JP2007057941A - Organic nonlinear optical material and nonlinear optical element using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic nonlinear optical material, for which a polymer binder having a high glass transition temperature, is utilized effectively, and which has superior nonlinear optical performance and superior stability combined with each other, and to provide a nonlinear optical element that uses the organic nonlinear optical material. <P>SOLUTION: The organic nonlinear optical material, formed by dispersing or bonding the organic compound having the nonlinear optical activity in or to the polymer binder, is characterized by containing at least one kind of tertiary amine derivatives represented by general Formula (1) as the nonlinear optically active organic compound. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is an optical modulator, an optical switch, an optical integrated circuit, an optical computer, an optical memory, a wavelength useful in fields such as information communication, information processing, and imaging using electromagnetic waves such as visible light, infrared light, and THz waves. The present invention relates to a nonlinear optical element that can be applied to a conversion element, a holographic element, a THz wave generating element, and the like. Furthermore, this invention relates to the organic nonlinear optical material which is a Key material which forms this nonlinear optical element.

  Most of the functional elements such as wavelength conversion elements, optical modulators, optical switches, etc., which are important in the fields of optical information communication, optical information processing, and imaging using light, use nonlinear optical materials, especially second-order nonlinear optical materials. Is embodied by. Inorganic nonlinear optical materials such as lithium niobate and potassium dihydrogen phosphate have already been put to practical use and widely used as secondary nonlinear optical materials. In recent years, however, these nonlinear materials have high nonlinear optical performance. Attention has been focused on inexpensive materials and organic nonlinear optical materials having advantages such as manufacturing cost, high mass productivity, and the like, and active research and development for practical use is being conducted.

  The second-order nonlinear optical effect is indispensable in principle that there is no symmetry center in the system, and a system in which an organic compound having nonlinear optical activity is crystallized into a crystal structure without a symmetry center (referred to as a crystal system). ), And a system in which an organic compound having nonlinear optical activity is contained or bonded to a polymer binder, the nonlinear optically active organic compound is oriented by some means, and the center of symmetry is missing (referred to as a polymer system). The Crystalline organic nonlinear optical materials are known to exhibit very high nonlinear optical performance, but artificial control of the crystal structure is impossible at present, and a crystal structure without a symmetrical center can be obtained. It is rare that even if it is obtained, it is difficult to produce a large organic crystal necessary for device formation, and the strength of the organic crystal is very fragile and breaks in the device formation process. There is. In contrast, polymer organic nonlinear optical materials are provided with favorable properties such as film formability, mechanical strength, and the like that are useful for device formation due to the binder polymer. Is highly promising.

  In the polymer-based organic nonlinear optical material, it is required that the nonlinear optically active organic compound is uniformly dispersed or bonded in the polymer binder without agglomeration and becomes optically homogeneous and transparent. Furthermore, as described above, in order to exhibit the second-order nonlinear optical effect, the nonlinear optically active organic compound must be oriented by some means to impart anisotropy, and when used for a functional element. Must be stably maintained over a long period of time in the temperature and humidity environment where the element is placed.

  Therefore, the nonlinear optically active organic compound used for the polymer organic nonlinear optical material is required to have low cohesiveness and excellent compatibility with the binder polymer in addition to high nonlinear optical performance. In addition, since the polymer organic nonlinear optical material is generally formed into an element in the form of a thin film, and the wet coating method is suitably used as a method for forming the thin film, the nonlinear optical active organic material used for the polymer organic nonlinear optical material is used. The compound is required to have high solubility in a coating solvent. On the other hand, the binder polymer is required to have a high glass transition temperature in order to stably maintain the orientation state of the encapsulating nonlinear optically active organic compound in addition to high film formability and mechanical strength.

  In order to generate a second-order nonlinear optical activity in a polymer organic nonlinear optical material, it is necessary to orient the nonlinear optically active organic compound as described above. As the alignment method, an electric field poling method is generally used. The electric field poling method is an alignment method in which an electric field is applied to a nonlinear optical material, and the nonlinear optically active compound is aligned in the applied electric field direction by the Coulomb force between the dipole moment of the nonlinear optically active compound and the applied electric field. In addition to the application, the molecular motion of the nonlinear optically active compound is promoted by heating to a temperature near the glass transition temperature.

  Examples of the nonlinear optically active organic compound include Disperse Red 1 (generally abbreviated as DR1) and 4- (Dicyanomethylene) -2-methyl-6- (4-dimethylaminostyryl) -4H-pyran (generally abbreviated as DCM). And the like are well known (see, for example, Non-Patent Document 1).

  On the other hand, polymethylmethacrylate (generally abbreviated as PMMA) has been most studied as the binder polymer, but the glass transition temperature of PMMA is as low as about 100 ° C., and PMMA is used as the binder polymer. It is known that the orientation state of the molecular organic nonlinear optical material gradually relaxes even at room temperature, and the nonlinear optical performance is significantly deteriorated with time, so that it cannot be put into practical use as a functional element (for example, non-patent Reference 2). In order to solve this problem, the search for binder polymers to replace PMMA was actively conducted, and the effectiveness of polymers with higher glass transition temperatures than PMMA such as polycarbonate, polyimide, polyarylate, polysulfone, and polycyclic olefin was reported. However, using these binder polymers having a high glass transition temperature increases the heating temperature required to promote molecular motion during electric field poling, and DR1 and DCM are used as nonlinear optically active organic compounds. When these are used, there has been a problem that those low molecules are lost by sublimation or are oxidized and deteriorated. In addition, the compatibility between the binder polymer having a high glass transition temperature and DR1 or DCM is not always good, and when DR1 or DCM is added at a high concentration in order to improve nonlinear optical performance, they aggregate or crystallize. In addition, there is a problem that even at a low concentration, aggregation or crystallization occurs due to heating or aging.

