JPH02179622A - Nonlinear optical material and nonlinear optical element - Google Patents

Abstract

PURPOSE:To obtain high nonlinearity and to improve moldability by using the solid soln. which is formed by uniformly dispersing a ferroelectric high- polymer liquid crystal and a nonlinear optical compd. and has excellent mechanical strength and processability. CONSTITUTION:A guest org. compd. which is the nonlinear optical compd. having nonlinear optical characteristics is easily and uniformly compatible in the host high-polymer liquid crystal compd. to form the solid soln. having the excellent mechanical strength and processability. A side chain type high- polymer liquid crystal and a main chain type high-polymer liquid crystal, etc., are usable as the ferroelectric high-polymer liquid crystal used in this case. Since the ferroelectric high-polymer liquid crystal is a high polymer, the nonlinear optical material obtd. in such a manner has the high stability in terms of maintenance of the oriented state and the easy disturbance of the orientation by shock, etc., is obviated. The nonlinear optical element formed by subjecting such nonlinear optical material to an orientation treatment is easy to form and has a high memory characteristic and switching characteristic.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a nonlinear optical material and an element made of the material, and in particular to a nonlinear optical material suitable for forming a portion such as a thin film or fiber waveguide. Regarding.

[Prior art] Conventionally, nonlinear optical materials include KDP and LiNb0.
Inorganic single crystals such as :+ and organic single crystals such as urea are known, and have been used, for example, in wavelength conversion elements of lasers. However, it is technically difficult to obtain such a single crystal of sufficient size, and it is not possible to obtain one at a low cost.

Furthermore, it is known that forming a thin-film or fiber-like waveguide using a nonlinear optical material can improve the nonlinear optical effect by focusing the incident light. It is not easy to form such a waveguide. For example, in LiNbO3, Ti and H are diffused and exchanged into a single crystal, which takes time and is difficult to control.

For example, attempts have been made to obtain large single crystals in the form of thin films or fibers by vapor deposition or zone melting in a capillary. [Naya Bee
K “A C S Symbosia J” (Nayar,
B, K, ; AC3sym,) 153 pages, 19
[1983], however, in this method, the phase-matched orientation required to efficiently obtain second harmonic generation (SHG) and third harmonic generation (THG), which are nonlinear optical effects, cannot be achieved. It is not easy to control single crystals.

As described above, nonlinear optical elements made only of single crystals have problems in terms of workability, cost, etc. Therefore, as a means to solve such problems, a nonlinear optical element has been proposed in which fine nonlinear optical compounds are dispersed and oriented in a polymer. Note that the polymer is usually called a host polymer, and the dispersed compound is called a guest compound.

As an optical material consisting of a host polymer and a guest compound, for example, an azo dye is dissolved in a polymethyl methacrylate resin to form a thin film, heated above the glass transition point, and a voltage is applied to arrange the azo dye molecules. There are some that are formed by cooling and fixing the structure.
A nonlinear optical constant of 6X 1O-9esu has been observed for this material.

[Singer, K.D., Thorn, J.E., Lalama, N.J., Applied Physics Letters J (Singer, D., 5ohn,
J.

E, and Lalama, S, J; App
l, Phys, Lett, ) 49.248 pages,
1986].

Further, for example, Japanese Patent Application Laid-Open No. 62-84139 discloses a nonlinear optical element using an acrylamide resin as a host polymer and a nonlinear optically responsive organic compound as a guest compound.

Moreover, for example, JP-A-57-45519 and US Pat. No. 4,428,873 disclose devices using a host polymer and a guest compound that is a nonlinear optically responsive organic compound.

Further, for example, Japanese Patent Application Laid-Open No. 62-246962 discloses an element formed by growing a compound having a chiral center (guest compound) in polyoxyalkylene oxide (host polymer).

An element composed of a host polymer and a guest compound as described above is superior to a single crystal element in terms of workability and cost, and is suitable for device production.

However, such devices have the following problems. In other words, in order to increase the nonlinear optical effect of the device, the content of the guest compound in the solid solution is increased, and a large amount of the low-molecular polar compound as a guest is added to the high-molecular polymer, for example, at least 203! It is difficult to uniformly blend at a molecular level of E amount % or more, and disadvantages such as partial phase separation of guest molecules and crystallization may occur.

