JPH06130435A - Organic nonlinear optical material - Google Patents

Abstract

PURPOSE:To provide a nonlinear optical material which excels in transparency and crystalinity and which presents an SHG efficiency several times as great as that of urea. CONSTITUTION:An organic nonlinear optical material consists of carboxylic acid optically active amine salt prepared from amino-carboxylic acid as at least one of three compounds given by Formulas I-III and an optical by active organic amine as at least one of three compounds given by Formulas IV-VI.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel organic nonlinear optical material.

[0002]

2. Description of the Related Art Non-linear optical materials cause phenomena such as frequency exchange, amplification, start-up, and switching of laser light.
It can be applied to harmonic generation (SHG), third harmonic generation (THG), high-speed shutter, optical memory, optical operation element, and the like.

As described above, the non-linear optical material has a function of converting the optical frequency and can be applied to an optical switch or the like which makes the best use of the characteristic that the refractive index is changed by an electric field. Research is ongoing.

Since the origin of the nonlinearity is intramolecular π-electrons in the organic nonlinear optical material, lattice vibration is not accompanied with the optical response, and therefore the response is faster than that of the inorganic nonlinear optical material.
Further, it is possible to synthesize a material having a large non-linear optical constant or a material having a variable absorption region. Moreover, the method of forming the material element is not limited to single crystallization, and various methods such as an LB film, a vapor deposition method, a liquid crystal, and a polymer can be considered.

Regarding research on these non-linear optical materials, for example, "Nonlinear Optical P
properties of Organic Mole
cules and Crystals Vo1. I
And Vol. II ”D. S. CHEMLA, J .; Z
Edited by YSS (Academic Press, 1987)
The latest research status is summarized in the literatures such as "Annual Nonlinear Optical Material" by Shinsuke Umegaki (Bunshin Publishing Co., Ltd., 1990).

Among the nonlinear optical effects required as a nonlinear optical material, the second harmonic generation (SHG) is particularly positioned as a basic technique for wavelength conversion, and the nonlinear optical constant of the nonlinear optical constant is used to efficiently cause SHG. Large materials are required.

As described in detail in the above-mentioned document, in order to exhibit SHG activity in an organic nonlinear optical material, the crystal has no symmetry center, that is, the arrangement of molecules in the crystal has inversion symmetry. It is necessary not to occur.

Recently, as such an organic nonlinear optical material, as described in JP-A-2-135427, a carboxylic acid optically active amine salt obtained from a carboxylic acid containing an allyl group and an optically active organic amine is known. ing.

[0009]

However, the carboxylic acid optically active amine salt containing an allyl group has a problem that it is inferior in light transparency. In particular, there is a problem that the transparency for light of a short wavelength is poor.

That is, in order to efficiently convert the frequency of light, it is necessary that the incident light and the converted light pass through the nonlinear optical material efficiently without being absorbed. In other words, it is necessary that the incident light and the converted light have good transparency. However, organic compounds generally have poor transparency to short light, and thus often the converted light is absorbed. The carboxylic acid optically active amine salt containing the above allyl group is one of them.

Therefore, as a result of various studies, the present inventor found that
The present inventors have found that such a problem can be solved by using a carboxylic acid containing a pyridine group instead of using a carboxylic acid containing an allyl group, and have completed the present invention.

That is, the object of the present invention is that it has no inversion symmetry, has a non-linear optical effect, is excellent in transparency, which is a requirement for a wavelength conversion material, and further has crystallinity, thermal and chemical properties. It is to provide a material having excellent thermal stability.

[0013]

The present invention has been made to solve the above problems and achieve the above objects.
At least one type of aminopyridinecarboxylic acid selected from the three types of compounds represented by the following (1), (2), and (3), and three types of compounds represented by the following (4), (5), and (6) And an optically active amine salt of a carboxylic acid obtained from at least one optically active organic amine selected from the following.

[0014]

[Chemical 2]

[0015]

The three kinds of aminopyridinecarboxylic acid represented by the above (1), (2) and (3) have excellent transparency and have a relatively large nonlinear susceptibility β as compared with conventional nonlinear optical materials. , Forms a crystal with central symmetry, and the crystal has no nonlinear effect.

Therefore, these three kinds of aminopyridinecarboxylic acids are used as the three kinds of optically active organic amines represented by the above (4), (5) and (6), which have optical activity without having a symmetry center in the molecule itself. By reacting to form a salt, the inversion symmetry of the crystal was canceled and the nonlinearity came to appear.

Therefore, these compounds are excellent non-linear optical materials because they have excellent crystallinity and SHG efficiency several times that of urea. Furthermore, the wavelength is 20 nm shorter than that of the conventional benzene derivative, and it can be said that the material has excellent transparency.

Further, these crystals are thermally stable and are not easily damaged by light, and since they are salts, they have high hardness and are easy to process. Therefore, it can be easily made into a device. The compound of the present invention can be used as a nonlinear optical material in various forms such as powder, single crystal and solution.

[0019]

EXAMPLES Next, the present invention will be specifically described with reference to examples, but it goes without saying that the present invention is not limited to these examples.

(Examples 1 to 3) (Preparation of salt and evaluation of SHG efficiency) Aminopyridinecarboxylic acid of three kinds of compounds represented by the following (1), (2) and (3) shown in Table 1 (Table In 1 referred to as pyridines)
10 mmol are each dissolved in 20 ml of methanol.

[0021]

[Chemical 3]

15 mmol of three kinds of optically active organic amines (referred to as amines in Table 1) represented by the following (4), (5) and (6) are added to the aminopyridinecarboxylic acid solution.
Are added so that the combinations shown in Table 1 are obtained, and the mixture is refluxed for 2 hours. When this solution is cooled to an appropriate temperature, salt precipitates.

[0023]

[Chemical 4]

Further, finely divided powder crystals of the salt obtained were mixed with Nb: Y.
AG laser (wavelength = 1.064 μm, output 10 mJ /
When pulsed), the second harmonic is generated (SHG)
However, green light having a wavelength (532 nm) that is half that of the incident light could be observed. The measurement results are shown in Table 1.

[0025]

[Table 1]

These crystals were stable at room temperature, had excellent transparency, and showed no optical damage.

[0027]

As described above, the organic nonlinear optical material of the present invention has high SHG efficiency and excellent transparency.

Further, the organic nonlinear optical material of the present invention is extremely important in practical use because it has excellent crystallinity and good workability.

Claims (1)

[Claims] 1. At least one aminopyridinecarboxylic acid selected from the three compounds represented by the following (1), (2) and (3) and represented by the following (4), (5) and (6): An organic non-linear optical material comprising a carboxylic acid optically active amine salt obtained from at least one optically active organic amine selected from the above three compounds. [Chemical 1]