JPH05196977A - Nonlinear optical element - Google Patents

Abstract

PURPOSE:To obtain the optical element which can be easily synthesized and has excellent ray transmittance, moldability, mechanical strength, nonlinear optical characteristics, etc., by using a high polymer of a specific polyurea system for a nonlinear optical medium. CONSTITUTION:The high polymer of the polyurea system contg. the repeating unit expressed by formula is used for the nonlinear optical medium of the nonlinear optical element contg. the nonlinear optical medium having a surface on which light is made incident and the surface from which the light is emitted. In the formula, A, B are a methylene chain or the arom. cyclic group selected form (substd.) benzene, biphenyl, terphenyl, stilbene, azobenzene, benzylidene, diphenylmethane, diphenyl ether, diphenyl thioether, acrydine, fluorene, indole, heterocycle; X, Y are a hydrogen atom or the arom. cyclic group selected from (substd.) benzene, biphenyl, pyridine, azobenzene and benzylidene.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurea 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 1960s, many inorganic materials have been discovered that exhibit strong nonlinear optical characteristics. Well-known inorganic materials include 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 ) and the like. The inorganic material is
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 macromolecules that can be designed into molecules have become very interesting in the field of nonlinear optics. Organic molecules and polymer materials have characteristics such as large optical non-linearity, large laser light resistance, high-speed response, and light weight suitable for certain fields, and thus have high possibility of application in the field of non-linear optics. In organic conjugated polymers, third-order nonlinearity due to π electron system is obtained, and polyacetylene, poly (p-phenylene), polythiophene, polypyrrole,
Many conjugated polymers such as phthalocyanines, polyanilines, heteroaromatic ladder polymers and related copolymers have been investigated. 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 a high third-order nonlinear susceptibility at short wavelengths are extremely demanded for producing high-power lasers in the ultraviolet and near-infrared wavelength regions by wavelength conversion.

The existing reports related to these are as follows. Edited by DL Williams "Nonlinear optical propertie
s of organic and polymeric materials '' ACS Symposiu
mSeries Volume 233, American Chemical Society, Wash
ington D. C. (1983), edited by T. Kobayashi "Nonlin
ear optaics of organics and semiconductors "Spring
er Proceedings in Physics, Volume 36, Springer-Ver
19 at lag, Berlin (1989) and the SPIE Society
There are papers published between the years 85-1990.

[0004]

The third-order nonlinear susceptibility is
It is sensitively dependent on the delocalization distance of π electrons and the band spacing of the conjugated polymer structure. Therefore, Physical Review by Agrawal et al.
As illustrated in B17, p. 776 (1978) and the like, a large third-order nonlinear susceptibility is easily obtained by a conjugate structure having a small band spacing. AKBakhsgi and J. Ladik
As shown in Soid State Communications, Volume 60, page 361 (1986), azoethene, azine,
It is known that copolymers having a methineimine and acetylene structure show smaller band intervals.
However, the small band spacing causes a longer wavelength at the absorption edge,
It is not preferable in manufacturing the device. It is necessary to realize high nonlinear optical characteristics with wide band intervals.

Second-order nonlinear optics is only observed in non-centrosymmetric crystals. For example, p-nitroaniline has a large molecular nonlinear hyperpolarizability, but it has centrosymmetry, so no second order nonlinear optical effect is observed. Many methods have been proposed to obtain non-centrosymmetry. For example, electrical polarization and guest-host system mixing method, hydrogen bonding,
There are structural regulations, etc. Organic materials include single crystals, Langmuir-Blodgett films, guest-host systems, superlattice structures,
Alternatively, it can be used in various ways such as a polymer polarized under an electric field. Related reports include DSChemla and
J. Zyss `` Nonlinear Optical Properties of Organic
Molecules and Crystals "Volumes 1 and 2, Academic Pre
ss, (1987), HS Nalwa 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) and others. 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]

The object of the present invention is to provide a novel organic polymer which can be used as a nonlinear optical material. Another object of the present invention is to provide an optically nonlinear organic material exhibiting a large second-order and third-order nonlinear optical effect. Another object of the present invention is to provide a non-linear optical element using a polymer and a copolymer that are easy to synthesize and are excellent in light transmittance, moldability, mechanical strength, thermal oxidation stability and low toxicity.

