JPH01204030A - Production of organic nonlinear optical base body - Google Patents

Abstract

PURPOSE:To obtain a nonlinear base body having high second harmonics generating (SHG) strength and high optical damage threshold by impressing an electric field to a mixture composed of a specific org. nonlinear optical material and photosetting resin and projecting high-energy rays thereon, thereby curing the mixture. CONSTITUTION:The org. nonlinear optical material having a pi electron conjuga tion chain in the molecule and having an electron-donating group and electron- accepting group respectively at both ends of the molecule, for example, p- nitroaniline, etc., and the thermosetting resin are mixed to, for example, 1:20. This mixture is injected into a sample holder 1 which is pinched by 'NESA(R)' glass plates 2, 2 and while 5,000V voltage is impressed to electrodes 3, 3' from a high-voltage supply, the UV rays are projected thereon for 2min by a high- pressure mercury lamp. As a result, the strength of the second harmonics attains the value of 5 times the value indicated by urea when, for example, the p- nitroaniline is used; in addition, the nonlinear base body having the high optical damage threshold is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an organic nonlinear optical material that has a π-electron conjugated chain in its molecule and an electron-donating group and an electron-accepting group at both ends of the molecule. The present invention relates to a method of manufacturing an optical substrate.

Conventional nonlinear optical effects include optical mixing, optical parametric effects, high frequency generation, etc., but in recent years, second high frequency generation (hereinafter referred to as SHG), which is important for applications, has been
-Methyl-4-nitroaniline (MNA) is KH2PO
It has been discovered that organic materials have a nonlinear constant of 50 times or more than 4, and as a result, organic materials have started to attract attention.

Large organic substances such as SHG have an electron-donating group such as a dimethylamino group and an electron-accepting group such as a nitro group at both ends of a π-electron conjugated molecule such as benzene, pyridine, stilbene, and azobenzene, and the entire molecule is It has a shape with strong electronic polarization in the long axis direction. However, these organic substances often do not produce SHG in the crystalline state. This is because during crystallization, the molecules align in a way that neutralizes the charge, resulting in an inverted central symmetry in the crystal. be.

As a method to suppress such inversion symmetry, attempts have been made to control the crystal system by introducing hydrogen-bonding substituents or chiral substituents. It has also been proposed to eliminate the center of inversion symmetry by 〈Japanese Patent Publication No. 61-1472
It is also known to develop nonlinearity by applying an electric field while heating a system in which π-electron conjugated molecules are added to a polymer film. Because they move, there is a problem in aligning the polarization directions of the molecules.

On the other hand, various proposals have been made to manufacture nonlinear optical elements using materials for nonlinear optical elements that can be patterned. (Unexamined Japanese Patent Publication No. 61-197630, No. 61-13713
Issues to be Solved by the Invention In any case, in order to put organic nonlinear optical materials into practical use, it is necessary to obtain a high 380 intensity without impairing large nonlinearity at the molecular level. However, in the prior art, there is no known simple, flexible and sufficient method for obtaining high 380 strength.

Furthermore, even in the case of making a nonlinear optical element by patterning, there is a problem in that a polymer resin with a special structure must be manufactured as a material for the nonlinear optical element that can be patterned.

The present invention was made against this background.

Therefore, the present invention has a π-electron conjugated chain in the molecule,
The present invention also provides a method for easily producing an organic nonlinear optical substrate having high S H0 intensity and a high optical damage threshold using an organic nonlinear optical material having an electron donating group and an electron accepting group at both ends of the molecule. be.

Means for Solving the Problem The present inventors homogenized a photocurable resin and an organic nonlinear optical material that has a π-electron conjugated chain in its molecule and has an electron donating group and an electron accepting group at both ends of the molecule. It has been shown that by mixing the materials and photocuring them under the application of an electric field, it is possible to suppress the generation of inversion symmetry, and it is possible to easily obtain an organic nonlinear optical substrate with high 380 intensity and a high photodamage threshold. This heading led to the completion of the present invention.

