JPH0391725A - Novel organic nonlinear optical material and method for converting light wavelength by using this material - Google Patents

Abstract

PURPOSE:To provide the org. nonlinear optical material which exhibits high org. non-responsiveness by using a specific benzotriazole compd. CONSTITUTION:The compd. expressed by general formula is used as the org. nonlinear optical response compd. The group expressed by R<1> is a hydrogen atom, alkyl group, aryl group and the alkyl group is examplified as, for example, a methyl group, ethyl group and propyl group. The aryl group is exemplified by a phenyl group, tolyl group, 4-chlorophenyl group. The hydrogen atom is more preferable among the above-mentioned groups. The group expressed by R<2> is an electron donative group. The electron donative group is exemplified by a methyl group, phenyl group, amino group, dimethyl amino group, acetyl amino group, hydroxy group, methoxy group, methylthio group, etc. The nonlinear optical materia of this invention is particularly useful as the material for light wavelength conversion of a laser beam.

Description

[Detailed description of the invention] (Industrial application field)? The present invention relates to nonlinear optical materials suitable for use in various devices that utilize nonlinear optical effects, such as wavelength conversion devices. It also relates to a method of converting optical wavelength using nonlinear optical materials. (Prior Art) In recent years, materials with a nonlinear optical effect - nonlinearity (1) between polarization and electric field that appears when a strong optical electric field such as that of a laser beam is applied have attracted attention.

Such materials are known as nonlinear optical materials and are described in detail in e.g.
'Nonliner Optical Property
ies of Organic and Poly+le
ric Material″ACS SYMPOSIt
lMSERIES 2 3 3 David
J. lI1st1iams [(Amer
jcanChemical Society, 1983
(published in 1985), "Organic Nonlinear Optical Materials" supervised by Masao Kato and Hachiro Nakanishi (CMC, published in 1985) "Nonli
near Optical Properties of
Organic molecules and er
yStals"Vol1 and Vol2 D.S.Ch
emla and Zyssm (Acaclemie
Press, 1987). One of the applications of nonlinear optical materials is second harmonic generation (SHG) based on second-order nonlinear effects and wavelength conversion devices using sum frequency and difference frequency. What has been used in practice so far is
It is an inorganic berovskite represented by lithium niobate. However, in recent years, it has become known that π-electron conjugated organic compounds with electron-donating and electron-withdrawing groups have various properties as nonlinear optical materials that far exceed those of the inorganic materials mentioned above. Therefore, as an organic compound exhibiting a nonlinear optical response to be used in this material, the higher the nonlinear susceptibility in the molecular state, the more desirable it is.

However, in order to be useful as a second-order nonlinear optical material, performance in the molecular state alone is insufficient, and it is essential that the molecular arrangement in the aggregate state has no inversion symmetry.

However, currently it is extremely difficult to predict the molecular arrangement, and the probability of its existence among all organic compounds is not high.

(Problems to be Solved by the Invention) Therefore, the first object of the present invention is to provide an organic nonlinear optical material exhibiting high organic non-responsiveness. The second purpose is to provide a method that utilizes the nonlinear response related to optical wavelength conversion. (Means for Solving the Problem) As a result of extensive research, the present inventors have found that the object of the present invention can be achieved by using a compound represented by the following general formula as an organic nonlinear optically responsive compound. I discovered that.

General formula R1 (In the formula, R represents a hydrogen atom, an alkyl group, or an aryl group. R2 represents an electron-donating group.) The group represented by R' is a hydrogen atom, an alkyl group, or an aryl group, and an alkyl group. Examples include methyl group, ethyl group, and proyl group. Examples of the aryl group include a phenyl group, a tolyl group, and a 4-chlorophenyl group. Among these, hydrogen atoms are preferred.

The group represented by R2 is an electron-donating group, and examples of the electron-donating group include a methyl group, a phenyl group, an amino group, a dimethylamino group, an acetylamino group, a hydroxy group, a methoxy group, and a methylthio group. Note that the above-mentioned electron-donating group refers to a substituent having a negative Swain Lupton substituent constant R.

The above-mentioned substituent constants can be found in "Structure-Activity Relationships of Drugs - Guidelines for Drug Design and Mechanism Research," published by Akebono Society for Structure-Activity Relationships, Akebono, "Region of Chemistry," Special Issue No. 122, pp. 95-111, published by Nankodo Publishing Co., Ltd., and Colvin. /'% Nshu (Corwin -
Hansch), Albert Leo
Lea), ``Substituent Constance for Correlation Analysis in Chemistry and Biology'' (Substit.
uent Constants for Correl
ation^nalysts iri Chesist
ry and Biology) 6 9 ~ 1 61
Page John Wiley & Sons
ley and Sons).

Specific examples of compounds used in the present invention are shown below, but the present invention is not limited to these.

Compound l Compound 2 Compound 3 Compound 4 Compound 5 Compound 11116 CHs Compound 7 Compound 9 Compound 11 Compound 8 Compound 10 Compound 12 Compound 13 Compound 14 C. HS Compound 15 S The compound of the present invention can be prepared by a general synthesis method of penzotriazoles (for example, by R.E. Elderfield (R.
E. Elderfield) & i Heterocyclic Compounds, Volume 7, Page 384, Jijin・
Wiley and Sons (Heterocyclic
Compounds. Vol'? , P 3 8 4
, John Wiley and Sons) 196
1). As is clear from the Examples described below, the nonlinear optical material of the present invention is particularly useful as a material for converting the optical wavelength of laser light.

