JPH0795175B2 - Organic nonlinear optical material and nonlinear optical device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an organic nonlinear optical material, and more specifically to an organic nonlinear optical material and a nonlinear optical device useful as a material for a nonlinear optical element such as an optical bistable element. Is.

[Prior Art] Third-order nonlinear optical materials are used for the third harmonic generation (hereinafter, THG
Abbreviated. ) Has a frequency conversion function, and because it can be applied to optical switches and optical memories that utilize the optical bistable phenomenon, it is attracting attention as a central material for future optical devices.

Among them, organic nonlinear optical materials are KH ₂ PO ₄ (KDP) ・ LiN
Compared with inorganic ferroelectric crystals such as bO ₃ , the nonlinear optical constant is large, the response speed is faster than inorganic semiconductors such as gallium-arsenide, and high-speed response and room temperature operation have been confirmed for cuprous chloride (CuCl). Active material search is being pursued because it has the possibility of satisfying all the requirements that could not be satisfied at the same time with conventional materials, such as difficulty in thinning to the μm order, and the like.

Currently, organic non-linear optical materials with a large third-order effect are π-conjugated polymer systems represented by polydiacetylene (particularly PTS; 2,4-hexadiyne-1,6-bis (p-toluenesulfonate)) and polyacetylene. And aminonitrostilbene (particularly DEANS; N, N-diethyl-4-amino-4'-nitrostilbene), which is a low molecular weight system in which a donor-acceptor is asymmetrically substituted. Here, the dimethylamino group and the ethylamino group serve as donors,
The nitro group or the cyano group acts as an acceptor.

[Problems to be Solved by the Invention] However, the above-mentioned optical nonlinearity of the π-conjugated polymer system is based on the polarization of free electrons in the valence band, and therefore has a defect very similar to that of an inorganic semiconductor, that is, a narrow band gap. It cannot escape from the decrease in the response speed due to the resonance effect. Furthermore, there is also the problem that no specific guidelines for material design that surpass the current PTS have been clarified.

In addition, in the above donor-acceptor asymmetrically substituted low-molecular-weight system, in order to realize a nonlinear optical effect higher than that of the current DEANS and its analogs, expansion of π-electron conjugated system or substitution of stronger donor-acceptor pair has been attempted. There is. However, when the π-electron conjugated system is expanded, twist of the conjugated system is induced, and the effective conjugation length is shortened. Also, when a stronger donor-acceptor pair is replaced, spontaneous polarization proceeds, so the difference in dipole moment between the ground state and the excited state does not become as large as expected, but rather as a material such as deterioration due to light absorption or deterioration of response speed. Promotes shortcomings.

In addition, the increase in molecular size and the extreme increase in spontaneous polarization significantly reduce the solubility and crystallinity in solvents, polymer matrices, etc. and cause the workability required for device formation to be impaired. Become.

However, although these types of organic nonlinear optical materials have complicated problems as described above, they are still the favorite of organic materials exhibiting a high-speed and highly efficient optical nonlinear response, and vigorous material development is underway. ing.

Further, FIG. 2 schematically shows a non-linear optical device using an organic material, in which input light is gated with gate pulse light to obtain output light corresponding to the time waveform of the gate pulse. is there.

In FIG. 2, reference numeral 1 is a nonlinear refractive index medium having a length of 1 m.
CS ₂ (carbon disulfide) liquid is enclosed in a glass cell of m, and reference numerals 2a and 2b are two polarizers arranged such that their polarization axes are orthogonal to each other. In this configuration, only while the gate pulse light Pg is incident, the polarizer 2a
The linearly polarized light of the input light Pi that has passed through is converted into elliptically polarized light due to the change in the refractive index of the nonlinear refractive index medium 1, so that a part of the light can pass through the orthogonal polarizer 2b, and the output light Pt is obtained. That is, the input light Pi is optically switched by the pulse of the gate pulse light Pg.

