JPH03142419A - Nonlinear optical element - Google Patents

Abstract

PURPOSE:To obtain a nonlinear optical element having a significant nonlinear optical effect and superior durability by using a naphthalenone compd. having a compsn. represented by a prescribed formula. CONSTITUTION:An org. nonlinear optical element is made of a naphthalenone compd. represented by formula 1, wherein each of R<1>-R<7> is a substituent selected among H, a 1-20C aliphat., alicyclic or arom. group, acyl, amino, cyano, nitro, azo and halogen. Since the naphthalenone compd. has a significant nonlinear optical effect, superior suitability to crystal growth and superior durability, the org. nonlinear optical element is adaptable to various uses applying a nonlinear optical effect.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an organic nonlinear optical element used in the field of optoelectronics such as optical information processing and optical communication.

(Prior Art) In recent years, materials that have nonlinear optical effects (such as development in which when a substance is irradiated with laser light, an emitted light having a different component from the incident light is obtained due to the interaction) have been attracting attention.

Such materials are commonly known as nonlinear optical materials. A nonlinear optical material refers to a material that has a so-called nonlinear optical effect, in which the induced polarization of electrons induced by the interaction between a substance and an electric field of light produces a nonlinear response to the electric field, and is generally expressed by the following equation. This is caused by more than the second-order term.

P=χIll E+χ(21E・E+χ"'EE-E-E
+・・・−・・・(In the formula, P is the polarizability of the substance, E is the electric field,
(χ(0) represents the nth-order nonlinear susceptibility) According to a phenomenon known as second harmonic generation (SHG), which utilizes the second-order effect in particular, the incident light is the second harmonic 2 It becomes a light wave with twice the frequency. Also, the refractive index changes depending on the voltage. These are, for example, rNon
1iner OpticalProperties
of Organic and Polymeric
MaterialsJ ACS, SXMPOSIU
M 5ERIES 233. David J.

Williams (ed., ACS, 1983); "Organic Nonlinear Optical Materials", edited by Masao Kato and Hebe Nakanishi (CMC, published in 1985), etc.

One of the applications of nonlinear optical materials is second harmonic generation based on second-order nonlinear optical effects, and wavelength conversion devices using sum frequency and difference frequency.

It plays an extremely important role in optical signal processing.

So far, the material that has been practically used for such nonlinear optical elements is potassium dihydrogen phosphate (KD
P): Inorganic ferroelectric crystals such as lithium niobate (LiNbO-) are known.

However, in recent years, it has become known that conjugated benzene derivatives having an electron-donating group and an electron-withdrawing group have various performances as nonlinear optical materials that far exceed those of the above-mentioned inorganic crystals.

An important point of such organic conjugated systems is that the cause of nonlinear optical effects is the polarization of the π-electron cloud and strong intermolecular interactions, unlike the displacement or rearrangement of nuclear coordinates found in inorganic materials.

Organic materials that exhibit such nonlinear optical effects are required to have a π-electron conjugated system in their molecules and a high degree of intramolecular charge transfer, but they also need to have no inversion symmetry in their crystals. It becomes a requirement. For example, although p-nitroaniline or dimethylaminonitrostilbene have a high molecular polarizability, they have inversion symmetry in the crystalline state, so no second harmonic generation is observed.

In consideration of these points, various compounds having structures capable of suppressing the inversion symmetry of crystals have been proposed as organic materials having nonlinear optical effects. For example, 2-methyl-4
-Nitroaniline (MNA) has inversion symmetry p-
It has a structure in which a methyl group is bonded to the ortho position of nitroaniline, and the effect of this methyl group suppresses inversion symmetry, resulting in large second harmonic generation.

(Problem to be solved by the invention) However, there are no organic nonlinear optical materials such as crystals or thin films that do not have inversion symmetry in the bulk state, and have an absorption maximum on the short wavelength side, and at the same time have large nonlinear optical properties of molecules. At present, there is a strong desire to find organic materials that meet these conditions and apply them to nonlinear optical elements.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, an object of the present invention is to provide a nonlinear optical element using an organic nonlinear optical material that has no inversion symmetry and has a large nonlinear optical effect.

