol per 1 mol of trivalent erbium. Further, the solvent and reaction conditions used when the rare earth metal salt and the metal alkoxide are reacted may be appropriately determined so that the reaction between the two is completed, and is not particularly limited.

<Optical doping material>
The light doping material can be prepared by mixing the complex and a carboxylic acid compound in an organic solvent. Of course, a solution containing the complex in an organic solvent and a carboxylic acid in the organic solvent. You may mix and produce the solution containing a compound. By previously treating the composite with the carboxylic acid compound in this way, it is possible to suppress gelation that occurs when the composite is added directly to the fluorinated polyimide precursor. In addition, the method and conditions for mixing the complex and the carboxylic acid compound are not particularly limited.

  Although it does not specifically limit as said carboxylic acid compound, The thing whose pKa value (the acid dissociation constant in 25 degreeC in water) is 1.5 or less is preferable, and what is 1.0 or less is more preferable. When a carboxylic acid compound having a pKa value exceeding 1.5 is used, the varnish tends to gel.

  The carboxylic acid compound preferably has a boiling point of less than 300 ° C., and preferably has a boiling point lower than that of the organic solvent. If the boiling point of the carboxylic acid compound exceeds 300 ° C. or exceeds the boiling point of the organic solvent, the excess carboxylic acid compound tends to remain in the film made of the varnish of the present invention.

（式中、Ｘは０〜５の整数）
で表されるカルボン酸化合物を用いることが好ましく、具体的には、トリフルオロ酢酸（ＴＦＡ）、ペンタフルオロプロパン酸（ＦＰＡ）、ヘプタフルオロブタン酸（ＦＢＡ）、トリデカフルオロヘプタン酸（ＦＨＡ）等が挙げられる。より好ましくは、一般式のＸが０〜２のカルボン酸化合物である。 Moreover, it is preferable that the said carboxylic acid compound does not contain an aliphatic C-H bond in the structure. When an aliphatic C—H bond is included in the optical waveguide material, the light absorbed from the excited rare earth metal, particularly erbium, is absorbed as vibration energy, so that a desired amplification effect can be obtained. Cannot be performed (vibration is deactivated). Therefore, it is preferable that the carboxylic acid compound containing an aliphatic C—H bond replaces the hydrogen of the C—H bond with halogen or the like. Specifically, as the carboxylic acid compound, the following general formula (I)

(Where X is an integer from 0 to 5)
And specifically, trifluoroacetic acid (TFA), pentafluoropropanoic acid (FPA), heptafluorobutanoic acid (FBA), tridecafluoroheptanoic acid (FHA), etc. Is mentioned. More preferably, it is a carboxylic acid compound in which X in the general formula is 0 to 2.

  Moreover, it is preferable to mix | blend the said carboxylic acid compound so that it may become in the range of 50-400 mol with respect to 1 mol of rare earth metals in a composite, and it is more preferable to mix | blend so that it may become the range of 100-300 mol. preferable. By making the compounding quantity of the said carboxylic acid compound into the said range, it becomes possible to suppress the gelatinization of a varnish effectively. In addition, when a carboxylic acid compound having a relatively low pKa value (less than 2) such as trifluoroacetic acid is used, it is sufficiently gelled by setting its blending amount in the range of 50 to 100 mol. Can be suppressed. On the other hand, when a carboxylic acid compound having a slightly larger pKa value (about 2 to 4) is used, the blending amount is preferably 300 to 400 mol, thereby effectively suppressing gelation of the varnish. Is possible.

  Further, the organic solvent is not particularly limited. For example, dimethylacetamide, N-methyl-2-pyrrolidone, N, N-dimethylformamide, γ-butyrolactone, propylene glycol monomethyl ether, propylene glycol monoethyl ether, Examples include propylene glycol monopropyl ether, propylene glycol monobutyl ether, butylene glycol monomethyl ether, butylene glycol monoethyl ether, butylene glycol monopropyl ether, and butylene glycol monobutyl ether.

<Varnish of the present invention>
The varnish of the present invention is characterized by containing the above-mentioned photo-doping material and a fluorinated polyimide precursor, and can be obtained, for example, by mixing the above-mentioned photo-doping material and a fluorinated polyimide precursor. It can also be obtained by synthesizing a fluorinated polyimide precursor by polymerizing a tetracarboxylic dianhydride and a diamine component in the light doping material. In the former case, it is preferable that the solvent used in the synthesis of the fluorinated polyimide precursor and the solvent of the above-described photo-doping material are the same, and in the latter case, the solvent of the photo-doping material of the present invention. Is preferably a known solvent used in the synthesis of fluorinated polyimide precursors. Such a varnish of the present invention is suitable as a material for an optical waveguide (core part) of an optical waveguide amplifier because it has excellent film forming properties and can contain a rare earth metal at a high concentration. The film formed by coating and curing exhibits excellent strength and transparency, like the fluorinated polyimide film.

  Further, the blending ratio of the above-mentioned light doping material and the fluorinated polyimide precursor may be appropriately determined in consideration of the desired rare earth metal concentration in the fluorinated polyimide film, and is not particularly limited. In consideration of film forming property, light amplification effect, etc., it is preferable to blend 0.01% to 20% by weight of the fluorinated polyimide precursor with respect to 1 mole of the rare earth metal in the light doping material. It is more preferable to blend 1% by weight to 10% by weight.

  In addition, the varnish of the present invention realizes a state in which the composite is uniformly dispersed without causing disproportionation such as gelation when preparing a fluorinated polyimide precursor varnish containing the composite. It is characterized by being able to. Therefore, by forming the varnish of the present invention into a film, a resin film in which the composite is uniformly dispersed can be obtained. In order to achieve uniform dispersion, the composite preparation and the light doping material have special characteristics. In that sense, the photo-doping material of the present invention is suitably used for varnishes containing a fluorinated polyimide precursor as a matrix, but can also be used for varnishes containing a resin other than a fluorinated polyimide. Needless to say. That is, the varnish of the present invention includes those obtained by mixing the photo-doping material of the present invention and a resin other than a fluorinated polyimide or a precursor thereof as a matrix.

  The resin other than the fluorinated polyimide (hereinafter referred to as matrix resin) is not particularly limited as long as it is generally used for optical applications and the molded product has transparency. Specifically, acrylic resin, phenoxy resin, polystyrene, polycarbonate, polycycloolefin, natural rubber, polyisoprene, poly-1,2-butadiene, polyisobutene, polybutene, poly-2-heptyl-1,3-butadiene, (Di) enes such as poly-2-t-butyl-1,3-butadiene, poly-1,3-butadiene, polyoxyethylene, polyoxypropylene, polyvinyl ethyl ether, polyvinyl hexyl ether, polyvinyl butyl ether, and other poly Preferred examples include ethers, polyesters such as polyvinyl acetate and polyvinyl propionate, polyurethane, ethyl cellulose, polyvinyl chloride, polyacrylonitrile, polymethacrylonitrile, polysulfone, polysulfide, and the like. It may be used in combination of two or more.

  In addition to the above, polyimide resin, polybenzimidazole resin, polybenzoxazole resin, ethylene vinyl acetate copolymer, modified ethylene-vinyl acetate copolymer, polyethylene, ethylene-propylene copolymer, ethylene-acrylic acid copolymer Polymer, ethylene-acrylate copolymer, ethylene-acrylate copolymer, acrylate rubber, polyisobutylene, atactic polypropylene, polyvinyl butyral, acrylonitrile-butadiene copolymer, styrene-butadiene block copolymer Synthetic rubbers such as coalescence, styrene-isoprene block copolymer, ethylene cellulose, polyamide, silicone rubber, polychloroprene, silicone, polyvinyl ether, etc. are applicable, and these may be used alone or in combination of two or more. It is also possible to have.

  In addition, silicone resin, polysilane, polysilazane, organic-inorganic hybrid resin by a sol-gel method, and the like can also be used.

  The matrix resin needs to be appropriately selected depending on the application. In the optical waveguide amplifier application of the present invention, it is necessary to consider the transparency in the wavelength range to be used. Here, the wavelength range used should be considered about both the wavelength range used for excitation light, and the wavelength range used as signal light.

  In applications where heat resistance is required in the optical waveguide amplifier manufacturing process or usage environment, polyimide resins, epoxy resins, polyamide resins, polyquinoline resins, and the like are preferable. Examples of the polyimide resin include polyimide resin, poly (imide / isoindoloquinazolinedioneimide) resin, polyetherimide resin, polyamideimide resin, and polyesterimide resin.

  As the excitation light used in the optical waveguide amplifier, a light source having a light intensity higher than that of the signal light is used. Therefore, a matrix resin should be selected in consideration of resistance to the excitation light source and long-term reliability. Also from this viewpoint, it is preferable to select a resin having high heat resistance as described above in consideration of a temperature rise caused by excitation light.

  When the wavelength of the light source used in the optical waveguide amplifier is in the near infrared region, it is preferable to use a resin containing fluorine from the viewpoint of transparency. As the resin containing fluorine, an amorphous fluororesin can be suitably used, and examples thereof include Teflon AF manufactured by DuPont and Cytop manufactured by Asahi Glass. From the viewpoint of having both transparency and heat resistance, fluorinated polyimide is most preferable. In the present invention, “fluorinated polyimide” means a polyimide resin having fluorine in the structure. For example, a polyimide resin having fluorine, poly (imide / isoindoloquinazolinedioneimide) having fluorine. Examples thereof include a resin, a polyetherimide resin having fluorine, and a polyamideimide resin having fluorine.

