JP2005227378A - 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 which can solve the conventional problem of stability and the like while a favorable effect such as excellent nonlinear performance and high productivity that an organic material potentially has is maintained by using a special resin binder satisfying various needed characteristics and to provide a nonlinear optical element using the same. <P>SOLUTION: The organic nonlinear optical material formed by incorporating an organic compound having nonlinear optical activity into the resin binder is characterized in that the resin binder is a cyclic olefinic resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to nonlinear optics that can be effectively used for wavelength conversion elements, optical modulators, optical switches, optical integrated circuits, optical computers, etc., which are important in the fields of optical information communication using light, optical information processing, imaging, etc. It relates to an element. Furthermore, this invention relates to the organic nonlinear optical material required in order to produce the said 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 secondary nonlinear optical materials. Is embodied by. As the second-order nonlinear optical material, inorganic nonlinear optical materials such as lithium niobate and potassium dihydrogen phosphate have already been put into practical use and widely used. However, in recent years, 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 and high manufacturability, and active research and development for practical use is being conducted.

  In principle, a secondary organic nonlinear optical material is required to have no target center in the system, and a system in which an organic compound having nonlinear optical activity is crystallized into a crystal structure having no symmetry center (hereinafter, “ And a system in which an organic compound having nonlinear optical activity is contained in a resin binder and the organic compound having nonlinear optical activity is oriented by some means (hereinafter referred to as “resin dispersion system”). It is divided roughly into.

  The crystalline organic nonlinear optical material is known to exhibit extremely high nonlinear performance, but it is difficult to produce a large organic crystal necessary for device formation, and the strength of the organic crystal is very fragile. There are problems such as breakage in the element fabrication process. On the other hand, the organic dispersion optical material of the resin dispersion system is provided with favorable characteristics such as film formability and mechanical strength useful for elementization by the resin binder, and has potential for practical use. Highly promising.

  In the nonlinear optical material of the resin dispersion system, it is required that the organic compound having nonlinear optical activity is uniformly dispersed in the resin binder without agglomeration and becomes optically homogeneous and transparent. Furthermore, as described above, in order to exhibit the second-order nonlinear optical effect, an organic compound having nonlinear optical activity must be oriented by some means to impart anisotropy as a system, and can be used as a functional element. In doing so, the orientation state must be maintained stably over a long period of time in a temperature and humidity environment where the element is placed.

  Therefore, as a resin binder used for an organic nonlinear optical material of a resin dispersion system, a high glass for stably maintaining the high compatibility with an organic compound having nonlinear optical activity and the orientation state of the organic compound having nonlinear optical activity. A transition temperature is required. In general, a resin-dispersed organic nonlinear optical material is formed into an element in the form of a thin film, and a wet coating method is suitably used as a method for forming the thin film. Therefore, the resin binder used for the resin-dispersed organic nonlinear optical material is required to have high solubility in a coating solvent.

  In general, when a resin-dispersed organic nonlinear optical material is made into an element, the resin-dispersed organic nonlinear optical material is often used by being formed on the surface of any substrate or other resin thin film. In many cases, another thin resin film is formed on the surface of the thin film. Therefore, as the resin binder used in the organic nonlinear optical material of the resin dispersion system, a resin excellent in adhesion and adhesion to the substrate and other resin thin films is preferable.

  In addition, resin binders used for organic nonlinear optical materials of resin dispersion generally have low birefringence, low hygroscopicity, high amorphousness, colorless transparency, and low optical distortion. In addition, it is necessary to satisfy various requirements such as high light stability and high thermal stability.

  Conventionally, polymethylmethacrylate resin (generally abbreviated as PMMA) has been best studied as a resin binder used for resin-dispersed organic nonlinear optical materials, but the glass transition temperature of PMMA is as low as about 100 ° C., The alignment state of a resin dispersion organic nonlinear optical material using PMMA as a resin binder gradually relaxes even at room temperature, and the nonlinear optical performance deteriorates remarkably over time, so it cannot be put into practical use as a functional element. It is known (for example, refer nonpatent literature 1).

  In order to solve this problem, a search for a resin binder instead of PMMA has been actively conducted, and the effectiveness of a resin having a glass transition temperature higher than that of PMMA such as a polycarbonate resin, a polyimide resin, or a polysulfone resin has been reported ( For example, see Patent Document 1). However, no material satisfying all the required properties for the resin binder for organic nonlinear optical materials of the resin dispersion system has been found yet.