The instantaneous transmittance T of the input light Pi becomes maximum when the polarization direction of the gate pulse light Pg and the polarization direction of the input light Pi are inclined by 45 °. In this case, T = sin ² (Δψ / 2) (1) Δψ = 2πn ₂ LIin / λ (2) Where L is the medium length, λ is the input light wavelength, and Li
n is the intensity of the gate pulse light Pg, and n ₂ is the nonlinear refractive index. When Δφ is sufficiently small in the above equation (1), T∝n ₂ ² L ² Iin ² (3) is obtained, so that it is understood that T is proportional to the square of n ₂ . The present inventors have additionally tested the optical gate optical switch of CS ₂ shown in FIG. ₂ and found that λ = 0.83 μm, L = 1 mm, Lin = 300 M
Instantaneous transmittance T = 1% was obtained at W / cm ² .
From this result, the equation (1), when calculating the nonlinear refractive index n ₂ of CS ₂ by using the expression ^{_{(2), n 2 = 8.8 × 10 -14}} cm 2 / W ... (4). When the nonlinear susceptibility x ⁽³⁾ is calculated from this n ₂ value, x ⁽³⁾ = 4.2 × 10 ^-12 esu.

It has been confirmed that the response speed of the above-mentioned CS ₂ optical gate optical switch exhibits a high-speed response of about 1 picosecond, and is therefore widely used in measurement systems such as instantaneous photography and high-speed spectroscopy. However, as determined by the equation (4), the non-linear efficiency is not necessarily large, and therefore, there is a drawback that an extremely large gate light intensity is required.

The present invention has been made in view of the above problems, overcoming the drawbacks of the above conventional techniques, excellent solubility and crystallinity, high speed,
An object of the present invention is to provide an organic nonlinear optical material exhibiting highly efficient optical nonlinear response, and as a result, to provide a nonlinear optical device that operates even at low light intensity.

[Means for Solving the Problems] Main features of the organic nonlinear optical material of the present invention are as follows.
It has the maximum optical nonlinear response efficiency as a substituted low molecular weight nonlinear optical material in which the donor and acceptor substituents are asymmetrically arranged, and secondly, the processability (solvent, high That is, the large solubility in a molecular matrix and the crystallinity capable of producing a large single crystal are sufficiently satisfied.

The organic nonlinear optical material of the present invention basically comprises a β-nitrostyrene derivative having a para-substituted amino group represented by the following general formula [1] and para- (β-nitroethylenyl) -representing the following general formula [2]. It is a urolidine derivative.

(However, R ₁ and R ₂ represent either an alkyl group other than a methyl group or a hydroxyalkyl group, and may be the same or different from each other, and X ₁ , X ₂ , X ₃ and X ₄ are hydrogen or Represents one of a hydroxyl group, a halogen, an alkyl group, an alkoxy group, an alkyl ester group, and an alkylamide group,
They may be equal to or different from each other. ) (However, X _1, X ₂ is hydrogen or a hydroxyl group, a halogen, an alkyl group, an alkoxy group, an alkyl ester group, or an alkyl amide group, may be different even equal, in particular R _1, R ₂ carbon atoms is preferable that 2 to 6.) Furthermore nonlinear optical device of the present invention, which consists of an optical medium having a nonlinear refractive index, a polarizer, an optical element such as an optical resonator and the reflector Therefore, as the optical medium, a β-nitrostyrene derivative having a para-substituted amino group represented by the general formula [1] and a para-nitrostyrene derivative represented by the general formula [2] are used.
It is a (β-nitroethylenyl) -eurolidine derivative, that is, a compound having a styrene structure in the molecule is used as a π-conjugated system.

In the organic nonlinear optical material of the present invention, it is important that the structure having a π-electron conjugated chain is styrene. Styrene has a higher nonlinear polarizability per unit volume than stilbene, which has a large number of π electrons, and because of its compact structure, it is superior in solubility and crystallinity to stilbene and other compounds having a π electron structure. .

A β-nitrostyrene derivative having a para-substituted amino group represented by the above general formula [1], wherein R ₁ and R ₂ are ethyl groups, and X ₁ , X ₂ , X ₃ and X ₄ are all hydrogen. ,
Alternatively, when _one of R ₁ and R ₂ is an ethyl group and the other is a hydroxyethyl group, especially an ethanol group, a large effect can be obtained in terms of both electron donating property and solubility.

The structure of the electron-donating moiety of the para- (β-nitroethylenyl) -urolidine derivative represented by the general formula [2] has a π-electron delocalization due to conjugation between the π-electron skeleton and the amine independent electron pair. , Contributes to the improvement of solubility due to the bulkiness of the methylene group.