（式中、ｎは１である）
で表されるフッ素化ポリアミド酸であることがより好ましい。 In manufacturing an optical waveguide amplifier, it is necessary to select a matrix resin in consideration of the fact that a core layer and a cladding layer as an optical waveguide must be laminated. In other words, when laminating the core layer and the clad layer by film formation, select a resin and manufacturing method that can avoid problems such as dissolution of the lower layer or intermixing with the lower layer when forming the upper layer. There is a need to. From this point of view, select a resin that is insolubilized by crosslinking, etc., at the time of film formation or after film formation, or a resin that is insolubilized due to a change in solubility in a solvent due to a reaction during film formation or after film formation. It is preferable. Examples of the former include thermosetting resins in a narrow sense, that is, resins that form a network structure and resins that cause intermolecular crosslinking. Examples of the latter include polyimide precursor varnishes such as polyamic acid, and the precursor varnish is converted to a polyimide skeleton structure by heat treatment at 200 to 400 ° C. Become insoluble. The polyamic acid is not particularly limited, but is preferably a fluorinated polyamic acid in which an aliphatic C—H bond hydrogen is substituted with fluorine, and the following general formula (II)

(Where n is 1)
The fluorinated polyamic acid represented by the formula is more preferable.

  The polyimide precursor varnish is usually obtained by the reaction of tetracarboxylic dianhydride and diamine in a polar solvent such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, γ-butyrolactone, dimethyl sulfoxide, If at least one of tetracarboxylic dianhydride and diamine has fluorine, it becomes a fluorinated polyimide precursor. The diamine component and the carboxylic dianhydride component are preferably reacted as approximately equimolar amounts, the reaction temperature is usually 0 to 40 ° C., and the reaction time is usually in the range of 30 minutes to 50 hours. In the present invention, unless otherwise specified, both a fully fluorinated polyimide and a partially fluorinated polyimide are expressed as fluorinated polyimide.

  Examples of tetracarboxylic dianhydrides having fluorine include (trifluoromethyl) pyromellitic dianhydride, di (trifluoromethyl) pyromellitic dianhydride, di (heptafluoropropyl) pyromellitic dianhydride , Pentafluoroethylpyromellitic dianhydride, bis {3,5-di (trifluoromethyl) phenoxy} pyromellitic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane Dianhydride, 5,5'-bis (trifluoromethyl) -3,3 ', 4,4'-tetracarboxybiphenyl dianhydride, 2,2', 5,5'-tetrakis (trifluoromethyl)- 3,3 ', 4,4'-tetracarboxybiphenyl dianhydride, 5,5'-bis (trifluoromethyl) -3,3', 4,4'-tetracarbo Sidiphenyl ether dianhydride, 5,5'-bis (trifluoromethyl) -3,3 ', 4,4'-tetracarboxybenzophenone dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} benzene dianhydride Bis {(trifluoromethyl) dicarboxyphenoxy} (trifluoromethyl) benzene dianhydride, bis (dicarboxyphenoxy) (trifluoromethyl) benzene dianhydride, bis (dicarboxyphenoxy) bis (trifluoromethyl) Benzene dianhydride, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene dianhydride, 2,2-bis {(4- (3,4-dicarboxyphenoxy) phenyl} hexafluoropropane dianhydride, bis {(Trifluoromethyl) dicarboxyphenoxy} bi Phenyl dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} bis (trifluoromethyl) biphenyl dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} diphenyl ether dianhydride, bis (dicarboxyphenoxy) bis (Trifluoromethyl) biphenyl dianhydride, 1,4-bis (2-hydroxyhexafluoroisopropyl) benzene bis (trimellitic anhydride), 1,3-bis (2-hydroxyhexafluoroisopropyl) benzene bis (tri Merit acid anhydride), and the like.

  Examples of tetracarboxylic dianhydrides having no fluorine include pyromellitic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, 3,3 ′, 4,4′-diph. Enyltetracarboxylic dianhydride, 2,2 ', 3,3'-diphenyltetracarboxylic dianhydride, 2,3,3', 4'-diphenyltetracarboxylic dianhydride, p-terphenyl -3,4,3 ", 4" -tetracarboxylic dianhydride, m-terphenyl-3,4,3 ", 4" -tetracarboxylic dianhydride, 1,2,5,6-naphthalenetetra Carboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,2,4,5-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic acid Dianhydride, 2,6-dichloronaphthalene-1, , 5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8, tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4 , 5,8-tetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 3,3 ', 4 , 4'-Benzophenone tetracarboxylic dianhydride, 2,2 ', 3,3'-benzophenone tetracarboxylic dianhydride, 2,3,3', 4'-benzophenone tetracarboxylic dianhydride 3,3 ', 4,4'-biphenyl ether tetracarboxylic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, 3,3', 4,4'-tetraphenylsilane tetracarboxylic acid Dianhydride, 3,3'-4,4'-diph Phenyl ether tetracarboxylic dianhydride, 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3-tetramethyldisiloxane dianhydride, 1- (2,3-dicarboxyphenyl) ) -3- (3,4-dicarboxyphenyl) -1,1,3,3-tetramethyldisiloxane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4- Dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxy) Phenyl) sulfone dianhydride, Nanthrene-1,8,9,10-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride Bis (3,4-dicarboxyphenyl) dimethylsilane dianhydride, bis (3,4-dicarboxyphenyl) methylphenylsilane dianhydride, bis (3,4-dicarboxyphenyl) diphenylsilane dianhydride Anhydride, 1,4-bis (3,4-dicarboxyphenyldimethylsilyl) benzene dianhydride, 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3-tetra Methyldicyclohexane dianhydride, p-phenylbis (trimellitic acid monoester acid anhydride) ethylene glycol bis (trimellitic acid anhydride), propanediol bis (trimellitic acid) Water), butanediol bis (trimellitic acid anhydride), pentanediol bis (trimellitic acid anhydride), hexanediol bis (trimellitic acid anhydride), octanediol bis (trimellitic acid anhydride), decanediol bis (trimellitic acid) Anhydride), ethylenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, decahydronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 4,8 -Dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride Pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, bis (exo -Bicyclo [2,2,1] heptane-2,3-dicarboxylic anhydride) sulfonbicyclo- (2,2,2) -oct (7) -ene-2,3,5,6-tetracarboxylic acid Anhydride, 4,4'-bis (3,4-dicarboxyphenoxy) diphenylsulfide dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene- 1,2-dicarboxylic anhydride, tetrahydrofuran-2,3,4,5-tetracarboxylic dianhydride, and the like may be mentioned, and two or more kinds may be mixed and used.