(Means for Solving the Problems) As a result of intensive research, the present inventors have solved the above problems and achieved the present invention.

That is, the nonlinear optical element of the present invention has the following general formula (1) (wherein, R1 to R7 may be the same or different, a hydrogen atom, an aliphatic group having 1 to 20 carbon atoms, an alicyclic group, or It is characterized by consisting of a naphthalenone compound represented by a substituent selected from an aromatic group, an acyl group, an amino group, a cyano group, a nitro group, an azo group, and a halogen atom.

In R'-R' in the general formula (1) of the present invention, examples of the aliphatic group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, undecyl, and heptadecyl; Haloalkyl groups such as propyl; hydroxyalkyl groups such as 2-hydroxyethyl and 3-hydroxypropyl; benzyl, 2-
Arylalkyl groups such as phenylethyl: methoxy,
Alkoxy groups such as ethoxy and butoxy: methylthio,
Alkylthio groups such as ethylthio; alkoxycarbonyl groups such as methoxycarbonyl, ethoxycarbonyl, and butoxycarbonyl; and the like.

Examples of the alicyclic group include cycloalkyl groups such as cyclohexyl; and cycloalkyl groups such as cyclohexenyl.

Aromatic groups include phenyl, tolyl, xylyl, 4-
Aryl groups such as t-butylphenyl, 4-aminophenyl, 4-nitrophenyl, 4-methoxyphenyl, 4-cyanophenyl, naphthyl: phenoxy, 4-t-butylphenoxy, 4-aminophenoxy, 4-nitrophenoxy, etc. Aryloxy group: Examples include arylthio groups such as phenylthio and tolylthio.

Examples of the acyl group include alkanoyl groups such as acetyl, propionyl, hexanoyl, and undecanoyl, and aroyl groups such as benzoyl.

As an amino group, unsubstituted amino: carbon WX such as methylamino, ethylamino, propylamino, inpropylamino, hexylamino, etc. Alkylamino group substituted with an alkyl group of 1 to 6 carbon atoms; dimethylamino, diethylamino, dipropylamino , diisopropylamino, diethylamino, methylethylamino, methylpropylamino, ethylbutylamino, and other alkyl groups having 1 to 6 carbon atoms substituted dialkylamino groups; phenylamino, diphenylamino, and other aryl groups having 6 to 8 carbon atoms; Substituted arylamino groups; examples include alkylarylamino groups such as methylphenylamino and ethylphenylamino.

can be lost.

Examples of the halogen atom include fluorine, chlorine, and bromine.

In the naphthalenone compound represented by the general formula (1) of the present invention, preferred substituents R1 to R? Examples include hydrogen atoms, alkyl groups, alkoxycarbonyl groups, and aromatic groups with or without substituents.

Examples of particularly preferred substituents R'-R' are shown in Table 1 below.

No. table 1 2 ■３ 4 s 6 v 1 1! 1 1 1] 1 coocaus C11゜ 1 1 Us 1! 1 cooctns The above naphthalenone compound (1) teeth, example For example, it can be manufactured as follows.

Substituted dihydroxynafucrene represented by the general formula (2) (wherein R1-R6 are as defined above) is reacted with methyl iodide and potassium carbonate, and the substituted dihydroxynafucrene represented by the general formula (3) (in the formula, After producing a compound represented by the general formula (4) (wherein RI, , R11 is the same as the above), it is reacted with sodium and liquid ammonia. There is a method of producing a compound represented by ) and then reacting the compound with hydrochloric acid.

Any reaction solvent may be used as long as it is inert to the reaction components. For example, when synthesizing product (3),
Examples include ketone solvents such as acetone and methyl ethyl ketone; when synthesizing product (4), ether solvents such as tetrahydrofuran and diethyl ether; when synthesizing product (1), using solvents such as water. Examples include solvents.