Further, examples of cyclic olefin resins having excellent heat resistance and the like applied to optical materials such as light guide plates, optical lenses, and optical disks have been reported (for example, see Patent Document 2 and Non-Patent Document 2). The resin binder for optical materials has not been studied at all, and the compatibility with organic compounds having nonlinear optical activity and the characteristics as organic nonlinear optical materials have not been known.
Thus, at present, resin-dispersed organic nonlinear optical materials have not been put into practical use.

In addition, as a development system of organic nonlinear optical materials of resin dispersion, research on nonlinear optically active polymer compounds in which a nonlinear optically active structure is introduced into the side chain and / or main chain is also being conducted. It is difficult to design a polymer compound having favorable polymer properties such as mechanical strength and film formability, and the degree of polymerization is increased in the synthesis of a polymer compound having a nonlinear optically active structure. However, there are problems such as decomposition of the nonlinear optically active structure during the polymerization reaction, difficulty in purification, etc., and it is not necessarily suitable for practical use at this stage.
Chemical Reviews, 1994, 94, 1, 31-75 Functional materials, 2000, 20 volumes, No. 8, pp. 16-22 JP-A-6-202177 JP 2001-324618 A

The object of the present invention is to solve the problems of the prior art as described above.
That is, the present invention uses conventional resin binders that satisfy the above-mentioned required characteristics, while maintaining the favorable effects of organic materials such as excellent non-linear performance and high productivity, with the conventional problems. An object of the present invention is to provide an organic nonlinear optical material that can solve problems such as stability, and a nonlinear optical element using the organic nonlinear optical material.

  As a result of intensive studies on the resin binder and the organic compound having nonlinear optical activity in order to solve the above-mentioned problems, the present inventors can solve the above-mentioned problems by utilizing a specific resin binder. As a result, the present invention has been completed.

That is, the present invention
<1> An organic nonlinear optical material comprising an organic compound having nonlinear optical activity in a resin binder, wherein the resin binder is a cyclic olefin resin.

<2> The <1> characterized in that the cyclic olefin-based resin is a polymer of a monomer containing at least a bicyclic olefin represented by the following general formula (1) or a hydrogenated product of the polymer. The organic nonlinear optical material described.

In the above formula, R ^{1 to} R ⁴ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group, and any two or more may be linked to each other to form a ring structure. m and p each independently represent 0 or a positive integer.

  By using the polymer or a hydrogenated product of the polymer, particularly advantageous effects are exhibited in terms of glass transition temperature, amorphousness, optical quality, hygroscopicity, and the like.

<3> The polymer containing the bicyclic olefin represented by the general formula (1) or the hydrogenated product of the polymer is a polymer containing a repeating unit represented by the following general formula (2). The organic nonlinear optical material according to <2>.

  In the above formula, X and Y each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group.

  By using the cyclic olefin-based resin containing the repeating unit, compatibility with organic compounds having nonlinear optical activity, solubility in coating solvents, adhesion and adhesion to substrates, chemical stability, etc. Thus, a particularly preferable effect is exhibited.

<4> The organic nonlinear optical material according to any one of <1> to <3>, wherein the organic compound having nonlinear optical activity is a tertiary amine derivative represented by the following general formula (3): It is.

In the above formula, Z ¹ and Z ² are each independently a monovalent organic group, L ¹ is a substituted or unsubstituted aromatic group, L ² is a π-conjugated group, and A is an electron-withdrawing group. It is a group. Any of Z ¹ , Z ² and L ¹ may be linked to form a ring structure. Furthermore, L ² may be linked to L ¹ or A to form a ring structure.

  By using the tertiary amine derivative, particularly advantageous effects are exhibited in terms of nonlinear optical performance, compatibility with a resin binder, chemical stability, heat resistance, and the like.

<5> A nonlinear optical element using the organic nonlinear optical material according to any one of <1> to <5>.