  Examples of diamines having fluorine include 4- (1H, 1H, 11H-eicosafluoroundecanoxy) -1,3-diaminobenzene, 4- (1H, 1H-perfluoro-1-butanoxy) -1 , 3-diaminobenzene, 4- (1H, 1H-perfluoro-1-heptanoxy) -1,3-diaminobenzene, 4- (1H, 1H-perfluoro-1-octanoxy) -1,3-diaminobenzene, 4-pentafluorophenoxy-1,3-diaminobenzene, 4- (2,3,5,6-tetrafluorophenoxy) -1,3-diaminobenzene, 4- (4-fluorophenoxy) -1,3-diamino Benzene, 4- (1H, 1H, 2H, 2H-perfluoro-1-hexanoxy) -1,3-diaminobenzene, 4- (1H, 1H, 2H, 2H-par Fluoro-1-dodecanoxy) -1,3-diaminobenzene, (2,5-) diaminobenzotrifluoride, bis (trifluoromethyl) phenylenediamine, diaminotetra (trifluoromethyl) benzene, diamino (pentafluoroethyl) benzene 2,5-diamino (perfluorohexyl) benzene, 2,5-diamino (perfluorobutyl) benzene, 1,4-bis (4-aminophenyl) benzene, p-bis (4-amino-2-trifluoro) Methylphenoxy) benzene, bis (aminophenoxy) bis (trifluoromethyl) benzene, bis (aminophenoxy) tetrakis (trifluoromethyl) benzene, bis {2-[(aminophenoxy) phenyl] hexafluoroisopropyl} benzene 2,2 ′ -Bis (G Fluoromethyl) -4,4'-diaminobiphenyl, 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, octafluorobenzidine, bis {(trifluoromethyl) aminophenoxy} biphenyl, 4, 4'-bis (4-amino-2-trifluoromethylphenoxy) biphenyl, 4,4'-bis (4-amino-3-trifluoromethylphenoxy) biphenyl, 1,4-bis (anilino) octafluorobutane, 1,5-bis (anilino) decafluoropentane, 1,7-bis (anilino) tetradecafluoroheptane, 3,3'-difluoro-4,4'-diaminodiphenyl ether, 3,3 ', 5,5'- Tetofluoro-4,4'-diaminodiphenyl ether, 2,2'-bis (trifluoromethyl) -4, 4'-diaminodiphenyl ether, 3,3'-bis (trifluoromethyl) -4,4'-diaminodiphenyl ether, 3,3 ', 5,5'-tetrakis (trifluoromethyl) -4,4'-diaminodiphenyl ether 3,3'-difluoro-4,4'-diaminodiphenylmethane, 3,3'-di (trifluoromethyl) -4,4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetrafluoro-4 , 4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetrakis (trifluoromethyl) -4,4'-diaminodiphenylmethane, 3,3'-difluoro-4,4'-diaminodiphenylpropane, 3, 3 ', 5,5'-tetrafluoro-4,4'-diaminodiphenylpropane, 3,3'-bis (trifluoromethyl)- , 4'-diaminodiphenylpropane, 3,3 ', 5,5'-tetra (trifluoromethyl) -4,4'-diaminodiphenylpropane, 3,3'-difluoro-4,4'-diaminodiphenylsulfone, 3,3 ', 5,5'-tetrafluoro-4,4'-diaminodiphenylsulfone, 3,3'-bis (trifluoromethyl) -4,4'-diaminodiphenylsulfone, 3,3', 5 5'-tetrakis (trifluoromethyl) -4,4'-diaminodiphenylsulfone, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) diphenylsulfone, 4,4'-bis (3-amino -5-trifluoromethylphenoxy) diphenylsulfone, 3,3'-difluoro-4,4'-diaminodiphenyl sulfide, 3,3 ', 5 5'-tetrafluoro-4,4'-diaminodiphenyl sulfide, 3,3'-bis (trifluoromethyl) -4,4'-diaminodiphenyl sulfide, 3,3 ', 5,5'-tetrakis (trifluoro Methyl) -4,4'-diaminodiphenyl sulfide, 3,3'-difluoro-4,4'-diaminobenzophenone, 3,3 ', 5,5'-tetrafluoro-4,4'-diaminobenzophenone, 3,3 '-Bis (trifluoromethyl) -4,4'-diaminobenzophenone, 3,3', 5,5'-tetra (trifluoromethyl) -4,4'-diaminobenzophenone, 4,4'-diamino-p -Terphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylhexafluoropropane, 3,3'-dimethoxy-4,4'-diamino Diphenylhexafluoropropane, 3,3'-diethoxy-4,4'-diaminodiphenylhexafluoropropane, 3,3'-difluoro-4,4'-diaminodiphenylhexafluoropropane, 3,3'-dichloro-4, 4'-diaminodiphenylhexafluoropropane, 3,3'-dibromo-4,4'-diaminodiphenylhexafluoropropane, 3,3 ', 5,5'-tetramethyl-4,4'-diaminodiphenylhexafluoropropane 3,3 ′, 5,5′-tetramethoxy-4,4′-diaminodiphenylhexafluoropropane, 3,3 ′, 5,5′-tetraethoxy-4,4′-diaminodiphenylhexafluoropropane, 3, , 3 ', 5,5'-Tetrafluoro-4,4'-diaminodiphenylhexafluoro Lopan, 3,3 ′, 5,5′-tetrachloro-4,4′-diaminodiphenylhexafluoropropane, 3,3 ′, 5,5′-tetrabromo-4,4′-diaminodiphenylhexafluoropropane, 3 , 3 ', 5,5'-tetrakis (trifluoromethyl) -4,4'-diaminodiphenylhexafluoropropane, 3,3'-bis (trifluoromethyl) -4,4'-diaminodiphenylhexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (anilino) hexafluoropropane, 2,2-bis {4- (4-aminophenoxy) phenyl} hexafluoropropane, 2,2 -Bis {4- (3-aminophenoxy) phenyl} hexafluoropropane, 2,2-bis {4- (2-amino) Enoxy) phenyl} hexafluoropropane, 2,2-bis {4- (4-aminophenoxy) -3,5-dimethylphenyl} hexafluoropropane, 2,2-bis {4- (4-aminophenoxy) -3 , 5-ditrifluoromethylphenyl} hexafluoropropane, 2,2-bis {4- (4-amino-3-trifluoromethylphenoxy) phenyl} hexafluoropropane, bis [{(trifluoromethyl) aminophenoxy} phenyl ] Hexafluoropropane, 1,3-diamino-5- (perfluorononenyloxy) benzene, 1,3-diamino-4-methyl-5- (perfluorononenyloxy) benzene, 1,3-diamino-4 -Methoxy-5- (perfluorononenyloxy) benzene, 1,3-diamino-2,4,6 -Trifluoro-5- (perfluorononenyloxy) benzene, 1,3-diamino-4-chloro-5- (perfluorononenyloxy) benzene, 1,3-diamino-4-bromo-5- (per Fluorononenyloxy) benzene, 1,2-diamino-4- (perfluorononenyloxy) benzene, 1,2-diamino-4-methyl-5- (perfluorononenyloxy) benzene, 1,2-diamino -4-methoxy-5- (perfluorononenyloxy) benzene, 1,2-diamino-3,4,6-trifluoro-5- (perfluorononenyloxy) benzene, 1,2-diamino-4- Chloro-5- (perfluorononenyloxy) benzene, 1,2-diamino-4-bromo-5- (perfluorononenyloxy) benzene, 1,4-di Mino-3- (perfluorononenyloxy) benzene, 1,4-diamino-2-methyl-5- (perfluorononenyloxy) benzene, 1,4-diamino-2-methoxy-5- (perfluoronone) Nyloxy) benzene, 1,4-diamino-2,3,6-trifluoro-5- (perfluorononenyloxy) benzene, 1,4-diamino-2-chloro-5- (perfluorononenyloxy) Benzene, 1,4-diamino-2-bromo-5- (perfluorononenyloxy) benzene, 1,3-diamino-5- (perfluorohexenyloxy) benzene, 1,3-diamino-4-methyl-5 -(Perfluorohexenyloxy) benzene, 1,3-diamino-4-methoxy-5- (perfluorohexenyloxy) benzene, 1,3-di Mino-2,4,6-trifluoro-5- (perfluorohexenyloxy) benzene, 1,3-diamino-4-chloro-5- (perfluorohexenyloxy) benzene, 1,3-diamino-4-bromo -5- (perfluorohexenyloxy) benzene, 1,2-diamino-4- (perfluorohexenyloxy) benzene, 1,2-diamino-4-methyl-5- (perfluorohexenyloxy) benzene, 1,2 -Diamino-4-methoxy-5- (perfluorohexenyloxy) benzene, 1,2-diamino-3,4,6-trifluoro-5- (perfluorohexenyloxy) benzene, 1,2-diamino-4- Chloro-5- (perfluorohexenyloxy) benzene, 1,2-diamino-4-bromo-5- (perfluorohexyl) Senyloxy) benzene, 1,4-diamino-3- (perfluorohexenyloxy) benzene, 1,4-diamino-2-methyl-5- (perfluorohexenyloxy) benzene, 1,4-diamino-2-methoxy- 5- (perfluorohexenyloxy) benzene, 1,4-diamino-2,3,6-trifluoro-5- (perfluorohexenyloxy) benzene, 1,4-diamino-2-chloro-5- (perfluoro Hexenyloxy) benzene, 1,4-diamino-2-bromo-5- (perfluorohexenyloxy) benzene and the like may be used, and two or more kinds may be mixed and used.

