JPH0381746A - Organic nonlinear optical material - Google Patents

Abstract

PURPOSE:To obtain an excellent nonlinear optical material by incorporating 3, 4-dihydroxy-beta-cyano-beta-methoxy carbonyl styrene expressed by specific formula into this material. CONSTITUTION:3, 4-Dihydroxy-beta-cyano-beta-methoxy carbonyl styrene expressed by the formula is incorporated into the nonlinear optical material. The compd. of the crystal has no symmetrical center and, therefore, exhibits a nonlinear optical effect. The efficiency of generating the second harmonic wave of the fine crystal powder is as high as the efficiency of generating the second harmonic wave of urea. The max. wavelength is 446nm and exists in a short wavelength region. The crystal is stable at room temp., is hardly optically damaged and allows easy working. This compd. is usable as the nonlinear optical material in the form of powder, single crystal, soln., etc. The compd. is synthesized by the condensation reaction of, for example, 3, 4-hydroxyaldehyde and methyl cyanoacetate with methanol, etc., as a solvent and a piperizine, etc., as a catalyst.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an organic nonlinear material that is used as a light control element in a wide range of fields such as optical computers and optical communications. The present invention relates to an organic nonlinear optical material made of 3,4-dihydroxy-β-cyano-β-methoxycarbonylstyrene that has excellent damage resistance, high SHG (second harmonic generation) activity, and good crystallinity.

[Conventional technology]

Nonlinear optical materials produce phenomena such as frequency conversion, amplification, oscillation, and switching of laser light, and generate second harmonics (
It can be applied to Sl(G), third harmonic generation (THG), high-speed shutter, optical memory, optical arithmetic element, etc. In addition, nonlinear optical materials can be applied to optical switches and the like that take advantage of the property that their refractive index changes depending on an electric field.

Conventionally, KH, PO4, NH4H have been used as nonlinear optical materials.
Inorganic single crystal materials such as z PO4, L i N bus and KNbOs are known, but recently urea, p-nitroaniline, 2-methyl-4-nitroaniline (MNA), m-nitroaniline Aniline (mNA), 4
- Development of organic nonlinear optical materials such as (N,N-dimethylamino)-4'-nitrostilbene (DANS) is progressing.

Polymer materials such as polydiacetylene and polyvinylidene fluoride are also being considered for application to waveguides with control functions, optical ICs, etc. by utilizing their nonlinear optical effects.

Organic nonlinear optical materials generally have nonlinearity originating from intramolecular π electrons, so they do not involve lattice vibration in response to light, and therefore have faster response than inorganic materials. It is possible to synthesize a material whose absorption region can be changed. Moreover, the methods of making materials into devices are not limited to single crystallization, but also include LB film, vapor deposition, etc.
Various methods such as liquid crystal formation and polymerization are possible.

For recent research results on nonlinear optical materials, see e.g.
Kato, lifestyle supervisor ``Organic nonlinear optical materials'' (CM
S CHEMLA, Spear, S CHEMLA, Published in 1985)
J, ZYSS edition “Non1inear 0ptical
Pro-perties and (:rystal
s″Vol1. I, Vol, 'II, etc.

By the way, nonlinear optical materials are required to have the following characteristics.

(1) Among nonlinear optical effects, especially second harmonic generation (S
HG) is positioned as a basic technology for wavelength conversion due to its high conversion efficiency, and SHG efficiency (1
) is required.

(2) For a material to exhibit optical nonlinearity, it is practically required that the material has no spatial inversion symmetry, and in particular, its crystal must have no center of symmetry.

(3) It is desired that the material be stable at room temperature and form a single crystal as large as possible.

(4) The wavelength of current semiconductor lasers is about 800 nm, so the maximum wavelength (Lmax) and cutoff wavelength (Lmax)
cutoff) is desirably in the shortest wavelength region as possible.

However, known inorganic nonlinear optical materials are expensive to produce single crystals with high purity, have deliquescent properties, and are generally made of SHG.
It has the disadvantage of low efficiency.

On the other hand, although it is known that some organic nonlinear optical materials generally have high SHG efficiency, it is difficult to prepare stable and large crystals at room temperature. For example, MNA
Although it has high SHG efficiency, it is difficult to obtain large single crystals. Urea is easy to obtain large single crystals and has a white color.
Although it is transparent and has a short cutoff wavelength of 200 nm, it has the disadvantage of poor moisture resistance. Further, DANS, which is a stilbene derivative, exhibits a very large second-order nonlinear polarizability β at the molecular level, but when crystallized, the molecular arrangement has inversion symmetry and therefore does not exhibit a nonlinear optical effect.

As described above, the conventional technology is still insufficient in providing an organic nonlinear optical material that has high SHG efficiency, is stable, and is easy to grow into a large single crystal.

[Problems to be Solved by the Invention] An object of the present invention is to overcome the problems of the prior art described above, to form a single crystal that is stable at room temperature, has excellent resistance to light damage, and has no center of symmetry, and to The object of the present invention is to provide an organic nonlinear optical material that can be grown into a large single crystal and has a high SHG activity.