  The organic nonlinear optical material of the present invention is characterized in that an organic compound having nonlinear optical activity is dispersed in a cyclic olefin resin binder excellent in various properties, and an organic compound having nonlinear optical activity at a high concentration in the material. Even in the presence of compounds, they do not agglomerate and take a uniform dispersion state. Therefore, they have both high optical quality and nonlinear optical activity, and the thermal stability and temporal stability of the alignment state of organic compounds with nonlinear optical activity. It has a favorable effect such as being high and capable of maintaining excellent characteristics 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>
The organic nonlinear optical material of the present invention is an organic nonlinear optical material in which an organic compound having nonlinear optical activity is contained in a resin binder, wherein the resin binder is a cyclic olefin resin.

  The cyclic olefin-based resin in the present invention is a polymer of a monomer containing at least one cyclic olefin or a chemically modified product of the polymer, and includes an alicyclic structure in the main chain. Examples include the resin groups shown in the following (A) to (D).

(A) Ring-opening (co) polymer of one or more polycyclic olefins (B) Hydrogenated product of the ring-opening (co) polymer (C) Addition (co) polymer of one or more cyclic olefins ( D) Addition copolymer of one or more cyclic olefins and one or more unsaturated double bond-containing compounds In the present invention, the above-mentioned bicyclic olefin constitutes the ring structure in the ring structure of the cyclic compound. A cyclic olefin having a structure in which any two or more of atoms are connected via another organic group and a plurality of ring structures are fused.

  Cyclic olefin-based resins are bulky in the main chain and contain a highly hydrophobic alicyclic structure, so they are excellent in amorphousness, chemical stability, etc. In addition, they are high glass for resin-dispersed organic nonlinear optical materials. Compared to polyimide resins, polycarbonate resins, polysulfone resins and the like disclosed as transition temperature resin binders, they have preferable characteristics such as remarkably low birefringence and low hygroscopicity.

  In addition, as described above, a cyclic olefin resin has not been studied as a resin binder of an organic nonlinear optical material, but the present inventors have described that an organic compound having a nonlinear optical activity as described later. The present inventors have found that the compatibility with a compound is excellent, and completed the organic nonlinear optical material of the present invention having high nonlinear optical characteristics and stability.

  As the cyclic olefin-based resin, in particular, a polymer of a monomer containing at least a bicyclic olefin represented by the following general formula (1) or a hydrogenated product of the polymer has glass transition temperature, optical quality, and the like. And particularly preferred.

In the above formula, R ^{1 to} R ⁴ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group, and any two or more may be linked to each other to form a ring structure. m and p each independently represent 0 or a positive integer.

  Among them, the cyclic olefin resin containing the repeating unit represented by the following general formula (2) is easy to synthesize, compatible with organic compounds having nonlinear optical activity, solubility in coating solvents, substrates, etc. It is particularly preferable from the viewpoints of adhesion and adhesion to the surface, chemical stability, and the like.

  In the general formula (2), X and Y each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group.

  As the alkyl group, an alkyl group having 1 to 4 carbon atoms is preferable, and a methyl group is particularly preferable. Moreover, X and / or Y may have a reactive functional group that exhibits a connectivity with an organic compound having cross-linking curability and / or nonlinear optical activity.

In the cyclic olefin resin represented by the general formula (2), m in the monomer represented by the general formula (1) is 1, p is 0, R ¹ is COOY, R ² is X, R ³ and It corresponds to a hydrogenated product of a ring-opened polymer of bicyclic olefin in which R ⁴ is a hydrogen atom.

  Specific examples of the bicyclic olefin represented by the general formula (1) and the repeating unit represented by the general formula (2) include “JP 2001-324618 A”, “Functional Materials, 2000, Vol. 20, No. 8. , Pp. 16-22, etc. Among these, a cyclic olefin resin represented by the general formula (2) in which X and Y are both methyl groups is particularly preferable in terms of low birefringence and high amorphousness.

As a method for synthesizing the cyclic olefin resin in the present invention, the ring-opening polymerization method described in “JP 2001-324618 A” or the like can be used.
For example, a cyclic olefin-based resin can be obtained by ring-opening (co) polymerizing one or more bicyclic olefins represented by the general formula (1). Moreover, a cyclic olefin resin is also obtained by ring-opening copolymerization of one or more bicyclic olefins represented by the general formula (1) and any cyclic olefin such as cyclobutene, cyclopentene, cycloheptene, and cyclooctene. be able to. The cyclic olefin resins obtained by ring-opening (co) polymerization have a carbon-carbon double bond and are inferior in chemical stability. It is preferable to carry out chemical modification of to make a saturated product.