  Examples of diamines having no fluorine include p-phenylenediamine, m-phenylenediamine, 2,6-diaminopyridine, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, benzidine, 3,3′- Dimethylbenzidine, 3,3'-dimethoxybenzidine, 3,3'-diaminobenzophenone, 3,3'-dimethyl-4,4'-diaminobenzophenone, 3,3'-dimethoxy-4,4'-diaminobenzophenone, 3, 3,3'-diethoxy-4,4'-diaminobenzophenone, 3,3'-dichloro-4,4'-diaminobenzophenone, 3,3'-dibromo-4,4'-diaminobenzophenone, 3,3 ', 5 , 5'-tetramethyl-4,4'-diaminobenzophenone, 3,3 ', 5,5'-tetramethoxy-4,4'-di Minobenzophenone, 3,3 ′, 5,5′-tetraethoxy-4,4′-diaminobenzophenone, 3,3 ′, 5,5′-tetrachloro-4,4′-diaminobenzophenone, 3,3 ′, 5,5'-tetrabromo-4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,3'-dimethyl- 4,4'-diaminodiphenyl ether, 3,3'-diisopropyl-4,4'-diaminodiphenyl ether, 3,3'-dimethoxy-4,4'-diaminodiphenyl ether, 3,3'-diethoxy-4,4'- Diaminodiphenyl ether, 3,3'-dichloro-4,4'-diaminodiphenyl ether, 3,3'-dibromo-4, '-Diaminodiphenyl ether, 3,3', 5,5'-tetramethyl-4,4'-diaminodiphenyl ether, 3,3 ', 5,5'-tetraethyl-4,4'-diaminodiphenyl ether, 3,3' , 5,5'-tetramethoxy-4,4'-diaminodiphenyl ether, 3,3 ', 5,5'-tetraethoxy-4,4'-diaminodiphenyl ether, 3,3', 5,5'-tetrachloro -4,4'-diaminodiphenyl ether, 3,3 ', 5,5'-tetrabromo-4,4'-diaminodiphenyl ether, 3,3'-diisopropyl-5,5'-dimethyl-4,4'-diaminodiphenyl ether 3,3′-diisopropyl-5,5′-diethyl-4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl Tan, 3,3'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethoxy-4 , 4'-diaminodiphenylmethane, 3,3'-diethoxy-4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,3'-dibromo-4,4'-diamino Diphenylmethane, 3,3 ', 5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 3,3', 5,5'-tetraisopropyl-4,4'-diaminodiphenylmethane, 3,3 ', 5 , 5'-tetramethoxy-4,4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetraethoxy-4,4'-diaminodiphenylmethane 3,3 ', 5,5'-tetrachloro-4,4'-diaminodiphenylmethane, 3,3', 5,5'-tetrabromo-4,4'-diaminodiphenylmethane, 3,3 ', 5 5'-tetraisopropyl-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl-5,5'-diethyl- 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 3,3'-dimethyl-4,4'-diaminodiphenylpropane, 3,3'-dimethoxy-4 , 4'-diaminodiphenylpropane, 3,3'-diethoxy-4,4'-diaminodiphenylpropane, 3,3'-dichloro-4,4 -Diaminodiphenylpropane, 3,3'-dibromo-4,4'-diaminodiphenylpropane, 3,3 ', 5,5'-tetramethyl-4,4'-diaminodiphenylpropane, 3,3', 5 5'-tetramethoxy-4,4'-diaminodiphenylpropane, 3,3 ', 5,5'-tetraethoxy-4,4'-diaminodiphenylpropane, 3,3', 5,5'-tetrachloro- 4,4'-diaminodiphenylpropane, 3,3 ', 5,5'-tetrabromo-4,4'-diaminodiphenylpropane, 3,3'-diisopropyl-5,5'-dimethyl-4,4'-diamino Diphenylpropane, 3,3'-diisopropyl-5,5'-diethyl-4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylsulfone, 3,3 ' -Diaminodiphenyl sulfone, 3,3'-dimethyl-4,4'-diaminodiphenyl sulfone, 3,3'-dimethoxy-4,4'-diaminodiphenyl sulfone, 3,3'-diethoxy-4,4'-diamino Diphenylsulfone, 3,3'-dichloro-4,4'-diaminodiphenylsulfone, 3,3'-dibromo-4,4'-diaminodiphenylsulfone, 3,3 ', 5,5'-tetramethyl-4, 4'-diaminodiphenyl sulfone, 3,3 ', 5,5'-tetramethoxy-4,4'-diaminodiphenyl sulfone, 3,3', 5,5'-tetraethoxy-4,4'-diaminodiphenyl sulfone 3,3 ', 5,5'-tetrachloro-4,4'-diaminodiphenyl sulfone, 3,3', 5,5'-tetrabromo-4,4'-diamidine Diphenylsulfone, 3,3'-diisopropyl-5,5'-dimethyl-4,4'-diaminodiphenylsulfone, 3,3'-diisopropyl-5,5'-diethyl-4,4'-diaminodiphenylsulfone, 4 , 4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 3,3'-dimethyl-4,4'-diaminodiphenyl sulfide, 3,3'-dimethoxy-4,4'-diaminodiphenyl sulfide, 3, 3,3'-diethoxy-4,4'-diaminodiphenyl sulfide, 3,3'-dichloro-4,4'-diaminodiphenyl sulfide, 3,3'-dibromo-4,4'-diaminodiphenyl sulfide, 3,3 ', 5,5'-tetramethyl-4,4'-diaminodiphenyl sulfide, 3,3', 5,5 ' Tetramethoxy-4,4'-diaminodiphenyl sulfide, 3,3 ', 5,5'-tetraethoxy-4,4'-diaminodiphenyl sulfide, 3,3', 5,5'-tetrachloro-4,4 '-Diaminodiphenyl sulfide, 3,3', 5,5'-tetrabromo-4,4'-diaminodiphenyl sulfide, 1,4-bis- (4-aminophenoxy) benzene, 1,3-bis- (4- Aminophenoxy) benzene, 2,2-bis- (4-aminophenoxyphenyl) propane, bis- (4-aminophenoxyphenyl) sulfone, bis- (4-aminophenoxyphenyl) sulfide, bis- (4-aminophenoxyphenyl) ) Biphenyl, 4,4'-diaminodiphenyl ether-3-sulfonamide, 3,4'-diaminodiphenyl Ether-4-sulfonamide, 3,4'-diaminodiphenyl ether-3'-sulfonamide, 3,3'-diaminodiphenyl ether-4-sulfonamide, 4,4'-diaminodiphenylmethane-3-sulfonamide, 3,4 '-Diaminodiphenylmethane-4-sulfonamide, 3,4'-diaminodiphenylmethane-3'-sulfonamide, 3,3'-diaminodiphenylmethane-4-sulfonamide, 4,4'-diaminodiphenylsulfone-3-sulfonamide 3,4'-diaminodiphenylsulfone-4-sulfonamide, 3,4'-diaminodiphenylsulfone-3'-sulfonamide, 3,3'-diaminodiphenylsulfone-4-sulfonamide, 4,4'-diamino Diphenyl sulfide-3-sulfonami 3,4'-diaminodiphenyl sulfide-4-sulfonamide, 3,3'-diaminodiphenyl sulfide-4-sulfonamide, 3,4'-diaminodiphenyl sulfide-3'-sulfonamide, 1,4-diaminobenzene -2-sulfonamide, 4,4'-diaminodiphenyl ether-3-carbonamide, 3,4'-diaminodiphenyl ether-4-carbonamide, 3,4'-diaminodiphenyl ether-3'-carbonamide, 3,3 ' -Diaminodiphenyl ether-4-carbonamide, 4,4'-diaminodiphenylmethane-3-carbonamide, 3,4'-diaminodiphenylmethane-4-carbonamide, 3,4'-diaminodiphenylmethane-3'-carbonamide, 3, , 3'-Diaminodiphe Rumethane-4-carbonamide, 4,4'-diaminodiphenylsulfone-3-carbonamide, 3,4'-diaminodiphenylsulfone-4-carbonamide, 3,4'-diaminodiphenylsulfone-3'-carbonamide, 3,3'-diaminodiphenylsulfone-4-carbonamide, 4,4'-diaminodiphenyl sulfide-3-carbonamide, 3,4'-diaminodiphenyl sulfide-4-carbonamide, 3,3'-diaminodiphenyl sulfide -4-carbonamide, 3,4'-diaminodiphenyl sulfide-3'-carbonamide, 1,4-diaminobenzene-2-carbonamide, 4-aminophenyl-3-aminobenzoic acid, 2,2-bis (4 -Aminophenyl) propane, bis- (4-aminophenol) Nyl) diethylsilane, bis- (4-aminophenyl) diphenylsilane, bis- (4-aminophenyl) ethylphosphine oxide, bis- (4-aminophenyl) -N-butylamine, bis- (4-aminophenyl) -N-methylamine N- (3-aminophenyl) -4-aminobenzamide, 2,4-bis- (β-amino-t-butyl) toluene, bis- (p-β-amino-t-butyl-phenyl) ether, bis- (P-β-methyl-γ-amino-pentyl) benzene, bis-p- (1,1-dimethyl-5-aminopentyl) benzene, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, deca Methylenediamine, tetramethylenediamine, propylenediamine, 3-methylhept Methylenediamine, 4,4'-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis- (3-aminopropoxy) ethane, 2,2-dimethylpropylenediamine, 3-methoxy-hexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 5-methylnonamethylenediamine, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10 -Dimethyldecane, 1,12-diaminooctadecane, etc. are mentioned, and two or more kinds may be mixed and used.

  Silicon diamine may be used as part of the diamine. Silicon diamines include 1,3-bis (3-aminopropyl) -1,1,1-tetraphenyldisiloxane, 1,3-bis (3-aminopropyl) -1,1,1-tetramethyldisiloxane 1,3-bis (4-aminobutyl) -1,1,1-tetramethyldisiloxane. When using silicon diamine, it is preferable to use 0.1-10 mol% of these with respect to the total amount of diamine. Two or more of the above tetracarboxylic dianhydrides and diamines may be used in combination. As the polyimide resin precursor solution, one having photosensitivity can also be used.

  In addition, when reacting a diamine component or a tetracarboxylic dianhydride component, if there is a large amount of water in the polar solvent, the two will not react easily and a predetermined viscosity cannot be obtained. The viscosity of the fluorinated polyimide precursor varnish suitable for application to an optical material or electronic component material utilizing an amplification function is preferably 1 poise or more, more preferably 5 poise or more, from the coating strength, coating thickness, etc. In particular, it is preferably 10 poise or more. In order to obtain a fluorinated polyimide precursor varnish having a viscosity of 1 poise or more, the water content in the polar solvent during the reaction is preferably 0.05% by weight or less, more preferably 0.03%. % By weight or less, particularly preferably 0.01% by weight or less. A polar solvent with a low water content can be obtained by adding a dehydrating agent such as molecular sieve to the polar solvent and storing it.

  Moreover, the fluorinated polyimide precursor varnish obtained by reacting the diamine component and the tetracarboxylic dianhydride component is heated to 40 ° C. to 80 ° C. to adjust the desired viscosity. When added, a fluorinated polyimide precursor varnish having excellent viscosity stability when stored at a low temperature can be obtained. From the viewpoint of viscosity stability, the amount of water added is preferably such that the water content in the fluorinated polyimide precursor varnish is 0.13 wt% or more and 1.0 wt% or less, 0.20 wt% It is more preferable to add it so that it may become% or more and 1.0 weight% or less, and it is especially preferable to add so that it may become 0.25 weight% or more and 1.0 weight% or less. Note that the water content also takes into account the amount of water contained in the polar solvent. When the water content in the fluorinated polyimide precursor varnish is less than 0.13% by weight, when the fluorinated polyimide precursor varnish is stored at a low temperature, the viscosity tends to increase. On the other hand, when the water content in the fluorinated polyimide precursor varnish exceeds 1.0% by weight, the coating film tends to be whitened when the polyimide coating film is formed.