The present invention relates to a non-linear optical element including a non-linear optical medium having a light incident surface and a light emitting surface, and a polyurea polymer whose repeating unit is represented by the following general formula (1) is added to the non-linear optical medium. A non-linear optical element characterized by being used.

[0008]

[Chemical 2]

However, A and B are methylene chains or optionally substituted benzene, biphenyl, terphenyl, stilbene, azobenzene, benzylidene, diphenylmethane, diphenylether, diphenylthioether, acridine, fluorene, indole, and an aromatic ring selected from a heterocycle. And X and Y are hydrogen atoms, or an aromatic ring group selected from optionally substituted benzene, biphenyl, pyridine, azobenzene, and benzylidene.

Polymers having the following repeating units are used in the present invention.

[0011]

[Chemical 3]

However, 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, in particular, a novel polyurea polymer having the following repeating unit is used.

[0014]

[Chemical 4]

However, 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]

[Chemical 5]

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

[0018]

[Chemical 6]

[0019]

[Chemical 7]

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

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

[0022]

[Chemical 8]

However, D is an aromatic ring group selected from optionally substituted benzene, biphenyl, terphenyl, stilbene, azobenzene, benzylidene, acridine, fluorene, indole and heterocycle, and E is diphenylmethane, dimethyldiphenyl, It is an organic group selected from dimethoxydiphenyl, m-xylene and tolylene.

Further, in the structure of the above polymer, 1,3,5-
A novel polyurea-based polymer composition containing a triazine ring, a silicon atom, or an organometallic compound is used.

The above polymer has a molecular weight of 100 to 55.
It is desirable that it is 000.

The above polymer is preferably used in a film thickness of 1 to 500 μ.

These polymers are far superior to conventional performances in that they are second-order nonlinear optical elements, third-order nonlinear optical elements, electro-optical elements, laser frequency conversion elements, optical switches, optical modulators, optical waveguides, four-wave mixing. It can be used as an optical bistable device.

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

[0029]

[Chemical 9]

Here, D is an optionally substituted aromatic ring selected from 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.

Examples of the repeating structural unit of the polymer used in the present invention are shown below, but the present invention is not limited thereto, and other well-known polymers such as polystyrene, polymethacrylate and polyacrylate are also not limited thereto. Copolymers with polyazine are also included in the present invention.

[0032]

[Chemical 10]

[0033]

[Chemical 11]

[0034]

[Chemical 12]

[0035]

[Chemical 13]

[0036]

[Chemical 14]

Here, Ar ₅ is an aromatic group selected from the following structural formulas.

[0038]

[Chemical 15]

Polymers having the following repeating units are used in the present invention.

[0040]

[Chemical 16]

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

[0042]

[Chemical 17]

Polymers having the following repeating units are used in the present invention.

[0044]

[Chemical 18]

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

[0046]

[Chemical 19]

Polymers having the following repeating units are used in the present invention.

[0048]

[Chemical 20]

Various charge transfer substituents are used in the present invention, and these are appropriately introduced at appropriate positions in the above-mentioned compound of the present invention. However, the present invention is not limited to these. As the electron-withdrawing substituent, 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 acetamide group, Examples include allyl groups such as methoxy, ethoxy, and phenyl groups.

The polymer composition of the present invention can be molded into a continuous film or coating having a film thickness of 1 to 500 μm by various existing methods such as solution coating, spin coating and molding. Also, the molecular weight is 10 by controlling the reaction conditions.
It can be produced in the range of 0 to 550,000.

The polymer composition of the present invention exhibits good light transmittance and excellent thermal stability in the atmosphere and an inert gas atmosphere. Further, it has been confirmed in experiments using a copolymerized polymer that it exhibits high second-order and third-order nonlinear optical properties, and particularly that the third-order nonlinear optical property increases with an increase in conjugated moieties.

The polymer of the present invention can be applied to a tin oxide transparent substrate under a condition of heating at about 80 ° C. to form a thin film, and corona poling can be performed. An electric field of 4 to 8 kW can be used depending on the discharge breakdown characteristics of the material, and heating is preferably performed at a high temperature of 5 to 10 ° C., which is the glass transition point. The polling time is 2 to 4 hours.

