JP3271463B2 - Nonlinear optical material and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-linear optical material used for an optical switch and an optical memory which is important in the future in optical information processing and an optical communication system, and an optical signal composed of the optical switch and the optical memory. The present invention relates to a nonlinear optical device such as an arithmetic processing device.

[0002]

2. Description of the Related Art The nonlinear optical effect means that when light is incident on a substance, the electric polarization P of the substance is expressed by the following general formula (Equation 1):

[0003]

(Equation 1)

P = χ ⁽¹⁾ E + χ ⁽²⁾ E ² + χ ⁽³⁾ E ³ +...

[0005] In contrast, 効果⁽ⁱ⁾ is the i-th electric susceptibility and E is the electric field intensity of light. In particular, the second harmonic generation (SHG) according to the second term and the third harmonic generation (THG) according to the third term are well known as wavelength conversion effects, but the third term also depends on the light intensity. It is important to give a change in optical constants, for example, a nonlinear refractive index effect or a nonlinear absorption effect. For example, the nonlinear refractive index effect is one in which the refractive index n of a substance changes in proportion to the intensity of incident light.
= N ₀ + n ₂ I (n ₀ is a constant and n ₂ is a nonlinear refractive index coefficient). By combining nonlinear optical materials that exhibit this effect with other optical elements such as optical resonators, polarizers, and reflectors, optical information processing and optical communications such as optical bistable elements, optical switches, and phase conjugate wave generators can be realized. Important devices for future use in the system are possible.

As a conventional example of a nonlinear optical device using a nonlinear optical material exhibiting such a nonlinear refractive index effect as a medium,
An example of the optical bistable element will be described below with reference to FIG.
5 is an optical bistable element, 21 is an optical material having a nonlinear refractive index (a nonlinear refractive index medium), and 22A and 22.
B is a dielectric vapor deposition mirror coated on both sides of the nonlinear refractive index medium 21 and having a reflectivity of about 90%. In this configuration, if the resonance condition is satisfied by slightly changing the wavelength of the input light, the output light Pt exhibits the characteristics shown in FIGS. 6A and 6B with respect to the input light intensity Pi. [Refer to Applied Physics Letters II for the operating principle. App
l. Phys. Lett., 35, 451 (1976)
Detailed). These correspond to limiter operation and bistable operation, respectively, and can be applied to optical communication and optical information processing systems, such as waveform shaping of input optical pulses, optical switches, optical signal memory, and optical logic operation. It is. That is, FIG. 6 is a diagram showing (A) limiter operation characteristics and (B) bistable operation characteristics of the nonlinear optical device (optical bistable element). Arrows in the figure indicate paths that show the characteristics of Pt when Pi increases and decreases. Incidentally, in this kind of nonlinear optical device, three values of a usable input light wavelength and input light intensity and a response time that can follow a change in the intensity of an optical signal are important as characteristics. For example, as the nonlinear optical medium 21 in FIG.
In an example using a superlattice crystal fabricated by alternately and repeatedly growing semiconductor thin films of aAlAs, the refractive index exhibits light intensity dependence by excitons excited in the crystal along with light absorption ( Since the operation principle is based on the absorption-dependent effect, the coefficient of the third term of the general formula (Equation 1) is large (that is, the efficiency of the third-order nonlinearity is high), and the input light intensity required for the operation is 5 × 10 ^4. Although it is excellent in that it can be as small as about W / cm ² , the usable input light wavelength is limited to an extremely narrow range near the exciton absorption spectrum, and the response time is determined by the exciton lifetime, 3x
There is a problem that it cannot be used for optical signal processing faster than 10 ^-8 sec. Further, in another conventional example using a glass cell filled with carbon disulfide (CS ₂ ) as a nonlinear optical liquid as a nonlinear optical medium and using an external mirror instead of the dielectric vapor deposition mirrors 22A and 22B, Since the principle of operation is that the refractive index shows light intensity dependence due to the rotational arrangement of molecules according to the optical electric field (molecular rotation nonlinear effect), the usable input light wavelength ranges from the visible to the near infrared. Although the point is excellent, the third-order nonlinear effect is not so high, the input light intensity required for operation is as large as about 10 ⁸ W / cm ² , and the response time is determined by the rotation relaxation time of the molecule. 10 ^-11 to 10
There is a problem that it cannot be used for optical signal processing faster than ^-12 sec.

