JPH02285329A - Nonlinear optical material - Google Patents

Abstract

PURPOSE:To convert the nonlinear optical material which can form crystals having no inversion symmetrical centers to a material active to a quadratic nonlinear optical effect by constituting the material of a specific N,N'- bis-(methoxycarbophenyl)-methane diamine deriv. CONSTITUTION:This material consists of the N,N'-bis-(methoxycarbophenyl)- methane diamine deriv. expressed by formula I. In the formula I, X denotes hydrogen or deuterium; Y denotes hydrogen, alkyl group, deuterium substd. alkyl group or group consisting of an electron-donating group; Z denotes hydrogen, deuterium, methyl group or deuterium substd. methyl group. The symmetricalness is lowered by connecting the amino methyl ester benzoate deriv. having the high tendency to form the crystals of the inversion symmetrical center for the purpose of a large bipolar moment by a methylene bond. The above-mentioned material is converted to the material active to the quadratic nonlinear optical effect in the wide wavelength region in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an organic nonlinear optical material that has a large supramolecular polarizability β and can form a crystal without a center of inversion symmetry.

[Prior art] Nonlinear optical effects are phenomena in which when extremely strong light passes through an object, the material is polarized by the electric field of the light, and this induced polarization generates optical harmonics and changes in the incident light itself. say.

Although this phenomenon was known before the invention of lasers, it has received much attention since the advent of laser light. In particular, optical harmonic generation, optical parallax, IJT oscillation and amplification, which have recently been attracting attention for application to optical functional devices,
The elucidation of phenomena such as optical phase conjugation and optical bistability owes much to the invention of the laser. These nonlinear optical effects can be applied to conversion of infrared light into visible light or ultraviolet light, optical amplification, optical switches, optical modulation, distortion-free transmission of optical signals, etc.

Nonlinear optical effect elements are positioned as functional materials that hold the key to the fields of optical information processing and optical communications, where demand will continue to increase in the future.

Conventionally, substances that exhibit nonlinear optical effects include, for example, potassium dihydrogen phosphate (KDP) and lithium niobate (L
iNbOs), β-barium borate (BBO), etc. have been studied, and some of them have been put into practical use as element materials. However, substances exhibiting nonlinear optical effects are not limited to inorganic dielectric compounds, but are also found among organic compounds. Moreover, the nonlinear optical action of organic compounds is caused by the movement of π electrons that are delocalized within the molecule, so the σ
Compared to electrons, the induced polarization is much faster and larger. In fact, 2
Methyl-4-nitroaniline (MNA) exhibits a figure of merit more than 2000 times that of lithium niobate (Il, F,
LEV・1NEet al, J, App! y, Phys.
, Vol. 50.2523 (1979)).

For this reason, research on the practical application of second-order nonlinear optical effects, especially optical second harmonic generation (SHG), which is expected to be applied as optical functional devices the earliest among nonlinear optical effects, is targeting organic compounds. For example, MNA (JP-A-55-500960), nitropyridine-1-oxide derivative (JP-A-56-92)
Substances such as those disclosed in Japanese Patent No. 870 and Publication No. 56-9433311) have already been proposed as nonlinear optical materials.

(Problem to be solved by the present invention) In organic compounds, in order to enhance the second-order nonlinear optical effect, it is sufficient to increase the dipole moment of the molecule. It is well known that introducing groups is effective.

However, important unresolved issues remain in this regard. In other words, it must be a crystal without a center of inversion symmetry. However, when organic compounds that have a large dipole moment in their molecules are arranged so that their dipole moments cancel each other out when they crystallize, the molecules have a large second-order supramolecular polarizability β but are crystallized or As a molecular assembly, it may not exhibit second-order nonlinear optical effects because it has a center of inversion symmetry. In fact, there are a large number of such organic compounds.

Therefore, when developing an organic nonlinear optical material that focuses on second-order nonlinear optical effects, it is necessary to develop a compound that has a large supramolecular polarizability β as a molecule and from which high-quality crystals with no center of inversion symmetry can be easily obtained. Synthesis is an important issue.