  The ring-opening (co) polymerization reaction can generally be performed by using a metathesis catalyst. The hydrogenation reaction can be carried out by adding a hydrogenation catalyst to a solution containing a ring-opening (co) polymer and allowing hydrogen gas at normal pressure to 300 atm to act thereon. In addition, although there is no restriction | limiting in particular as a hydrogenation catalyst, Palladium, platinum, Wilkinson complex, etc. are suitable.

  Further, the cyclic olefin-based resin in the present invention can also be obtained by addition (co) polymerizing one or more kinds of the bicyclic olefin represented by the general formula (1) using a Ziegler catalyst or a metallocene catalyst. .

  At this time, olefin derivatives such as ethylene, propylene, butadiene, cyclohexene, 1,5-hexadiene, tetrafluoroethylene; styrene derivatives such as styrene, vinylnaphthalene, 4-chloromethylstyrene, 4-hydroxystyrene; maleimide, N-phenyl Any unsaturated double bond-containing compound such as maleimide derivatives such as maleimide, acrylic acid derivatives such as methyl acrylate, methyl methacrylate, and hydroxyethyl methacrylate; may be added and copolymerized.

  As the molecular weight of the cyclic olefin resin in the present invention, the polystyrene equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is preferably in the range of 2,000 to 1,000,000, and Mw is 10,000 to 10,000. A range of 500,000 is more preferable.

Moreover, it is preferable that the glass transition temperature of cyclic polyolefin resin in this invention is the range of 100-300 degreeC, and it is more preferable that it is the range of 150-250 degreeC.
In the present invention, a differential scanning calorimeter (DSC) is used to measure the glass transition temperature of the polymer binder and the organic nonlinear optical material described later, and is measured from room temperature at a heating rate of 10 ° C. per minute. The temperature corresponding to the intersection between the slope of the rising end of the endothermic process and the baseline was taken as the glass transition temperature.

  In addition, the birefringence of the cyclic polyolefin resin in the present invention is preferably 100 nm or less, and more preferably 50 nm or less. The birefringence is a retardation value measured with an ellipsometer on a disk molded product having a thickness of 1.2 mm.

  Furthermore, the water absorption rate of the cyclic polyolefin-based resin in the present invention is preferably 2% by mass or less, more preferably 0.5% by mass or less as a saturated water absorption rate.

(Organic compound having nonlinear optical activity)
The organic compound having nonlinear optical activity used in the present invention is not particularly limited, and is described in “Jounal of the American Chemical Society, 1993, 115, 26, 12599-12600”, “Industrial & Engineering Chemistry Research, 1999. Year, Vol. 38, No. 1, pp. 8-33 ”,“ Chemistry of Materials, 2002, Vol. 14, No. 11, pp. 4669-4675 ”and the like can be used.

  In particular, in the present invention, the use of a tertiary amine derivative represented by the following general formula (3) exhibits favorable effects in terms of nonlinear optical performance, compatibility with a resin binder, chemical stability, heat resistance, and the like. Is done.

In the above formula, Z ¹ and Z ² are each independently a monovalent organic group, L ¹ is a substituted or unsubstituted aromatic group, L ² is a π-conjugated group, and A is an electron-withdrawing group. It is a group. Also, any ^one of Z ¹ , Z ² and L ¹ may be linked to form a ring structure. Furthermore, L ² may be linked to L ¹ or A to form a ring structure.

Specific examples of the tertiary amine derivative represented by the general formula (3) include compounds shown in the following (3-1) to (3-12). In these, “Me” represents a methyl group, “Et” represents an ethyl group, “Bu” represents a butyl group, “ ^t Bu” represents a tertiary butyl group, and “Ac” represents an acetyl group.

  The sublimation temperature of the organic compound having nonlinear optical activity used in the present invention is preferably 120 ° C. or higher, and more preferably 170 ° C. or higher. By using an organic compound having nonlinear optical activity having a sufficiently high sublimation temperature, disappearance due to sublimation of the organic compound having nonlinear optical activity can be prevented in the poling treatment described later.