  Recently, it has been reported that the nonlinear optically active organic compound represented by the following structural formula (1) is excellent in compatibility with the binder polymer, has high nonlinear optical performance, and is promising as a THz wave generating element ( For example, refer nonpatent literature 3.). However, since this nonlinear optically active organic compound has an alkylamino structure, it has a plastic effect when dispersed in a polymer binder because it has a long flexible alkyl group or alkoxyalkyl group that is easily photooxidatively decomposed. Even if a binder polymer with a large glass transition temperature is used, there is a problem regarding stability, such as the glass transition temperature being significantly reduced as a dispersion film.

［構造式（１）中、Ｒはヘキシル基または１−メトキシエチル基である。］

[In the structural formula (1), R represents a hexyl group or a 1-methoxyethyl group. ]

  In addition, the nonlinear optically active organic compound represented by the following structural formula (2) has high nonlinear optical performance, and further a nonlinear optically active organic represented by the following structural formula (3) in which a dendron group is introduced into the basic skeleton. It has been reported that the compound has excellent compatibility with the binder polymer and has higher nonlinear optical performance than the nonlinear optically active organic compound represented by the following structural formula (2) (for example, see Non-Patent Document 4). .)

In addition, a nonlinear optically active organic compound having a specific structure of a dendron group and having excellent amorphous properties is disclosed (for example, see Patent Document 1). However, since these nonlinear optically active organic compounds all have an alkylamino structure, there are problems such as low chemical stability to heat and light.
JP 2002-258337 A Japanese Patent Application Laid-Open No. 2002-266331 Chemistry of Materials, 1999, 11, 25554-2561 Chemical Reviews, 1994, 94, 1, 31-75 Journal of Physical Chemistry B, 2004, 108, 25, 8515-8522 Chemical Communications, 2002, 888-889

  The object of the present invention is to solve the problems of the prior art as described above, and by using a specific nonlinear optically active organic compound that is excellent in amorphousness, chemical stability, resistance to sublimation, etc. and is easy to synthesize. An object of the present invention is to provide an organic nonlinear optical material that can effectively utilize a polymer binder having a glass transition temperature and has excellent nonlinear optical performance and excellent stability, and a nonlinear optical element using the organic nonlinear optical material.

As a result of intensive studies on the nonlinear optically active organic compound and the binder polymer in order to solve the above problems, the present inventors can solve the above problems by using a specific nonlinear optically active organic compound. As a result, the present invention has been completed.
That is, the said subject is solved by the following this invention.

<1> An organic nonlinear optical material obtained by dispersing or bonding an organic compound having nonlinear optical activity in a polymer binder, and the tertiary amine derivative represented by the following general formula (1) as the nonlinear optically active organic compound It is an organic nonlinear optical material characterized by containing at least one kind.

［一般式（１）中、Ｚ¹、Ｚ²、及びＺ³は互いに独立に置換基を有してもよい芳香族基であり； Ｌは置換基を有してもよいπ共役基であり； Ａは置換基を有してもよいπ共役系電子吸引性基であり； ｍは０または１を表す。Ｚ¹〜Ｚ³、Ｌ、Ａは任意のいずれかが連結して環構造を形成していてもよい。但し、Ｚ¹、Ｚ²、Ｚ³、Ｌ、及びＡのうちの少なくとも一つは必ず置換基を有し、且つＺ¹、Ｚ²、Ｚ³、Ｌ、及びＡが有する置換基の内のＺ¹、Ｚ²、Ｚ³、Ｌ、及びＡのπ共役系と環形成していない部分の分子量の合計が、該３級アミン誘導体の分子量の４０％以上である。］

[In General Formula (1), Z ¹ , Z ² , and Z ³ are each independently an aromatic group that may have a substituent; L is a π-conjugated group that may have a substituent; A represents a π-conjugated electron-withdrawing group which may have a substituent; m represents 0 or 1; Any ^{one of} Z ^{1 to} Z ³ , L and A may be linked to form a ring structure. However, at least one of Z ¹ , Z ² , Z ³ , L, and A necessarily has a substituent, and among the substituents that Z ¹ , Z ² , Z ³ , L, and A have The sum of the molecular weights of Z ¹ , Z ² , Z ³ , L, and A that are not ring-formed with the π-conjugated system is 40% or more of the molecular weight of the tertiary amine derivative. ]

<2> The organic nonlinear optical material according to <1>, wherein A of the tertiary amine derivative has three or more cyano groups.

<3> The organic nonlinear optical material according to <2>, wherein A of the tertiary amine derivative has a structure represented by the following general formula (2) or (3).

［一般式（２）、（３）中、Ｒ¹とＲ²は互いに独立に任意の置換基であり、Ｒ³は任意の置換基を有してもよい芳香族基である。尚、Ｒ¹とＲ²は互いに連結して環構造を形成していてもよい。］

[In General Formulas (2) and (3), R ¹ and R ² are each independently an arbitrary substituent, and R ³ is an aromatic group that may have an arbitrary substituent. R ¹ and R ² may be connected to each other to form a ring structure. ]

<4> The organic nonlinear optical material according to <3>, wherein at least one of R ¹ and R ² of the tertiary amine derivative is a substituent having a molecular weight larger than that of a methyl group.

<5> The organic nonlinear optical material according to <4>, wherein at least one of R ¹ and R ² of the tertiary amine derivative is an aromatic group which may have an arbitrary substituent. It is.

<6> Any one of <1> to <5>, wherein at least one of Z ¹ and Z ² of the tertiary amine derivative is an aromatic group having a substituent having a molecular weight larger than that of a methyl group. It is an organic nonlinear optical material as described above.