Dimethylaminonitrostyrene (DMA-NS), which has hitherto been known as an organic nonlinear optical material, has low solubility in organic solvents. For example, 5% by weight for dimethylformamide (DMF) and 2% by weight for ethanol.
Only dissolves to some extent. On the other hand, N, N-diethylaminonitrostyrene (DEANST), which is the organic nonlinear optical material of the present invention, can dissolve 50% by weight or more in DMF and 40% by weight or more in ethanol. . In addition, the previously known diethylaminonitrostilbene (DEANS) was added to polymethylmethacrylate (PMMA) at 2.5.
DEAN according to the present invention dissolves only about wt%
ST can be dissolved in 30% by weight or more. Similarly to DEANST, 2-hydroxy-4- (N, N-dimethylamino) nitrostyrene (Oh-DEANST) can be dissolved in PMMA in an amount of 25% by weight or more, and p- (N-ethyl- N-Ethanolamino) Nitrostyrene (EOEANS
Similarly, T) can be dissolved in various organic solvents in an amount of 30% by weight or more.

Furthermore, X ₁ , X ₂ , X ₃ , X ₄ (in the case of general formula [2], X ₁ , X ₂ )
May be all hydrogen, or one of them may be a hydroxyl group, a halogen, an alkyl group, an alkoxy group,
Similar to the above, a large non-linear effect and processability tend to be obtained even when the rest of all of the alkyl ester group and alkyl amide group is hydrogen.

Further, since all of the organic nonlinear optical materials of the present invention have excellent solubility, they can be dispersed at a high concentration in a polymer matrix and can be dissolved at a high concentration in an organic solvent. In particular, it can be dissolved at a high concentration in an organic solvent having a higher dielectric constant than chloroform, or a mixed solvent of the above-mentioned organic solvent having a high dielectric constant and another organic solvent.

Furthermore, since the nonlinear refractive index changes depending on the type of solvent used, there is an effect that a desired nonlinear refractive index can be easily realized. In order to obtain a large non-linear refractive index, it is preferable to use a solvent having a dielectric constant equal to or higher than that of chloroform. Examples of such a solvent include the following organic solvents. it can. That is, N-methylacetamide, N-methylformamide, formamide, acetamide, dimethylformamide, N, N-dimethylacetamide, acetonitrile, nitromethane, acrylonitrile, methanol, diethylene glycol, benzonitrile, ethanol, acetaldehyde, propanol, benzaldehyde, benzyl alcohol, pyridine. Etc. In particular, it is preferable because it can be dissolved at a high concentration in an organic solvent having a dielectric constant higher than that of chloroform and having an aromatic ring, or a mixed solvent thereof, and high nonlinear efficiency can be obtained.

The organic nonlinear optical material represented by the above general formula [1] or [2] can form an ester condensate with a low molecular weight or high molecular weight carboxylic acid derivative and can be dispersed in a high molecular weight polymer. A polymer material in which a condensate and an organic nonlinear optical material are dispersed also exhibits high nonlinear response efficiency and good processability.

For example, a β-nitrostyrene derivative having a para-substituted amino group represented by the general formula [1] and polymethylmethacrylate (PMMA) are separately dissolved in acetone, and then these are mixed and then acetone is mixed. The organic nonlinear optical material of the present invention can be dispersed in PMMA by removing the.

It is also possible to disperse the organic nonlinear optical material in the polymer by melting the transparent polymer and imparting fluidity thereto, then adding the organic nonlinear optical material of the present invention, mixing and cooling. . The transparent polymer used here may be a polymer, a copolymer, or a mixture thereof.

Furthermore, X ₁ , X ₂ , X ₃ , X ₄ (in the case of general formula [2], X ₁ , X ₂ ,
X ₂ ), at least one of which is a hydroxyl group, or at least one of R ₁ and R ₂ is a hydroxyethyl group,
In particular, in the case of an ethanol group, ester condensation with a polymeric carboxylic acid derivative is possible.

The dispersion-type and pendant-type polymer materials produced in this manner complement the low-molecular-type high-quality crystal and play a role in expanding the application range of the styrene-based nonlinear optical material of the present invention.

Furthermore, it is difficult to obtain a large single crystal by a conventional recrystallization method using a DMA-NS known in the art, and only a maximum of 3 × 5 × 10 mm ³ is obtained. Then, 8 × 10 × by recrystallization method from solvent
A single crystal with a size of 50 mm ³ can be easily obtained, and a larger crystal can be obtained.