In addition, in such a blend polymer, particularly when the content of low-molecular polar guest molecules increases, the flexibility of the polymer itself tends to be lost, and the mechanical strength tends to decrease significantly.

Also, speaking of second-order nonlinear optical effects.

Even if the guest molecule alone has a large polarizability β, if it is an unoriented, centrosymmetric crystal, it will have no SHG activity or only a small amount if mixed with a conventional polymer. Therefore, it was necessary to make it into a film and apply an electric or magnetic field or stretch it to orient it.

Furthermore, as shown in the report by Zinger K.D. et al., the energy of the electric field is small compared to the natural energy, that is, there is a strong tendency for thermal diffusion, so even if the electric field is applied close to dielectric breakdown, it will not work. It was not possible to obtain molecular orientation or large nonlinear susceptibility. In order to solve such problems, a proposal has been made to use a polymer having liquid crystal properties as a host polymer.

For example, attempts have been made to align polar molecules using the electric field orientation of the polymer liquid crystal using a polymer liquid crystal as a host and polar molecules as a guest, and SHG has been observed by applying a voltage [Mereditis G.R. et al. Macromolecules” (Meredith, G, R+et
al ; Macromolecules, ) 151
385, 1982] In order to solve the above-mentioned problems, it has also been proposed to impart nonlinear optical properties to the liquid crystalline polymer itself without using a guest compound.

For example, JP-A No. 62-190230, JP-A No. 62-1902
-1902:13, JP-A-62-190208, JP-A-62-201419, etc. disclose polyvinyl polymers, polyoxyalkyl polymers, polycyclohexane, etc. as liquid crystalline polymers having nonlinear optical properties. system polymers, etc. are disclosed.

However, even in devices using these liquid crystalline polymers, the molecular orientation and the nonlinear optical properties obtained from the orientation are still insufficient, and large nonlinear optical effects cannot be obtained.

On the other hand, to further improve the asymmetric central molecular orientation,
JP-A-6:1-192030 discloses a side chain type polymer liquid crystal having a nonlinear optical side chain having a chiral group. This side-chain polymer liquid crystal has a structure similar to that of dimethylaminonitrostilbene, and has a similarly large molecular nonlinear susceptibility (β), 2-methyl-4-nitroaniline (M
It is an inorganic material that has been copolymerized with a side chain that has a side chain of about 10 times that of NA), and is used in practical applications.
Nonlinearity on the same level as NA has been confirmed. However, the molecular nonlinear susceptibility of the nonlinear side chain used here is still small, and the degree of molecular orientation is insufficient. Furthermore, the side chain type polymer liquid crystal used here is not a ferroelectric liquid crystal having a chiral smectic C phase, and therefore has poor molecular orientation memory properties.

Furthermore, JP-A No. 63-204235 discloses a nonlinear optical element in which a ferroelectric side-chain polymer liquid crystal exhibiting a chiral smectic C phase is used in the core or crut portion of an optical fiber in order to obtain an asymmetric central alignment. has been disclosed, but a highly nonlinear molecular structure has not been introduced;
The nonlinearity is only about 10 times that of an amorphous polymer doped with dimethylaminonitrostilbene and oriented in an electric field.

[Problems to be Solved by the Invention] The present inventors have already disclosed in Japanese Patent Application No. 6:1-179097 that a guest organic compound having a large nonlinear polarizability can easily be added to a host polymeric liquid crystal compound. They are uniformly compatible, and the second-order and third-order nonlinear optical effects of the guest organic compound do not deteriorate when blended with the host polymeric liquid crystal compound, and furthermore, even when a large amount of the guest organic compound is contained. To provide a new solid solution with flexibility and excellent mechanical strength and processability, and to provide a second-order nonlinear optical effect, β is large, but the guest organic compound alone is a centrosymmetric crystal, and has SHG activity. The purpose of the present invention is to provide a solid solution that can exhibit large SHG activity by blending a guest organic compound that does not exhibit any properties with the host polymeric liquid crystalline compound. showed a nonlinear optical material containing

Furthermore, compared to such conventional methods, the present invention has a greater degree of asymmetric central alignment, exhibits large nonlinearity due to the unique structure of ferroelectric polymer liquid crystal, and has excellent moldability. The object of the present invention is to provide a nonlinear optical material that exhibits the following characteristics.