<7> The organic material according to any one of <1> to <6>, wherein at least one of Z ¹ and Z ² of the tertiary amine derivative and A have a substituent containing a dendron structure. It is a nonlinear optical material.

<8> The organic material according to any one of <1> to <7>, wherein the organic binder contains at least one of polyimide, polycarbonate, polyarylate, polysulfone, and polycyclic olefin. It is a nonlinear optical material.

<9> A nonlinear optical element using the organic nonlinear optical material according to any one of <1> to <8>.

<10> The nonlinear optical element according to <9>, wherein the nonlinear optical element operates based on an electro-optic effect.

  The organic nonlinear optical material of the present invention is obtained by dispersing or bonding a specific nonlinear optically active organic molecule excellent in nonlinear optical performance, amorphousness, heat resistance, and sublimation resistance to a polymer binder having a high glass transition temperature. It has a high optical quality and non-linear optical performance because the non-linear optically active organic molecules do not aggregate even at high concentrations, and has a high optical quality and non-linear optical performance. High effects such as being high and capable of maintaining excellent performance over a long period of time. For this reason, by using the organic nonlinear optical material of the present invention, a nonlinear optical element having excellent characteristics and stability can be realized.

Hereinafter, the present invention will be described in detail according to embodiments.
<Organic nonlinear optical material>
-Nonlinear optically active organic compounds-
The present invention relates to an organic nonlinear optical material obtained by dispersing or bonding an organic compound having nonlinear optical activity in a polymer binder, and the tertiary amine represented by the above general formula (1) as the nonlinear optically active organic compound It contains at least one derivative. The tertiary amine derivative represented by the general formula (1) is excellent in chemical stability such as heat resistance, oxidation resistance, and light resistance, and has high amorphous properties and excellent compatibility with various binder polymers. . Furthermore, the sublimation temperature is very high, and the above-described problem of sublimation during electric field poling is avoided. Furthermore, it has very good non-linear performance.

In the general formula (1), Z ^{1 to} Z ³ are aromatic groups that may have a substituent independently of each other, Z ¹ and Z ² are monovalent aromatic groups, and Z ³ is 2 Valent aromatic group. At least one of Z ¹ and Z ² is particularly preferably an aromatic group having a substituent having a molecular weight larger than that of the methyl group in terms of amorphousness, resistance to sublimation, and the like. As the substituent having a molecular weight larger than that of the methyl group, the hydrocarbon group having 2 to 60 carbon atoms which may have a substituent, for example, one or more halogen atoms such as trifluoromethyl group and 1-chloropropyl group Alkyl group having; alkoxy group such as methoxy group, isopropoxy group, cyclohexyloxy; alkyl group having 2 or more carbon atoms such as ethyl group, isopropyl group, t-butyl group, cyclohexyl group; phenyl group, tolyl group, xylyl group, Aryl groups such as naphthyl groups; aryloxy groups such as phenoxy groups and perfluorophenoxy groups; among these, alkyl groups containing a branched structure or a ring structure having 3 or more carbon atoms, and those having 3 or more carbon atoms. Alkoxy and aryl groups containing a branched or ring structure are soluble, amorphous, heat resistant, and easy to synthesize. Preferred.
Z ³ is preferably a substituted or unsubstituted 1,4-phenylene group, more preferably an unsubstituted 1,4-phenylene group, from the viewpoint of ease of synthesis and the like.
Examples of the substituent when Z ³ has a substituent include a halogen atom, a methyl group, a trifluoromethyl group, and a hydroxymethyl group.

In General Formula (1), L is a π-conjugated group which may have a substituent, and m represents 0 or 1. When the π-conjugated system represented by Z ³ -L _m is formed by connecting five or more unsaturated bonds across the both ends, a particularly preferable effect is exhibited in terms of nonlinear optical performance. Specific examples of Z ³ -L _m in which 5 or more unsaturated bonds are formed continuously at both ends include the following. In the following specific examples, both ends are indicated by *, and numbers are added to the unsaturated bonds that are continuous over both ends.

In General Formula (1), A is a π-conjugated electron-withdrawing group which may have a substituent, and has a structure having 3 or more (preferably 3 to 5) cyano groups. In particular, it is preferable in that high nonlinear optical performance is realized.
The structure having three or more cyano groups is preferably a structure represented by the following general formula (2) or (3).

R ¹ and R ^{2 in} the general formula (2) are arbitrary substituents independently of each other, but at least one is a substituent having a molecular weight larger than that of a methyl group (preferably a hydrocarbon group having 2 to 60 carbon atoms). It is preferable in terms of solubility, amorphousness, chemical stability, and the like. More preferably, at least one of R ¹ and R ² is an aromatic group that may have a substituent. Examples of the substituent having a molecular weight larger than that of the methyl group include the same ones listed as the substituents for Z ¹ and Z ² . R ¹ and R ² may be linked to each other to form a ring structure, and those having a substituted or unsubstituted fluorene ring structure are particularly preferable in terms of chemical stability and the like. .
R ^{3 in the} general formula (3) is an aromatic group which may have a substituent, and a substituted or unsubstituted phenyl group is particularly preferable from the viewpoint of easiness of synthesis.
Examples of the substituent in the case where R ³ has a substituent, a halogen atom, those same as those exemplified as a methyl group, the substituent of the Z ¹ and Z ^2, etc., and particularly the Z ¹ Among these And the same as those mentioned as the substituent for Z ² are preferred.

  Examples of such a specific basic skeleton of A are shown below. The ends are indicated by *.

In general formula (1), any ^one of Z ^{1 to} Z ³ , L, and A may be linked to form a ring structure.

