JP2789957B2 - Nonlinear optical element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurea-based polymer effective for optical application technology and a non-linear optical element using the same.

[0002]

BACKGROUND OF THE INVENTION Since the discovery of lasers in the 1960's, a number of inorganic materials exhibiting strong nonlinear optical properties have been discovered. As well-known inorganic materials, urea, quartz, lithium niobate (LiNbO ₃ ), potassium dihydrogen phosphate (KD)
P: KH ₂ PO ₄ ), ammonium dihydrogen phosphate (AD
P: NH ₄ H ₂ PO ₄ ). Inorganic materials are
Since so-called molecular design is difficult, optimization of nonlinear optical characteristics and intentional production of other physical properties cannot be performed. Therefore, organic molecules and polymers capable of molecular design have become very interesting in the field of nonlinear optics. Organic molecules and polymer materials exhibit properties such as large laser non-linearity, high laser light resistance, high-speed response, and light weight suitable for certain fields, and thus are highly applicable to the field of non-linear optics. In organic conjugated polymers, third-order nonlinearity due to the π-electron system is obtained, and polyacetylene, poly (p-phonylene), polythiophene, polypyrrole,
Many conjugated polymers such as phthalocyanines, polyanilines, heteroaromatic ladder polymers and related copolymers have been studied. However, many of these conjugated polymers have a resonance type nonlinear susceptibility of about 1/10 ⁹ esu, which is not sufficient for practical use. Conjugated polymers having high third-order nonlinear susceptibilities at short wavelengths are extremely demanded for producing high-power lasers in the ultraviolet and near-infrared wavelength regions by wavelength conversion.

[0003] Existing reports relating to these include the following. DLWilliams Edit `` Nonlinear optical propertie
s of organic and polymeric materials '' ACS Symposiu
mSeries Volume 233, American Chemical Society, Wash
tonington D. C. (1983), edited by T. Kobayashi, "Nonlin
ear optaics of organics and semiconductors '' Spring
er Proceedings in Physics, Vol. 36, Springer-Ver
lag, Berlin (1989) and SPIE Society 19
There are papers published between the years 85-1990.

[0004]

The third-order nonlinear susceptibility is
It depends sensitively on the delocalization distance of π electrons and the band spacing of the conjugated polymer structure. Therefore, Physical Review by Agrawal et al.
As exemplified in B17, p. 776 (1978), a large third-order nonlinear susceptibility is easily obtained by a conjugate structure having a small band interval. AKBakhsgi and J. Ladik
As shown in Soid State Communications, Vol. 60, p. 361 (1986), azoethene, azine,
It is known that a copolymer having a methine imine and acetylene structure shows a smaller band interval.
However, a small band spacing causes a longer wavelength at the absorption edge,
It is not preferable in element production. It is necessary to realize still higher nonlinear optical characteristics with a wide band interval.

[0005] Second-order nonlinear optics are observed only in non-centrosymmetric crystals. For example, p-nitroaniline has a large molecular non-linear hyperpolarizability, but has central symmetry, and therefore no second-order non-linear optical effect is observed. Many methods have been proposed to achieve non-centrosymmetric. For example, electrical polarization and guest-host mixing, hydrogen bonding,
There are structural regulations, etc. Organic materials include single crystals, Langmuir-Blodgett films, guest-host systems, superlattice structures,
Alternatively, various materials such as a polymer polarized under an electric field can be used. Related reports include DSChemla and
J. Zyss, Nonlinear Optical Properties of Organic
Molecules and Crystals "Volumes 1 and 2, Academic Pre
ss, (1987), HSNalwa et al., Optical Second
−Harmonic Generation in Organic Molecular and Pol
ymeric Materials '' Photochemistry and Photophysic
s, Volume 5, Chapter 4, Pages 103-105, CRCPress, Boc
a Raton, Florida, (1991). Similarly,
It is difficult to achieve both high nonlinear characteristics and transparency.
In addition, various properties such as ease of synthesis, moldability, mechanical strength, and chemical stability are required for practical use.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide
Easy, light transmittance, moldability, mechanical strength, thermal oxidation stability
Nonlinearity using polymers and copolymers with excellent properties and low toxicity
It is to provide an optical element.