The above complex may cause disproportionation such as gelation and precipitation due to the presence of water in the solvent, but by using the above-mentioned material for photodoping of the present invention, even in a solution containing water. The complex can be uniformly dispersed. That is, the optical doping material of the present invention has been completed as a result of intensive studies so that it can be suitably mixed with a fluorinated polyimide precursor varnish containing water. Therefore, the varnish of the present invention is preferably a varnish containing the above-mentioned photo-doping material, a fluorinated polyimide precursor, and the above-mentioned predetermined range of water. In addition, the storage temperature of the fluorinated polyimide precursor varnish is preferably 0 ° C. or less, more preferably −10 ° C. or less, and particularly preferably −20 ° C. or less from the viewpoint of viscosity stability. When storage temperature is higher than 0 degreeC, the viscosity of a fluorinated polyimide precursor varnish will fall.

  In addition, the content of the composite in the varnish of the present invention is appropriately determined according to the use form, such as the transparency of the cured product (film) produced using the varnish, the amplification factor by stimulated emission, and the refractive index. Although there is no particular limitation, it is preferably in the range of 0.01 to 50% by weight, and more preferably in the range of 0.1 to 40% by weight. More preferably, it is 0.1-20 weight%, More preferably, it is 1-10 weight%. When the optical waveguide of the optical waveguide amplifier is configured, if the length of the optical waveguide, that is, the length contributing to the amplification of the optical signal is long, the content of the composite in the varnish (core layer) of the present invention is The effect as an optical amplifier can be obtained even with a small amount. In this case, since transparency can be reduced by containing the composite, that is, an increase in light loss can be minimized, and an increase in refractive index due to the composite can be reduced. An optical waveguide amplifier having a small refractive index difference between the core and the clad can be realized, and as a result, coupling loss in connection with a normal optical fiber can be reduced. In the conventional rare earth-doped optical fiber, there is a problem that the loss in connection with the optical fiber increases because the relative refractive index difference between the core and the cladding increases. In order to avoid this, it is necessary to add a process such as performing a special process such as a TEC process on the connection part, which increases the manufacturing cost.

  On the other hand, when the content of the complex in the varnish (core layer) of the present invention is increased, conventionally, fluorescence is deactivated by concentration quenching or multiphonon relaxation, and excited rare earth ions are in a form other than the light emission process. Although there was a problem that the amplification effect could not be obtained due to loss of energy, in the present invention, as shown in the examples described later, even if the composite was contained in a high concentration in the varnish (core layer), the loss was lost. Fluorescence can be observed without being activated. Thus, it is one of the effects of the present invention that the complex can be contained at a high concentration, and if the complex is contained at a high concentration, the amplification factor per unit length is increased. Therefore, a predetermined optical gain can be obtained even with a short length. That is, if the optical waveguide of the optical waveguide amplifier is configured using the varnish of the present invention containing the composite at a high concentration, the optical waveguide amplifier can be reduced in size and the manufacturing cost can be greatly reduced. The content of the composite is more accurately measured from the residue obtained by heating the varnish of the present invention or a cured product thereof to 900 ° C. at a heating rate of 10 to 50 ° C./min and thermally decomposing it. it can.

  In addition, the shape of the cured product obtained by curing the varnish of the present invention with heat or light may be appropriately determined according to the use form, and is not particularly limited, but when used as an optical waveguide amplifier in the present invention. A thin film is desirable. Further, when an optical amplifier or laser is configured as a spatial coupling type or a micro optical element, it can be processed into a bulk shape or a block shape. In addition, the optical doping material of the present invention or the varnish of the present invention can be used in a liquid state and combined with an excitation laser to form an optical amplifier or laser.

<Optical waveguide amplifier>
The optical waveguide amplifier of the present invention is characterized by comprising at least an optical waveguide (core part) formed using the varnish of the present invention, and the varnish of the present invention containing a rare earth metal in a high concentration. By using the optical waveguide amplifier, as described above, it is possible to reduce the size and weight of the optical waveguide amplifier. The signal light can be amplified by passing through the core layer of the optical waveguide amplifier of the present invention together with the excitation light. The wavelength of the excitation light used at this time depends on the type of rare earth metal contained in the core layer, What is necessary is just to determine suitably in consideration of the wavelength etc. of signal light, and it does not specifically limit. Specifically, it is preferable to select an excitation wavelength near the peak wavelength of the excitation spectrum where fluorescence is observed in the wavelength range of the signal light to be used.

  FIG. 1 shows a substrate 1, a lower cladding layer 2 formed on the substrate 1, a core layer 3 formed on the lower cladding layer 2 using the varnish of the present invention, and the core layer 3. 1 shows an embodiment of an optical waveguide amplifier of the present invention having an upper clad layer 4.

  In order to obtain the configuration of the optical waveguide amplifier of the present invention, at least the varnish of the present invention is applied by a known method such as a coating method, a molding method, a laminating method, and is cured by heat treatment at 200 to 400 ° C. Forming a core layer. When configuring an optical waveguide amplifier using a normal single mode optical fiber as input / output, the thickness and width of the core layer are used to match the optical mode field of the optical waveguide amplifier unit with the optical mode field of the optical fiber unit. Since it is preferable to reduce the thickness, a method such as spin coating that can accurately control the film thickness of the thin film is preferable. Moreover, the optical waveguide which has an optical circuit pattern can also be formed by the irradiation of the coating which consists of the varnish of this invention by a well-known method, or the irradiation of the electromagnetic wave containing light, or the particle beam containing an electron beam.

  Further, as the substrate, a substrate made of quartz, silicon, gallium arsenide, indium phosphide, or the like can be used, and is not particularly limited. In FIG. 1, the substrate and the lower cladding layer are described as different layers, but the substrate itself can also function as the lower cladding layer. That is, the lower clad layer in FIG. 1 can be omitted. In this case, it goes without saying that the refractive index of the optical waveguide core layer should be selected to be larger than the refractive index of the substrate. Further, for example, a silicon substrate can be used, and an oxide film layer on the surface of the substrate can be used as a cladding layer. This is preferable because the flatness of the silicon wafer obtained at low cost can be effectively utilized.

  The clad layer may be a layer having a refractive index smaller than that of the core layer formed of the varnish of the present invention. For example, the refractive index of the matrix resin or the cured product is smaller than that of the core layer. It can be formed using the varnish of the present invention.

  In the former case, that is, when the varnish of the present invention is adopted only for the core layer, there is an advantage that it becomes easy to realize an optical waveguide having a high Δ (relative refractive index difference). A high Δ is preferable, particularly when excitation light is incident coaxially, since the confinement of light in the core region can be strengthened, and the amplification efficiency can be increased. As will be described later, when a channel-type optical waveguide is configured, an increase in bending loss can be reduced by using a high Δ optical waveguide. It can also be adopted, and the size of the optical waveguide amplifier can be reduced. On the other hand, if the confinement is too strong, that is, if the relative refractive index difference between the core and the clad is too large, the connection loss will increase when a normal optical fiber is used as the input / output of signal light. The configuration of the layers and cladding layers should be determined taking into account the required amplification factor, dimensions, cost, etc. of the optical amplifier as a whole. When the relative refractive index difference between the core and the clad becomes too large, for example, a resin having a larger refractive index than the matrix resin (fluorinated polyimide) constituting the core layer is adopted as the resin constituting the clad layer. It is preferable to adjust, and considering temperature dependency, polarization dependency, wavelength dependency, etc., it is preferable to adjust by adopting the same type and different structure as the matrix resin constituting the core layer. In the case of a polyimide resin whose copolymer composition can be continuously changed, it is possible to suitably select a clad and a core.

  In the latter case, that is, when both the core layer and the clad layer are formed using the varnish of the present invention, the content of the composite of the varnish of the present invention forming both is the same or different. The refractive index, the core size, the excitation wavelength, and the signal wavelength may be selected as appropriate. In this case, the optical waveguide design can be implemented based on the difference in refractive index when the matrix resin of the core layer and the cladding layer is added in the composite ratio, so that a low Δ optical waveguide can be easily configured. it can. Therefore, when a normal optical fiber is used as the input / output means, the connection loss can be reduced, which is convenient. In addition, by using a resin with a composite added to the core layer and the clad layer at the same concentration, long-term degradation of optical amplification performance due to diffusion of the composite, especially when a matrix resin with low heat resistance is used. Can escape.

  The core layer and the clad layer may contain a known transparent polymer composition, various glasses, metal oxides, semiconductor oxides and other inorganic materials, and can be selected according to the application. .

  Further, when the composite content in the varnish of the present invention is sufficiently large, the gain per unit length can be increased, so it is not always necessary to take the optical waveguide configuration as shown in FIG. For example, the cured varnish of the present invention can be arranged in the gap between the two input / output optical fibers. In the case of this configuration, the gap between the two optical fibers is determined by the amplification factor per unit length and the required amplification factor as an optical amplifier, but when the amplification factor per unit length is large, Since it is not necessary to provide light collecting means such as a collimator for both optical fibers, the number of parts can be reduced and the manufacturing cost is reduced, which is preferable. The gap width that does not require the light collecting means is, for example, 100 μm or less, and more preferably, 50 μm or less. When it exceeds 100 μm, it is desirable to provide a light collecting means such as the collimator or lens. In addition, when providing the optical waveguide part of the optical waveguide amplifier in the slab optical waveguide type, the propagation light is confined in the vertical direction, but the lateral direction (the direction horizontal to the substrate surface and perpendicular to the signal light propagation direction). In this case, it is desirable to use a collimator or the like together when designing a long length.