In the method for producing an organic nonlinear optical substrate of the present invention, π is present in the molecule.
A homogeneous mixture of an organic nonlinear optical material having an electron conjugated chain and an electron donating group and an electron accepting group at both ends of the molecule and a photocurable resin is cured by irradiating it with high energy rays while applying an electric field. It is characterized by

The present invention will be explained in detail below.

In the present invention, the organic nonlinear optical material having a π-electron conjugated chain in the molecule and having an electron donating group and an electron accepting group at both ends of the molecule is a compound represented by the following general formula (I).

D-π-A (I) (where π is benzene, naphthalene, anthracene,
Represents pyridine, biphenyl, pyridylbenzene, stilbene, diphenylacetylene, diphenyl diacetylene, azobenzene and derivative residues thereof, and D is
Represents an electron-donating amino group, dimethylamino group, pyrrolidino group, methoxy group, methyl group, and their substituents, and A represents an electron-accepting nitro group, cyano group, halogen atom, carbonyl group, and their substituents. Representative examples of organic nonlinear optical materials used in the present invention include p-nitroaniline, 2-methyl-4-nitroaniline, p-methoxynitrobenzene, ρ-aminobenzonitrile, p-nitrophenol, -dimethylaminobenzaldehyde, 4-nitro-4'-dimethylaminostilbene, 4-dimethylamino-4'-nitroazobenzene, 4-nitro-4'-dimethylaminodiphenyldiacetylene, 4-nitro-4'-dimethoxydiphenyldiacetylene Acetylene, 1-(4'-aminophenyl)-4
-(4”nitrophenyl)diacetylene, 2-(2-hydroxymethylpyrrolidino)-5-nitropyridine, 1
-pyrrolidino-2-acetamido-4-nitrobenzene and the like.

On the other hand, photocurable resins include unsaturated polyester resins, vinyl polymerized resins obtained from acrylic monomers using benzoin alkyl ethers as a surface starter, and addition polymerized resins made of allyl unsaturated resins and mercapto group-containing resins. Examples include ultraviolet curable resins such as epoxy ring-opening cationic polymerization type resins using Lewis acid catalysts and acid-curing amino alkyd type resins made of urea melamine resins and alkyd resins using mold resins and epoxy resins.

In the present invention, the organic nonlinear optical material and the photocurable resin are mixed at a mixing ratio of, for example, 1:20 to 1:10 to 1:5 to form a solid solution, and the mixture is applied with an electric field. The application is accompanied by ultraviolet light or other high-energy radiation. In this case, the mixture may be processed while being surrounded by a transparent conductive glass plate such as Nesa Glass, or
Alternatively, the treatment may be performed while being coated on a substrate.

The electric field can be applied either directly in contact with the homogeneous mixture or in a non-contact manner.For example, when processing is performed while the electric field is sandwiched between transparent conductive glass plates, A voltage can be applied directly through the transparent conductive glass plate, or if the coating is applied on the substrate, a corotron wire can be used to charge the thin film formed on the substrate in a non-contact manner. I can let you do it.

The voltage to be applied is preferably in the range of 1 V/am to 30 KV/am.

In addition to ultraviolet rays, lasers, electron beams, etc. can also be used as high-energy rays. The temperature for photocuring by irradiation with these high energy rays is -30 to +30
The temperature range of 0.degree. C. is preferred because no thermal motion of the molecules occurs upon heating, resulting in a product with high SHG strength.

The present invention can be applied to manufacturing a nonlinear optical element of an optical waveguide system. That is, the above-described mixture may be applied onto a substrate, the formed film may be cured by irradiating a pattern of high-energy rays while applying an electric field, and then the uncured portions may be removed by development.