Another object of the present invention is to provide a nonlinear optical element that has a portion formed by orienting this nonlinear optical material, is easy to produce, and exhibits excellent properties such as high memory and switching characteristics. be.

[Means for Solving the Problems] As a result of extensive studies to achieve the above object, the inventors have discovered that a material containing a ferroelectric polymer liquid crystal and a nonlinear optical compound has large nonlinearity. Heading This led to the completion of the present invention.

That is, the present invention provides a nonlinear optical material characterized by containing a ferroelectric polymer liquid crystal and a nonlinear optical compound,
A nonlinear optical element is characterized in that it has a portion formed by orienting the nonlinear optical material.

The present invention will be explained in detail below.

The reason why the nonlinear optical material of the present invention exhibits good orientation and nonlinearity is considered to be due to the following reasons.

That is, in the liquid crystal structure of a ferroelectric polymer liquid crystal, since the center of inversion symmetry is removed, if there is no other symmetry, a polarization component parallel to the two-fold rotation axis will generally appear. This is important for second-order nonlinear optics,
The presence of such a polarization component causes second-order nonlinear susceptibility to occur in the ferroelectric polymer liquid crystal alone, and in combination with the nonlinearity of the nonlinear optical compound, the material as a whole exhibits good nonlinearity.

Note that the conventional liquid crystal host polymers as described above (for example, those reported by Meredity G.R. et al.) are polymeric liquid crystal compounds that are not ferroelectric.

The guest organic compound, which is a nonlinear optical compound having nonlinear optical properties, used in the present invention is as follows.
It is desirable that the next-order molecular nonlinear susceptibility β is 10 × 10-” esu or more. This is because the guest organic compound effectively aligns against the internal electrolysis that accompanies the alignment of the ferroelectric polymer liquid crystal. more preferably 20x 10
A guest organic compound having a second-order molecule nonlinear susceptibility greater than or equal to ``esu'' is used.

In the nonlinear optical compound, it is desirable that the anisotropy resulting from the molecular shape developed when combined with the host polymer liquid crystal matches the anisotropy of its transition moment.

This facilitates control for phase matching and improves the degree of freedom in device design. The agreement of the anisotropy of this nonlinear optical compound can be estimated by its dichroic ratio, and is preferably 0.3 or more.

Next, as the ferroelectric polymer liquid crystal used in the present invention, side chain type polymer liquid crystals, main chain type polymer liquid crystals, etc. can be used. Examples of the # type polymer liquid crystal used in the present invention include those having the following structure.

(* is an asymmetric carbon, R is H, Cf!, CHi, n
=5~50.000. m-0~30. p-1~
20. q=1-, -20) Examples of the main chain polymer liquid crystal used in the present invention include those having the following structures.

(In the formula, n=5 to 50,000.m=1 to 5.K
= 1~5, f! =1~10. Note that the ferroelectric polymer liquid crystal used in the present invention is not limited to the above structure.

Next, the nonlinear optical compound used in the nonlinear optical material of the present invention, which has a secondary molecular nonlinear susceptibility of IOX 1O-30esu or more, has at least one of an electron-donating group and an electron-withdrawing group in the skeleton having a π-electron system. It is a structure with

