JPH05303126A - Organic nonlinear optical material and nonlinear optical element using the material - Google Patents

Abstract

PURPOSE:To increase the activity in second harmonic generation-(SHG) and to suppress the absorption in the SHG region by forming the material with a specified quinolinic compd. CONSTITUTION:This org. nonlinear optical material consists of a quinolinic compd. shown by the formula. In the formula, X, Y and Z are hydrogen or an electron donating or accepting substituent, X, Y and Z are not hydrogen at the same time, and X, Y and Z are hydrogen, halogen, an amino group or a nitrile group. The quinolinic compd. is dispersed in a single crystal or high- polymer film, the single crystal or film is used as the optical waveguide, and the film is oriented in a strong electric field. The high polymer has no absorption in >=400nm. In the optical waveguide consisting of a clad layer and a core, the quinolinic compd. is dispersed in a single crystal or high-polymer film to form the core.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic nonlinear optical material and a nonlinear optical element using the same.

[0002]

2. Description of the Related Art Non-linear optical materials are materials that exhibit a second-order and third-order non-linear response due to interaction with a strong electromagnetic field such as laser light, and include harmonic generation, optical mixing, optical parametric oscillation, optical modulation, optical Since it has many element functions such as a switch, it has attracted attention as a wavelength conversion element for lasers and an element for optical computing.

Conventionally, non-linear optical materials have been lithium niobate (LiNbO ₃ ), potassium dihydrogen phosphate (KDP),
Inorganic materials such as gallium arsenide (GaAs) and semiconductor materials have been mainly investigated. However, inorganic and semiconductor materials have many problems in terms of compound modification, deliquescent, and response speed. On the other hand, organic compounds are easy to modify molecules, have large nonlinear optical constants in terms of nonlinearity, and there is a possibility that materials with fast response speed may be obtained. Research and development have become popular. As organic non-linear optical materials, materials having excellent non-linear optical characteristics such as methylparanitroaniline (MNA) and methylparanitro-N-oxidepyridine (POM) have already been found, but especially semiconductor lasers. None of them achieved both transparency and characteristics, which are indispensable for generating the second harmonic wave.

[0004]

In developing a second-order organic nonlinear optical material, first, the nonlinearity of the molecule itself,
That is, it is important that the supramolecular polarizability β is large. For that purpose, compounds having various electron-donating groups or electron-withdrawing groups introduced into a molecule having a π-electron conjugated system have been designed and synthesized. However, for the second-order nonlinear optical material, it is necessary that the crystal structure of the material has no inversion symmetry center and that the compound does not have absorption in the second harmonic generation (SHG) region. When the dipole moment of the molecule is increased by introducing an electron-donating group or an electron-withdrawing group into the system, the crystal tends to have a structure having an inversion symmetry center, and the compound easily absorbs in the long wavelength region. Become.
That is, in designing the organic nonlinear optical material, not only the supramolecular polarizability β must be increased, but also the transmittance in the SHG region and the crystal structure must be sufficiently considered. The wavelength of the output light of the current semiconductor laser is about 850
Since it is 750 nm, it is desirable that the absorption wavelength edge of the nonlinear optical material is in the SHG region of the laser, that is, approximately 430 nm or less, but shortening the absorption wavelength edge leads to a decrease in the supramolecular polarizability β. , It is difficult to solve the problem of nonlinearity and transmittance in the SHG region at the same time. Furthermore, regarding the crystal structure, it is difficult to predict the crystal structure of the compound at the stage of molecular design. p-nitroaniline, 4-dimethylamino-4'-
Nitrostilbene, p-nitro-N-oxide pyridine, etc. are examples of compounds that do not show non-linearity as a crystal because the crystal has a structure with an inversion symmetry center even though the supramolecular polarizability β is large. is there.

Therefore, an object of the present invention is to provide an organic nonlinear optical material having a large SHG activity and having no absorption in the SHG region.

[0006]

In order to achieve the above object, as a result, in a semiconductor laser wavelength conversion device comprising a semiconductor laser light source, a lens, and a nonlinear optical medium, the heterocyclic triallylamine compound is added to the nonlinear optical medium. It was found that the wavelength conversion of the semiconductor laser can be efficiently performed by using the above. The gist of the present invention is as follows. An organic nonlinear optical material comprising a quinoline compound represented by the following general formula [6],

[0007]

[Chemical 6]

[Wherein X, Y and Z are hydrogen or an electron-donating or electron-accepting substituent, and the case where X, Y and Z are all hydrogen is excluded. In particular, X, Y and Z in the general formula [6] are organic non-linear optical materials characterized by comprising a quinoline-based compound which is any one of hydrogen, halogen, amino group or nitro group.

The quinoline compound represented by the general formula [6] is formed into a single crystal or a film dispersed in a high molecular weight polymer, and the single crystal or film is used as an optical waveguide. In particular, the non-linear optical element is characterized in that the film dispersed in the polymer is oriented in a strong electric field. Further, the high molecular weight polymer is 400 n
It is a non-linear optical element characterized by being a polymer having no absorption above m.