[0007] The present invention, in the nonlinear optical device having a nonlinear optical medium having a surface for emitting surface and the light incident light, having a repeating unit represented by the following general formula (2) as the nonlinear optical medium a nonlinear optical element, which comprises using a polyurea-based polymer.

[0008]

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Wherein A and B are methylene chains or optionally substituted benzene, biphenyl, terphenyl, stilbene, azobenzene, benzylidene, diphenylmethane, diphenylether, diphenylthioether, acridine, fluorene, indole, or a heterocyclic ring. X and Y are a hydrogen atom or an aromatic ring group selected from benzene, biphenyl, pyridine, azobenzene and benzylidene which may be substituted.

In the present invention, a polymer having the following repeating unit is used.

[0011]

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Here, Ar ₁ and Ar ₂ are organic groups having a benzene ring, and X is an organic group having an aromatic ring. R is an alkyl group such as a methyl group or a propyl group.

Among these, a novel polyurea polymer characterized by having the following repeating unit is used.

[0014]

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Here, Ar ₃ and Ar ₄ are organic groups selected from the following structural formulas, and Z is an aromatic ring group selected from optionally substituted benzene, pyridine, azobenzene and benzylidene.

[0016]

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Further, a polyurea polymer having the following repeating unit is used.

[0018]

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[0019]

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Wherein Z is a nitro group, a cyano group,
An aromatic ring group selected from benzene, pyridine, azobenzene, and benzylidene having a substituent selected from a carboxyl group and a carboxylester group. m and n are integers of 1 or more.

Further, a polyurea polymer having the following repeating unit is used.

[0022]

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Here, D is an aromatic ring group selected from benzene, biphenyl, terphenyl, stilbene, azobenzene, benzylidene, acridine, fluorene, indole and heterocyclic ring which may be substituted, and E is diphenylmethane, dimethyldiphenyl, An organic group selected from dimethoxydiphenyl, m-xylene, and tolylene.

Furthermore, 1,3,5-
A novel polyurea polymer composition containing a triazine ring, a silicon atom or an organometallic compound is used.

The above-mentioned polymer has a molecular weight of 100 to 550,
000 is desirable.

[0026] The above polymer is preferably used in a thickness of 1 ~ 500μ m.

These polymers greatly improve the performance of the prior art, such as second-order nonlinear optical elements, third-order nonlinear optical elements, electro-optical elements, laser frequency conversion elements, optical switches, optical modulation elements, optical waveguides, four-wave mixing. It can be used as a device or an optical bistable element.

The compound of the present invention comprises a dianilino compound or an aromatic diamino compound and an aromatic diisocyanate.
It is synthesized according to an existing method such as condensation in ym-tetrachloroethane. For example, Oishi, outside (Y. Ohishi, et
al), Journal of PolymerScience, Polymer Chemistr
y ed., Vol. 25, p. 2185 (1987), or
Takahashi, outside (Y.Takahashi, et al), Japanese Journal of
Applied Physics, Vol. 28, L2245 (1989)
Year) can be used. According to the present invention, a random copolymer having a substituted polyurea moiety having a conjugated system can be formed. For example, a conjugated copolymer having the following structural formula as a repeating unit is synthesized by a reaction of condensing a diisocyanate with a diamino conjugated structure as described below.

[0029]

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Here, D is an aromatic ring selected from optionally substituted benzene, pyridine, biphenyl, terphenyl, stilbene, naphthalene, anthracene, phenanthrene, benzidine, azobenzene, benzylidene, acridine, fluorene, indole and heterocycle. OCN-E-NCO is 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, m- Xylene-α, α'-diisocyanate and the like.