  As described above, as a combination of the cyclic olefin resin used in the present invention and the organic compound having nonlinear optical activity, from the viewpoint of nonlinear optical performance, film homogeneity, molecular orientation, stability, etc. For example, with respect to the cyclic olefin resin containing the repeating unit represented by the general formula (2), the tertiary amine represented by the general formula (3) has a structure such as (3-7) or (3-8). It is preferable to use a compound.

  The organic nonlinear optical material of the present invention is formed from at least the cyclic olefin resin and an organic compound having nonlinear optical activity. The form may be 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 made of 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, and a wet coating method can be used. Spinning a solution in which at least the cyclic olefin-based resin and an organic compound having nonlinear optical activity are dissolved in an organic solvent from the viewpoints of properties, film quality (thickness uniformity, few defects such as bubbles), etc. A wet coating method in which a film is formed by coating on an appropriate substrate by a method such as a coating method, a blade coating method, a dip coating method, a spray coating method, or an inkjet coating method is preferable.

  The organic solvent used in the wet coating method may be anything as long as it can dissolve the cyclic olefin resin to be used and the organic compound having nonlinear optical activity, but the boiling point thereof is in the range of 50 to 200 ° C. Those are preferred. If an organic solvent with a boiling point of less than 50 ° C is used, solvent volatilization will occur during storage of the coating solution, and the viscosity of the coating solution will change (increase), or the solvent will volatilize too quickly during coating and condensation may occur. There is a tendency for problems such as looseness to become prominent. On the other hand, when an organic solvent having a boiling point exceeding 200 ° C. is used, it may be difficult to remove the solvent after coating, and the remaining organic solvent may act as a plasticizer for the resin binder and cause problems such as a decrease in glass transition temperature. is there.

  Examples of preferred organic solvents include tetrahydrofuran, methyltetrahydrofuran, dioxane, diethylene glycol dimethyl ether, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl acetate, cyclohexanol, dichloroethane, toluene, chlorobenzene, xylene, N, N-dimethylformamide, N, N. -Dimethylacetamide, dimethylsulfoxide, etc. are mentioned. These organic solvents may be used alone or in combination.

  In the organic nonlinear optical material of the present invention, the content of the organic compound having nonlinear optical activity varies depending on the type of the organic compound having nonlinear optical activity to be used, the required nonlinear optical performance, mechanical strength, etc. In general, it is preferably in the range of 1 to 200% by mass with respect to the cyclic olefin-based resin. The reason is that if the amount is less than 1% by mass, sufficient nonlinear optical performance cannot be obtained in many cases, and if it exceeds 200% by mass, sufficient mechanical strength cannot be obtained. This is because problems such as aggregation or crystallization tend to occur. The more preferable range of the content is in the range of 5 to 100% by mass, and further preferably in the range of 20 to 70% by mass.

  In addition to the cyclic olefin resin and the organic compound having nonlinear optical activity, various additives can be added to the organic nonlinear optical material of the present invention as necessary. For example, known antioxidants such as 2,6-di-t-butyl-4-methylphenol and hydroquinone may be used for the purpose of suppressing oxidative degradation of cyclic olefin-based resins and / or organic compounds having nonlinear optical activity. For the purpose of suppressing ultraviolet degradation of an olefin resin and / or organic compound having nonlinear optical activity, a known ultraviolet absorber such as 2,4-dihydroxybenzophenone or 2-hydroxy-4-methoxybenzophenone is used to smooth the surface of the coating film. A known leveling agent such as silicone oil for the purpose of improving the properties, or a known curing catalyst or curing aid for the purpose of accelerating the crosslinking and curing when a cyclic olefin resin having a crosslinking curable functional group is used. Furthermore, when the cyclic olefin resin and the organic compound having nonlinear optical activity have a linking functional group, The ligation reaction may be added a known reaction catalyst and reaction aid such as the purpose of accelerating the on.

The organic nonlinear optical material of the present invention is produced by forming the coating liquid produced as described above as a thin film by, for example, the above-described spin coating method. As described above, in the present invention, a cyclic olefin-based resin having a relatively high glass transition temperature is used as a resin binder. However, an organic nonlinear optical material containing an organic compound having nonlinear optical activity is also suitable for heat resistance and the like. From the viewpoint, it is desirable that the glass transition temperature is high.
Therefore, the glass transition temperature of the organic nonlinear optical material is preferably in the range of 80 to 250 ° C, more preferably in the range of 120 to 200 ° C.