When the organic nonlinear optical material of the present invention is used as an optical medium of a nonlinear optical device, it is possible to obtain a device that can operate with low light intensity and is excellent in responsiveness. In order to use the organic nonlinear optical material of the present invention as an optical medium, the following may be mentioned. That is, a solution medium dissolved in a single organic solvent or a mixed solvent, a solid medium dissolved in a transparent polymer material and solidified, or a crystal medium crystallized as it is In this case, it is preferable to use an organic solvent having a higher dielectric constant than chloroform as the solvent, particularly an aromatic compound. In the case of a solid medium, the polymer having transparency is preferably a polymer or copolymer having a refractive index of PMMA or less.

The representative material group of the organic nonlinear optical material of the present invention is shown below.

in (2,2,3,3-Tetrafluoropropylmethacrylate-MMA) Copolymer DEANST- (Fluororesin-MMA) Copolymer [Example] (Production Example 1) 4- (N, N-diethylamino) -β-nitrostyrene (D
Synthesis of EANST p- (N, N-diethylamino) benzaldehyde 118g
To a solution of (0.57 mol) in 500 ml of nitromethane was added 17 g of ammonium acetate. The mixture was heated at 100 ° C. for 5 hours with stirring. Then, the reaction solution was cooled in a dry ice-acetone bath until crystallization was completed, and the precipitated solid was separated by filtration and vacuum dried. Recrystallization was performed twice with ethanol as a solvent to obtain red crystals.

Yield; 107 g, yield; 75%, melting point; 95 ° C.

(Production Example 2) Synthesis of 4- (β-nitroethylenyl) urolidine (JANST) 60 g (0.3 mol) of p-formylurolidine was added to nitromethane.
8 g of ammonium acetate was added to the solution dissolved in 250 ml. The mixture was heated at 100 ° C. for 5 hours with stirring.
Then, the reaction solution was cooled in a dry ice-acetone bath until crystallization was completed, and the precipitated solid was separated by filtration and vacuum dried. Recrystallization was performed twice with ethanol as a solvent to obtain red crystals.

Yield; 50 g., Yield; 69%.

(Production Example 3) 4- (N-ethyl-N-hydroxyethylamino) -β
-Synthesis of nitrostyrene (EOEANST) 8 g of ammonium acetate was added to a solution of 60 g (0.31 mol) of p- (N-ethyl-N-ethanolamino) benzaldehyde in 250 ml of nitromethane. The mixture was heated at 100 ° C. for 5 hours with stirring. Then, the reaction solution was cooled in a dry ice-acetone bath until crystallization was completed, and the precipitated solid was separated by filtration and vacuum dried. Recrystallization was performed twice with acetonitrile as a solvent to obtain red crystals.

Yield; 42 g, yield; 66%.

(Production Example 4) Synthesis of 4- (N, N-diethylamino) -β-nitro-2-hydroxystyrene (Oh-DEANST) 2-hydroxy-4- (N, N-diethylamino) benzaldehyde 60 g (0.31 mol) 8 g of ammonium acetate was added to the solution dissolved in 250 ml of nitromethane. The mixture was heated at 100 ° C. for 5 hours with stirring. Then, the reaction solution was cooled in a dry ice-acetone bath until crystallization was completed, and the precipitated solid was separated by filtration and vacuum dried. Recrystallization was performed twice with acetonitrile as a solvent to obtain red crystals.

Yield; 34 g, yield; 53%.

(Production Example 5) Synthesis of 4- (N, N-diethylamino) -β-nitro-3-chlorostyrene (Cl-DEANST) 34 g (0.16 mol) of 3-chloro-4- (N, N-diethylamino) benzaldehyde was added. 5 g of ammonium acetate was added to the solution dissolved in 150 ml of nitromethane. The mixture was heated at 100 ° C. for 5 hours with stirring. Then, the reaction solution was cooled in a dry ice-acetone bath until crystallization was completed, and the precipitated solid was separated by filtration and vacuum dried. Recrystallization was performed twice with acetonitrile as a solvent to obtain red crystals.