As apparent from the above, the performance of a nonlinear optical device is almost determined by the characteristics of the nonlinear optical material. Therefore, there is a keen need to develop a material having a wide usable wavelength range, high third-order nonlinear efficiency, low input light intensity required for operation, and short response time, and active research is being conducted toward it. is the current situation. As a tertiary nonlinear optical material exhibiting such a nonlinear refractive index effect, an organic nonlinear optical material having π-electron conjugation such as a benzene ring, a double bond, or a triple bond has recently received particular attention. For example, in the case of polydiacetylenebis- (paratoluenesulfonate) (abbreviated as PTS), the constant of the third-order effect χ ⁽³⁾ is χ ⁽³⁾ = 1 × 10 ⁻¹⁰ esu [n ₂ = 2 × 10 ^-12 (W / c
m ²⁾ has the value becomes ^-1], 2 from the above CS ₂ Liquid
Order of magnitude larger. Also, the mechanism of this nonlinear effect is not due to absorption and interaction with molecules or crystal lattices, but is purely derived from electronic polarization, so that it can follow changes in the intensity of optical signals. Response time 10
^An extremely high speed of ^-14 sec is a major feature of the organic nonlinear optical material. Further, it has an excellent characteristic that the usable input light wavelength ranges from about 0.65 μm to 2.0 μm or more. However, since polydiacetylene such as PTS is generally a crystalline polymer, when it is actually used as a medium for an optical switch or an optical memory, it is necessary that the entire medium is a single crystal. . If an amorphous part is present in a part of the medium, or if the whole is in a polycrystalline state and is an aggregate of minute single crystals, the scattering loss of incident light increases, and No. Therefore,
In manufacturing optical devices using polydiacetylene, techniques such as growing large crystals or thin-film crystallization according to the purpose are indispensable, and even when these crystals are obtained, It is necessary to establish a processing technique for polishing and polishing the surface. These peripheral technologies for polydiacetylene have not yet been solved. Polyacetylene, which is a typical conductive polymer material, also has a large third-order nonlinear optical constant (χ ⁽³⁾ > 10 ⁻⁹ esu) exceeding the above PTS.
Since it is a crystalline polymer like S, it is inferior in light transmittance and workability, and is difficult to use as a medium for optical switches and optical memories from a practical viewpoint. As described above, none of the conventionally known polymer materials having a high nonlinear optical effect, such as polydiacetylene or polyacetylene, which can be applied to a nonlinear optical device at a practical level has been realized.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and utilizes a nonlinear refractive index of a conventional optical bistable element, an optical switch, a phase conjugate wave generator, and the like. It is an object of the present invention to eliminate disadvantages applied to a non-linear optical device, i.e., to eliminate disadvantages such as the above-mentioned wavelength limitation, low-speed response, high operation input light intensity, or the inability to easily obtain a desired optical material. A high-efficiency nonlinear optical material that can be used in a wide range of wavelengths, has a high-speed response, and has a small operating input light intensity, and a high-performance nonlinear optical device using the same. Is an issue.

[0009]

SUMMARY OF THE INVENTION In summary, the first invention of the present invention relates to a nonlinear optical material, and relates to a heteroaromatic ring having a donor property, a heteroaromatic ring having an acceptor property, and ethynylene. Wherein the π-electron conjugated polymer is represented by the following general formula (Formula 1):

[0010]

Embedded image (Ar and Ar ′ represent a substituted or unsubstituted heteroaromatic ring, Ar has a donor property with respect to a π-conjugated system, and Ar ′
Has an acceptor property with respect to a π-conjugated system. n and m are integers of 1 to 6, at least one of which is 2 or more). The second invention of the present invention relates to a non-linear optical device, and comprises a non-linear optical device including an optical medium having a non-linear refractive index and an optical element such as an optical resonator, a polarizer, or a reflecting mirror. Wherein the optical medium having the non-linear refractive index is polyarylene ethynylene represented by the general formula (Formula 1).

In order to solve the above-mentioned problems, the present invention has the above-mentioned configuration. That is, the present invention has found that the polyarylene ethynylene represented by the general formula (Formula 1) can easily obtain a thin film having an extremely large nonlinear optical effect and excellent light transmittance. .

That is, the conventional π-electron conjugated polymer-based nonlinear optical material is based on the fact that the π-electron conjugate length is increased or the nonlinear optical effect is increased by expanding the π-electron conjugate system in a plane. Whereas
In the polyarylene ethynylene of the present invention, the π-electron conjugated polymer material has a heteroaromatic ring having an acceptor property and a heteroaromatic ring having a donor property with respect to a π-conjugated system with ethynylene in the molecule, and It has been found that since both are composed of a plurality of heteroaromatic rings, large charge transfer easily occurs in the molecule, and this significantly improves the nonlinear optical properties of the π-electron conjugated polymer material [the above-mentioned π. Regarding the acceptor property and the donor property of the conjugated system, see the following book. New York City, John Wiley Sands, 1982, G.C. R. Newcome (GR) and W.K. W. Co-authored by WW Paudler, “Contemporary heterocycli
c chemistry). However, in this book, the acceptor property and the donor property of the π-conjugated
−π-deficient, π-excessive). In addition, the polyarylene ethynylene of the present invention is composed of different types of aromatic rings, so that its crystallinity is inhibited and an amorphous polymer can be easily obtained. As a result, a thin film having excellent optical transparency can be produced. Turned out to be easy.

Various compounds such as pyridine, pyrimidine, pyrazine, pyridazine, triazine, tetrazine, benzothiazole, benzoxazole and their alkyl or alkoxy substituents can be used as the heteroaromatic ring having an acceptor property for the π-conjugated system. ,
In particular, it has been found that the effect of the present invention is particularly large when pyridine is used. Further, as the heteroaromatic ring having a donor property, various compounds such as thiophene, selenophene, furan, pyrrole, tellurophen, and their alkyl or alkoxy substituents can be used, and when the compound is thiophene or selenophene, the effect of the present invention can be obtained. It was found to be particularly large. A polyaryleneethynylene-based π-electron conjugated polymer composed of a repeating unit containing one heteroaromatic ring having one acceptor property and one heteroaromatic ring having one donor property has a large nonlinear optical effect and forms a thin film. Have been made clear by the present inventors [T. Yamamoto,
M. Takagi, K. Scratch, T. Maruyama, K. Kubota,
H. Kambara, T. Kurihara and T.S. Kainou (T. Yamamot
o, M. Takagi, K .; Kizu, T .; Maruyama, K .; Kubot
a, H. Kanbara, T .; Kurihara, T .; Kaino), Chemical Communications (Chem. Commun.), No. 9, p. 797 (1993)]. Here, in the case where the heteroaromatic ring having an acceptor property in the π-conjugated system is pyridine and the heteroaromatic ring having a donor property is 3-hexylthiophene, the optical non-linearity due to the charge transfer effect from 3-hexylthiophene to pyridine is obtained. It has been found that gender increases. However, in order to specifically apply such a material to an ultra-high-speed optical switching device, even larger nonlinear optical characteristics are required. The inventors of the present invention have thought that it is necessary to cause charge transfer within a larger molecule in a π-electron conjugate system in order to obtain a larger nonlinear optical characteristic. In order to achieve this object, in a nonlinear optical material comprising a π-electron conjugated polymer containing a heteroaromatic ring having a donor property and a heteroaromatic ring having an acceptor property, polyarylene ethynylene is selected as the π-electron conjugated polymer. are doing. Further, a heteroaromatic ring having an acceptor property with respect to a π-conjugated system is pyridine or pyridine substituted with an alkyl group or an alkoxy group, and a heteroaromatic ring having a donor property is substituted with thiophene or selenophene, or an alkyl group or an alkoxy group. Thiophene or selenophene or a compound obtained by combining these selenophenes or thiophenes, and is composed of a compound in which both or one or both of a heteroaromatic ring having a donor property and a heteroaromatic ring having an acceptor property are linked to each other. It has been found that the effect of the present invention is particularly large. Conventionally, it has not been clarified that increasing the intramolecular charge transfer of the π-electron conjugated polymer by such a method contributes to the improvement of the nonlinear optical characteristics.

In the polyarylene ethynylene of the present invention, pyridine and thiophene or selenophene may be a compound in which two to six aromatic rings are linked alternately with ethynylene interposed therebetween. A compound in which six compounds are linked and a thiophene ring or a selenophene ring alternately or randomly, or a compound in which two or more molecules are bonded may be alternately bonded via ethynylene. Although a non-linear optical effect is also observed in a compound in which a donor aromatic ring and an acceptor aromatic ring are each linked 7 or more, the reason for this is not necessarily clear, but the planarity of the molecule tends to decrease, Since the effect of increasing the intramolecular charge transfer cannot be utilized, in the present invention, the effect of the invention is remarkable in a compound in which two to six aromatic rings are linked.

Although the polymer material according to the present invention is soluble in formic acid or the like, it may be preferable that the polymer material has a structure soluble in an organic solvent. To achieve this object, thiophene or selenophene substituted with an alkyl group or an alkoxy group as a heteroaromatic ring having a donor property, or pyridine substituted with an alkyl group or an alkoxy group as a heteroaromatic ring having an acceptor property is used. It is effective to use. In this case, the aromatic ring has 1 to 6
It is not necessary that an alkyl group or an alkoxy group be substituted on all aromatic rings of the pyridine, thiophene or selenophene compounds connected individually, and an alkyl group or an alkoxy group is substituted on any aromatic ring in consideration of easiness of synthesis. Just do it. One of the effects of the present invention is that the substitution with an alkyl group or an alkoxy group not only improves the solubility of the polyaryleneethynylene-based π-electron conjugated polymer but also contributes to the improvement of the planarity of the π-electron conjugated polymer. It is. As a result, thiophene or selenophene not substituted with an alkyl group or an alkoxy group,
The effect of improving the nonlinear optical properties as compared with a polyaryleneethynylene-based π-electron conjugated polymer composed of a pyridine ring not substituted with an alkyl group or an alkoxy group, or a compound in which one or two pyridine rings are linked to each other. .

The present invention also relates to a nonlinear optical device comprising an optical medium having a non-linear refractive index and an optical element such as an optical resonator, a polarizer, or a reflecting mirror. Characterized by using a polyaryleneethynylene-based π-electron conjugated polymer material composed of a compound in which each of a heteroaromatic ring having a property and a heteroaromatic ring having an acceptor property, or one of which is connected to 2 to 6 heteroaromatic rings. It is. Regarding the π-conjugated system, a polyaryleneethynylene-based π-electron conjugated polymer material composed of a heteroaromatic ring having an acceptor property and a heteroaromatic ring having a donor property includes (I) to (I) in the following formula (Formula 2). A π-electron conjugated polymer material composed of pyridine and thiophene represented by (IV), or pyridine and selenophene represented by (V) to (VIII) in the following formula (3) Conjugated polymer material to be used, or (IX) to (IX) in the following formula (Formula 4)
A polyaryleneethynylene-based π-electron conjugated polymer material composed of pyridine, thiophene, and selenophene as shown by (X) is exemplified. When a heteroaromatic ring has asymmetry, it is a substance that is formally a copolymer even if it is not strictly composed of a single repeating unit, and if only a so-called head-to-tail structure is used. Alternatively, a so-called head-to-head portion may be formed. However, most of the repeating units of the heteroaromatic ring are regular, and the effect of the present invention is small even if some irregular portions are present. Even in the case of a compound having a so-called random structure, the effect of a structural change based on the asymmetry of the heteroaromatic ring on optical non-linearity or solubility does not cause any particular problem.