In the compound (tertiary amine derivative) represented by the general formula (1) which is an essential constituent element of the present invention, at least one of Z ¹ , Z ² , Z ³ , L, and A always has a substituent, and Z ¹ , Z ² , Z ³ , L, and A have a total molecular weight of a portion that is not ring-formed with the π-conjugated system of Z ¹ , Z ² , Z ³ , L, and A, It is characterized by being 40% or more of the molecular weight of the compound.
Here, the sum of the molecular weights of the portions that are not ring-formed with the π-conjugated system of Z ¹ , Z ² , Z ³ , L, and A is preferably 50% or more of the molecular weight of the entire molecule, More preferably, it is 80%.

Originally, secondary nonlinear optically active organic compounds are based on a structure having a π electron donating group at one end of a π conjugated system and a π electron withdrawing group at the other end. Due to the large child moment, the molecular association is very high and the solubility and resin compatibility are poor. Although it is a qualitatively known fact that the association between molecules can be reduced by introducing a substituent having a weak intermolecular interaction at a position deviating from the π-conjugated plane formed by the basic skeleton, There was no disclosure of quantitative guidance. Although the mechanism of the present inventors is not necessarily clear, in the nonlinear optically active organic compound having the basic skeleton represented by the general formula (1), Z ¹ , Z ² , Z ³ , L, and A At least one of which has a substituent, and Z ¹ , Z ² , Z ³ , L, and A π-conjugated system among the substituents of Z ¹ , Z ² , Z ³ , L, and A and When the total molecular weight of the non-ring-forming portion is 40% or more (preferably 50% or more, more preferably 60 to 80%) of the molecular weight of the compound, high solubility and excellent resin compatibility are obtained. I found it guaranteed. Conversely, if the total molecular weight is less than 40% of the molecular weight of the compound, the association between molecules cannot be sufficiently reduced, and the effects of the present invention cannot be obtained. This is because, in order to spatially shield the basic planar skeleton and suppress the association between molecules, the volume of the substituent portion occupying the whole molecule is an important factor, and the molecular weight of the portion occupies 40% or more of the whole. This is presumably because the necessary conditions have been satisfied. Further, when the total molecular weight exceeds 80% of the molecular weight of the compound, sufficient nonlinear optical performance may not be obtained. Incidentally, ^{Z 1, Z 2, Z 3} , L, and ^{Z 1, Z 2, Z 3} , L, and π conjugated system and portions not forming the ring of A of the substituent A has the specific gravity It is desirable that it is composed of small non-metallic atoms, and when it contains metal atoms, it is desirable to limit it to only metal atoms having an atomic number of 32 or less. This is because, when the portion contains a metal atom having an atomic number of 33 or more having a large specific gravity, the ratio of the molecular weight of the portion to the whole molecule is set to a very large value in order to obtain an effective effect for suppressing molecular associability. This is because there is a need, and in this case, the nonlinear optical performance tends to be lowered.

In particular, when at least one of Z ¹ and Z ² and A have a substituent having a molecular weight larger than that of the methyl group, the solubility and the resin compatibility are remarkably improved. As the substituent larger than the methyl group, an aromatic group which may have a substituent is preferable, and a substituent including a dendron structure is more preferable. The dendron structure means a tree-like multi-branch structure whose topological structure is controlled. The dendron structure has a large molecular weight and a bulky spherical molecular structure, and has a great effect of suppressing the association between the molecules. Specific examples of the dendron structure include Japanese Patent Application Laid-Open No. 2002-258337, Japanese Patent Application Laid-Open No. 2002-296331, “Chemical Communications, 2002, 888-889”, “Angewandte Chemie International Edition, 2001, Vol. 40, 1 No., pages 74 to 91 ”.

  Specific examples of the compound represented by the general formula (1) include the following.

  As a method for synthesizing the tertiary amine derivative represented by the general formulas (1) and (2), any arbitrary method can be used. For example, a method of dehydrating and condensing a corresponding formyl compound and an electron-withdrawing compound having an active methyl group in the presence of a base as shown below is useful. The formyl compound can be synthesized by a method using a formylation method such as the Vilsmeier method, and particularly, those having m of 0 can be synthesized very easily. As a method for synthesizing an electron-withdrawing compound having an active methyl group, `` Synthetic Communications, 1995, 25, 19, 3045-3051 '', `` Chemistry of Materials, 2002, 14, 2393-2400 '' Etc. can be used.

  As a method for synthesizing the tertiary amine derivative represented by the general formulas (1) and (3), any arbitrary method can be used. For example, as described in “Journal of The American Chemical Society, 1999, Vol. 121, No. 2, pp. 472-473”, a method of reacting the corresponding acetylene derivative with tetracyanoethylene is useful. The acetylene derivative can be synthesized by a method using the Sonogashira coupling method described in the literature or “Liquid Crystal, 2005, Vol. 9, No. 1, pp. 22-30”.

  Regarding the synthesis of the tertiary amine derivative represented by the general formula (1) having a substituent containing a dendron structure, the dendron structure is included as the above formyl compound, electron-withdrawing compound having an active methyl group, or acetylene derivative. It can synthesize | combine by using what has a substituent. It can also be synthesized by synthesizing a tertiary amine derivative represented by the general formula (1) having a reactive group and reacting the reactive group with a compound containing a dendron structure. Examples of the reactive group include a hydroxyl group, an amino group, and a carboxy group. Examples of the compound having a dendron structure that can be reactively linked to these reactive groups include dendron derivatives having a halogenated alkyl group such as 3,5-Bis [3,5-bis (benzyloxy) benzyloxy] benzyl Bromide. . In synthesizing the tertiary amine derivative represented by the general formula (1) having a reactive group, the reactive group is protected with an appropriate protective group, and is reacted with a compound having a dendron structure. It is preferable to deprotect immediately before.