Effect: Although the organic nonlinear optical material used in the present invention does not exhibit large molecular polarizability at the molecular level, the SHG intensity decreases in the crystalline state. However, according to the present invention, such an organic nonlinear optical material is homogeneously mixed with a photocurable resin, and an electric field is applied when this mixture is irradiated with high-energy rays. The inter-dipole-dipole interaction is canceled by the application of an electric field, and the dipoles of the molecule are photocured and fixed in alignment, resulting in an unprecedentedly high SHG intensity and no photodamage. The threshold value becomes high.

Examples Hereinafter, the present invention will be explained by examples.
These examples are not intended to be equally limiting.

Example 1 5 g of p-nitroaniline was added with 20 f of a polyol polyene type ultraviolet curable resin (ADEKA OPTOMER-BY9006, manufactured by Asahi Denka@J) and an exacerbating agent (Irgacure 651).
1 g (manufactured by Ciba Geigy) was added thereto, mixed and stirred, and the mixture was passed through a Teflon filter. The resulting mixture was processed using the cell shown in FIG. That is,
As shown in the drawing, the sample was injected into the sample holder 1 sandwiched between two Nesa glass plates 2.2', and the high voltage was Irradiation was performed for 2 minutes through the Nesa glass plate using a mercury lamp (Minicure, manufactured by Ushio Inc.). After that, the voltage application was stopped.

When a 1.064-chain Nd:YAG laser was transmitted through the obtained sample, the wavelengths of 0 and 5, which are the second harmonics, were transmitted.
32- green light was observed. When the intensity was measured using a photomultiplier tube, it was confirmed that the intensity was about five times that of urea.

Example 2 5 g of 4-nitro-4'-dimethylaminostilbene,
Acrylic modified epoxy resin (Beckpox VEM3
7/1, manufactured by Hoechst Japan) and 1 g of benzophenone as a sensitizer were added, mixed and stirred, and the mixture was passed through a Teflon filter. The obtained mixture was irradiated with ultraviolet rays in the same manner as in Example 1 while applying an electric field. When the second harmonic was measured for the obtained sample, green light with a wavelength of 0.532 Im was observed. When the intensity was measured using a photomultiplier tube, it was confirmed that the intensity was about three times that of urea.

Ratio example: 1 g each of ρ-nitroaniline and 4-nitro-4'-dimethylaminostilbene, thermosetting acrylic
Polyol resin (Rethane 4000, manufactured by Kansai Paint ■)
23.5. , and triisocyanate curing agent (
3.5 g of N3200 (manufactured by Kansai Paint ■) was dissolved in 73 g of methylene chloride and placed in a sample holder sandwiched between two Nesa glass plates. This was heated to a temperature of 115 to 130°C, and gradually cooled and cured while applying a voltage of 5000V. Example 1 for the obtained sample
When measurements were made in the same manner as in , no second harmonic was observed.

Effects of the Invention According to the present invention, the intermolecular dipole of an organic nonlinear optical material
The interaction of dipoles is canceled by the application of an electric field, and the dipoles of the molecules are photocured and fixed in alignment, resulting in a nonlinear SHG with unprecedentedly high strength and a high photodamage threshold. Optical substrates can be manufactured.

The nonlinear optical substrate produced according to the present invention has high sensitivity and excellent resolution to high-energy rays, and is made of an organic polymer solidified by crosslinking, so the nonlinear optical substrate has high nonlinearity as an organic nonlinear optical material. It has excellent mechanical strength and is less susceptible to photodamage while maintaining its properties.

Furthermore, the present invention can be applied to patterning, and an optical waveguide-based nonlinear optical element can be easily manufactured.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a cell used in an embodiment of the present invention. 1... Sample holder, 2.2'... Nesa glass plate,
3.3'...electrode.

Claims (1)

[Claims] (1) High energy while applying an electric field to a homogeneous mixture of a photocurable resin and an organic nonlinear optical material that has a π-electron conjugated chain in its molecule and has an electron donating group and an electron accepting group at both ends of the molecule. A method for producing an organic nonlinear optical substrate, characterized by curing it by irradiating it with radiation.