The repeating structural units of the polymer used in the present invention will be illustrated below, but the present invention is not limited thereto. Other well-known polymers such as polystyrene, polymethacrylate and polyacrylate And polyazines are also included in the present invention.

[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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Here, Ar5 is selected from the following structural formula:
It is an aromatic group.

[0038]

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In the present invention, a polymer having the following repeating unit is used.

[0040]

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Here, Ar ₆ is an organic group selected from the following structural formula.

[0042]

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In the present invention, a polymer having the following repeating unit is used.

[0044]

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Here, Ar ₇ is an organic group selected from the following structural formula.

[0046]

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In the present invention, a polymer having the following repeating unit is used.

[0048]

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In the present invention, various charge-transferring substituents are used, and these are appropriately introduced at appropriate positions of the above-mentioned compound of the present invention. However, the present invention is not limited to these. Examples of the electron-withdrawing substituent include a nitro group,
Nitrile group, a carboxyl group, an amido group such as -CONH _2, an aldehyde group, -SO ₂ R, an acetyl group, -SO
₂ NH ₂ and others —NH ₃ . Examples of the electron donating substituent include an amino group, an alkylamino group, a dialkylamino group, a halogen group such as -F, -Cl, -Br, and -I, an alkyl group such as a methyl group and an ethyl group, a hydroxyl group, an acetamido group, Allyl groups such as methoxy, ethoxy and phenyl groups.

The polymer composition of the present invention has a film thickness of 1 to 5 by various existing methods such as solution coating, spin coating and molding.
It can be formed into a thin film of 500μ m. The molecular weight can be produced in a range of 100 to 550,000 by controlling the reaction conditions.

The polymer composition of the present invention exhibits good light transmittance and excellent thermal stability in air and inert gas atmospheres. Further, it has been confirmed by experiments using copolymerized polymers that they exhibit high second-order and third-order nonlinear optical properties, and that the third-order nonlinear optical properties increase with an increase in the conjugated moiety.

The polymer of the present invention is applied on a tin oxide transparent substrate under the condition of being heated to about 80 ° C. to form a thin film, and corona poling can be performed. Electric field, depending on the breakdown characteristics of the material, 4 ~ 8k V can be used, the heating is preferably 5 ~ 10 ° C. hot glass transition point. Polling time is 2 to 4
Time.

[0053] third-order nonlinear susceptibility, Nd-YAG laser fundamental wave of a (1.064 ~ 2.1μ m) as a light source, it can be measured by the manufacturer fringe method.

FIG. 1 shows an example of a well-known nonlinear optical element according to the present invention. The output light 6 of the light source 1 is applied to the non-linear optical medium sample 3 of the polyurea polymer according to the present invention through the semi-transmissive mirror 2,
, The output light 7 is obtained. Here, by known techniques to place the resonance position adapted semitransparent mirror 2 and 4 to use light, it is possible to enable an effective non-linear response or a bi-stable operation in the optical operation against the incident light of the output light it can. FIG. 2
As shown in (1), the operation can be performed more efficiently by using the return light 11 that has passed through the semi-transmissive mirrors 8, 9 and the reflecting mirror 10. As shown in FIG. 3, it is also possible to perform an optical operation using the incident light as the sum of the light beams 6 and 12, using one as the pump light and the other as the probe light. As the light source 1, all existing light sources can be used. For example, light of 1.9 to 2.1 μm based on optical parametric oscillation of YAG laser light of 1.06 μm is used for the third harmonic generation.

[0055]

EXAMPLES The effects of the present invention will be described more specifically with reference to the following examples.

Example 1 1.30 g of α, α'-dianilino-p-xylene and 1.13 g of 4,4'-diphenylmethane diisocyanate were placed in 8 ml of sym-tetrachloroethane at 80 ° C. under a nitrogen atmosphere. , For 12 hours. The resulting viscous solution was diluted with chloroform,
The precipitate was diffused in 300 ml of methanol, and the obtained precipitate was filtered and dried at 60 ° C. under vacuum. Yield 1.0 g. The repeating unit is N-phenylpolyurea of the following structural formula. It had a maximum absorption wavelength (λmax) of 258 nm and a glass transition point of 125 ° C., and was thermally decomposed in air at around 290 ° C. When a thin film obtained by applying this polymer as a solution with chloroform was polled, favorable second harmonic generation was confirmed.