Examples of the skeleton having a π-electron system include mono-substituted benzene derivatives, di-substituted benzene derivatives, tri-substituted benzene derivatives,
Tetra-substituted benzene derivatives, mono-substituted biphenyl derivatives, di-substituted pyrrole derivatives, tri-substituted biphenyl derivatives,
Tetra-substituted biphenyl derivatives, mono-substituted naphthalene derivatives, di-substituted naphthalene derivatives, tri-substituted naphthalene derivatives, tetra-substituted naphthalene derivatives, mono-substituted pyridine derivatives, di-substituted pyrazine derivatives, tri-substituted pyridine derivatives, tetra-substituted pyridine derivatives, mono-substituted pyrazine derivatives, di-substituted pyrazine derivatives, tri-substituted pyrazine derivatives, tetra-substituted pyrazine derivatives, mono-substituted pyrimidine derivatives,
Di-substituted pyrimidine derivatives, tri-substituted pyrimidine derivatives,
Tetra-substituted pyrimidine derivatives, mono-substituted azulene conductors, di-substituted azulene derivatives, tri-substituted azulene derivatives, tetra-substituted azulene derivatives, mono-substituted pyrrole derivatives, di-substituted pyrrole derivatives, tri-substituted pyrrole derivatives, tetra-substituted pyrrole conductors, mono-substituted thiophenes derivatives, di-substituted thiophene derivatives, tri-substituted thiophene derivatives, tetra-substituted thiophene derivatives, mono-substituted furan derivatives, di-substituted furan derivatives, tri-substituted furan derivatives, tetra-substituted furan derivatives, mono-substituted pyrylium salt derivatives, di-substituted biryllium salt derivatives, Substituted pyrylium salt derivatives, tetra-substituted biryllium salt derivatives, mono-substituted quinoline derivatives, di-substituted quinoline derivatives, tri-substituted quinoline derivatives, tetra-substituted quinoline derivatives, mono-substituted pyridazine derivatives, di-substituted pyridazine derivatives, tri-substituted pyridazine derivatives, tetra-substituted pyridazine derivatives , monosubstituted triazine derivatives,
Di-substituted triazine derivatives, tri-substituted triazine derivatives,
Mono-substituted tetrazine derivatives, di-substituted tetrazine derivatives,
Mono-substituted anthracene derivatives, di-substituted anthracene derivatives, tri-substituted anthracene derivatives, tetra-substituted anthracene derivatives, etc. can be used.

Electron-donating substituents to be bonded to these groups include amino groups, alkyl groups (methyl, ethyl, isopropyl, n-
Propyl, n-butyl, t-butyl, 5ec-butyl,
n-octyl, t-octyl, n-hexyl, cyclohexyl, etc.), Al, koxy groups (methoxy, ethoxy,
propoxy, butoxy), alkylamino group (N-
methylamino, N-ethylamino, N-propylamino, N-butylamino, etc.), hydroxyalkylamino groups (N-hydroxymethylamino, N-(2-hydroxyethyl)amino, N-(2-hydroxypropylamino, etc.) (biru)amino, N-(3-hydroxypropyl)amino, N-(4-hydroxy)butylamino, etc.), dialkylamino groups (N,N-dimethylamino, N,N-
Diethylamino, N, N-dipropylamino, N, N-
dibutylamino, N-methyl-N-ethylamino, N-
methyl-N-propylamino), hydroxyalkyl-alkylamino group (N-hydroxymethyl-N
-methylamino, N-hydroxymethyl-N-ditylamino, N-hydroxymethyl-N-ethylamino,
N-(2-hydroxyethyl)-N-methylamino,
N-(2-hydroxyethyl)-N-ethylamino,
N-(3-hydroxypropyl)-N-methylamino, N-(2-hydroxypropyl)-N-ethylamino, N-(4-hydroxybutyl)N-butylamino, etc.), dihydroxyalkyl Amino group (N,N-dihydroxymethylamino, N,N-di(2-hydroxyethyl)amino, N,N-c(2-hydroxypropyl)amino, N,N-di(3-hydroxypropyl)amino , N-hydroxymethyl-N-(2
-hydroxyethyl)amino), mercapto group,
Alternatively, a hydroxy group or the like can be used.

Further, as electron-withdrawing substituents, nitro group, cyano group, halogen atom (chlorine atom, bromine atom, iodine atom, fluorine atom), trifluoromethyl group, carboxyl group,
A carboxyester group, carbonyl group, sulfonyl group, etc. can be used.

Next, specific examples of the nonlinear optical compound used in the present invention include the following compounds (1) to (33).

(1) 0-nitroaniline (2) p-nitroaniline CH3-C) = CH-CH pef = 0 (X0 = r' IO:l., NO2", @toC
H=CICOOθC1!0. e, BF4θ*R
e 04 e-CII :s CS Ox e) ■ o, N-C) -C ■ - Old 12 CH.

N5 O□N+CI = CH-◎ (2,') H,N-o-CH= CH-◎ CH*-(:H-C)IzCf(+ (ko1) CR+CH= CN+ N Ox HJ+CI= (:H+ NO□ Poly-γ-benzyl-glutamate (Poly-
y-benzyl-L-glutamate) The nonlinear optical material of the present invention is made of nonlinear optical compounds typified by the above-mentioned examples of compounds having electron-donating groups and electron-withdrawing groups in the ferroelectric polymer liquid crystal described in detail above. It can be obtained by uniformly dispersing selected ones alone or two or more.