Yield: 16 g, yield: 39% (Production Example 6) Synthesis of 4- (N, N-diethylamino) -β-nitro-2-methoxystyrene (MeO-DEANST) 2-methoxy-4- (N, N- To a solution of 30 g (0.14 mol) of diethylamino) benzaldehyde in 150 ml of nitromethane was added 4 g of ammonium acetate. The mixture was heated at 100 ° C. for 5 hours with stirring. Then, the reaction solution was cooled in a dry ice-acetone bath until crystallization was completed, and the precipitated solid was separated by filtration and vacuum dried. Recrystallization was performed twice with acetonitrile as a solvent to obtain red crystals.

Yield: 16 g, yield: 44% (Production Example 7) Synthesis of 4- (N, N-diethylamino) -β-nitro-2-acetyloxystyrene (AcO-DEANST) 2-acetyloxy-4- (N, 23.5 g (0.10 mol) of N-diethylamino) benzaldehyde 100 ml of nitromethane
3 g of ammonium acetate was added to the solution dissolved therein. The mixture was heated at 100 ° C. for 5 hours with stirring. afterwards,
The reaction solution was cooled in a dry ice-acetone bath until crystallization was completed, and the precipitated solid was separated by filtration and vacuum dried. Recrystallization was performed twice with acetonitrile as a solvent to obtain red crystals.

Yield: 10 g, yield: 36% (Production Example 8) Synthesis of 4- (N, N-diethylamino) -β-nitro-3-methylstyrene (Me-DEANST) 3-Methyl-4- (N, N- To a solution of 30 g (0.16 mol) of diethylamino) benzaldehyde in 150 ml of nitromethane was added 5 g of ammonium acetate. The mixture was heated at 100 ° C. for 5 hours with stirring. Then, the reaction solution was cooled in a dry ice-acetone bath until crystallization was completed, and the precipitated solid was separated by filtration and vacuum dried. Recrystallization was performed twice with acetonitrile as a solvent to obtain red crystals.

Yield: 17 g, yield: 45% (Production Example 9) Synthesis of 4- (N, N-diethylamino) -β-nitro-3-acetylaminostyrene (AcNH-DEANST) 3-Acetylamino-4- (N, To a solution of 28 g (0.12 mol) of N-diethylamino) benzaldehyde in 120 ml of nitromethane was added 4 g of ammonium acetate. The mixture was heated at 100 ° C. for 5 hours with stirring. Then, the reaction solution was cooled in a dry ice-acetone bath until crystallization was completed, and the precipitated solid was separated by filtration and vacuum dried. Recrystallization was performed twice with acetonitrile as a solvent to obtain red crystals.

Yield: 11 g, Yield: 33% (Production Example 10) Production of DEANST-PMMA 9.8 wt% DEANST chloroform solution and 18.2 wt% PMMA chloroform solution were mixed at a ratio of 1: 1 and then mixed on a glass substrate. The coating was applied by spin coating to prepare a 35 wt% DEANST-PMMA film having a thickness of 1 μm.
This DEANST-PMMA film was irradiated with visible light and its absorption spectrum was measured. The results are shown in FIG.

(Production Example 11) Production of DEANST- (fluororesin-MMA) Copolymer 12 wt% DEANST acetone solution and 18 wt% 2,2,3,3-tetrafluoropropylmethacrylate-methylmethacrylate (MMA) 2: 1 copolymer The combined acetone solution was mixed at a ratio of 1: 1. This mixed solution was spin-coated on a glass substrate to prepare a 40% by weight DEANST- (fluororesin-MMA) copolymer film having a thickness of 1.5 μm.

(Production Example 12) Synthesis of DEANST-AP In 70 ml of dehydrated dioxane, 4.5 g of methyl methacrylate was added.
And 4- [N-ethyl-N- (2'-acryloyloxyethyl) amino] -β-nitrostyrene (24.2 g) and azoisobutyronitrile (AIBN) (0.14 g) were dissolved and degassed and sealed at 60 ° C. And reacted for 24 hours. The reaction solution was poured into hexane to precipitate the desired product. This was separated by filtration, washed with methanol, and then dried to obtain DEANST-AP. The copolymer fraction of the produced polymer is PMMA0.3-DEANST-AP0.7.
Met.

Example 1 A Nd-YAG laser (wavelength: 1.06 μ) was used as a light source for THG measurement.
m, strength: 50 MW / cm ² ) was used. After cutting visible light, the sample was irradiated with a beam focused by a lens, the light emitted from the sample was passed through a filter, and the intensity of only THG light was detected by Photomal. As the measurement sample, the crystal of the organic nonlinear optical material of the present invention obtained in the above Production Examples 1 to 11 was crushed to have a uniform particle size of 105 to 120 μm.