  In order to produce secondary nonlinear optical activity in a resin-dispersed organic nonlinear optical material, it is necessary to orient an organic compound having nonlinear optical activity. As an alignment method for this purpose, a resin-dispersed organic nonlinear optical material is applied onto a substrate having an alignment film on the surface, and the nonlinearity in the resin-dispersed organic nonlinear optical material depends on the orientation of the base alignment film. There is a method for inducing the orientation of an organic compound having optical activity. 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 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 (polled) in the direction of the applied electric field 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

  Since the 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, by using a resin binder having a higher glass transition temperature, In use, this problem can be substantially solved. The cyclic olefin resin used in the present invention has a high glass transition temperature due to the bulky alicyclic structure in the main chain, and can guarantee high alignment stability.

  As an index for confirming whether or not the polling is performed, there is a numerical value (order parameter: φ) indicating how many nonlinear optical molecules (generally having dichroism) are oriented in the electric field direction. Specifically, when the absorbance when the orientation of the molecules is random is A0 and the absorbance when oriented in the electric field direction (film thickness direction) is At, φ is 1- (At / A0). It can be calculated.

  The order parameter is a numerical value that is 1 in an ideal state in which all molecules are perfectly oriented, and 0 when completely random, and indicates that the larger the value, the higher the degree of molecular orientation as a whole. By measuring this value, it can be determined how efficiently polling has been performed, and its stability can be evaluated.

<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 a second-order nonlinear 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 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-arsenic; 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 oxide-indium oxide composite oxide); conductive polymers such as polythiophene, polyaniline, polyparaphenylene vinylene, and polyacetylene. These conductive films are formed by using a known dry film forming method such as vapor deposition or sputtering, or a known wet film forming method such as dip coating or electrolytic deposition, and a pattern is formed as necessary. May be. Note that the conductive substrate or the conductive film formed on the substrate as described above is used as an electrode at the time of polling or operation as an element (hereinafter abbreviated as “lower electrode”).

  The substrate surface is further provided with an adhesive layer for improving the adhesion between the film formed on the substrate and the substrate, a leveling layer for smoothing irregularities on the substrate surface, or these functions, if necessary. Some intermediate layer provided in a lump may be formed. The material for forming such a film is not particularly limited, and examples thereof include acrylic resins, methacrylic resins, amide resins, vinyl chloride resins, vinyl acetate resins, phenol resins, urethane resins, vinyl alcohol resins, acetal resins, and the like. Known products such as a crosslinked product of zirconium chelate compound, titanium chelate compound, silane coupling agent and the like, and a co-crosslinked product thereof can be used.

  The electro-optical element which is the nonlinear optical element of the present invention is preferably formed 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, a channel-type waveguide can be formed by changing the refractive index of the irradiated portion by patterning and irradiating a part of the core layer with UV light, an electron beam or the like. Further, by patterning the lower cladding layer and forming a core layer thereon, an inverted ridge waveguide can be formed.

  A basic electro-optic element is formed by forming an electrode (hereinafter referred to as “upper electrode”) for applying an input electric signal to the surface of the upper cladding layer in a desired region of the upper cladding layer. be able to.

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

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.
<Example 1>
(Production of organic nonlinear optical materials)
The following structure which is a kind of a polymer containing a repeating unit represented by the general formula (2) on a glass substrate (2 cm × 2 cm) provided with a pair of gold parallel electrodes (distance between electrodes: 20 μm) on the surface 8 parts by mass of the cyclic olefin resin of the formula (manufactured by JSR, trade name: Arton, glass transition temperature: 170 ° C., saturated water absorption: 0.4 mass%, birefringence: 20 nm), and the general formula (3) 4- [N-ethyl-N- (hydroxyethyl)] amino-4′-nitroazobenzene (manufactured by Aldrich), which is one of the tertiary amine derivatives shown, is added to cyclopentanone (boiling point: 130 ° C.). ) A solution dissolved in 90 parts by mass was applied by spin coating, and dried at 100 ° C. for 1 hour to obtain a thin film 1 having a thickness of 0.2 μm.
The thin film 1 was very clear, and the tertiary amine derivative was homogeneously dispersed. Moreover, the glass transition temperature of the thin film 1 was 140 degreeC.

