JPH04223449A - Nonlinear optical material - Google Patents

Abstract

PURPOSE:To improve nonlinear optical, performance by using 2,6-dibromo-N,N- dimethyl-4-nitroaniline. CONSTITUTION:2,6-Dibromo-N,N-dimethyl-4-nitroaniline represented by formula I is used. This compd. has a nitro group as an acceptor group and a dimethylamino group as a donor group in the structure. Since the acceptor and donor groups are separated by a benzene ring, large dipole moment especially in an excited state is obtd. and high nonlinear sensitivity is ensured. Since two Br atoms are introduced, the compd. has low sublimability.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to optical parametric oscillation,
This paper relates to new nonlinear optical materials that are important in optical signal processing systems such as harmonic generation and optical switching.

0002

[Prior Art] Nonlinear optical materials, which are expected to play an important role in optical communication technology, exhibit functions such as optical mixing, parametric oscillation, harmonic generation, and switching based on the nonlinear optical responsiveness of the material. , conventionally, KH2PO4
, NH4H2PO4, etc. have been used. However, these materials do not meet the requirements of the aforementioned applications due to their deliquescent nature, low nonlinear susceptibility and low failure threshold. Organic nonlinear optical materials that utilize the polarization of the π-electron system have been widely researched and developed in various fields because of their superior nonlinear optical constants, which are larger than inorganic materials, and which are generally non-deliquescent and have a high destruction threshold. ing. Regarding recent achievements, for example, “Nonlinear Optical Properties of Organic Molecules and Crystals”
al Properties of Organ
ic Molecules and Crystal
als)” Vol. 1 and Vol. 2,D. S. Che
mla, J. Zyss edition (1987 Academ
(published by IC Press).

However, no material has been found that has a nonlinear optical constant large enough to achieve the purpose with a low-output laser such as a semiconductor laser, and there is a strong need for the development of new materials. .

0004

SUMMARY OF THE INVENTION The present invention provides a novel organic nonlinear optical material having a high nonlinear optical constant.

[0005]

[Means for Solving the Problems] The present invention comprises a nonlinear optical material comprising 2,6-dibromo-N,N-dimethyl-4-nitroaniline represented by formula (I) and a composition containing this compound. Concerning nonlinear optical materials.

[Case 2]

2,6-dibromo-N,N-dimethyl-4-nitroaniline used in the present invention can be obtained, for example, by reacting N,N-dimethyl-p-nitroaniline with bromine. 2,6-dibromo-N,N-dimethyl-4-nitroaniline can be obtained using a solution method (solvent distillation method, temperature drop method, etc.) from an organic solvent such as acetone.
It can be used in the form of a single crystal obtained by a melt method (Bridgeman method, Czochlaski method, etc.).

The nonlinear optical material of the present invention is a composition in which 2,6-dibromo-N,N-dimethyl-4-nitroaniline represented by the above formula (I) is dispersed or dissolved in a polymer compound. It may be. Examples of polymer compounds include methyl (meth)acrylate (representing methacrylate or acrylate; the same applies hereinafter), ethyl (meth)acrylate, n-butyl (meth)acrylate,
Cyclohexyl (meth)acrylate, (meth)acrylic acid, styrene, vinyltoluene, divinylbenzene,
Homopolymers or copolymers of monomers such as vinyl chloride and β-hydroxyethyl (meth)acrylate, polyesters, polyamides, polyurethanes, polycarbonates, cellulose esters, polyethers, etc. are used. A composition may be obtained by mixing 2,6-dibromo-N,N-dimethyl-4-nitroaniline represented by formula (I) and a corresponding monomer and then polymerizing it by the action of heat or light. High molecular compound and 2,6- represented by formula (I)
The composition may be obtained by dissolving and mixing dibromo-N,N-dimethyl-4-nitroaniline using an appropriate solvent and then removing the solvent. In the former case, the nonlinear optical performance can be improved by performing poling during polymerization, or in both the former and latter cases, by performing poling after obtaining the composition. Alternatively, 2,6-dibromo-N,N-dimethyl-4-nitroaniline represented by the above formula (I) is heated to a temperature higher than the melting point in the presence of a DC electric field to melt it, and then gradually heated while maintaining the electric field. By cooling or quenching, it is also possible to obtain a single crystal or molecular glass with high nonlinear optical performance in which the direction of molecular orientation is controlled.

[0008]

[Operation] The compound of the present invention has a nitro group as an acceptor group and a dimethylamino group as a donor group in its structure, and the acceptor group and donor group are separated by a benzene ring, resulting in a large dipole moment (especially A high nonlinear susceptibility is obtained because the excited state dipole moment is obtained. Furthermore, the disadvantage of high sublimation, which was a problem with conventional 2-methyl-4-nitroaniline, can be suppressed by introducing two bromine atoms.

[0009]

EXAMPLES The nonlinear optical material of the present invention will be explained by way of examples. Synthesis of 2,6-dibromo-N,N-dimethyl-4-nitroaniline 19.96 g (78 mmol) of commercially available N,N-dimethyl-p-nitroaniline (Tokyo Kasei) was placed in a 300 ml eggplant-shaped flask, and 100 ml of After adding 25 g (156 mmol) of acetic acid, the temperature was maintained at 65° C. and 25 g (156 mmol) of bromine was slowly added dropwise while stirring well. The dropwise addition took about 5 hours, and heating and stirring were continued for an additional hour. When the reaction mixture was poured into 2 liters of ice-cold water, a yellow precipitate formed, which was filtered off, washed several times with water, and then dried in a vacuum desiccator. The obtained crude crystals were recrystallized from methanol. The structure of the product was confirmed by nmr etc. When the absorption spectrum of this product was measured in methylene chloride, the absorption maximum was 370.6 nm. Since the absorption maximum of N,N-dimethyl-p-nitroaniline is 394.2 nm, the wavelength is shortened by about 14 nm by dibromination.

The second harmonic generation of 2,6 dibromo-N,N-dimethyl-4-nitroaniline obtained according to the above synthesis method was investigated by a powder method. An overview of the powder method can be found in the ``Journal of Applied Physics'' (Jou
rnal of Applied Physics
s) Vol. 36 (1968), pp. 3798-3813. Particle size 100μm~125μm
The classified sample powder was placed between non-fluorescent glass slides (made by Matsunami Glass), and a pulsed Nd:YAG laser (Model SL303, output 850) made by Spectro Laser System was used.
mJ, half width 15ns, output per pulse 50MW,
Light was irradiated with a beam diameter of 9.5 mm, a wavelength of 1.064 μm, and a repetition frequency of 10 Hz). The intensity of the generated second high frequency wave of 532 nm was measured with a photomultiplier tube through an infrared filter and a UV filter, and the result was that it was 35 times that of urea, 2-
It was 1.6 times that of methyl-4-nitroaniline.

[0011]

[Effects of the Invention] The nonlinear optical material of the present invention has excellent nonlinear optical performance.

Claims (2)

[Claims] 1. A nonlinear optical material comprising 2,6-dibromo-N,N-dimethyl-4-nitroaniline represented by formula (I). [Chemical formula 1] [Claim 2] 2 represented by the formula (I) according to Claim 1
, 6-dibromo-N,N-dimethyl-4-nitroaniline.