Further observed THG effects are urea and MNA (2-methyl-
In order to confirm that the effect is purely the third-order effect, rather than the second-order cascade effect (ω + 2ω → 3ω) as seen in (4-nitroaniline) and the like, the second harmonic generation of the same sample (hereinafter, SHG) is also measured. The results are shown in Table 1 below. The SHG intensity in Table 1 is the relative SHG intensity based on urea,
The intensity is the relative THG intensity based on MNA.

(Comparative Examples 1 to 4) Further, as a comparative example of Examples 1 to 9 above, THG and SHG of the following four similar materials were measured.

The results are also shown in Table 1.

From the results in Table 1, the relative TH of conventional organic nonlinear optical materials
While the G intensity was 50 to 80, it was confirmed that all of the organic nonlinear optical materials of the present invention showed a favorable value of 300 to 720.

Example 2 An example of an optical gate optical switch device using DEANST obtained in Production Example 1 as an optical medium is shown below. As the nonlinear refractive index medium, a solution prepared by dissolving DEANST in DMF (dimethylformamide: dielectric constant ε = 37.8) enclosed in glass was used, and the other constitution was made the same as that of the apparatus shown in FIG.

FIG. 3 shows the instantaneous transmittance characteristics of the optical switch according to this embodiment.
It is shown as a function of DEANST concentration. In Fig. 3,
The solid line shows this embodiment, and the broken line shows the CS ₂ liquid of the conventional material. As can be seen from this graph, the instantaneous transmittance increased in proportion to the square of the concentration of the nonlinear optical material, and when the concentration was 23% by weight or more, the characteristics exceeding the CS ₂ of the conventional material were obtained. The value of the nonlinear refractive index n _{2 at} a concentration of 40% by weight is n ₂ = 1.5 × 10 ⁻¹³ cm ² / W (x
⁽³⁾ = 7.3 × 10 ^-12 esu).

Example 3 Next, in order to investigate the influence of the type of the organic solvent that dissolves the organic nonlinear optical material of the present invention on the nonlinear refractive index n ₂ , DE
ANST was dissolved in various organic solvents with the same molar concentration and different dielectric constants, and their nonlinear refractive indices were investigated. Figure 4 shows
3 is a graph showing the relationship between the dielectric constant of these organic solvents and the nonlinear refractive index n ₂ .

As an organic solvent, an aromatic system, A: nitrobenzene,
B: A mixture of nitrobenzene and chlorobenzene, C: chlorobenzene, D: benzene, E: dimethylformamide (DMF) as a non-aromatic system, F: acetone, G: chloroform, respectively, and an aromatic organic solvent was used. The non-linear refractive index in the case is shown by a solid line and the non-aromatic organic solvent is shown by a broken line. For comparison, the non-linear refractive index when CS ₂ of the conventional material is dissolved in various organic solvents is shown as a chain line.

As can be seen from FIG. 4, as the solvent, the higher the dielectric constant, the better, and the aromatic type is superior to the non-aromatic type. That is, the most efficient characteristics were obtained when DEANST was dissolved to the maximum concentration using nitrobenzene, which is an aromatic high dielectric constant material. The n ₂ value at this time is 2.2 × 10 ⁻¹³ cm ² / W, which is 2.5 times that of CS ₂ of the conventional material. The transmittance is CS
₂ as compared to (2.5) also show efficiency six times a ² was identified.

The optimization of the solvent described above is a finding first found in the present invention. Examples of such an optimum solvent include N-methylacetamide, N-methylformamide, formamide, acetamide, dimethylformamide, N, N-dimethylacetamide, acetonitrile, nitromethane, acrylonitrile, methanol, in addition to the above solvents.
Diethylene glycol, benzonitrile, ethanol,
Acetaldehyde, propanol, benzaldehyde,
Examples include benzyl alcohol and pyridine, which have a higher dielectric constant than chloroform.

Further, in addition to the nonlinear refractive index medium of the solution used in this example, a medium obtained by dissolving DEANST shown in Production Example 1 in a polymer material having excellent transparency and solidifying it as in Production Example 10 is used. Is also possible. Furthermore, even when a DEANST single crystal plate was used, similarly good results were confirmed.