4-Nitroaniline is the simplest aromatic compound with an electron-donating group and an electron-withdrawing group, and is one of the compounds that has a large supramolecular polarizability β among organic compounds.
The crystal has a center of inversion symmetry because the molecules are arranged so that their dipole moments cancel each other out, and it does not exhibit second-order nonlinear optical effects. Also, due to intramolecular charge transfer by nitro groups and amine groups, Large electronic transition absorption exists in the near-ultraviolet to visible range. For this reason, 4-nitroaniline is colored extremely yellow.

The present inventors have conducted intensive studies on improving the symmetry and transparency of aromatic compounds such as 4-nitroaniline, which have an electron-withdrawing group and an electron-donating group at the rose position of the benzene ring. The present invention was developed after confirming that certain benzoic acid derivatives do not have centers of inversion symmetry when they form crystals or molecular aggregates, and that they can significantly improve transparency in the near-ultraviolet to visible range. It is something that

The purpose of the present invention is to further expand the wavelength range by using a nonlinear optical material that has a large supramolecular polarizability β derived from amine benzoic acid with an intramolecular charge transfer structure and is capable of forming crystals without an inversion center of symmetry. In order to achieve this goal, we provide a nonlinear optical material whose cutoff wavelength is shortened.

(Means for Solving the Problems) A nonlinear optical material according to the present invention for achieving the above object is represented by the following chemical formula. It is characterized in that it is composed of an N,N-bis-(methoxycarbonylphenyl)-methanediamine derivative.

lI Z Z
IIo
0 However, in the above formula, X is hydrogen or deuterium, Y
is one or more groups selected from the group consisting of hydrogen, an alkyl group, a deuterium-substituted alkyl group, or an electron-donating group; Z is hydrogen, deuterium, a methyl group, or a deuterium-substituted methyl group; shall point.

Regarding the positions of the substituents, the ester group is substituted at the 4-position of the phenyl group, and the alkyl group, deuterium-substituted alkyl group, or electron-donating group constituting Y is substituted at the 2-position of the phenyl group. preferable.

Examples of the alkyl group constituting Y include a methyl group and an ethyl group, and examples of the electron-donating group include a methoxy group and a dimethylamino group. The most preferred Y component is a methyl group, a methoxy group, or a deuterium-substituted methyl or methoxy group.

The above chemical formula 〇N,N'-bis-(methoxycarbonylphenyl)-methanediamine derivative can be obtained by, for example, reacting the corresponding amine methyl benzoate derivative with formaldehyde after selecting the reaction solvent and the pH of the reaction solution. You can get it by doing this.

Methyl amine benzoate derivatives include methyl 4-aminobenzoate, methyl 3-aminobenzoate, methyl 3-methyl-4-aminobenzoate, methyl 3-methoxy-4-aminobenzoate, 5-methyl-3-amino Methyl benzoate, N
-methyl-4-methoxycarbonylaniline, methyl 3-chloro-4-aminobenzoate, and the like. These have high solubility: methanol, ethanol, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran,
React with formaldehyde using dimethylformamide as a solvent.

The obtained N,N'-bis-methoxycarbonylphenyl)-methanediamine derivative was powdered in Nd:Y
When irradiated with AG laser (λ = 101064n), it generates an extremely strong green second harmonic.Furthermore, in the single crystal state, it is possible to phase match over a wide range, and the second harmonic has an intensity that far exceeds that of powder. occurs.

Generally, the propagation constants of the fundamental wave and harmonics in a crystal do not match, so it is difficult to generate harmonics in the crystal state. This failure is called phase matching, and unless this phase matching is achieved, it is not possible to observe the generation of harmonics.

In addition, it is white in powder state and colorless and transparent in single crystal state.
The cutoff wavelength is significantly shifted by a single wavelength.

If the fundamental wave is infrared light of 1-1.2 tt-, the fundamental wave may be absorbed overlapping with the overtone absorption of the C-H stretching vibration and converted into thermal vibration. Therefore, when the intensity of the fundamental wave is strong, the temperature of the crystal increases and the phase matching conditions change.
The angle of the emitted light changes.

In the present invention, if a compound form is adopted in which the hydrogen of an alkyl group with particularly large overtone absorption is replaced with deuterium, the absorption region shifts to the longer wavelength side, and this phenomenon can be effectively prevented.

[Function] According to the present invention, aminobenzoic acid methyl ester derivatives, which have a strong tendency to form crystals with a center of inversion symmetry due to their large dipole moment, are connected with methylene bonds to reduce the symmetry, thereby making it possible to reduce the symmetry in a wide wavelength range. It is possible to provide a nonlinear optical material with novel physical properties that is converted into a material that is active against second-order nonlinear optical effects.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

Example 1 Methyl 4-aminobenzoate 7.56 g (50 mmol)
is dissolved in methanol 100m+, and formaldehyde (37χ) dissolved in water is added to this solution. & tog was diluted with 20 ml of methanol, and the mixture was stirred and reacted at room temperature for 3 hours. After the reaction was completed, the concentrated and precipitated reaction product was poured, washed three times with 20 ml of methanol, and dried at 50°C under reduced pressure to obtain NN'-bis-(4-methoxycarbonylphenyl)-methanediamine. Ta.

The cutoff wavelength of this N,N'-bis-(4-methoxycarbonylphenyl)-methanediamine was measured and was found to be 3300 nm.

Examples 2 to 8 Various N, N'-bis-(methoxycarbonylphenyl) in which X is hydrogen and Y and Z are different according to the above production method
-Methanediamine derivative was synthesized.

A sample of each of the above derivatives prepared to a particle size of 60-10 On was sandwiched between slide glasses, and a Q-switched Na:Y
10nSec by AG laser (λ” 101064n)
The intensity of the second harmonic generated by the sample was measured. The SHG intensity was expressed as a relative intensity ratio with urea as 1. The results are shown in Table 1.

Table 1 Examples 9 to 12 Deuterium-substituted N,N'-bis-(methoxycarbonylphenyl)-methanediamine derivatives using heavy formaldehyde instead of formaldehyde and heavy methanol instead of methanol in Example 1 was synthesized.

For each of these derivatives, SH
O was measured. The results are calculated based on the compound form of the sample used (
Table 2 shows a comparison of the substitution components of X, Y, and Z.

Table 2 [Effects of the Invention] As described above, the nonlinear optical material of the present invention comprising an N,N'-bis-(methoxycarbonylphenyl)-methanediamine derivative has a starting material that is SHO
Although it has no or very weak activity, it shows higher SHO efficiency than urea, and depending on the form of the compound, it shows more than 50 times the SHO efficiency.

Furthermore, existing nonlinear materials such as MNA that have a large nonlinear optical effect generally have a cutoff wavelength that extends to a long wavelength range (MNA: 480rv+), and are suitable for use as nonlinear optical materials, especially wavelength conversion materials. is narrowing down. Since the N,N'-bis-(methoxycarbonylphenyl)-methanediamine derivative according to the present invention has a cutoff wavelength of 33 Onm, it can be used in a wide wavelength range.

Therefore, various uses can be expected in a wide wavelength range as materials for various optical functional devices that utilize nonlinear optical effects and electro-optic effects, such as wavelength conversion devices and light control devices.

Applicant: Miya 1) Kiyoshi Kura (3 others) Agent: Patent Attorney Masaya Takahata

Claims (1)

[Scope of Claims] 1. A nonlinear optical material comprising an N,N'-bis-(methoxycarbonylphenyl)-methanediamine derivative represented by the following chemical formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ However, in the above formula, X is hydrogen or deuterium, and Y is 1 selected from the group consisting of hydrogen, an alkyl group, a deuterium-substituted alkyl group, or an electron-donating group. species or groups,
Z refers to hydrogen, deuterium, a methyl group, or a deuterium-substituted methyl group. 2. The nonlinear optical material according to claim 1, wherein the group Y in the chemical formula is a methyl group or a deuterium-substituted methyl group. 3. The nonlinear optical material according to claim 1, wherein the group Y in the chemical formula is a methoxy group or a deuterium-substituted methoxy group.