However, the application of the nonlinear optics of the present invention is not limited to wavelength conversion elements, but can be used for any element that utilizes nonlinear optical effects. Specific examples of elements in which the nonlinear optical material of the present invention can be used include:
In addition to wavelength conversion elements, optical bistable elements (optical storage elements, optical pulse waveform control elements, optical limiters, differential amplification elements, optical transistors, A/D conversion elements, optical logic elements, optical multivibrators, optical flip-flop circuits, etc.) ), light modulation elements, phase conjugate optical elements, etc. The compounds of the invention may be present, for example, in the form of a powder, in the form of molecular inclusions in a host lattice (bolimers, clathrates, solid solutions, liquid crystals), in the form of thin layers deposited on a support (Langmeer-Prodgett membranes), etc. It can be used as a nonlinear optical material in various forms such as single crystal form, solution form, etc.).

The compound of the present invention can also be used in the form of a pendant bonded to a polymer, polydiacetylene, etc.

For details on these methods, see D.J. Wtll
It is described in the works of ia■s Akebono.

(Example) Next, the present invention will be explained in detail based on an example. Example 1 The second-order nonlinear susceptibility β in the molecular state was calculated.

β is calculated using the PPP method (Pariser-Parr-P
ople) and Ward's formula (JP Ward,
Rev. Mod. Phys. , 37, 1 (196
5)) was used. The results are shown in Table 3.

Note that the value obtained by this method is experimentally calculated from dc-SHG.
It is known that the value obtained by Table 1 (Compound A) H It can be seen that the compound of the present invention is an excellent nonlinear optical material with significantly larger β than Compound A described in JP-A No. 62-210430.

Example 2 Second harmonic generation was measured by S.K. Kurz (S.K.
κurLz), T.T.Berry (T.T.Pe
J. Appl, Phys., Volume 3 9, 379
This was carried out on the powder of the compound of the present invention according to the method described on page 8 (published in 1968). Measurements were performed using the equipment shown in Figure 1. That is, the measurement was performed using pulsed YAG laser light (λ-1,064 μm,
Beam diameter! :t1kakuφ, beakbowerζIQMw/cj
) was used as the fundamental wave, and the intensity of its second harmonic was measured using the evaluation device shown in FIG. The measurement was performed by relative comparison with the intensity of the second harmonic of urea. In addition, when the intensity was weak, visual observation was performed. In particular, in order to distinguish between light emission due to two-photon absorption of the fundamental wave (mainly yellow and red light emission) and second harmonics, a spectrometer was installed to measure only the second harmonics. Furthermore, the main purpose of powder method measurement is to determine the presence or absence of nonlinearity in the substance, and the intensity ratio is a reference value for the magnitude of nonlinearity.

The results are shown in Table 2. Table 2 Example 3 In order to investigate the transmittance of blue light, the absorption edge of the following compound was measured.

The results are shown in Table 3. 1) Wavelength showing 95% transmittance in ethanol solution of 4×10-' haze o1/l.

MNA As is clear from Table 3, the compounds of the present invention are excellent in blue light transmittance.

(Effects of the Invention) Compounds that exhibit SHG activity by these powder methods can be used as wavelength conversion elements by the method described below.

1. The above compound is single-crystalized in the core part of the fiber,
It is possible to create a wavelength conversion element using glass as the cladding material, input YAG laser light, and generate its second harmonic. Furthermore, as another method, it is possible to similarly generate a second harmonic by using a waveguide type wavelength conversion element. The phase matching method used at this time is the Cerenkov radiation method. However, it is not limited to these, and phase matching between waveguides is also possible. Wavelength converted waves are not only limited to second harmonics, but can also be used to generate third harmonics, sum and difference frequencies. 2. Next, the above compound is single-crystalized, a bulk single crystal is cut out from it, and YAG
It is possible to generate a second high wave by inputting laser light. Angular phase matching is used as the phase matching method at this time. These bulk single crystals can be used not only outside the laser cavity, but also inside the cavity of a solid-state laser such as an LD-pumped solid-state laser to improve wavelength conversion efficiency. Furthermore, the wavelength conversion efficiency can also be increased by placing it within the resonator of an external resonator type LD.

The Bridgman method, solvent evaporation method, etc. are used for the above single crystallization.

The wavelength-converted wave is not limited to second harmonics, but can also be used to generate third harmonics and sum-difference frequencies.

[Brief explanation of drawings]

Figure 1 shows the powder method measuring device, and the numbers in the figure indicate the following.

Claims (1)

[Claims] (1) An organic nonlinear optical material comprising a compound represented by the following general formula. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R^1 represents a hydrogen atom, an alkyl group, or an aryl group. R^2 represents an electron-donating group.) (2) Laser light and nonlinearity A method of converting a light wavelength using the organic nonlinear optical material according to claim 1 as a nonlinear optical material when converting a light wavelength using an optical material.