As a result of intensive research, the present inventors found that 3゜4-dihydroxy-β-cyano-β-methoxycarbonylstyrene, which is a styrene compound and has a specific substituent and structure, is suitable for the above purpose, Based on this knowledge, we have completed the present invention.

[Means for Solving the Problems] That is, according to the present invention, an organic compound comprising 3,4-dihydroxy-β-cyano-β-methoxycarbonylstyrene represented by the following formula [I]H A nonlinear optical material is provided.

Hereinafter, the constituent elements of the present invention will be explained in detail.

[3,4-dihydroxy-β-cyano-β-methoxycarbonylstyrene J 3, which is a compound used as an organic nonlinear material in the present invention,
4-dihydroxy-β-cyano-β-methoxycarbonylstyrene exhibits excellent nonlinear optical effects because its crystals do not have a center of symmetry, and the SHG efficiency of microcrystalline powder is comparable to that of urea.

Further, the L max of the compound of the present invention is 446 nm, which is in a relatively short wavelength region.

As is clear from the above formula, the compound of the present invention has a relatively large π-electron conjugated system, and has two hydroxy groups as electron-donating groups, and a cyano group and a methoxycarbonyl group as electron-withdrawing groups. It can be assumed that by having such a structure, the symmetry of the crystal is broken and, at the same time, SHG activity is expressed due to polarization caused by each substituent.

The compound of the present invention has stable crystals at room temperature, is less susceptible to photodamage, and is easy to process, so it can be easily fabricated into devices. Crystals of this compound exhibit excellent nonlinear optical effects, as evidenced by the SHG efficiency comparable to that of urea. The compound of the present invention can be used as a powder,
It can be used as a nonlinear optical material in various forms such as a single crystal or a solution.

(Production method) The 3,4-dihydroxy-β-cyano-β-methoxycarbonylstyrene of the present invention can be produced, for example, by a condensation reaction of 3,4-dihydroxyaldehyde and methyl cyanacetate, as shown in the reaction formula below. Can be synthesized.

OH This condensation reaction is carried out, for example, using an organic solvent such as methanol in the presence of a catalyst such as piperidine.

〔Example〕

The present invention will be specifically described below with reference to Examples, but the present invention is not limited only to these Examples.

[Example 1] (1) Synthesis example of 34-dihydroxy-β-cyano-β-methoxycarbonylstyrene 3.4-dihydroxybenzaldehyde 1.38 g
(10mmo 1) and methyl cyanoacetate 2.0mβ,
After adding 30 mj2 of methanol to form a solution, 10 drops of piperidine were slowly added dropwise while stirring. The solution was refluxed for 5 hours and then cooled to form a precipitate.

The precipitate was filtered and recrystallized from methanol to obtain the target compound 3.4-dihydroxy-β-cyano-β-methoxycarbonylstyrene. The yield was 1.6g.

Next, the results of measuring the IRl'H-NMR, UV, and melting point (m, p, ) of the product are shown below.

Melting point (ff1.p,): 200℃IR: 22
40(-CN), 1700(-GO-0-1,1600
゜(KBr) 1580 (Ar-C=C
), 1195 (Ar-OH) [cm-1] 'H-NMR: 3.91 (S, 3H), 6.91 (d,
2H, J=8.1).

((:D(J,) 7゜39(d, 2H, J:
l! , 1), 7.67 (s, IH).

8.15 (s, LH) [δ (ppm) ] UV
Absorption: max=446 nm.

(EtOH) From these analysis results, it was confirmed that this compound was 3,4-dihydroxy-β-cyano-β-methoxycarbonylstyrene. It can also be seen that the maximum wavelength (λwax) is 446 nm, which is in a relatively short wavelength region.

(2) Confirmation experiment of nonlinear optical effect Nd: YA was applied to the obtained fine powder crystals of 3,4-dihydroxy-β-cyano-β-methoxycarbonylstyrene.
When irradiated with G laser (wavelength = 1.064 μm, output 10 mJ/pulse), second harmonics are generated (SHG).
, Green light with half the wavelength (532 nm) of the incident light could be observed. It was also confirmed that its strength (SHG efficiency) was comparable to that of urea.

Crystals of this compound were stable at room temperature, had good crystallinity, and no photodamage was observed.

From the above facts, it can be seen that this compound is an excellent nonlinear optical material.

〔Effect of the invention〕

According to the present invention, SHG is stable at room temperature and has good crystallinity.
The organic nonlinear optical material of the present invention can provide an organic nonlinear material with high activity and excellent photodamage resistance.
It has important practical significance as it can be used as a wavelength conversion element for lasers.

Claims (1)

[Claims] (1) Organic nonlinear optics characterized by consisting of 3,4-dihydroxy-β-cyano-β-methoxycarbonylstyrene represented by the following formula [I] ▲Mathematical formulas, chemical formulas, tables, etc.▼[I] material.