<Binder polymer>
The binder polymer used in the present invention may be any polymer as long as it is excellent in optical quality and film formability, but preferably has a glass transition temperature of 120 ° C. or higher. Particularly preferred are those having a glass transition temperature of 170 ° C. or higher and high mechanical strength, and specific examples include polyimide, polycarbonate, polyarylate, polysulfone, and polycyclic olefin.

  The organic nonlinear optical material of the present invention is formed from at least the nonlinear optically active organic compound and a binder polymer. The nonlinear optically active organic compound may be dispersed in a molecular state in the binder polymer, or may be chemically linked to the side chain or main chain of the binder polymer.

  The organic nonlinear optical material of the present invention may be in any form, but is generally used in the form of a thin film for application to a nonlinear optical element. As a method for producing a thin film containing the organic nonlinear optical material of the present invention, known methods such as an injection molding method, a press molding method, a soft lithography method, a nanoimprint method, a wet coating method, etc. can be used. From the viewpoints of simplicity, mass productivity, film quality (thickness uniformity, few defects such as bubbles), etc., at least the nonlinear optically active organic compound and the binder polymer were dissolved in an organic solvent. A wet coating method in which a film is formed by coating a solution on a suitable substrate by a method such as a spin coating method, a blade coating method, a dip coating method, or an ink jet method is preferable.

  The organic solvent used in the wet coating method may be anything as long as it can dissolve the nonlinear optically active organic compound to be used and the binder polymer, but preferably has a boiling point in the range of 50 to 200 ° C. . If an organic solvent with a boiling point of less than 50 ° C is used, solvent volatilization occurs when the coating solution is stored, and the viscosity of the coating solution changes (increases). There is a tendency for such problems to become prominent. On the other hand, when an organic solvent having a boiling point exceeding 200 ° C. is used, it is difficult to remove the solvent after coating, and the remaining organic solvent acts as a plasticizer for the polymer binder and causes a decrease in the glass transition temperature. There is a case. Examples of preferred organic solvents include tetrahydrofuran, methyltetrahydrofuran, dioxane, diethylene glycol dimethyl ether, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl acetate, cyclohexanol, dichloroethane, toluene, xylene, N, N-dimethylformamide, N, N-dimethyl. Examples include acetamide and dimethyl sulfoxide. These organic solvents may be used alone or in combination.

  In the organic nonlinear optical material of the present invention, the content of the nonlinear optically active organic compound varies depending on the required nonlinear optical performance and mechanical strength, the type of the nonlinear optically active organic compound used, etc. Generally, it is preferable that it is in the range of 1 to 95% by mass as a proportion of the total weight of the organic nonlinear optical material. The reason is that if it is less than 1% by mass, sufficient nonlinear optical performance is often not obtained, and if it exceeds 95% by mass, there is a tendency that sufficient mechanical strength cannot be obtained. Because. A more preferable range of the content of the nonlinear optically active organic compound is 10 to 80% by mass, and further preferably 25 to 70% by mass.

  In addition to the nonlinear optically active organic compound and the binder polymer, various additives can be added to the organic nonlinear optical material of the present invention as necessary. For example, a known antioxidant such as 2,6-di-t-butyl-4-methylphenol and hydroquinone may be used for the purpose of suppressing the oxidative degradation of the nonlinear optically active organic compound and / or the binder polymer. In order to suppress UV degradation of the compound and / or binder polymer, known UV absorbers such as 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone are used. In the case of using a known leveling agent such as silicone oil for the purpose of improving the surface smoothness of the coating film, or a nonlinear optically active organic compound and / or binder polymer having a crosslinkable curable functional group in the coating solution, A known curing catalyst or curing aid may be added for the purpose of accelerating the crosslinking and curing.

  In order to generate a second-order nonlinear optical activity in a polymer nonlinear optical material, it is necessary to orient the nonlinear optically active organic compound as described above. As the alignment method, a polymer-based nonlinear optical material is applied onto a substrate having an alignment film on the surface, and the alignment of the substrate-aligned film causes the alignment of the nonlinear optically active organic compound in the polymer-based nonlinear optical material. There is a method of inducing this. Also, known polling methods such as an optical poling method, an optically assisted electric field poling method, and an electric field poling method can be used effectively. Among these, the electric field poling method is particularly preferable in terms of the simplicity of the apparatus and the high degree of orientation obtained.

  The electric field poling method is roughly divided into a contact electrode poling method in which a nonlinear optical material is sandwiched between a pair of electrodes and an electric field is applied, and a corona poling method in which a corona discharge is applied to the surface of the nonlinear optical material on the substrate electrode and a charging electric field is applied. Is done. The electric field poling method is an alignment method in which the nonlinear optically active compound is aligned in the applied electric field direction by the Coulomb force between the dipole moment of the nonlinear optically active compound and the applied electric field. In the electric field poling method, generally, by applying an electric field and heating to a temperature in the vicinity of the glass transition temperature of the nonlinear optical material, the alignment movement in the electric field direction of the nonlinear optically active compound is promoted and sufficient alignment is achieved. After the induction, the applied electric field is removed after cooling to room temperature with the electric field applied and freezing the alignment state. However, since this orientation state is basically a thermodynamic nonequilibrium state, even if the temperature is lower than the glass transition temperature, it is gradually randomized over time, and the fundamental problem is that nonlinear optical activity decreases. Have Randomization of the orientation state over time progresses more gradually as the difference between the environmental temperature where the nonlinear optical material is placed and the glass transition temperature is larger. Therefore, in actual use, the binder resin having a higher glass transition temperature is used. This problem can be solved.