  In addition, the configuration is the same as that in the case where the two optical fibers are input / output, but a normal optical waveguide (not having an amplification function) is adopted in the gap portion, and a groove is formed so as to cross the optical path of the optical waveguide. An optical waveguide amplifier filled with the groove is realized by forming and inserting the cured product of the varnish of the present invention into the groove (for example, FIG. 17) or pouring the varnish of the present invention into the groove and curing. You can also In this case, the dimension of the groove can be accurately manufactured, which is preferable.

  Also, a three-dimensional optical waveguide can be configured as the optical waveguide portion of the optical waveguide amplifier. In this configuration, unlike in the case of the slab type optical waveguide, light confinement can be realized in the lateral direction, so that leakage of propagation light or diffraction spread can be prevented even over a long length. Further, in this case, the multiplexing / demultiplexing function of the excitation light and the signal light, which is necessary in the case of the configuration in which the excitation light is coaxially irradiated, is integrated with the three-dimensional optical waveguide portion of the optical waveguide amplifier as an integrated / demultiplexed optical waveguide. Therefore, it is preferable for miniaturization of the entire optical amplifier.

  Further, as shown in FIG. 15, the optical waveguide amplifier of the present invention, a light incident prism 6 as a light incident means for making light incident on the core layer 3 on the core layer 3 or the optical waveguide amplifier 10, and the core You may provide the light emission prism 7 which is a light emission means for taking out light from the layer 3. FIG. The incident angle of light is an angle within a range where light is totally reflected in the core layer 3 and light is guided. The incident light is either or both of excitation light and signal light. When both the excitation light and the signal light are incident through the prism, it is necessary to set the incident angle according to the respective wavelengths. In the case where both or both of the excitation light and the signal light are input / output from the prism, the other can be input / output from the end of the optical waveguide. Moreover, you may provide the optical fiber in both or one of the light-incidence means for injecting light into a core, and a light-projection means. The core layer may constitute a patterned three-dimensional optical waveguide by a known method such as photolithography or molding. In the case of configuring an optical waveguide amplifier including an optical fiber, it is possible to easily mount the optical fiber by disposing a guide groove for mounting the optical fiber on a substrate integrated with a portion where the optical waveguide amplifier is provided (passive). (For example, FIG. 17).

  As described above, in the optical waveguide amplifier of the present invention, at least the core layer of the optical waveguide is made of the varnish of the present invention, and the electrons of the central rare earth element (ions) are excited by the irradiation of the excitation light and relaxed to the amplification start level. After that, the signal light intensity is amplified by stimulated emission by the signal light. Therefore, in order to construct an optical waveguide amplifier, an optical waveguide portion made of the varnish of the present invention and an optical fiber or an optical waveguide for inputting / outputting an optical signal to / from the optical waveguide are connected and pumped to an optical amplification functional part. It is comprised with the means to irradiate light. The excitation light irradiating means can irradiate the optical waveguide from the side (for example, FIG. 16), or can irradiate coaxially with the optical waveguide as a common waveguide. In conventional rare earth-doped optical fiber amplifiers, coaxial excitation is usually adopted because it is difficult to increase the concentration of rare earth elements. In the present invention, since the rare earth element can be added at a high concentration, the excitation light irradiation method can be appropriately determined.

  The thickness of the optical waveguide core layer of the optical waveguide amplifier of the present invention is not particularly limited, but is preferably 1 to 50 μm, more preferably 2 to 20 μm, and further preferably 2 to 10 μm. 2 to 7 μm is more preferable. When the thickness of the core layer exceeds 50 μm, the thickness of the optical waveguide amplifier increases, and warpage due to stress based on the difference in expansion coefficient from the substrate is likely to occur. Moreover, it becomes difficult to achieve uniformity in the thickness of the entire core layer. The thickness of the core layer is controlled to a predetermined thickness by changing the concentration of the resin solution, the viscosity, the rotation speed of the spinner, and the like.

  In addition, the thickness of the core layer should be determined in consideration of detection light incidence and emission means. For example, when a single-mode optical fiber is used for either incidence and emission, incidence or emission means, In many cases, the thickness of the core layer is around 5 μm in consideration of the consistency with the optical fiber as the transmission line. In addition, for example, when a multimode optical fiber is used for any of the incident and exit, entrance or exit means, the thickness of the core layer is generally set to about 50 μm in consideration of consistency with the optical fiber that is the transmission path. There are many cases.

  Further, the thickness of the optical waveguide core layer is appropriately selected depending on the relative refractive index difference between the core layer and the cladding layer, the wavelength used, etc. It is preferably designed to reduce coupling losses. For example, when configuring an optical amplifier for signal light in the wavelength range used for FTTH, that is, 1.3 μm band, 1.49 μm band, 1.55 μm band, etc., the thickness of the core layer of the optical waveguide is 4 to 10 μm. The relative refractive index difference of the optical waveguide amplifier when it is in the range is preferably about 0.3% to 3%, more preferably 0.3% to 1%, and still more preferably 0.3%. 3% to 0.5%. By designing in this way, a normal optical fiber can be suitably used for signal input / output, and the coupling loss at the connection portion can be kept small. In addition, this refractive index can be controlled by the association state and the amount of the composite. Further, when the thickness of the core layer is in the range of 1 to 50 μm, the light propagation loss at a wavelength of 1200 to 1600 nm of the optical waveguide portion before excitation light irradiation is preferably 5 dB / cm or less, preferably 3 dB / cm. More preferably, it is 1 dB / cm or less. In the above description, the thickness of the core layer of the optical waveguide has been described. However, when a three-dimensional optical waveguide core is employed, these descriptions can be applied to the width in the horizontal direction of the core as well. There is no.

  In addition, the optical waveguide portion of the optical waveguide amplifier needs to have transparency, that is, a small propagation loss. The propagation loss of an optical waveguide is usually indicated in units of dB / cm. That is, the longer the propagation distance, the greater the propagation loss as an optical waveguide. On the other hand, the amplification factor of the optical waveguide amplifier is also typically expressed in units of dB / cm. The propagation loss and the amplification factor of the optical waveguide cancel each other because they have different signs. It is preferable that the absolute value of the amplification factor exceeds the absolute value of the propagation loss. For this reason, although the required transparency as an optical waveguide differs depending on the size of the optical waveguide amplifier and the optical amplification factor, the total propagation loss over the entire length is preferably 10 dB or less. More preferably, the total propagation loss over the entire length is 3 dB or less. Particularly preferably, the total propagation loss over the entire length is 1 dB or less. That is, when the total length of the optical waveguide portion of the optical waveguide amplifier is 1 cm, the propagation loss of the composite-containing resin used for the core layer (propagation loss in a state where no excitation light is irradiated) is 10 dB / cm or less. It is preferable that it is 3 dB / cm or less, and it is especially preferable that it is 1 dB / cm or less. The propagation loss when the total length of the optical waveguide portion of the optical waveguide amplifier is 10 cm is preferably 1 dB / cm or less.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these description.

<Synthesis of complex>
(Synthesis Example 1)
An erbium / aluminum composite was synthesized according to <Preparation of Inorganic Dispersed Phase> in Example 1 described in the specification of Patent Document 4 described above. That is, about 1.9 g of erbium acetate hydrate was dried for about 2 hours at 120 ° C./8 mmHg and dehydrated, and 1.36 g of erbium acetate obtained under a dry argon gas stream was weighed and dried. It was added and dispersed in 13.6 g of propylene glycol monomethyl ether. Next, the mixture was heated to about 119 ° C. in an oil bath while stirring under an argon stream, and then a separately prepared propylene glycol monomethyl ether solution (concentration 34.9% by weight) of aluminum tri-s-butoxide. 8.47 g was added. Next, the mixture was stirred for 2 hours while maintaining the same temperature, and then cooled to room temperature to obtain an erbium / aluminum composite (Er / Al = 1/3 mol). Further, 15 g of dimethylacetamide was added to the propylene glycol monomethyl ether solution containing the complex, and after sealing, the temperature was raised to 40 ° C., and propylene glycol monomethyl ether was preferentially removed under a reduced pressure of about 10 mmHg. When evaporation of the solvent was not observed under the conditions, the mixture was cooled to room temperature and returned to normal pressure while blowing argon gas. By the above method, a pink dimethylacetamide solution containing an erbium / aluminum complex was obtained (total oxide equivalent concentration of Er and Al of about 5% by weight). The oxide equivalent concentration is a value obtained by calculating the molar amount of the metal oxide from the rare earth metal compound and other metal compounds and calculating the oxide equivalent concentration from the weight corresponding to the molar amount.

(Synthesis Example 2)
A green dimethylacetamide solution containing a praseodymium / aluminum complex was obtained in the same manner as in Synthesis Example 1 except that praseodymium acetate was used instead of erbium acetate (Pr / Al = 1/3 mol, Pr and Al). The total oxide equivalent concentration is about 5% by weight).

※１ 複合体中の希土類金属１モルに対するカルボン酸化合物のモル数
※２ トリフルオロ酢酸（沸点：７２．４℃／７６０ｍｍＨｇ）
※３ ペンタフルオロプロパン酸（沸点：９６℃／７６０ｍｍＨｇ）
※４ ヘプタフルオロブタン酸（沸点：１２０℃／７５５ｍｍＨｇ）
※５ トリデカフルオロヘプタン酸（沸点：１７５℃／７４２ｍｍＨｇ） <Preparation of light doping material>
Light doping materials A to M were prepared by mixing about 2 g of the dimethylacetamide solution of the composite obtained in the above synthesis example with a dimethylacetamide solution containing each carboxylic acid compound shown in Table 1.