[0057]

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Example 2 1.30 g of di (p-nitrophenylamino) methane synthesized from p-nitroaniline and formaldehyde and 1.13 g of 4,4'-diphenylmethane diisocyanate in 8 ml of sym-tetrachloroethane The mixture was polymerized at room temperature for 2 hours, left to stand for a day to form a precipitate, filtered, and dried at 60 ° C. under vacuum. Yield 1.30 g. The repeating unit is a polyurea in which p-nitroaniline having the following structural formula is grafted. Maximum absorption wavelength (λ
max) 390 nm. When this polymer-coated thin film was polled, good second harmonic generation was confirmed.

[0059]

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Example 3 2-anilino-4-aminoanilino-6-aminophenyl-1,3,5-triazine and an aromatic diisocyanate were condensed in dimethylacetamide to form a 1,3,5-triazine ring. A polyurea was obtained. Details of synthesis are outside JKLin: Journal of Polym
er Science, vol. 40, p. 2113 (1990). The glass transition point of this polymer is approximately 20
It was 0 ° C. and stable up to 300 ° C. These polymers were dissolved in dimethylformamide, dimethylacetamide, dimethylsulfoxide and N-methyl-2-pyrrolidone to form a film.

Example 4 p-xylenediamine and p-
1.7 g of α, synthesized from fluoronitrobenzene
α'-Dinitroanilino-p-xylene and 1.13 g of 4,4'-diphenylmethane diisocyanate were polymerized in dimethylformamide. Yield 2.0 g. The repeating unit is a polyurea in which p-nitroaniline having the following structural formula is grafted. Maximum absorption wavelength (λmax) 378 nm. This polymer had side chains with a structure similar to p-nitroaniline and was active in nonlinear optical properties.

[0062]

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EXAMPLE 5 Di (2-methyl-nitro-aniline) synthesized from 2-methyl-4-nitroaniline and formaldehyde
By polymerizing 4-nitrophenylamino) methane and 4,4'-diphenylmethane diisocyanate, a polyurea having a repeating unit represented by the following structural formula was obtained. Maximum absorption wavelength (λmax) 3
90 nm. When this polymer-coated thin film was polled, good second harmonic generation was confirmed.

[0064]

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Example 6 Di (4-carboxymethylphenylamino) methane synthesized from methyl 4-aminobenzoate and formaldehyde was polymerized with 4,4'-diphenylmethane diisocyanate, and a polyurea having a repeating unit represented by the following structural formula: I got Maximum absorption wavelength (λmax) 310 nm.
When this polymer-coated thin film was polled, good second harmonic generation was confirmed.

[0066]

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Example 7 Di (2-nitro-nitropyridine) synthesized from 2-amino-5-nitropyridine and formaldehyde
By polymerizing 2-pyridylamino) methane and 4,4'-diphenylmethane diisocyanate, a polyurea having a repeating unit represented by the following structural formula was obtained. Maximum absorption wavelength (λmax) 310n
m. When this polymer-coated thin film was polled, good second harmonic generation was confirmed.