The third-order nonlinear susceptibility can be measured by the maker fringe method using the fundamental wave (1.064 to 2.1 μ) of the Nd-YAG laser as a light source.

An example of a well-known nonlinear optical element related to the present invention is shown in FIG. The output light 6 of the light source 1 is applied to the nonlinear optical medium sample 3 of the polyazine-based polymer described in the present invention through the semi-transmissive mirror 2, and the output light 7 is obtained through the semi-transmissive mirror 4 and the polarizing plate 5. . Here, the semitransparent mirrors 2 and 4
By the well-known technique of installing the light at a resonance position suitable for the used light, it is possible to enable the output light to have a non-linear response or a bistable operation that is effective for optical calculation with respect to the incident light. Similarly, as shown in FIG. 2, the feedback light 11 that has passed through the semi-transmissive mirrors 8 and 9 and the reflecting mirror 10 can be used to operate more efficiently. Further, as shown in FIG. 3, the incident light may be the sum of the light rays 6 and 12, one of which is the pump light and the other of which is the probe light for optical calculation. As the light source 1, all existing light sources can be used. For example, YAG laser light 1.
Light of 1.9 to 2.1 μm based on an optical parametric oscillation of 06 μm is used.

[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 in 8 ml of sym-tetrachloroethane at 80 ° C. under nitrogen atmosphere. , Condensed for 12 hours. The resulting viscous solution was diluted with chloroform,
The precipitate was dispersed in 300 ml of methanol, and the obtained precipitate was filtered and dried in vacuum at 60 ° C. Yield 1.0g. The repeating unit is N-phenyl polyurea having 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 the air from around 290 ° C. When a thin film coated with this polymer as a solution in chloroform was poled, good second harmonic generation was confirmed.

[0057]

[Chemical 21]

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 standing overnight to form a precipitate, filtered, and dried under vacuum at 60 ° C. Yield 1.30g. The repeating unit is polyurea grafted with p-nitroaniline having the following structural formula. Maximum absorption wavelength (λ
max) 390 nm. When a thin film coated with this polymer was poled, good second harmonic generation was confirmed.

[0059]

[Chemical formula 22]

Example 3 2-anilino-4-aminoanilino-6-aminophenyl-1,3,5-triazine was condensed with aromatic diisocyanate in dimethylacetamide to form a 1,3,5-triazine ring. A polyurea having was obtained. For details of synthesis, see JKLin: Journal of Polym.
er Science, 40, 2113 (1990). The glass transition point of this polymer is about 20.
It was 0 ° C. and was stable up to 300 ° C. Further, 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 2.0g. The repeating unit is polyurea grafted with p-nitroaniline having the following structural formula. Maximum absorption wavelength (λmax) 378 nm. This polymer had a side chain with a structure similar to p-nitroaniline, and was active for nonlinear optical properties.

[0062]

[Chemical formula 23]

Example 5 Di (2-methyl-) synthesized from 2-methyl-4-nitroaniline and formaldehyde.
4-Nitrophenylamino) methane and 4,4'-diphenylmethane diisocyanate were polymerized to obtain polyurea having a repeating unit of the following structural formula. Maximum absorption wavelength (λmax) 3
90 nm. When a thin film coated with this polymer was poled, good second harmonic generation was confirmed.

[0064]

[Chemical formula 24]

Example 6 Polyurea having a repeating unit of the following structural formula was prepared by polymerizing di (4-carboxymethylphenylamino) methane synthesized from methyl 4-aminobenzoate and formaldehyde and 4,4'-diphenylmethane diisocyanate. Got Maximum absorption wavelength (λ max) 310 nm.
When a thin film coated with this polymer was poled, good second harmonic generation was confirmed.

[0066]

[Chemical 25]

Example 7 Di (2-nitro-) synthesized from 2-amino-5-nitropyridine and formaldehyde
2-Pyridylamino) methane and 4,4'-diphenylmethane diisocyanate were polymerized to obtain polyurea having a repeating unit of the following structural formula. Maximum absorption wavelength (λmax) 310n
m. When a thin film coated with this polymer was poled, good second harmonic generation was confirmed.