<Nonlinear optical element>
The nonlinear optical element of the present invention is characterized by utilizing the organic nonlinear optical material of the present invention, and may be any element that operates based on the nonlinear optical effect. Specific examples thereof include, for example, a wavelength conversion element. , Photorefractive element, electro-optical element, and the like. Particularly preferable are electro-optical elements such as an optical switch, an optical modulator, and a phase shifter that operate based on the electro-optical effect.

  The electro-optical element is preferably used as an element having a structure in which a nonlinear optical material is formed on a substrate and is sandwiched between electrode pairs for input electric signals.

  As a material constituting such a substrate, metals such as aluminum, gold, iron, nickel, chromium and titanium; semiconductors such as silicon, titanium oxide, zinc oxide and gallium arsenide; glass; polyethylene terephthalate, polyethylene naphthalate, Plastics such as polycarbonate, polysulfone, polyetherketone, polyimide, etc. can be used.

  A conductive film may be formed on the surface of these substrate materials. Examples of the material of the conductive film include metals such as aluminum, gold, nickel, chromium, and titanium; tin oxide, indium oxide, ITO ( Conductive oxides such as tin-doped indium oxide); conductive polymers such as polythiophene, polyaniline, polyparaphenylene vinylene, and polyacetylene. These conductive films are formed using known dry film formation methods such as vapor deposition and sputtering, and known wet film formation methods such as dip coating, electrolytic deposition, plating, and electroless plating. A pattern may be formed. The conductive substrate or the conductive film formed on the substrate as described above is used as an electrode during polling or operation as an element (hereinafter abbreviated as “lower electrode”).

  On the substrate, if necessary, an adhesive layer for improving the adhesion between the film formed on the substrate and the substrate, a leveling layer for smoothing the unevenness of the substrate surface, or these functions are provided. Some intermediate layer provided in a lump may be formed. The material for forming such a film is not particularly limited. For example, ester resin, acrylic resin, methacrylic resin, amide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, urethane resin, vinyl alcohol resin, acetal resin And their copolymers; Cross-linked products such as zirconium alkoxide compounds, titanium alkoxide compounds, silane coupling agents, and their co-crosslinked products; and the like can be used.

  The nonlinear optical element of the present invention is preferably formed so as to include a waveguide structure, and it is particularly preferable that the nonlinear optical material of the present invention is contained in the core layer of the waveguide.

  A clad layer (hereinafter abbreviated as “lower clad layer”) may be formed between the core layer containing the nonlinear optical material of the present invention and the substrate. The lower cladding layer may be any layer as long as it has a lower refractive index than the core layer and is not affected by the formation of the core layer. As such materials, UV curable or thermosetting resins such as acrylic, epoxy, and silicone; polyimide; glass and the like are preferably used.

  After the core layer made of the nonlinear optical material of the present invention is formed, a clad layer (hereinafter, abbreviated as “upper clad layer”) may be further formed thereon in the same manner as the lower clad layer. As a result, a slab waveguide having a structure of substrate / lower cladding layer / core layer / upper cladding layer is formed.

  After forming the core layer, the core layer is patterned by a known method using a semiconductor process technology such as reactive ion etching (RIE), photolithography, electron beam lithography, etc. to form a channel type waveguide or a ridge type waveguide You can also Alternatively, it is possible to form a channel or a ridge-type waveguide by patterning and irradiating a part of the core layer with UV light, an electron beam or the like to change the refractive index of the irradiated part.

  Forming a basic electro-optic element by forming an electrode (hereinafter abbreviated as “upper electrode”) for applying an input electric signal to the surface of the upper clad layer in a desired region of the upper clad layer. Can do.

  When forming a channel-type waveguide or a ridge-type waveguide as described above, the core layer pattern may be a known device structure such as a linear type, a Y-branch type, a directional coupler type, or a Mach-Zender type. It can be configured, and can be applied to known optical information communication devices such as an optical switch, an optical modulator, and a phase shifter.

  It should be noted that ozone treatment, UV treatment, self-organization simple substance is used for the purpose of, for example, enhancing adhesion when the upper layer is laminated on any surface of the substrate, lower electrode, lower clad layer, core layer, and upper clad layer. Arbitrary processing such as molecular layer (SAM) adsorption processing may be performed.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1
A tertiary amine derivative of the following structural formula (A) represented by the above general formulas (1) and (3) is formed on a glass substrate having a gold parallel electrode pair (distance between electrodes = 20 μm) on the surface. 5 parts by weight of one kind of nonlinear optically active organic compound and Poly [Bisphenol A carbonate-co-4,4 '-(3,3,5-trimethylcyclohexylidene) diphenol carbonate] (produced by Aldrich, A solution prepared by dissolving 5 parts by mass of glass transition temperature (200 ° C.) in 90 parts by mass of cyclopentanone (boiling point: 130 ° C.) was applied by spin coating, dried at 120 ° C. for 30 minutes, and a film thickness of 0.1 μm A thin film was obtained. Incidentally, Z ¹ of the present tertiary amine ^{derivative, Z 2, Z 3, L} , and Z ¹ of the substituent A ^{has, Z 2, Z 3, L} , and π conjugated system A and are ring formation The sum of the molecular weights of the non-exposed parts (the parts enclosed by broken lines) corresponds to 61% of the molecular weight of the tertiary amine derivative, and Z ¹ , Z ² , and A have a substituent containing a dendron structure.