(Embodiment 4) FIG. 5 is a view for explaining another embodiment of the non-linear optical device of the present invention, in which the non-linear refractive index medium 1 used in the present invention is the same DEANST solution as described in the second embodiment. An optical resonator was constructed by facing the solution medium and dielectric multilayer mirrors 3a and 3b that reflect about 90% of input light and transmit the rest.

In order to operate this device, the resonance condition of the resonator may be adjusted by slightly changing the input light wavelength or slightly changing the resonator length (mirror interval). In the case of the present embodiment, 1.064 μm light from the Nd ³⁺ -YAG laser was used, so the adjustment depended on the method of changing the cavity length. Between the input light intensity Pi and the output light intensity Pt, the limiter operation and the bistable operation as shown in FIGS. 6 and 7 were obtained, respectively.

The minimum input light intensity (Pi min) required for operation is analytically Pi min = (Kλ) / (n ₂ l) (where λ is the wavelength of light, l is the optical medium length, and K (~ 0.00
1) is given by a coefficient determined by the reflectance of the mirror and the adjustment of the cavity length. In the present embodiment, λ = 1.064 μm, l = 1 mm, and n ₂ is n ₂ = 2.2 × 10 from the second embodiment. ^{Since it is -13} cm ² / W, Pi min = 5 × 10 ⁶ W / cm ² can be obtained.

When a semiconductor laser with an effective output of 50 mW (pulse oscillation) and an oscillation wavelength of 0.83 μm is used as the light source, if the beam diameter is narrowed down to 1 μm, the light intensity is calculated to be 6 × 10 ⁶ W / cm ^2, and the nonlinear optical at this wavelength It is sufficiently larger than the Pi min value of the device. In fact, this nonlinear optical device could operate even when a semiconductor laser was used as the light source.

The response time t of this material DEANST is estimated to be about 10 ^-12 seconds. However, the reaction time of the device is determined by the larger value of the medium response time t and the intracavity photon lifetime tp, and tp = −l op / (C ln R) (where l op is the resonator's The tp calculated from the optical length, C is the speed of light, and R is the reflectance of the mirror) is obtained as 6 × 10 ⁻¹¹ seconds. Since tp> t, this value is the response time of the device. In this example, it was confirmed that the response time was shorter than 10 ^-10 seconds.

(Embodiment 5) FIG. 8 is a diagram for explaining an embodiment of the phase conjugate wave generator. In the figure, symbols 4a and 4b are semi-transmissive mirrors, 5 is a total reflection mirror, and 1
Is the DEANST solution described in Example 3. This configuration is an optical arrangement called degenerate four-wave mixing, in which A ₁ , A ₂ (opposite direction to A ₁ ) and Ap (tilt incidence) are added to a medium with a nonlinear refractive index.
When the three light waves of are incident, a fourth light wave (Ac) in which only the spatial phase term is conjugated with Ap is generated.

Also in this example, high-speed response of the device and low operating input light intensity could be confirmed.

This phase conjugate wave is used for image correction in image information processing technology,
It is attracting attention as an effective means such as real-time holography. (For the application, see the document O plus E March issue, P.73 (1982).) Also in this example, the high-speed response of the device and the low operation input light intensity could be confirmed.

[Advantages of the Invention] As described above, the organic nonlinear optical material of the present invention is
Not only does it have a third-order nonlinear effect that is unprecedented, but also because it has excellent crystallinity and solubility, it is easy to process into a good quality large crystal or polymer thin film.

Further, in the organic nonlinear optical material of the present invention, it can be dissolved in a transparent polymer material and solidified to be used as an optical medium, and all of the organic nonlinear optical materials of the present invention are crystalline. Since it is excellent, a large crystal can be obtained, and a single crystal plate can be prepared and used as an optical medium.

Since the organic non-linear optical material of the present invention exhibits high non-linear optical characteristics, if it is used as a non-linear optical medium, an optical gate, an optical switch, an optical bistable element that can operate even with low intensity light are used. , And can be used as an optical element such as a phase conjugate generator.

Furthermore, since the nonlinear refractive index changes depending on the type of solvent used, there is an effect that a desired nonlinear refractive index can be easily realized. In order to obtain a large nonlinear refractive index, it is preferable to use a solvent having a dielectric constant equal to or higher than that of chloroform. In particular, when it is used by dissolving it in a high dielectric constant solvent such as nitrobenzene, a large nonlinear refractive index can be obtained, and an optical gate optical switch or optical bistable element capable of operating at low light intensity,
Furthermore, a phase conjugate wave generator or the like can be realized.