  Next, in a state where an electric field of 50 V / μm is applied between the parallel electrode pairs, the thin film 1 is held at 150 ° C. for 30 minutes, and after cooling to room temperature while applying the electric field, the electric field is removed. Polling was performed. Regarding the deterioration with time of poling of the thin film 1, both the order parameter immediately after fabrication and the order parameter after storage in a dark place for 10 days were both 0.35, and it was confirmed that no orientation relaxation occurred.

  Note that the above order parameters are for both the thin film A in which the nonlinear optically active compound is randomly oriented without performing the poling treatment and the thin film B in which the nonlinear optically active compound is oriented in the film thickness direction by the poling treatment. Then, immediately after the production of the thin film A and the thin film B, the absorption spectrum is measured with a spectrophotometer (Hitachi, U-3000), and from the wavelength λmax at which the absorption in the visible region of the thin film A and the thin film B is maximized, Calculated by (1).

φ = 1−At / A0 Formula (1)
(In the formula (1), φ represents the order parameter, At represents the absorbance at the wavelength λmax of the polled thin film B, and A 0 represents the wavelength at the wavelength λmax of the thin film A not subjected to the polling treatment. Represents absorbance.)

(Evaluation of organic nonlinear optical materials)
When the YAG laser light having an oscillation wavelength of 1064 nm is irradiated on the thin film 1 made of the organic nonlinear optical material of the present invention subjected to the electric field poling thus obtained, the second harmonic (wavelength: 503 nm) is applied. The generation of the corresponding green light was confirmed, and it was confirmed that it functions effectively as a nonlinear optical material. Furthermore, when this organic nonlinear optical material was kept in a high-temperature and high-humidity environment of 60 ° C. and 80% RH for 10 days and then irradiated again with YAG laser light, it was confirmed that green light having the same intensity as the initial generation was generated. It was confirmed that this organic nonlinear optical material has high heat resistance, moisture resistance and stability over time.

  In addition, when the thin film 1 after high-temperature, high-humidity environment maintenance was observed with the optical microscope, it was very clear and it has confirmed that the tertiary amine derivative was uniformly molecularly dispersed in cyclic olefin resin. Moreover, even if the thin film 1 bumped with tweezers, it was confirmed that the thin film 1 was firmly adhered on the substrate without peeling off.

<Comparative Example 1>
In the production of the organic nonlinear optical material of Example 1, the resin binder was changed from a cyclic olefin resin to a bisphenol A polycarbonate resin (manufactured by Aldrich, glass transition temperature: 150 ° C., water absorption: 0.4 mass%, birefringence: 60 nm). And an organic nonlinear optical material thin film subjected to electric field poling was produced in the same manner as in Example 1 except that the poling temperature was changed to 130 ° C.

  When the obtained thin film was evaluated in the same manner as in Example 1, initially, second harmonics having the same intensity as in Example 1 could be observed, but in a high-temperature and high-humidity environment of 60 ° C. and 80% RH, 10%. After holding for days, a clear decrease in strength was observed. In addition, when this thin film was observed with the optical microscope, the microcrystal of the tertiary amine derivative was confirmed although it was a little. Moreover, when this thin film was bumped with tweezers, it was easily peeled off from the substrate.

<Comparative example 2>
In the production of the organic nonlinear optical material of Example 1, the resin binder was changed from a cyclic olefin resin to a polymethyl methacrylate resin (manufactured by Aldrich, glass transition temperature: 90 ° C., water absorption: 2.0 mass%, birefringence: 20 nm). And an organic nonlinear optical material thin film subjected to electric field poling was produced in the same manner as in Example 1 except that the poling temperature was changed to 80 ° C.

  When the obtained thin film was evaluated in the same manner as in Example 1, initially, second harmonics having the same intensity as in Example 1 could be observed, but in a high-temperature and high-humidity environment of 60 ° C. and 80% RH, 10%. No generation of secondary harmonics was observed after holding for days.

<Example 2>
(Production of nonlinear optical elements)
On a glass substrate (2 cm × 2 cm) having an ITO conductive film as a lower electrode formed on the surface, UV curable acrylic resin (Norland, product name: NOA72) was applied by spin coating, and 100 mW / cm ^2. Was irradiated for 60 seconds, followed by a heat treatment at 120 ° C. for 30 minutes to form a lower cladding layer having a thickness of 2 μm.