* 1 Number of moles of carboxylic acid compound per mole of rare earth metal in the composite * 2 Trifluoroacetic acid (boiling point: 72.4 ° C / 760mmHg)
* 3 Pentafluoropropanoic acid (boiling point: 96 ° C / 760mmHg)
* 4 Heptafluorobutanoic acid (boiling point: 120 ° C / 755mmHg)
* 5 Tridecafluoroheptanoic acid (boiling point: 175 ° C / 742mmHg)

<Synthesis of fluorinated polyimide precursor>
(Synthesis Example 1)
Using a 1 liter glass four-necked flask, while passing dry nitrogen at a flow rate of 30 ml / min, 89.23 g of 2,2-bis (4-aminophenyl) hexafluoropropane and molecular sieve (Wako Pure Chemical Industries, Ltd.) N, N with a water content of 0.008% by weight (measured with Hiranuma Sangyo Co., Ltd. automatic moisture measuring device AQV-5SP), which was stored after the addition of Yaku Kogyo Co., Ltd. product name Molecular Sieves 4A1 / 8) -After adding and dissolving 850 g of dimethylacetamide, 60.77 g of pyromellitic dianhydride was added and stirred at room temperature for 10 hours to obtain a fluorine-containing polyimide precursor solution having a viscosity of 1000 poise. After adding 2.0 g of water to this solution, the mixture was stirred at 70 ° C. for 4 hours to obtain a fluorinated polyimide precursor varnish having a viscosity of 50 poise. The water content of this solution was 0.3% by weight.

(Synthesis Example 2)
Using a 1 liter glass four-necked flask, while passing dry nitrogen at a flow rate of 30 ml / min, 46.6 g of 4,4'-diaminodiphenyl ether and N-methyl having a water content of 0.01% by weight -2-pyrrolidone 850 g was charged and dissolved, and then 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride 103.4 g was added and stirred at room temperature for 15 hours to give a viscosity of 800 poise. A fluorine-containing polyimide precursor solution was obtained. After adding water 3.0g to this solution, it stirred at 65 degreeC for 3 hours, and obtained the fluorinated polyimide precursor varnish with a viscosity of 100 poise. The water content of this solution was 0.4% by weight.

(Synthesis Example 3)
Using a 1 liter glass four-necked flask and passing dry nitrogen at a flow rate of 30 ml / min, 62.8 g of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl and water After charging and dissolving 850 g of N, N-dimethylacetamide having a content of 0.008% by weight, 87.2 g of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride was added, The mixture was stirred at room temperature for 15 hours to obtain a fluorine-containing polyimide precursor solution having a viscosity of 800 poise. After adding water 3.0g to this solution, it stirred at 65 degreeC for 3 hours, and obtained the fluorinated polyimide precursor varnish with a viscosity of 50 poise. The water content of this solution was 0.4% by weight.

(Synthesis Example 4)
Using a 1 liter glass four-necked flask, while passing dry nitrogen at a flow rate of 30 ml / min, 57.4 g of 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 4, After charging 4.0 g of 4'-diaminodiphenyl ether and 850 g of N, N-dimethylacetamide having a water content of 0.008% by weight, 2,2-bis (3,4-dicarboxyphenyl) hexafluoro was dissolved. 88.6 g of propane dianhydride was added and stirred at room temperature for 15 hours to obtain a fluorine-containing polyimide precursor solution having a viscosity of 800 poise. After adding water 3.0g to this solution, it stirred at 65 degreeC for 3 hours, and obtained the fluorinated polyimide precursor varnish with a viscosity of 50 poise. The water content of this solution was 0.4% by weight.

<Production and Evaluation of Varnish of the Present Invention>
(Examples 1-9)
About 1 g of the light doping materials A to I obtained above are respectively added to about 5 g of the fluorinated polyimide precursor varnish obtained in Synthesis Example 4 above, stirred at room temperature for 30 minutes, and then allowed to stand for about 12 hours. Thus, varnishes A to I (Examples 1 to 9) were produced. In addition, gelation did not occur in each varnish.

Next, each varnish A to I is applied onto a 1 μm silicon substrate with an oxide film using a spin coater, and cured under conditions of 100 ° C. for 1 hour, 200 ° C. for 1 hour, and 350 ° C. for 2 hours to obtain a predetermined thickness. Films A to I were prepared. Thereafter, the appearance, strength, refractive index at wavelengths of 1300 nm and 1550 nm, and transmission loss at a wavelength of 1550 nm were evaluated. The results are shown in Table 2. The strength was measured by a cross-cut method, and the film thickness, refractive index, and transmission loss were measured by a prism coupler method (Price Coupler 2010 manufactured by Metricon).

(Reference Examples 1-4)
About 1 g of the light doping materials J to M obtained above are respectively added to about 5 g of the fluorinated polyimide precursor varnish obtained in Synthesis Example 4, stirred for 30 minutes at room temperature, and then allowed to stand for about 12 hours. In this case, varnishes J to M were produced, but all the varnishes were gelled, and subsequent film formation and evaluation could not be performed.

(Example 10)
0.09 g of the fluorinated polyimide precursor varnish obtained in Synthesis Example 4 above was added to 5 g of the light doping material B, stirred at room temperature for 30 minutes, and then allowed to stand for about 12 hours, whereby the varnish of Example 10 was obtained. Was made. The oxide equivalent concentration of the erbium / aluminum composite of this varnish was about 0.074% by weight.

(Examples 11 to 16)
Varnishes of Examples 11 to 16 were prepared in exactly the same manner as Example 10 except that the addition amount of the fluorinated polyimide precursor varnish obtained in Synthesis Example 4 added to 5 g of the light doping material B was changed. The oxide equivalent concentration of the erbium / aluminum composite in each varnish was 0.213 wt% (Example 11), 0.226 wt% (Example 12), 0.702 wt% (Example 13), 0 It was .748% by weight (Example 14), 1.099% by weight (Example 15) and 2.319% by weight (Example 16).

で表されるポリイミド（ｘ＝０．１）の前駆体であるポリアミド酸のＮ，Ｎ−ジメチルアセトアミド溶液（１５ｗｔ％）をスピンコートにより塗布し、加熱によってイミド化を行い、下部クラッド層（厚さ１０μｍ）を形成した（波長１５５０ｎｍにおけるＴＥ偏波の屈折率：１．５２１）。ついで、下部クラッド層上に、上記一般式で表されるポリイミド（ｘ＝０．１）の前駆体であるポリアミド酸のＮ，Ｎ−ジメチルアセトアミド溶液（１５ｗｔ％）と上記光ドーピング用材料Ｂとを混合したワニスＮを塗布・加熱してコア層（厚さ６．５μｍ）を設け（波長１５５０ｎｍにおけるＴＥ偏波の屈折率：１．５３２）、ホトリソグラフィとＯ₂ ガス系のドライエッチングを用いてコア層の不要部分を除去した。エッチングに用いたマスクを除去した後、上記コア層上に、上記下部クラッド層と同様にして上部クラッド層（平坦部における厚さ１５μｍ）を設けることで、シリコン基板上に光導波路アンプの光導波路を形成した。なお、上記一般式で表されるフッ素化ポリイミドは、２，２−ビス（３，４−ジカルボキシフェニル）ヘキサフルオロプロパン二無水物（６ＦＤＡ）と２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノビフェニル（ＴＦＤＢ）又は４，４′−ジアミノジフェニルエーテル（ＤＤＥ）とから合成されるフッ素化ポリイミドであり、ＤＤＥの比率、すなわち、一般式における（ｘ）を大きくすることによりその屈折率を大きくできる。ここでは、一般式における（ｘ）を上記の値に設定することにより、コア層とクラッド層との比屈折率差を０．７％に調整した。また、導波路幅は６．５μｍとした。 <Production and evaluation of optical waveguide amplifier>
Next, an example of manufacturing the optical waveguide amplifier of the present invention will be described. First, on the silicon substrate, the following formula

A N, N-dimethylacetamide solution (15 wt%) of polyamic acid, which is a precursor of polyimide represented by the formula (1), is applied by spin coating, imidized by heating, and a lower cladding layer (thickness) (The refractive index of TE polarized light at a wavelength of 1550 nm: 1.521). Next, an N, N-dimethylacetamide solution (15 wt%) of polyamic acid, which is a precursor of the polyimide represented by the above general formula (x = 0.1), and the above-mentioned light doping material B are formed on the lower cladding layer. The core layer (thickness 6.5 μm) is provided by applying and heating varnish N mixed with (refractive index of TE polarized light at a wavelength of 1550 nm: 1.532), using photolithography and O ₂ gas based dry etching Then, unnecessary portions of the core layer were removed. After removing the mask used for etching, an upper clad layer (thickness of 15 μm in the flat portion) is provided on the core layer in the same manner as the lower clad layer, so that the optical waveguide of the optical waveguide amplifier is formed on the silicon substrate. Formed. In addition, the fluorinated polyimide represented by the above general formula includes 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2′-bis (trifluoromethyl)- Fluorinated polyimide synthesized from 4,4′-diaminobiphenyl (TFDB) or 4,4′-diaminodiphenyl ether (DDE), and by increasing the ratio of DDE, that is, (x) in the general formula The refractive index can be increased. Here, the relative refractive index difference between the core layer and the cladding layer was adjusted to 0.7% by setting (x) in the general formula to the above value. The waveguide width was 6.5 μm.