Therefore, the organic nonlinear optical material of the present invention can be used as a central material for producing an optical integrated device for optical communication such as an optical bistable device, an optical switch and an optical memory.

[Brief description of drawings]

FIG. 1 is a graph showing a visible absorption spectrum of a film in which an organic nonlinear optical material of the present invention is dispersed in a polymer, and FIG. 2 is a schematic configuration diagram showing configurations of a nonlinear optical device and an optical switch according to the present invention, FIG. 3 is a graph showing the relationship between the concentration and the instantaneous transmittance when the organic nonlinear optical material of the present invention is dissolved in an organic solvent, and FIG. 4 is the nonlinearity of the organic nonlinear optical material of the present invention for various solvents. Fig. 5 is a graph showing the refractive index, Fig. 5 is a schematic configuration diagram showing another example of the nonlinear optical device of the present invention, and Figs. 6 and 7 show the operating characteristics of the device shown in Fig. 5. FIG. 6 is a graph showing the limiter operation, FIG. 7 is a graph showing the optical bistable operation, and FIG. 8 is a schematic configuration diagram showing an embodiment of the phase conjugate wave generator of the present invention. . 1 ... Non-linear refractive index medium, 2a, 2b ... Polarizer, 3a, 3b ...
Dielectric multilayer mirrors, 4a, 4b ... Semitransparent mirrors, 5 ... Total reflection mirrors.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C07D 455/04 C09K 9/02 B (72) Inventor Hirohisa Kambara 1-1-1, Uchisaiwaicho, Chiyoda-ku, Tokyo No. 6 Nihon Telegraph and Telephone Corporation (72) Inventor Kenichi Kuboji 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (9)

[Claims] 1. The following general formula [1] (However, R ₁ and R ₂ represent either an alkyl group other than a methyl group or a hydroxyalkyl group, and they may be the same or different, and X ₁ , X ₂ , X ₃ and X ₄ are hydrogen or Represents any one of a hydroxyl group, a halogen, an alkyl group, an alkoxy group, an alkyl ester group and an alkylamide group, and may be the same or different from each other.). 2. An organic nonlinear optical material, which is an ester condensation product of the organic nonlinear optical material represented by the general formula [1] according to claim 1 and a low molecular weight or high molecular weight carboxylic acid derivative. 3. An organic nonlinear optical material characterized in that the organic nonlinear optical material represented by the general formula [1] according to claim 1 is dispersed in a polymer. 4. The following general formula [2] (However, X ₁ and X ₂ represent any of hydrogen, a hydroxyl group, a halogen, an alkyl group, an alkoxy group, an alkyl ester group, and an alkylamide group, and they may be the same or different from each other.) Organic nonlinear optical material characterized by 5. An organic nonlinear optical material, which is an ester condensation product of the organic nonlinear optical material represented by the general formula [2] according to claim 4 and a low molecular weight or high molecular weight carboxylic acid derivative. 6. An organic nonlinear optical material characterized in that the organic nonlinear optical material represented by the general formula [2] according to claim 4 is dispersed in a polymer. 7. A non-linear optical device comprising an optical medium having a non-linear refractive index and an optical element such as a polarizer, an optical resonator, or a reflecting mirror, wherein the non-linear optical index has an optical medium. A non-linear solution characterized by using a solution medium in which the organic non-linear optical material according to claim 2, claim 3, claim 4, claim 5 or claim 6 is dissolved in a single organic solvent or a mixed solvent. Optical device 8. A non-linear optical device comprising an optical medium having a non-linear refractive index and an optical element such as a polarizer, a resonator or a reflecting mirror, wherein the optical medium having the non-linear refractive index is A nonlinear medium, characterized in that the organic non-linear optical material according to claim 2, claim 3, claim 4, claim 5 or claim 6 is dissolved in a polymer material having transparency to be solidified. Optical device 9. A non-linear optical device comprising an optical medium having a non-linear refractive index and an optical element such as a polarizer, a resonator or a reflecting mirror, wherein the optical medium having the non-linear refractive index is A non-linear optical device using a medium obtained by crystallizing the organic non-linear optical material according to claim 2, 4, or 5.