The nonlinear optical material of the present invention dissolved in a solvent is
The viscosity can be easily adjusted, and a uniform thin film can be easily obtained by a spin code method, dipping method, casting method, etc., so it is suitable for nonlinear optical elements using thin films.

Furthermore, when a ferroelectric polymer liquid crystal and a nonlinear optical compound are heated and melted and mixed, it is possible to obtain a fiber-like or film-like product by extruding it from a die, and by simultaneously performing a stretching process, etc. Good fibers and films can also be obtained.

It is also possible to combine one or more of the various methods described above, and a good film can also be obtained by a method in which a film obtained by casting is hot-pressed and melt-mixed. The thickness of the nonlinear optical material layer used as a thin film varies depending on the application, and is usually 0.01 pm.
~10 hm, preferably 0.1.1 h ~llp is used. If it is less than 0.01 ha, it is difficult to effectively trap light, and if it exceeds 10 ha, it is not effective because the nonlinear optical effect occurs only in a part of the element.

The amount of the nonlinear optical compound added to the ferroelectric polymer liquid crystal is from o,i to 80% by weight. If it is less than 0.1% by weight, the nonlinear optical effect of the nonlinear optical compound decreases and is not effective. Moreover, if it exceeds 80% by weight, it will have an adverse effect. More preferably, the nonlinear optical compound is 1 to 50
It is desirable to add it in a proportion of % by weight.

Furthermore, in the nonlinear optical material of the present invention, the nonlinear optical compound is uniformly dispersed in the ferroelectric polymer liquid crystal to form a solid solution.

The nonlinear optical material of the present invention obtained as described above exhibits a large second-order nonlinear effect even without any particular alignment treatment. In particular, a single crystal such as P-nitroaniline has central symmetry.

Even nonlinear optical compounds that do not exhibit second harmonic (S HG ) activity exhibit extremely large 5IIG activity when blended with ferroelectric polymer liquid crystals. One of the reasons for this is that between the ferroelectric polymer liquid crystal, which has a liquid crystal structure in which the center of inversion symmetry has been removed, and the guest molecules, there is a strong interaction between molecules that makes it difficult for the guest molecules to maintain central symmetry. This is thought to be due to working.

Furthermore, since the ferroelectric polymer liquid crystal used in the present invention is a polymer, it has high stability in terms of maintaining the alignment state, and similarly, the ferroelectric polymer liquid crystal used in the present invention has high stability in terms of maintaining the alignment state. Dielectric liquid crystals also have the ability to maintain alignment, but this is much better than dielectric liquid crystals, which easily disturb alignment due to shock or the like because they are low molecules.

Furthermore, compared to materials using other polymers, it is extremely superior in terms of memory properties because it is a ferroelectric liquid crystal. These two things greatly contribute to the stability of the nonlinearity over time of the nonlinear optical material of the present invention, and in fact, the nonlinearity of the nonlinear optical material containing the ferroelectric polymer liquid crystal and the nonlinear optical compound of the present invention greatly increases. The quality is stored semi-permanently at room temperature.

It is preferable that the nonlinear optical material of the present invention is prepared by forming a thin film waveguide or fiber as a nonlinear optical part on a substrate, and performing alignment treatment to enable phase matching.

Note that the nonlinear optical material of the present invention is formed on a substrate made of any material such as glass, plastic, or metal,
Furthermore, if necessary, a transparent electrode such as an ITO film or a patterned electrode can be formed on the substrate to constitute a recording medium or a display element.

In order to give the nonlinear optical material of the present invention provided on the substrate as described above the characteristics of orientation, the following methods can be used.

(1) The molecular axis direction of the horizontally oriented ferroelectric polymer liquid crystal is aligned horizontally with respect to the substrate surface) ■Rubbing method By solution coating method, vapor deposition, sputtering, etc. on the substrate, for example, silicon oxide, silicon dioxide, etc. Inorganic insulating materials such as silicon, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron nitride, polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylerin, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride,
A film of an organic insulating material such as polyamide, polystyrene, cellulose resin, melamine resin, urea resin, or acrylic resin is formed, and then the surface is rubbed in one direction with velvet, cloth, or paper to create an orientation control film. form.