  Next, the silicon substrate was cut by dicing, and both ends of the 6 cm-long optical waveguide were optically coupled with a single mode fiber to produce an optical waveguide amplifier, and its characteristics were evaluated. As a result, the insertion loss between the fibers was as small as 5.0 dB at the measurement wavelength of 1.55 μm.

<Observation of optical waveguide>
When a beam with a wavelength of 632.8 nm (HeNe laser) is coupled to the optical waveguide prepared above via a prism by the prism coupler method, it is observed that the light wave shows a good streak and propagates linearly. It was done. Further, good m-line was observed through the output prism. From this, it was confirmed that the composite obtained in Synthesis Example 1 was uniformly dispersed in the varnish N using fluorinated polyimide as a matrix.

<Fluorescence intensity measurement>
About the film | membrane B produced above, the fluorescence intensity spectrum in the room temperature at the time of exciting with the wavelength of 400 nm and 520 nm was measured using the NIR-PL system apparatus by Shimadzu Corporation. The results are shown in FIG. 2 and FIG.

  Further, using the same apparatus, the fluorescence intensity spectra of the composite solution obtained in Synthesis Example 1 and the light doping material B were measured (excitation wavelength: 520 nm). The results are shown in FIG. 4 and FIG. Since the same fluorescence spectrum was obtained in any spectrum, it was confirmed that there was no significant difference in the state of the central rare earth metal of the composite due to the addition of the carboxylic acid compound. 6 and 7 show the fluorescence excitation spectrum at the peak value (1550 nm) of the fluorescence intensity spectrum obtained in FIGS. Since the same fluorescence excitation spectrum was obtained in any spectrum, it was confirmed that there was no significant difference in the state of the central rare earth metal of the composite due to the addition of the carboxylic acid compound.

  Further, using the same apparatus, the fluorescence intensity spectrum at each of the excitation wavelengths 490, 525, 650, and 980 nm was measured for each of the varnishes of Examples 10 to 16, and the emission intensity of the fluorescence peak at 1550 nm at each excitation wavelength was determined. Plotted against the complex oxide equivalent concentration of each varnish. The results are shown in FIG. From this result, it was confirmed that concentration quenching did not occur even when Er was dispersed at a high concentration.

  From the above, signals for use as an optical waveguide amplifier in any of the composite solution, the optical doping material, the varnish obtained by mixing the optical doping material and the fluorinated polyimide precursor varnish (varnish of the present invention), and the film formation sample thereof It can be seen that a fluorescence peak was observed in the vicinity of 1550 nm, which is the light wavelength. That is, it was confirmed that the light doping material of the present invention, the varnish of the present invention, and the composite-containing fluorinated polyimide optical waveguide of the present invention function well and with high performance as an optical waveguide amplifier.

  12 and 13 show the fluorescence intensity spectrum measurement results of varnish I (Example 9) having praseodymium as the central rare earth metal at excitation wavelengths of 450 nm and 590 nm. In this case, since fluorescence emission is observed, even when the central rare earth metal is replaced with a lanthanide series metal other than Er, the light doping material of the present invention, the varnish of the present invention, and the composite of the present invention are contained. It was confirmed that the fluorinated polyimide optical waveguide functions satisfactorily and with high performance as an optical waveguide amplifier.

<Absorption spectrum measurement>
About the light doping materials A to I produced above, as a result of measuring absorption spectra at wavelengths of 400 nm to 2000 nm using UV-3600 manufactured by Shimadzu Corporation, similar spectra were obtained in any case. In FIG. 10, the measurement result of the material B for light doping was shown by the transmittance | permeability display. In FIG. 11, the measurement result of the light doping material B in the near infrared region is shown in absorbance display. In any of the figures, it can be seen that an absorption spectrum characteristic of erbium ions is obtained.

<Small angle X-ray scattering measurement>
Using the X-ray diffractometer for evaluation of thin film structure (ATX-G) manufactured by Rigaku Corporation, the films B, D, and E produced above were subjected to reflection measurement using a 50 kV, 300 mA CuKα ray as a radiation source. X-ray scattering measurement was performed. The measurement range of 0 ° ≦ 2θ / ω ≦ 10 ° was scanned at 1 ° / min (sampling step: 0.02 °). The attenuator was open and the offset was 0.1 °. The slit conditions were S1: 10 mm × 0.2 mm, S2: 10 mm × 0.1 mm, RS: 10 mm × 0.2 mm, and GS: 10 mm × 0.2 mm. In addition, for the analysis, a spherical model is adopted as a shape factor using a particle size / hole size analysis software “NANO-Solver (Ver. 3.1)” manufactured by Rigaku Corporation. Went.

In FIG. 8, the measurement data and calculation data (fitting analysis result) of the film B are shown together. Moreover, the particle size distribution obtained from this calculation data is shown in FIG. Since a good fitting was obtained and the width of the particle size distribution was narrow, it was confirmed that the composite produced in Synthesis Example 1 was uniformly dispersed in the film B using fluorinated polyimide as a matrix. Table 3 summarizes the average particle diameters and normalized dispersions of membranes B, D, and E obtained in the same manner.

1 is a schematic cross-sectional view showing one structural form of an optical waveguide amplifier of the present invention. Fluorescence intensity spectrum of film B produced in the example (excitation wavelength: 400 nm) Fluorescence intensity spectrum of film B produced in the example (excitation wavelength: 520 nm) Fluorescence intensity spectrum of the complex solution obtained in Synthesis Example 1 (excitation wavelength: 520 nm) Fluorescence intensity spectrum of light doping material B (excitation wavelength: 520 nm) Fluorescence excitation spectrum (fluorescence wavelength 1550 nm) of the complex solution obtained in Synthesis Example 1 Fluorescence excitation spectrum of light doping material B (fluorescence wavelength 1550 nm) Small-angle X-ray scattering intensity of film B produced in the examples Results of particle size distribution analysis of membrane B produced in Example Absorption spectrum of light doping material B (transmissivity display) Absorption spectrum of light doping material B (absorbance display) Fluorescence intensity spectrum of varnish I (excitation wavelength: 450 nm) Fluorescence intensity spectrum of varnish I (excitation wavelength 590 nm) The graph which shows the Er density | concentration dependence of the fluorescence intensity of each varnish of Examples 10-16 (excitation wavelength 490,525,650,980nm) 1 is a schematic cross-sectional view showing one structural form of an optical waveguide amplifier of the present invention. 1 is a schematic cross-sectional view showing one structural form of an optical waveguide amplifier of the present invention. 1 is a schematic cross-sectional view showing one structural form of an optical waveguide amplifier of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower clad layer 3 Core layer 4 Upper clad layer 5 Optical waveguide 6 Light incident prism 7 Light emitting prism 10 Optical waveguide amplifier

Claims (13)

A light doping material obtained by mixing a complex obtained by reacting a rare earth metal salt and a metal alkoxide, and a carboxylic acid compound in an organic solvent, and a fluorinated polyimide precursor,
Only including,
The carboxylic acid compound has a pKa value of 4 or less,
When the pKa value of the carboxylic acid compound is less than 2, the compounding amount of the carboxylic acid compound is 50 to 100 mol with respect to 1 mol of the rare earth metal,
When the pKa value of the carboxylic acid compound is 2 to 4, the amount of the carboxylic acid compound is 300 to 400 mol with respect to 1 mol of the rare earth metal .   The varnish according to claim 1, wherein the rare earth metal is a lanthanide.   The varnish according to claim 1, wherein the rare earth metal is at least one selected from the group consisting of praseodymium (Pr), neodymium (Nd), erbium (Er), and thulium (Tm).   The varnish according to any one of claims 1 to 3, wherein the carboxylic acid compound has a pKa value (in water, 25 ° C) of 1.5 or less.   The varnish according to any one of claims 1 to 4, wherein the carboxylic acid compound has a boiling point of less than 300 ° C.   The varnish according to any one of claims 1 to 5, wherein a boiling point of the carboxylic acid compound is not more than a boiling point of the organic solvent.   The varnish according to any one of claims 1 to 6, wherein the carboxylic acid compound does not contain an aliphatic CH bond in the structure.   The varnish according to any one of claims 1 to 7, wherein the carboxylic acid compound is a halide. The carboxylic acid compound is represented by the following general formula (I)

(Where X is an integer from 0 to 5)
The varnish according to any one of claims 1 to 8, which is a carboxylic acid compound represented by the formula:   The varnish according to any one of claims 1 to 9, wherein the light doping material is formed by blending 50 to 400 moles of the carboxylic acid compound with respect to 1 mole of the rare earth metal.   An optical waveguide amplifier comprising at least an optical waveguide formed using the varnish according to claim 1.   The optical waveguide amplifier according to claim 11, wherein the concentration of the rare earth metal in the core portion of the optical waveguide is 0.01 wt% to 20 wt%. And complexes obtained by reacting a rare earth metal salt and a metal alkoxide, Ri Na were mixed in a carboxylic acid compound and an organic solvent,
The carboxylic acid compound has a pKa value of 4 or less,
When the pKa value of the carboxylic acid compound is less than 2, the compounding amount of the carboxylic acid compound is 50 to 100 mol with respect to 1 mol of the rare earth metal,
Wherein when the pKa value of carboxylic acid compound is 2-4, the amount of the carboxylic acid compound, wherein the to Ruhikarishirube waveguide amplifier optical doping material that is 300 to 400 mol with respect to the rare earth metal 1 mole .

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