Next, with the electric field of 100 V / μm applied between the electrodes, the thin film was held at 115 ° C. for 30 min, cooled to room temperature while applying the electric field, and then the electric field was removed.
When the semiconductor laser light having an oscillation wavelength of 1550 nm is irradiated on the thin film made of the organic nonlinear optical material subjected to electric field poling of the present invention thus obtained, generation of the second harmonic of 775 nm can be observed, It was confirmed that it functions effectively as a nonlinear optical material. Furthermore, after this nonlinear optical material was kept in a high temperature environment of 50 ° C. for 10 days and again irradiated with laser light, it was possible to confirm the generation of second harmonics having the same intensity as the initial, and the nonlinear optical material was It was confirmed that it had high heat resistance and stability over time.
In addition, when this thin film was observed with the optical microscope, it was very clear and it has confirmed that the tertiary amine derivative was uniformly molecularly dispersed in the polycarbonate.
The above evaluation results are summarized in Table 1.

Each evaluation item in Table 1 was determined according to the following criteria.
-Membrane quality-
○: No defects such as cracks, crystal precipitation, and sublimation dissipation are observed at the time of film formation.
X: Some defect is recognized at the time of film-forming.
-Non-linear optical performance-
The level of generated light intensity of the second harmonic in Example 1 was set as ◯, and the determination was made as follows.
A: The generated light intensity of the second harmonic is 80% or more of that in Example 1.
(Triangle | delta): The generated light intensity of a 2nd harmonic is 30% or more of Example 1. FIG.
X: The generated light intensity of the second harmonic is less than 30% of Example 1.
-Thermal and temporal stability of film quality (molecular dispersion stability)-
○: Film quality after storage at 50 ° C. for 10 days is equivalent to the initial value.
X: Defects such as cracks and crystal precipitation are observed after storage at 50 ° C. for 10 days.
-Thermal and temporal stability of nonlinear optical performance (stability of orientation state)-
○: The second harmonic generation light intensity after storage at 50 ° C. for 10 days is 90% or more of the initial value.
(Triangle | delta): The generated light intensity of the 2nd harmonic after storage at 50 degreeC for 10 days is more than half of the initial stage.
X: The generated light intensity of the second harmonic after storage at 50 ° C. for 10 days is less than half of the initial value.

(Comparative Example 1)
A thin film made of an organic nonlinear optical material was produced in the same manner as in Example 1 except that the nonlinear optically active organic compound in Example 1 was changed to DR1 (manufactured by Aldrich). Significant precipitation of microcrystals was observed.

(Example 2)
The nonlinear optically active organic compound in Example 1 was added to 3 parts by mass of the nonlinear optically active organic compound which is one of the tertiary amine derivatives of the following structural formula (B) represented by the general formulas (1) and (2). Implemented except that the binder polymer was changed to 7 parts by mass of polycyclic olefin of the following structural formula (P) (trade name Arton, glass transition temperature 170 ° C., manufactured by JSR) and the poling temperature was changed to 125 ° C. In the same manner as in Example 1, a thin film made of an organic nonlinear optical material subjected to electric field poling was produced.

  When the obtained thin film was evaluated in the same manner as in Example 1, generation of second harmonics having the same intensity as in Example 1 was observed, and it was confirmed that the thin film effectively functions as a nonlinear optical material. Furthermore, even after 10 days at 50 ° C., the generation of second harmonics having the same strength as the initial stage was confirmed, and it was confirmed that the nonlinear optical material had high heat resistance and stability over time.

Incidentally, Z ¹ of the present tertiary amine ^{derivative, Z 2, Z 3, L} , and Z ¹ of the substituent A ^{has, Z 2, Z 3, L} , and π conjugated system A and are ring formation The sum of the molecular weights of the parts that are not present (the part enclosed by the broken line) corresponds to 41% of the molecular weight of the tertiary amine derivative.

(Comparative Example 2)
A thin film made of an organic nonlinear optical material subjected to electric field poling was prepared in the same manner as in Example 2 except that the nonlinear optically active organic compound in Example 2 was changed to a known tertiary amine derivative of the following structural formula (X). Then, when the nonlinear optical performance was evaluated in the same manner as in Example 1, although the generation of the second harmonic was observable, the intensity was as low as about 20% of Example 1. Further, after 10 days at 50 ° C., microcrystals of tertiary amine derivatives were precipitated and the transparency was lowered. Incidentally, Z ¹ of the present tertiary amine ^{derivative, Z 2, Z 3, L} , and Z ¹ of the substituent A ^{has, Z 2, Z 3, L} , and π conjugated system A and are ring formation The sum of the molecular weights of the parts not enclosed (parts surrounded by broken lines) corresponds to 10% of the molecular weight of the tertiary amine derivative, and falls within the category of the nonlinear optically active organic compound of the present invention represented by the general formula (1). not enter.

(Comparative Example 3)
The nonlinear optically active organic compound in Example 2 was changed to a tertiary amine derivative of the following structural formula (Y) that does not fall within the category of the nonlinear optically active organic compound of the present invention represented by the general formula (1). A thin film made of an organic nonlinear optical material subjected to electric field poling was produced in the same manner as in Example 2, and the nonlinear optical performance was evaluated in the same manner as in Example 1. Initially, the same strength as in Example 2 was obtained. Although the generation of the second harmonic was observed, after 10 days at 50 ° C., a slight amount of crystallites was observed, and the intensity of the second harmonic was reduced to about 80% of the initial value. It was.

  From Table 1 above, in Examples 1 and 2, satisfactory results were obtained in all of film quality, nonlinear optical performance, thermal and temporal stability of the film quality, and thermal and temporal stability of the nonlinear optical performance. On the other hand, in Comparative Example 1, defects were recognized at the time of thin film formation, and in Comparative Examples 2 to 3, even though the thin film could be formed, other various performances were inferior.