[0068]

[Chemical formula 26]

Example 8 Two kinds of N-phenylpolyureas (each a) and b) shown in the following repeating units contained in the present application.
Of a polymer) was spin-coated at a temperature of 80 ° C. to prepare a film. Next, under the temperature condition of 130 ° C., poling was performed in an electric field of 6 to 8 kV for 60 minutes. The second-order nonlinear optical constant d of this film was measured by the maker fringe method using Nd: YAG laser light (1.06 μm) with a pulse width of 10 ns and a repetition period of 10 Hz as a light source. In the measurement, quartz d ₁₁ = 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 is excellent not only in transparency but also in nonlinear optical characteristics. The ratio of d ₃₃ and d ₃₁ was close to the value of 1/3 predicted from the orientation in one direction, and the reliability of the experiment was confirmed. Further, the cut-off wavelengths corresponding to the absorption edge are all short wavelengths, and particularly Compound # 1 shows a value of 307 nm, which is a value that is significantly shorter than the conventional value.

[0070]

[Chemical 27]

[0071]

[Chemical 28]

[0072]

[Table 1]

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

[0074]

[Chemical 29]

[0075]

[Table 2]

[0076]

By the novel polyurea polymer of the present invention, a material which has excellent nonlinear optical characteristics and can be applied to a practical device is obtained.

[Brief description of 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 diagram of a nonlinear optical element according to a third embodiment of the present invention.

[Explanation of symbols]

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

Claims (20)

[Claims] 1. A non-linear optical element including a non-linear optical medium having a light incident surface and a light emitting surface, wherein the non-linear optical medium has a repeating unit having a repeating coupling unit represented by the following general formula (1). A non-linear optical element characterized by using a polyurea-based polymer. [Chemical 1] (However, A and B are methylene chain or optionally substituted benzene, biphenyl, terphenyl, stilbene, azobenzene, benzylidene, diphenylmethane, diphenyl ether, diphenyl thioether, acridine,
An aromatic ring group selected from fluorene, indole, and a heterocycle, and X and Y are hydrogen atoms, or an aromatic ring group selected from optionally substituted benzene, biphenyl, pyridine, azobenzene, and benzylidene). 2. The non-linear optical element according to claim 1, wherein X is a substituent selected from a nitro group, a cyano group, a carboxyl group and a carboxyl ester group at the para position. 3. A non-linear optical element comprising a polyurea-based polymer containing a 1,3,5-triazine ring. 4. A non-linear optical element comprising a polyurea-based polymer containing a silicon atom. 5. A non-linear optical element comprising a polyurea polymer having a molecular weight of 100 to 550,000. 6. A non-linear optical element comprising a polyurea polymer containing an organometallic compound. 7. A second-order nonlinear optical element characterized by using a polyurea-based polymer. 8. A third-order nonlinear optical element comprising a polyurea-based polymer. 9. A non-linear optical element comprising a thin film structure of polyurea polymer having a thickness of 1 to 500 μm. 10. A non-linear optical element using a polyurea-based polymer having a conjugated basic skeleton having a multiple quantum well structure at room temperature and high temperature. 11. A non-linear optical element using a polyurea-based polymer that gives a superlattice structure. 12. A non-linear optical element comprising a non-treated or poled non-linear optical medium of a polyurea-based polymer having a non-linear optical functional portion. 13. An electro-optical element comprising a polyurea-based polymer. 14. A laser frequency conversion device using a polyurea-based polymer. 15. A photoelectric modulation element using a non-linear medium composed of a polyurea-based polymer. 16. An optical waveguide using a non-linear medium composed of a polyurea polymer. 17. A four-wave mixer using a non-linear medium composed of a polyurea-based polymer. 18. An optical bistable device using a non-linear medium composed of a polyurea-based polymer. 19. A thermoelectric, piezoelectric or ferroelectric element using a medium made of polyurea polymer. 20. A non-linear optical element using a medium made of a polyurea polymer and having a cutoff wavelength of 400 nm or less.