[0068]

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Example 8 A polymer comprising two kinds of N-phenylpolyureas (each a) and b) shown in the following repeating unit) contained in the present application was heated to 80 ° C.
Was spin-coated under the following temperature conditions to produce a film. Next, polling was performed at 130 ° C. for 60 minutes in an electric field of 6 to 8 kV. Using a Nd: YAG laser beam (1.06 μm) having a pulse width of 10 ns and a repetition period of 10 Hz as a light source, a second-order nonlinear optical constant d of the film was measured by a maker fringe method. The measurement was quartz d11 =
1.19 × 10 −9 esu was used as a standard. The nonlinear optical constants shown in Table 1 were obtained, and it was found that the polymer of the present application was excellent not only in transparency but also in nonlinear optical characteristics. Note that d33
And the ratio of d31 is 1 / of the value expected from the orientation in one direction.
A value close to 3 confirmed the reliability of the experiment. Moreover, both the cutoff wavelength corresponding to the absorption edge in the short wavelength, especially a heavy
The union showed a value of 307 nm, which is much shorter than the conventional value.

[0070]

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[0071]

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[0072]

[Table 1]

Example 9 Table 2 shows the characteristic measurement results of the polyurea (c), (d), polymer (e) and f) of the present invention comprising the following repeating units. All show high decomposition temperature, non-linear characteristics and transparency, and the effect of the present invention is clear.

[0074]

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[0075]

[Table 2]

[0076]

According to the present invention , an optical element having excellent nonlinear optical characteristics can be obtained by using the novel polyurea-based polymer.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a nonlinear optical element according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a nonlinear optical element according to a second embodiment of the present invention.

FIG. 3 is an explanatory view of a nonlinear optical element according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, 2, 4, 8, 9 ... Semi-transmissive mirror, 3 ... Non-linear optical medium, 5 ... Polarizer, 6 ... Incident light, 7 ... Output light.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-174523 (JP, A) JP-A-4-362618 (JP, A) JOURNAL OF POLYMER R SCIENCE: PART A: POLYMER CHEMISTRY, VOL. 25 PP. 2185-2193 JAPANESE JOURNAL OF APPLIED PHYSICS S, VOL. 30 NO. 10A PP. L 1737-1740 JAPANESE JOURNAL OF APPLIED PHYSICS S, VOL. 28 NO. 12 PP. Proceedings of the 52nd Annual Meeting of the Japan Society of Applied Physics 3rd volume P.L. 1125 “Second harmonic generation and relaxation characteristics of 11PT-3 vapor-deposited polymerized thin film by electric field orientation” APPL. POLYM. SCI. , VOL. 40 NO. 11/12 P.P. 2113-2122 (58) Field surveyed (Int. Cl. ⁶ , DB name) G02F 1/35-3/02 C08G 18/32 CA (STN) REGISTRY (STN)

Claims (6)

(57) [Claims] 1. A nonlinear optical element having a nonlinear optical medium having a light incident surface and a light emitting surface, wherein the nonlinear optical medium includes a poly-element having a repeating unit represented by the following general formula (Formula 1). A non-linear optical element using a urea-based polymer. Embedded image (Where A is an optionally substituted structural formula:
1 ′) is an aromatic group, wherein B is a methylene chain,
Optionally represented by the following structural formula (Chemical Formula 1 ')
An aromatic group selected from an aromatic group , benzene, biphenyl, terphenyl, stilbene, azobenzene, benzylidene, diphenylmethane, diphenylether, diphenylthioether, acridine, fluorene, indole, and a heterocycle, and X and Y are hydrogen atoms or It is an aromatic ring group selected from benzene, biphenyl, pyridine, azobenzene, and benzylidene which may be substituted. ) 2. A nonlinear optical system according to claim 1, wherein said X is a polyurea polymer in the para position selected from a nitro group, a cyano group, a carboxyl group and a carboxylester group. element. 3. The nonlinear optical element according to claim 1, wherein a polyurea-based polymer containing a 1,3,5-triazine ring is used as the polyurea-based polymer. 4. A nonlinear optical element according to claim 1, wherein a polyurea polymer having a molecular weight of 100 to 550,000 is used as said polyurea polymer. 5. The nonlinear optical element according to claim 1, wherein an untreated or polled polyurea-based polymer is used as the polyurea-based polymer. 6. A nonlinear optical element according to claim 1, wherein a polyurea-based polymer having a cutoff wavelength of 400 nm or less is used as said polyurea-based polymer.