[0017]

Embedded image

[0018]

Embedded image

[0019]

Embedded image

The synthesis of these π-electron conjugated polymer materials is as follows:
Poly- (3-hexylthiophene-2,5) which has already been reported as a conductive polymer material having an amorphous structure
-Diylethynylene-pyridine-2,5-diyl-),
Alternatively, it can be carried out according to poly- (selenophene-2,5-diylethynylene, pyridine-2,5-diylethynylene). As will be described later, the nonlinear optical material according to the present invention synthesizes a polymer that is soluble not only in formic acid but also in an organic solvent such as chloroform, dimethylacetamide, dimethylformamide, dimethylsulfoxide, tetrahydrofuran, n-methylpyrrolidone, and toluene. It is excellent in moldability, easy to handle, and chemically stable.

A polyaryleneethynylene-based π-electron conjugated polymer material composed of a compound in which each of the heteroaromatic ring having a donor property and the heteroaromatic ring having an acceptor property, or one of which is linked to two or six, is The fact that the third-order nonlinear effect is extremely large and that the light transmittance is excellent
The present inventors were able to clarify for the first time. Also,
The nonlinear refractive index coefficient was confirmed to be large due to the large third-order effect, and this material was used as a nonlinear optical medium to construct nonlinear optical devices such as optical bistable elements, optical switches, and phase conjugate wave generators. It is the second point of emphasis that the present invention can be put to practical use.

[0022]

EXAMPLES Hereinafter, using the examples, in the π-conjugated system according to the present invention, each of a heteroaromatic ring having a donor property and a heteroaromatic ring having an acceptor property, or one of them, is 2 to 3.
The non-linear optical effect of a polyarylene ethynylene-based π-electron conjugated polymer material composed of six linked compounds and the characteristics of a non-linear optical device using the same will be described in detail.

Embodiment 1 The third order effect of an organic material is generally based on third harmonic light (THG).
It is evaluated by measuring the intensity of light. A laser pulse light is incident, and while the sample is rotated around an axis perpendicular to the incident direction of the laser light, the intensity of the emitted THG light is measured, and a material of which efficiency is already known (here, quartz glass is used) Can be measured with the same observation system and compared with the peak intensity of THG to measure the efficiency of the tertiary effect.
Letters (Electron. Lett.), Vol. 23, No. 11, p. 595 (1987)]. FIG. 7 shows a poly (bi-3-hexylthiophenediylethynylene-pyridinediylethynylene) (abbreviation: PAE-BTRPY) film (in this case, a thickness of 0.15 μm),
The result obtained by the G method is calculated as the third order electric susceptibility χ ⁽³⁾ (vertical axis,
× 10 ⁻¹⁰ esu) and the wavelength of incident light (horizontal axis, μm)
It is the result plotted against.値 The value of ⁽³⁾ is 8 × 1
It was about 0 ^-10 esu, and it was confirmed that the value was almost the same as the above-mentioned PTS. From this measured value, the nonlinear refractive index is calculated to be about n ₂ = 5 × 10 ⁻¹² (W / cm ² ) ⁻¹ . A method for producing the PAE-BTRPY film will be described. The following formula (Formula 5) is an example of a reaction scheme when synthesizing the nonlinear optical material PAE-BTRPY of the present invention.

[0024]

Embedded image

The desired polymer compound PAE-BTRP
Y is soluble in an organic solvent such as toluene and chloroform, and is dissolved (about 1% by weight), and a thin film of 0.02 to 0.5 μm is obtained by spin coating.

The absorption spectrum of PAE-BTRPY was measured with a spectrophotometer. As a result, it was found that the non-absorption wavelength range was extremely wide, 0.70 to 2.2 μm. That is, this material has a wider usable wavelength range than the PTS described above. Further, from the same consideration, a polyarylene ethynylene-based π-electron conjugate composed of a compound in which each of a heteroaromatic ring having a donor property and a heteroaromatic ring having an acceptor property or a compound in which one of the heteroaromatic rings has 2 to 6 atoms is connected. The response time of the polymer material is 1 like PTS.
It is estimated to be about 0 ^-14 sec and has a sufficient speed. On the other hand, when a film having a thickness of 2 μm was obtained by casting a toluene solution of PAE-BTRPY, and the light transmittance of this film was evaluated by the prism coupling method, an excellent light transmittance of 1.5 dB / cm at a wavelength of 1.3 μm was obtained. It was found to have