■Method vapor deposition method Oxide or fluoride such as SiO or Au, Aj)
An alignment control film is formed by depositing metals such as and their oxides from oblique angles onto the substrate.

(2) Oblique etching method The organic or inorganic insulating film shown in (3) is etched by obliquely irradiating the film with an ion beam or oxygen plasma to form an orientation control film.

■Use of stretched polymer film Stretch a polymer film made of polyester or polyvinyl alcohol.

■Grating method Grooves are formed on the surface of the substrate using photolithography, stump bar, or injection. In this case, the ferroelectric polymer liquid crystal is aligned in the direction of the groove.

(2) Vertical alignment (orienting the molecular axis direction of the ferroelectric polymer liquid crystal perpendicular to the substrate surface) ■ Forming a vertical alignment film.

A vertically aligned layer of organic silane, lecithin, polytetrafluoroethylene, etc. is formed on the surface of the substrate.

(2) Oblique Vapor Deposition (1) - Vertical alignment can be provided by appropriately selecting the deposition angle while rotating the substrate in the oblique vapor deposition method described in (1). Further, after oblique vapor deposition, a vertical alignment agent shown in (2) may be applied.

Further, when a DC electric field is applied to the nonlinear optical element at a temperature higher than the liquid crystal phase temperature simultaneously with or separately from the alignment treatment, and the DC electric field is cooled to a temperature lower than the liquid crystal phase temperature while the application is continued,
Better performance is obtained. As a method of applying a DC electric field, electrodes may be provided on both sides of the film, or corona discharge or the like may be used.

Further, the nonlinear optical element of the present invention has bistability due to interaction with the substrate interface without using an electric field, and therefore has excellent memory properties. To eliminate the helix in order to achieve bistability without using an electric field, the film thickness may be made thinner than the helical period of chiral smectic, and specifically, 50 pot layers or less is preferable. Further, in this case, since the nonlinear optical element of the present invention can switch each bistable state stably and rapidly by an electric field, the SHG signal to be emitted can also be modulated accordingly. Conventional SHG elements only generate SHG, and it is not possible to easily modulate the SHG signal just by using an electric field in this way. The nonlinear optical element of the present invention is excellent in this respect as well, and can be used as a high-speed switching optical modulation element for future optical computers.

[Example] EXAMPLES Hereinafter, the present invention will be explained in further detail by showing examples.

Synthesis Example 1 This synthesis example uses poly4-[4'(11-acryloyloxyundecanyloxy)benzoyloxy], which is a ferroelectric polymer liquid crystal according to the present invention and is represented by the following formula CI>.
The production of benzoic acid 2-methyl-3-hexyloxyethyl ester is illustrated.

(I) Step 1 Synthesis of 4-hydroxybenzoic acid 2-methyl-3-hexyloxyethyl ester 3.2 g of 4-hydroxybenzoic acid and 18.7 g of optically active 2-methyl-3-hexyloxyethanol were mixed in benzene. After concentrating the reaction solution heated under reflux with 1 mf of sulfuric acid for 20 hours, the product 6 was purified by column chromatography.
．． 2g (yield 91%) was obtained.

Step 2 Synthesis of 4-(11-hydroxyundecanyloxy)benzoic acid 5.4 g of p-hydroxybenzoic acid was added to the ethanol-dioxane mixed solvent, and further 6.6 g of potassium hydroxide was added.
After adding an aqueous solution containing , 12.5 g of 11-bromoundecanol was added dropwise, and the mixture was heated under reflux for 12 hours. After acidification and extraction with ethyl acetate, 7.3 g of product (yield 53%) was obtained by column chromatography.

Step 3 Synthesis of 4-(11-acryloyloxyundecanyloxy)benzoic acid 6.4 g of 4-(11-hydroxyundecanyloxy)benzoic acid and 5.8 g of acrylic acid were mixed in benzene in the presence of hydroquinone. The mixture was heated under reflux for 80 hours. The melt was distilled off and column chromatography was performed to obtain 2.9 g of product.
(yield 38%).

]22 Synthesis of 4-[4'-(11-acryloyloxyundecanyloxy)benzoyl]benzoic acid 2-methyl-3-hexyloxyethyl ester 4-(11-acryloyloxyundecanyloxy) ) 1.6g of benzoic acid 2,6
The mixture was heated under reflux for 3 hours in thionyl chloride 2011 in the presence of -di-t-butylphenol. The remaining thionyl chloride was distilled off, 20all of anhydrous THF and 5tall of triethylamine were added, and the mixture was heated at 5°C for 4 hours.
After adding 1.0 g of -hydroxybenzoic acid 2-methyl-3-hexyloxyethyl ester, the mixture was stirred at 50°C for 4 hours. The mixture was made acidic, extracted with ethyl acetate, and subjected to column chromatography to obtain 1.5 g of product (yield: 48%).

Polymerization step 4 - [4'-(11-acryloyloxyundecanyloxy)benzoyl]benzoic acid 2-methyl-3-hexyloxyethyl ester 0.500 g and 3 mo1% azobisisobutyronitrile (AIBN ) was freeze-degassed in anhydrous toluene 51, and then polymerized at 60°C for 24 hours. Repeated reprecipitation from methanol yielded 0.32 g (64%) of the desired polymer.

Number average molecular weight 8700, weight average molecular weight 10600 Phase transition behavior Synthesis example 2 This synthesis example is a ferroelectric polymer liquid crystal according to the present invention represented by the following formula (n), poly4'-(6-acryloyloxyhexyloxy). ) biphenyl-4-carboxylic acid 2-
The synthesis of methyl butyl ester is illustrated.

(II) Step 1 Synthesis of 4'-hydroxybiphenyl-4-carboxylic acid 2-methylbutyl ester 4'-hydroxybiphenyl-4-carboxylic acid 10.0
In benzene, 20.5 g of optically active 2-methylbutanol were heated under reflux for 20 hours with sulfuric acid. After filtration and concentration, recrystallization yielded 11.0 g of product (yield: 8
3%).

Step 2 4'-(6-hydroxyhexyloxy)biphenyl-
Synthesis of 4-carboxylic acid 2-methylbutyl ester 4'-hydroxybiphenyl-4-carboxylic acid 2-methylbutyl ester 2.84 g, potassium carbonate 4.14
4.10 g of 6-chloro-1-hexanol and 4.28 g of potassium iodide were heated under reflux in acetone for 48 hours. After filtration and concentration, 111 g of product (yield 34%) was obtained by column chromatography.

Step 3 Synthesis of 4'-(6-acryloyloxyhexyloxy)biphenyl-4-carboxylic acid 2-methylbutyl ester 4'-(6-hydroxyhexyloxy)biphenyl-
Acryloyl chloride 4-carboxylic acid 2-methylbutyl ester (1.60 g) was dissolved in anhydrous benzenetriethylamine in the presence of 2,6-di-t-butylphenol.
53 g was added dropwise at 5° C. and stirring was continued for 2 hours. The mixture was made acidic, extracted with ethyl acetate, and subjected to column chromatography to obtain 1.20 g (yield: 66%) of the product.

Polymerization step 4'-(6-acryloyloxyhexyloxy)biphenyl-4-carboxylic acid 2-methylbutyl ester 1.2
0g to 1% anhydrous toluene with 3 mo1% AIBN
After freezing and degassing in 2-p, polymerization was carried out at 60°C for 24 hours. Repeat reprecipitation with methanol to obtain the desired polymer! , 02g (yield 85%) was obtained.

Number average molecular weight 9200, weight average molecular weight 12500 Phase transition behavior 35°C 47°C Glass phase □ Smectic phase □ Smectic C74'C 96°C phase □ Smectic A phase - Isotropic phase [Measurement of 5IIG intensity] Next, the following example The SHG intensity was measured to investigate the nonlinear optical effect of the solid solution obtained.

A Nd: YAG laser is used as a light source to irradiate light with wavelength j and 06#L@ (output 17 mJ/pulse), and the intensity of the generated 5t (G light (0.53 gm)) is controlled by a photomultiplier. lJI was measured.

Example 1 Poly4-[4'-(11-
Acryloyloxyundecanyloxy)benzoyl]benzoic acid 2-methyl-3-hexyloxyethyl ester (75% by weight) and P-nitroaniline (25% by weight)
were melted at 170°C, mixed uniformly, and cooled to room temperature. When the obtained solid solution was irradiated with a Nd:YAG laser and the second harmonic was measured using a method based on the powder method, SHG with an intensity approximately 25 times that of urea was observed using a photomultiplier. This nonlinearity did not change at all even after 3 months.

Example 2 Poly4-[4'-(11-
A cast film was prepared by dissolving acryloyloxyundecanyloxy)benzoyl]benzoic acid 2-methyl-3-hexyloxyethyl ester (75 iffi%) and P-nitroaniline (25% by weight) in dimethylformamide.

The obtained solid solution was irradiated with Nd: YAG laser,
When the second harmonic was measured using a method based on the powder method, SHG with an intensity approximately 18 times that of urea was observed using a photomultiplier. This nonlinearity did not change at all after 3 months.

Example 3 Poly4'-(6-acryloyloxyhexyloxy)biphenyl-4-carboxylic acid 2 produced according to Synthesis Example 2
-Methyl butyl ester (75% by weight) and P-nitroaniline (25% by weight) were melted and mixed uniformly at 170°C, and the mixture was cooled to room temperature. Nd: YAG in the obtained solid solution
When irradiated with a laser and measured the second harmonic using a method compliant with the powder method, SH was found to have an intensity approximately 17 times that of urea.
G was measured using a photomultiplier. This nonlinearity did not change at all for two months.

Example 4 Poly4'-(6-acryloyloxyhexyloxy)biphenyl-4-carboxylic acid 2 produced according to Synthesis Example 2
- methyl butyl ester (75ffi%),
A cast film was prepared by dissolving P-nitroaniline (25% by weight) in THF.

The obtained solid solution was irradiated with Nd: YAG laser,
When the second harmonic was measured using a method based on the powder method, 5IIG with an intensity approximately 15 times that of urea was observed using a photomultiplier. This nonlinearity did not change at all for two months.

Example 5 The nonlinear optical element 1 shown in FIG. 1 was manufactured as follows. An ITO film was prepared on a 1+sm glass substrate 11, and a lower electrode 12 was formed by vapor depositing a rough A4 film to a thickness of 5000 mm. A polyamic acid solution (manufactured by Hitachi Chemical Co., Ltd., PIO: non-volatile content concentration 3% by weight) was applied onto this using a spin cord method, and the mixture was heated at 20°C for 30 minutes.
The polyimide alignment film N13 was formed by heating at 350° C. for 60 minutes and 30 minutes at 350° C. By rubbing this, uniaxial orientation was imparted.

Next, on the alignment film layer 13, the nonlinear optical material used in Example 2 is spin-coded to a film thickness of about [1].
After drying, AI2 was deposited thereon to a thickness of 1000 nm to form a nonlinear optical waveguide 14 and an upper electrode 15. Next, the lower electrode 12 and the upper electrode 15 were cooled from 130° C. while applying a DC voltage of 100 V.

In the optical element l of the present invention produced as described above, the first
As shown in the figure, when a 1.06H laser beam was irradiated from the laser light source 16 through the modulator 17 and the condensing lens 18, the generation of optical second harmonic was measured by a photomultiplier.

[Effects of the Invention] As explained above, the nonlinear optical material of the present invention exhibits large nonlinearity and excellent moldability due to the unique structure of ferroelectric polymer liquid crystal.

Furthermore, a nonlinear optical element having a portion formed by orientation processing of this nonlinear optical material is easy to produce and exhibits excellent properties such as high memory performance and switching characteristics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a thin film waveguide type nonlinear optical element produced in Example 5. l...Nonlinear optical element 12...Lower electrode 14...Nonlinear optical waveguide 16...Laser light source 18...Condensing lens

Claims (4)

[Claims] (1) A nonlinear optical material characterized by containing a ferroelectric polymer liquid crystal and a nonlinear optical compound. (2) The nonlinear optical material according to claim 1, wherein the ferroelectric polymer liquid crystal and the nonlinear optical compound form a solid solution. (3) The nonlinear optical material according to claim 1, wherein the ferroelectric polymer liquid crystal is a side chain type polymer liquid crystal. (4) A nonlinear optical element characterized by having a portion formed by aligning a nonlinear optical material containing a ferroelectric polymer liquid crystal and a nonlinear optical compound.