When synthesizing product (3), the reaction molar ratio is 2.0 to 8.0 times mole of methyl iodide and 0.2 times potassium carbonate to 1 mole of substituted dihydroxynaphthalene compound (2).
~8.0 times the molar amount is used, especially 2.0 to 4.0 times each
and 0.2 to 0.4 times the mole amount is preferable. In addition, the product (4
), 3.0-10.0 times the mole of sodium and 3-8β of liquid ammonia per 1 mole of product (3).
are used, especially 4.0 to 6.0 times the mole and 4 to 5β
is preferred. Moreover, when synthesizing the product (1), 1N hydrochloric acid 2-6Q is used with respect to 1 mol of the product (4), and 3-4Q is especially preferable.

The reaction temperature is 20 to 80 ℃ when synthesizing the product (3).
°C is used, particularly preferably 60 to 70 °C; when synthesizing product (4), -60 to -120 °C is used, particularly preferably -70 to -80 °C. Product (1
) is used at a temperature of 20 to 100°C, particularly preferably 70 to 80°C.

The appropriate reaction time is 1 to 10 hours in any case.

In addition, when introducing a substituent R7, a compound represented by the general formula (5) (in which R1, R2, R6 and R7 have the same meanings as above) and a compound represented by the general formula (6) (in the formula , R3, R4 and R6 are as defined above) in a reaction solvent in the presence of sodium, followed by acid treatment.

As the reaction solvent, alcoholic solvents such as methanol and ethanol are preferred.

The reaction molar ratio is 1 mole of compound (5) to 1 mole of compound (5).
6) 1.0-4.0 times mole and sodium 1.0-4.0
Double molar ratios are used, especially 1.0 to 1.5 and 1.0, respectively.
~1.5 times the mole is preferable).

The reaction temperature used is 0 to 60°C, especially 20 to 3°C.
0°C is preferred.

A suitable reaction time is 0.5 to 6 hours.

The naphthalenone compound thus obtained has -1R white crystals, good crystal growth properties, and a large second-order nonlinear optical effect.

Naphthalenone compounds can be used as nonlinear optical elements, for example in the form of thin films deposited on various supports, fibers, molecular inclusions in host lattices (polymers, clathrates, solid solutions, liquid crystals).

Methods for creating nonlinear optical elements using naphthalenone compounds include growing a crystal in a glass capillary to form a fiber waveguide, and growing a thin film crystal in a planar shape on a support (for example, a glass substrate) to create a planar waveguide. Methods such as creating wave paths can be used.

It is also possible to device elements in the form of molecular inclusions in host lattices (polymers, clathrates, solid solutions, crystals).

(Example) Next, the present invention will be explained in more detail with reference to Synthesis Examples and Examples.

Synthesis Example 1 (Synthesis of 4,4a,5.6-tetrahydroxy 2(H)naphthalenone) 2.7-dihydroxyoxynaphthalene (16.0 g
, O, l mail is dissolved in 150-acetone,
Add potassium carbonate (29 g, 0.21 mol) and methyl iodide (43 g, 0.3 mail) to it,
The reaction was carried out at 70°C for 6 hours.

Then excess potassium carbonate? After the acetone was distilled off from the resulting seven-house solution to obtain crude crystals of 2.7-simethoxynaphculene, this was further recrystallized using methanol to obtain 2.7-simethoxynaphthalene. i7. og
(Yield: 90%, mp.

138°C) was obtained.

Next, the obtained 2,7-simethoxynaphthalene (9 g,
0.048 mol) was dissolved in 40 d of tetrahydrofuran and 30 d of ethanol, and cooled to -78°C. Liquid ammonia 250-1 then sodium (6
g, 0.26 mall was added, and the mixture was reacted at -78°C for 1 hour. After the reaction was completed, liquid ammonia was distilled off, 40+d of ethanol and 500% of water were added, and the resulting solid content was separated in a furnace and further recrystallized with methanol to obtain 1.
44a,5,8.8a-hexahydroxy-2゜7-
Cymethoxynaphthalene 7.2g (yield near 7%, mp,
59°C) was obtained.