(Example 3)
On a glass substrate (2 cm × 2 cm) on which a gold thin film as a lower electrode was formed by sputtering, UV curable allyl resin (Norland, product name NOA72) was applied by spin coating, and 100 mW / cm. After irradiating ² ultraviolet light (high pressure mercury lamp manufactured by Ushio Electric Co., Ltd.) for 30 seconds, a heat treatment at 120 ° C. for 30 minutes was performed to form a thin film having a thickness of 2 μm to form a lower cladding layer.

  Next, a solution containing the organic nonlinear optical material of the present invention used in Example 2 is applied onto the lower clad layer by spin coating, and dried at 120 ° C. for 30 minutes to form a thin film having a thickness of 2 μm. The core layer was formed.

  Next, the same UV curable allyl resin as that of the lower cladding layer was formed on the core layer in the same manner as the lower cladding layer to form an upper cladding layer (film thickness: 2 μm).

  Next, a striped gold thin film (stripe width 20 μm, stripe interval 30 μm) was formed as an upper electrode on the upper clad layer by using a normal photolithography method and a sputtering method.

  The sample obtained as described above was cut into a 5 mm wide chip by a dicer (manufactured by Disco), the cut surface was polished with sandpaper, and a slab type waveguide device having the configuration shown in FIG. Produced.

  Next, an electric field poling treatment was performed in the same manner as in Example 2 by applying an electric field of 200 V / μm between the upper electrode and the lower electrode of this element.

  In order to confirm that the element subjected to the electric field poling treatment functions as an electro-optic element, the electro-optic is performed according to the method described in “Japanese Journal of Applied Physics, 1991, Vol. 30, No. 2, pp. 320 to 326”. The characteristics were evaluated. A schematic configuration diagram of the evaluation system is shown in FIG. Laser light (semiconductor laser, oscillation wavelength 850 nm) that has passed through the polarizer 23a is incident from one end face of the element, propagates through the core layer in the element, and is emitted from the other end face to the polarizer 23a. The light was detected by a photodetector after passing through a polarizer 23b having a uniform polarization plane. When an electric field was applied between the upper and lower electrodes of the device and the electric field intensity was changed from 0 V to 5 V, it was confirmed that the detected light intensity decreased as the electric field intensity increased. This is due to the fact that the present element has an electro-optic effect and a light modulation behavior is generated in response to the application of an electric field, and indicates that the present element functions effectively as a light modulator. Furthermore, after the nonlinear optical element was kept in a high temperature environment of 50 ° C. for 10 days, the same evaluation was performed again. As a result, light modulation characteristics equivalent to those in the initial stage could be confirmed. It was confirmed to have stability.

6 is a schematic cross-sectional view of a nonlinear optical element manufactured in Example 3. FIG. 6 is a schematic schematic diagram of an evaluation system used in Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Glass substrate 12 ... Lower electrode 13 ... Lower clad layer 14 ... Core layer 15 ... Upper clad layer 16 ... Upper electrode 21 ... Laser light source 22 ... Half wavelength Plates 23a, 23b ... Polarizer (Glan-Thompson prism)
24 ... Lens 25 ... Power supply 26 ... Pinhole 27 ... Photodetector 28 ... Electro-optic element

Claims (10)

An organic nonlinear optical material obtained by dispersing or binding an organic compound having nonlinear optical activity in a polymer binder,
An organic nonlinear optical material comprising at least one tertiary amine derivative represented by the following general formula (1) as the nonlinear optically active organic compound.

[In General Formula (1), Z ¹ , Z ² , and Z ³ are each independently an aromatic group that may have a substituent; L is a π-conjugated group that may have a substituent; A represents a π-conjugated electron-withdrawing group which may have a substituent; m represents 0 or 1; Any ^{one of} Z ¹ , Z ² , Z ³ , L, and A may be linked to form a ring structure. However, at least one of Z ¹ , Z ² , Z ³ , L, and A necessarily has a substituent, and among the substituents that Z ¹ , Z ² , Z ³ , L, and A have The sum of the molecular weights of Z ¹ , Z ² , Z ³ , L, and A that are not ring-formed with the π-conjugated system is 40% or more of the molecular weight of the tertiary amine derivative. ]   2. The organic nonlinear optical material according to claim 1, wherein A of the tertiary amine derivative has 3 or more cyano groups. The organic nonlinear optical material according to claim 2, wherein A of the tertiary amine derivative has a structure represented by the following general formula (2) or (3).

[In General Formulas (2) and (3), R ¹ and R ² are each independently an arbitrary substituent, and R ³ is an aromatic group that may have an arbitrary substituent. R ¹ and R ² may be connected to each other to form a ring structure. ] The organic nonlinear optical material according to claim 3, wherein at least one of R ¹ and R ² of the tertiary amine derivative is a substituent having a molecular weight larger than that of a methyl group. 5. The organic nonlinear optical material according to claim 4, wherein at least one of R ¹ and R ² of the tertiary amine derivative is an aromatic group which may have an arbitrary substituent. 6. The method according to claim ¹ , wherein at least one of Z ¹ and Z ² of the tertiary amine derivative is an aromatic group having a substituent having a molecular weight larger than that of a methyl group. Organic nonlinear optical material. 7. The organic nonlinear optical material according to claim 1, wherein at least one of Z ¹ and Z ² of the tertiary amine derivative and A have a substituent containing a dendron structure.   The organic nonlinear optical material according to any one of claims 1 to 7, wherein the polymer binder contains at least one of polyimide, polycarbonate, polyarylate, polysulfone, and polycyclic olefin.   A nonlinear optical element using the organic nonlinear optical material according to any one of claims 1 to 8.   The nonlinear optical element according to claim 9, wherein the nonlinear optical element operates based on an electro-optic effect.

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