Example 2 Poly- (biselenophen-2,5-diylethynylene-
Bi-4-methylpyridine-2,5-diylethynylene)
(Abbreviation PAE-BSBPYR) film (in this case, the thickness is 0.15 μm), and a third-order electric susceptibility χ ⁽³⁾
When the value was measured, it was about 2 × 10 ⁻⁹ esu, and it was confirmed that the value was about the same as the above-mentioned PTS. From this measured value, the nonlinear refractive index is n ₂ = 5 × 11 ^−11.
(W / cm ² ) ^-1 is calculated. Polymer compound PA
E-BSBPYR is dissolved in chloroform (about 1% by weight), and 0.02-1.5 μm is spin-coated.
An m-thick thin film is obtained. Also, PAE-BSB
The absorption spectrum of PYR was measured with a spectrophotometer. As a result, it was found that the non-absorption wavelength range was extremely wide, 0.70 to 2.2 μm. That is, this material has a wider usable wavelength range than the PTS described above. The response time of the nonlinear optical material PAE-BSBPYR of the present invention is PTS
It is estimated to be about 10 ^-14 sec in the same manner as described above, and it has a sufficiently high speed. On the other hand, a film having a thickness of 2 μm was obtained by casting a chloroform solution of PAE-BSBPYR, and the light transmittance of the film was evaluated by a prism coupling method.
/ Cm.

Examples 3 to 15 Tables 1, 2 and 3 show that the π-conjugated system according to the present invention is a heteroaromatic ring having a donor property and a heteroaromatic ring having an acceptor property, or one or two of which are linked. 3 shows nonlinear optical effects and light transmittance of various polyaryleneethynylene-based π-electron conjugated polymer materials composed of the above compounds. It can be seen that each of them has a highly nonlinear optical effect and excellent light transmittance.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

Embodiment 16 FIG. 1 is a schematic perspective view showing an example of the configuration of an optical bistable element according to the present invention, where 10 is an optical bistable element (external resonator), 20 is a nonlinear refractive index medium, and 23 A , 23B are dielectric multilayer mirrors, Pi is input light, and Pt is force output light. The external cavity wave and the PAE-BTRPY film produced by the above-described method are applied to the nonlinear refractive index medium 20.
This is an external optical resonator in which the dielectric multilayer mirrors 23A and 23B that reflect about 90% of the input light and transmit the rest are opposed to each other with the nonlinear refractive index medium 20 interposed therebetween. Here, the above-mentioned PAE-BTRPY film is P
A toluene solution of AE-BTRPY was cast on a glass substrate, and after removing the solvent, it was peeled off from the substrate to form a free-standing film-like nonlinear refractive index medium having a size of about 10 × 10 × 1 mm ³ . One used.

Embodiment 17 FIG. 2 is a schematic perspective view showing an example of the configuration of a light control optical switch according to the present invention. In FIG. 2, reference numeral 11 denotes a light control optical switch, 20 denotes a nonlinear refractive index medium of the present invention, and 24A,
24B is a polarizer, Pi is input light, Pt is output light, and Pg is gate pulse light. This light control optical switch 11 is composed of two polarizers 24 arranged so that their polarization axes are orthogonal to each other.
A orthogonal polarizer system composed of A and 24B is provided, and the nonlinear refractive index medium 20 is sandwiched between these orthogonal polarizers 24A and 24B. As the nonlinear refractive index medium 20, the PAE-BTRPY obtained in Example 1 was used. In this configuration, linearly polarized light that has passed through the orthogonal polarizer 24A only while the gate pulse light Pg is incident undergoes rotation of the polarization angle due to a change in the refractive index of the nonlinear refractive index medium 20, and passes through the orthogonal polarizer 24B. I do. That is, the input light Pi is optically switched by the gate pulse light Pg. In this apparatus, the usable wavelength range, the response time, and the value of the operation input light intensity (gate pulse light) are important, but it is clear from the first embodiment that the usable wavelength range and the response time are extremely excellent. It is.