Next, the obtained 1,4.4a,5,8,8a-hexahydroxy-2,7-simethoxynaphthalene (5.9 g,
Add IN hydrochloric acid 10C1al' to 8
The reaction was carried out at 0"C for 1 hour. After the reaction was completed, the reaction mixture was sufficiently cooled with ice water, and the precipitated solid content was separated and recrystallized with ethyl acetate to obtain a white product represented by the formula No. 1 below. 3 g (yield: 80%) of crystalline 4.4a5.6-tetrahydro-7-hydroxy 2(3H) naphthalenone was obtained.

The total yield of the entire process is It's 55% Ta.

(55%) Synthesis examples 2 to 10 In the same manner as in Synthesis Example 1, Shown below vinegar Na centre Ta Re of Compound No.

got 0 Ta.

( ) The value inside is the total yield.

(60%) (48%) No.

4 white crystal (58%) (52%) (50%) (41%) Example 1 Measurement of second harmonic generation (SHG) by S and K.

The method of Kurtz et al. (J, Appl, Phys.
39.

3798) on the powder of the compound of the present invention.

Nd: YAG laser (Spectra
A powder sample filled in a glass cell was irradiated with a 1.064 μ ray from a YAG laser DCR-3 manufactured by Physics (peak output 110 MW), and the green light generated was spectrally separated using a filter (532 nm) and photoelectron intensification was performed. Detected with double tube. Note that since it is difficult to determine the absolute value of harmonic conversion efficiency from the results of the powder method, Table 2 shows the results of evaluation as relative values using urea, which has been well studied, as a standard.

Table 2 Example 2 The manufacture of nonlinear optical elements is described, for example, in J.

■illiams et al.'Non 1inear 0p
tical properties of Organi
c and Polymeric Materials
” ACS.

This was carried out according to the method described in the 1983 publication. - For example, compound No. 1 is kept in a melt state in a furnace, etc., and a hollow glass fiber (for example, an outer diameter of 1100p and a hollow in the center with a diameter of about 2 to 10P is placed in the melt). The - end of the hole was infiltrated. Compound No. 1 in a molten state entered the hollow part of the glass fiber due to capillary action, and then the glass fiber was cooled to solidify Compound No. 1. Next, the glass fibers are gradually drawn out from the furnace, which is maintained at a temperature higher than the melting point of Compound No. 1, to the outside of the furnace, which is maintained at a temperature lower than the melting point. Single crystallization was carried out from the part drawn out to the outside.

The wavelength conversion efficiency of the nonlinear optical element manufactured in this way can be determined by using the same laser as in Example 1 and irradiating the end face of the nonlinear optical element with laser light focused by an objective lens. This was done by measuring the intensity of the generated second harmonic with a laser power meter. The wavelength conversion efficiency, which is the ratio of the second harmonic light intensity to the fundamental wave light output, was about 0.2% when the fundamental wave light output was about several hundred m². this is,
The wavelength conversion efficiency is comparable to the wavelength conversion efficiency of an element made of MNA as described above.

(Effects of the Invention) The organic nonlinear optical element according to the present invention is based on the use of a naphthalenone compound that has a large nonlinear optical effect, excellent crystal growth properties, and durability, and can be applied to various uses that apply the nonlinear optical effect. It is.

Claims (1)

[Claims] The following general formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (1) (In the formula, R^1 to R^7 may be the same or different, and hydrogen atoms , represents a substituent selected from aliphatic, alicyclic or aromatic groups having 1 to 20 carbon atoms, acyl groups, amino groups, cyano groups, nitro groups, azo groups and halogen atoms)
A nonlinear optical element comprising a naphthalenone compound represented by: