JPH0660984B2 - Organic nonlinear optical material - Google Patents

Description

The present invention relates to an organic nonlinear optical material useful as a material for a nonlinear optical element such as an optical bistable element.

[Conventional technology]

The third-order nonlinear optical material is used for the third harmonic generation (hereinafter, TH
In addition to having a frequency conversion function by abbreviated as G), it can be applied to optical switches and optical memories using the optical bistable phenomenon.
Active research and development is underway. Among them, organic nonlinear optical materials have (1) larger nonlinear optical constants than inorganic ferroelectric crystals such as KDP / LiNbO ₃ , (2) faster response speed than inorganic semiconductors such as gallium-arsenic,
(3) High-speed response · Room temperature operation has been confirmed. It is difficult to make thin films of the μm order, which is difficult with cuprous chloride (CuCl). There is a possibility of doing so, and active material search is underway.

At present, organic non-linear optical materials having a large third-order effect are polydiacetylene [particularly, PTS: 2,4-hexadiyne-1,6-bis (p-toluenesulfonate)], a π-conjugated polymer system represented by polyacetylene. And aminonitrostilbene (particularly, DEANS: N, N-diethyl-4-amino-4′-nitrostilbene), which is a low molecular weight system in which a donor / acceptor is asymmetrically substituted.

Since the non-linearity of the π-conjugated polymer system in [Problems to be solved by the invention] is rooted in the polarization of free electrons in the valence band, it is based on a drawback very similar to that of an inorganic semiconductor, that is, a narrow band gap. It cannot escape from the decrease in response speed due to the resonance effect. A donor-acceptor asymmetrically substituted small molecule system is currently in use (DEA
If it is attempted to increase the effect more than NS), the same drawback as in (1) is exposed due to the lengthening of the absorption band due to intramolecular charge transfer. Further, some of the crystals having an asymmetric center structure cause a problem in the reliability of nonlinear operation due to the mixing of secondary effects.

The object of the present invention is to overcome the above-mentioned drawbacks of the prior art,
An object of the present invention is to provide an organic nonlinear optical material exhibiting highly efficient optical non-linear response.

[Means for solving problems]

Briefly describing the present invention, the present invention relates to an organic nonlinear optical material, which is represented by the following general formula I: (Wherein D represents an electron-donating group).

The main characteristic of the organic nonlinear optical material according to the present invention is that it suppresses the absorption of a longer wavelength to prevent the response speed from lowering, and also has a larger third-order nonlinear optical effect than ever before. This is due to the disadvantage of the conventional technique that, when an attempt is made to increase the non-linear optical effect, the absorption wavelength becomes longer due to the expansion of π conjugation and the increase of charge transfer. -Aniline: TB
This is solved by symmetrically substituting a polarizing group having a strong donor property at both ends of the molecule A).

The organic nonlinear optical material of the present invention has a small polarization in the ground state and has a symmetric center structure in the excited electron cloud, unlike a small molecule system in which a donor / acceptor is asymmetrically substituted, which has been reported in the past. It is characterized by taking. Therefore, since the organic nonlinear optical material of the present invention is essentially a material that does not exhibit the second-order nonlinear optical effect, the operation of the nonlinear optical element may be affected by the mixture of the second-order nonlinear optical effect. I do not receive it.

The organic nonlinear optical material of the present invention is represented by the above general formula I.

Here, the group D is typically an amino group, a mono- or dialkylamino group, and a mono- or di (hydroxyalkyl) amino group.

For example, in the case where the donor (D) is a dialkylamino group, the diethylamino group and the dimethylamino group are more excellent in the donor property, and the diethylamino group, which easily takes a plane conjugated structure, exhibits a larger nonlinear optical effect. Furthermore,
Due to the increased flexibility, it has a high solubility and a melting point suitable for melt crystallization. The solubility is further improved by using an ethyl-hydroxyethylamino group donor. D-dimethylamino group material is DM-TBA, donor D is diethylamino group material is DE-TBA, D is ethylene-
The hydroxyethylamino group material is abbreviated as EOE-TBA.

The production examples of the compound represented by the general formula I are shown below, but the invention is not limited thereto.

Production Example 1, Synthesis of DE-TBA N, N-diethyl-p-phenylenediamine (3.6
g, 22 mmol of benzene-ethanol (1: 1) solution, terephthalaldehyde (1.3 g, 10 mmol of ethanol solution and catalytic amount of benzenesulfonic acid were added,
Stir at room temperature for 1 hour. Furthermore, on an oil bath for 3 hours,
Heated to reflux. The reaction solution was cooled to room temperature to completely precipitate the product, which was collected by filtration and sufficiently washed with cold ethanol. Recrystallization was performed using a mixed solvent of methylcyclohexane: o-dichlorobenzene (1: 1) to obtain orange scaly crystals (2.6 g). Melting point: 227 ° C. FIG. 1 shows the UV-VIS spectrum of the melt-crystallized thin film. That is, FIG. 1 shows an organic nonlinear optical material according to the present invention: DE-T.
It is the graph which showed the UV-VIS spectrum of the melt-crystallized thin film of BA with the relationship of wavelength (nm, abscissa) and light absorbency (arbitrary unit, ordinate). As is clear from FIG. 1, the thin film has no absorption in the long wavelength region (about 700 nm or more).

Production Example 2, Synthesis of DM-TBA N, N-dimethyl-p-phenylenediamine (3.0
g, 22 mmol) in ethanol solution, terephthalaldehyde (1.3 g, 10 mmol) in ethanol solution and catalytic amount of benzenesulfonic acid were added, and stirred at room temperature for 1 hour. Furthermore, the mixture was heated under reflux on an oil bath for 3 hours. The precipitate was collected by filtration, washed thoroughly with cold ethanol, and recrystallized from o-dichlorobenzene to obtain orange crystals (2.2 g). Melting point: 300 ° C or higher.

Production Example 3, Synthesis of EOE-TBA Sulfuric acid-4-amino-N- (β-hydroxyethyl) -N
-Ethylaniline (9.3 g, 33 mmol) was added to an ethanol-water (1: 1) solution, and an aqueous solution of sodium hydroxide was added to the solution to make it weakly acidic to give a homogeneous solution. The ethanol solution of 1) was added, and the mixture was heated under reflux for 3 hours at room temperature and further for 1 hour on an oil bath. The reaction solution was cooled to room temperature to precipitate a product, which was collected by filtration and thoroughly washed with a cold ethanol-water (1: 4) mixed medium and cold water. The crude crystals obtained were ethanol-
Recrystallized from water (1: 1) mixed solvent, orange crystals 5.5 g
Got Melting point 113-115 [deg.] C.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

Examples 1 to 3 Nonlinear optical characteristics of the compounds obtained in Production Examples 1 to 3 were measured.

The method of THG measurement is as described below. Nd: YAG laser (wavelength 1.06 μm, 10H
z, 50 MW / cm ² ) and cut visible light, irradiate the sample with the beam condensed by the lens, and let the light emitted from the sample pass through a monochromator to produce THG light (0.35
The intensity of only (μm) was detected by Photomal. The measurement sample is
DM-TBA, DE-TBA, EOE-TBA 105
What was pulverized to a particle size of 120 μm was used. Furthermore, the THG light observed is urea or MNA (2-methyl-4-).
Recognize that the effect is purely the third-order effect, not the second-order cascade effect [Nitroaniline] [generation of 3ω by the sum frequency of the fundamental wave (ω) and the second harmonic (2ω)]. Therefore, the second harmonic generation (hereinafter abbreviated as SHG) of the same sample was also measured. The results are shown in Table 1 below. As comparative data, the results of urea, MNA and DEANS are also shown.

As described above, the organic nonlinear optical material of the present invention is
Since it has a larger third-order nonlinear optical effect than ever before, it can be used as a central material for future optical integrated devices for optical communication, such as optical devices using this, such as optical bistable devices, optical switches, and optical memories.

[Brief description of drawings]

FIG. 1 shows an organic nonlinear optical material according to the present invention: DE-T
It is a UV-VIS spectrum figure of the melt-crystallized thin film of BA.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shiro Matsumoto, Tokai-mura, Naka-gun, Ibaraki 162 Shirahane, Shirahata, Nippon Telegraph and Telephone Corporation Ibaraki Telecommunications Research Institute (72) Inventor Tetsuya Goto Otsu, Shiga Prefecture 1-11 Sonoyama Toray Co., Ltd. Shiga Plant (72) Inventor Keiichi Egawa 1-1-1 Sonoyama, Otsu City, Shiga Toray Co. Ltd. Shiga Plant (56) Reference JP 61-78748 (JP, A)

Claims (4)

[Claims] 1. The following general formula I: (However, D shows an electron-donating group), The organic nonlinear optical material characterized by the above-mentioned. 2. The organic nonlinear optical material according to claim 1, wherein the group D is an amino group. 3. The organic nonlinear optical material according to claim 1 or 2, wherein the group D is a mono- or dialkylamino group. 4. The organic nonlinear optical material according to claim 1 or 2, wherein the group D is a mono- or di (hydroxyalkyl) amino group.