Embodiment 18 FIG. 3 is a schematic sectional view showing an example of the configuration of a phase conjugate wave generator according to the present invention. In FIG. 3, reference numeral 12 denotes a phase conjugate wave generator of the present invention, 20 denotes a nonlinear refractive index medium of the present invention,
25A, 25B are semitransparent mirror, 26 a total reflection mirror, Pi is the input light, Pt is the power output _{light, A 1, A 2, Ac} , Ap is the light wave. In the phase conjugate wave generator 12 of the present invention, the nonlinear refractive index medium 20 of the present invention is sandwiched between the first semi-transmissive mirror 25A and the total reflection mirror 26, and the light from the semi-transmissive mirror 25A is transmitted to the semi-transmissive mirror 25B. The transflective mirror 25A and the total reflection mirror 26 are arranged so as to be inclined to the optical axis and enter the nonlinear refractive index medium 20. As the nonlinear refractive index medium 20, the PAE-BTRPY obtained in Example 1 was used. This configuration is an optical arrangement called degenerate four-wave mixing. When three light waves A ₁ , A ₂ (in the opposite direction to A ₁ ), and Ap (oblique incidence) enter the nonlinear refractive index medium 20, Ap is applied to Ap. On the other hand, a fourth light wave Ac in which only the spatial phase term is conjugate is generated. This phase conjugate wave is attracting attention as an effective means for image correction in image information processing technology and real-time holography.
Also in this example, high-speed response and low operation input light intensity of the device were confirmed.

Example 19 The PAE-BTRPY obtained in Example 1 was dissolved in chloroform and spin-coated on a glass substrate to give a thickness of 2.0.
A μm thin film was obtained. This thin film operates as a three-layer slab type optical waveguide when light enters from the end face. FIG. 4 shows an optical control optical switch using this optical waveguide as a nonlinear refractive index medium. In FIG. 4, reference numeral 16 denotes an optical control optical switch, 24A and 24B denote polarizers, 27 denotes a dichroic mirror, 28 denotes a condensing lens, 29 denotes a glass substrate, and 30 denotes an optical waveguide layer made of a non-linear refractive index medium thin film of the present invention. , Pi
Is input light, Pt is output light, and Pg is gate pulse light. The length of the optical waveguide layer 30 was 1.5 cm. The optical control optical switch 16 has a configuration in which an optical waveguide layer 30 made of a non-linear refractive index medium is sandwiched between orthogonal polarizer systems including two polarizers 24A and 24B arranged so that their polarization axes are orthogonal to each other. The dichroic mirror 27 introduces the gate pulse light and separates it from the output light, and the condenser lens 28 introduces the input light and the gate pulse light into and out of the optical waveguide layer 30. In this configuration, the orthogonal polarizer 24 is applied only while the gate pulse light Pg is incident.
The linearly polarized light that has passed through B undergoes a rotation of the polarization angle due to a change in the refractive index of the optical waveguide layer 30, and passes through the orthogonal polarizer 24B. That is, the input light Pi is optically switched by the gate pulse light Pg. The optical control optical switch 16 operates at a gate Hals light intensity of about 1/20 compared to the optical switch 11 because the gate light and the signal light are confined in the optical waveguide layer. Was constructed. It is clear from Example 1 that this apparatus is also extremely excellent in the usable wavelength range and the response time.

[0036]

According to the present invention, a polyaryleneethynylene-based π-electron conjugated polymer material is converted into a heteroaromatic ring having a donor property and a heteroaromatic ring having an acceptor property for a π-conjugated system. By using a six-linked compound, it is possible to obtain a conventional high-order third-order nonlinear optical characteristic and to obtain a thin film having excellent light transmittance. Further, according to the present invention, it has a large nonlinear refractive index, and extremely high response speed,
Each of a heteroaromatic ring having a donor property and a heteroaromatic ring having an acceptor property having a light-transmitting property in a wide wavelength range from a visible region to a near-infrared region, or a polycyclic compound composed of a compound in which one or two are linked to each other. Using a film of an arylene ethynylene-based π-electron conjugated polymer material as a nonlinear refractive index medium, the nonlinearity that will be important in the future optical information processing or optical communication fields such as optical bistable elements, optical switches, or phase conjugate wave generators Since the optical device can be configured, it is much better in terms of wavelength dependence, response speed, and input light intensity required for operation than conventional nonlinear optical liquid or nonlinear optical device using semiconductor superlattice crystal. Thus, a non-linear optical device having practical value that an existing semiconductor laser can be used as a light source can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a configuration of an optical bistable element according to Example 16 of the present invention.