  Next, a solution containing the cyclic olefin resin and the tertiary amine derivative used in Example 1 was applied to the surface of the lower clad layer by a spin coat method, dried at 100 ° C. for 1 hour, and a film thickness of 2 μm. The core layer was formed. Further, the same UV curable acrylic resin as that of the lower cladding layer is formed on the surface of the core layer in the same manner as the lower cladding layer to form an upper cladding layer having a thickness of 2 μm, and the substrate / lower cladding layer / A slab waveguide having a structure of core layer / upper clad layer was produced.

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

  The sample obtained as described above is cut into a chip having a width of 5 mm by a dicer (manufactured by Disco), the cut surface is polished with sandpaper, and a non-linear optical element having a cross section shown in FIG. Produced.

(Evaluation of nonlinear optical elements)
Next, an electric field of 100 V / μm was applied between the upper electrode 16 and the lower electrode 12 of the nonlinear optical element, and an electric field poling process was performed at 150 ° C. for 30 minutes.
In order to confirm that the nonlinear optical element subjected to the electric field poling process functions as an electro-optical element, the electro-optical characteristics were evaluated by the evaluation system shown in FIG.

  In the evaluation system shown in FIG. 2, laser light (He-Ne laser, oscillation wavelength: 633 nm) that has passed through the half-wave plate and the polarizer 23a from the light source 21 is transmitted from one end face (left side in the figure) of the electro-optic element 28. Incident light is propagated through the core layer in the electro-optic element 28 and emitted from the other end face (the right side in the figure). The light passes through the pinhole 26 and the polarizer 23b having the same polarization plane as that of the light. The detector 27 is configured to detect. In the figure, reference numeral 24 denotes a lens.

  When the non-linear optical element produced as described above is installed as the electro-optical element 28 and an electric field is applied between the upper and lower electrodes by the power source 25 and the electric field intensity is changed from 0 V to 20 V, the electric field intensity increases. Along with this, the behavior that the detected light intensity decreases was confirmed. This is because the nonlinear optical element has an electro-optic effect, and the polarization plane is rotated in response to the application of an electric field. This indicates that the nonlinear optical element functions effectively as an optical modulator. is there. Further, when this nonlinear optical element was kept in a high temperature and high humidity environment of 65 ° C. and 80% RH for 10 days, the same evaluation was performed again. It was confirmed that the device had high heat resistance, moisture resistance, and stability over time.

It is typical sectional drawing which shows an example of the nonlinear optical element of this invention. It is a schematic block diagram of the evaluation system of a nonlinear optical element.

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-wave plate 23a, 23b Polarizer (Glan-Thompson prism)
24 lens 25 power supply 26 pinhole 27 photodetector 28 electro-optic element

Claims (5)

  An organic nonlinear optical material comprising an organic compound having nonlinear optical activity in a resin binder, wherein the resin binder is a cyclic olefin resin. 2. The organic material according to claim 1, wherein the cyclic olefin-based resin is a polymer of a monomer containing at least a bicyclic olefin represented by the following general formula (1) or a hydrogenated product of the polymer. Nonlinear optical material.

(In the above formula, R ^{1 to} R ⁴ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group, and any two or more may be linked to each other to form a ring structure. m and p each independently represent 0 or a positive integer.) The polymer containing a bicyclic olefin represented by the general formula (1) or a hydrogenated product of the polymer is a polymer containing a repeating unit represented by the following general formula (2). 2. The organic nonlinear optical material according to 2.

(In the above formula, X and Y each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group.) The organic nonlinear optical material according to claim 1, wherein the organic compound having nonlinear optical activity is a tertiary amine derivative represented by the following general formula (3).

(In the above formula, Z ¹ and Z ² are each independently a monovalent organic group, L ¹ is a substituted or unsubstituted aromatic group, L ² is a π-conjugated group, and A is an electron-withdrawing group. Z ¹ , Z ² , and L ¹ may be linked to each other to form a ring structure, and L ² is linked to L ¹ or A to form a ring. A structure may be formed.)   A nonlinear optical element using the organic nonlinear optical material according to claim 1.

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