FIG. 2 is a schematic perspective view showing a configuration of a light control optical switch according to Embodiment 17 of the present invention.

FIG. 3 is a schematic perspective view showing a configuration of a phase conjugate wave generator according to Embodiment 18 of the present invention.

FIG. 4 is a schematic perspective view showing a configuration of a light control optical switch according to Embodiment 19 of the present invention.

FIG. 5 is a schematic perspective view showing an example of a configuration of a conventional nonlinear optical device (optical bistable element).

FIG. 6 is a diagram showing (A) limiter operation characteristics and (B) bistable operation characteristics of the nonlinear optical device (optical bistable element).

FIG. 7 is a graph showing the dependence of the third-order nonlinear susceptibility χ ⁽³⁾ value of the polyaryleneethynylene-based π-electron conjugated polymer material according to the present invention on the wavelength of incident light, as measured by the THG method.

[Explanation of symbols]

10: optical bistable element (external resonator), 11: optical control switch, 12: phase conjugate wave generator, 15: optical bistable element, 16: optical control optical switch, 20: nonlinear refractive index medium of the present invention, 21: Conventional nonlinear refractive index medium, 22A and 22B: Dielectric deposited mirror (reflectance: about 90%), 23A
And 23B: (external) dielectric multilayer mirror, 24A and 24B: polarizer (constituting orthogonal polarizer system), 25
A and 25B: semi-transmissive mirror, 26: total reflection mirror, 27: dichroic mirror, 28: condenser lens, 29: glass substrate, 30: optical waveguide layer made of the non-linear refractive index medium thin film of the present invention, Pi: input light , Pt: output light, Pg: gate pulse light

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-289444 (JP, A) Macromolecules, Vol. 27, No. 2,562-571 (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/361 CA (STN) JICST file (JOIS)

Claims (4)

(57) [Claims] 1. A nonlinear optical material comprising a π-electron conjugated polymer composed of a heteroaromatic ring having a donor property, a heteroaromatic ring having an acceptor property, and ethynylene,
The π-electron conjugated polymer is represented by the following general formula (Formula 1): (Ar and Ar ′ represent a substituted or unsubstituted heteroaromatic ring, Ar has a donor property with respect to a π-conjugated system, and Ar ′
Has an acceptor property with respect to a π-conjugated system. n and m are integers of 1 to 6, and at least one of them is 2 or more), which is a polyarylene ethynylene. 2. In the general formula (Formula 1), Ar is a thiophene or selenophene ring, or a group from a compound obtained by combining thiophene and selenophene, or an alkyl or alkoxy substituent thereof, and Ar ′ is a pyridine ring or The nonlinear optical material according to claim 1, which is an alkyl- or alkoxy-substituted product thereof. 3. A nonlinear optical device comprising an optical medium having a nonlinear refractive index and an optical element such as an optical resonator, a polarizer, or a reflecting mirror, wherein the optical medium having the nonlinear refractive index is represented by the following general formula: (Chemical 1): (Ar and Ar ′ represent a substituted or unsubstituted heteroaromatic ring, Ar has a donor property with respect to a π-conjugated system, and Ar ′
Has an acceptor property with respect to a π-conjugated system. n and m are integers of 1 to 6, and at least one of them is 2 or more.) is a polyarylene ethynylene represented by the following formula: 4. In the general formula (Formula 1), Ar is a thiophene or selenophene ring, or a group from a compound obtained by combining thiophene and selenophene, or an alkyl or alkoxy substituent thereof, and Ar ′ is a pyridine ring or 4. The nonlinear optical device according to claim 3, wherein the non-linear optical device is an alkyl- or alkoxy-substituted product thereof.