Further, in an optical waveguide comprising a clad layer and a core portion, the core portion is a single crystal of a quinoline compound represented by the above general formula [6] or a film dispersed in a polymer. It is an optical waveguide characterized by being formed.

In a non-linear optical element including an optical waveguide composed of a clad layer and a core portion, the core portion is a dispersion of a quinoline compound represented by the above general formula [6] in a single crystal or a polymer. It is a non-linear optical element characterized by being a body.

An optical wavelength having a light source, a condensing means for condensing the light from the light source, and a harmonic generating means for receiving the light condensed by the condensing means to generate a second harmonic In the conversion device, the second harmonic generation means includes a single crystal of the quinoline compound represented by the general formula [6] or a dispersion in a high molecular weight polymer in the optical path. It is a characteristic optical wavelength conversion device.

As the single crystal of the organic nonlinear optical material, a shape of 0.1 to 10 mm square is used in terms of the element structure, but 10 to 10 is used in an element such as quasi phase matching.
A size of 0 μm, and a size of about 1 μm is also used for a fiber type element or the like. As the polymer for dispersing the organic nonlinear optical material, monomers represented by acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, styrene and the like are used. A polymerized transparent high molecular polymer is used. Particularly, the polymer is preferably a polymer having no absorption at 400 nm or more. The dispersion is oriented under a strong electric field. Further, the dispersion can be obtained by previously dispersing a non-linear medium in the monomer and polymerizing the non-linear material in the strong electric field while orienting the non-linear material. It can also be obtained by polymerizing a monomer in which the non-linear material is dispersed, heating the polymer above the glass transition temperature, and then gradually cooling it under a strong electric field.

Further, the organic non-linear optical material of the present invention is used as a non-linear optical element provided with an optical waveguide having a core or a polymer dispersion thereof as a core and the core being surrounded by a cladding layer.

1 to 3 are schematic configuration diagrams of an optical wavelength conversion device to which the nonlinear optical element of the present invention is applied. In the figure, reference numeral 1 is a light source used in the nonlinear optical element of the present invention. 2, 4,
Reference numerals 8 and 9 are semi-transmissive mirrors used in the device of the present invention. 5
Is a polarizing plate. Reference numerals 6 and 7 denote incident light and output light.
Reference numeral 10 is a reflecting mirror, 11 is return light, and 12 is other incident light.

FIG. 4 is a schematic view of a specific example of an optical wavelength conversion device to which the nonlinear optical element of the present invention is applied. A laser beam 14 from a laser diode 13 (GaAlAs semiconductor laser beam; wavelength 0.88 to 0.8) is applied to an SHG element 18 having a core of a single crystal of the organic nonlinear material or a polymer dispersion thereof and a cladding layer surrounding the core. 75 μm) is transmitted through the collimator 15, the anamorphic prism pair 16 and the condenser lens 17 to obtain the second harmonic (SHG) light 19 of blue light (wavelength 0.44 to 0.37 μm). be able to. By using the SHG element 18 of the present invention, an optical wavelength conversion device having a short cutoff wavelength and excellent laser light resistance can be obtained.

Representative examples of the compound of the present invention are shown below.
The scope of the present invention is not limited to these.

[0018]

[Chemical 7]

[0019]

[Chemical 8]

[0020]

[Chemical 9]

[0021]

[Chemical 10]

[0022]

[Chemical 11]

Further, the organic nonlinear optical material of the present invention can be applied to second-order nonlinear devices such as optical rectification, optical mixing, parametric amplification and EO modulator.

The organic nonlinear optical material of the present invention can be applied to a third-order nonlinear device such as third harmonic generation, Kerr shutter, light mixing, optical memory utilizing optical bistability, and optical operation element.

In the organic nonlinear optical material of the present invention, a single crystal is prepared by a method of precipitating a crystal from an organic solvent, a Bridgman method, a Czochralski method, a sublimation method, or the like. It can be used as a conversion element. It can also be used as a Cherenkov type non-linear device.

[0026]

In the molecular structure of the quinoline derivative of the present invention, the non-linearity of the molecule alone becomes larger due to the sum of CT vectors.
Further, the crystal structure is likely to be a non-centrosymmetric structure, and a larger non-linearity can be exhibited even in the crystalline state.

[0027]

【Example】

[Examples 1 to 6] With respect to 8-quinolinol having chlorine or fluorine introduced at positions 2, 6 or 7, its second-order nonlinear optical constant β was calculated using the ab initio molecular orbital method, and other positions were calculated. The substitution products were compared. For the calculation, the molecules were also optimized using the ab initio molecular orbital method (GAUSSIAN 80). HONDO-7 (STO-3G basis) for non-linear constant calculation
It was used. The calculation results are shown in Tables 1 and 2. Table 1 shows the case where fluorine (F) is used as the substituent. As shown in the table, it is clear that the position 2, 6, or 7 of the present invention is different from the positions of the other comparative examples, and has the effect of enhancing the non-linear characteristic. Table 2 shows the case of chlorine (Cl), but the effect of the present invention is exhibited in exactly the same manner.

[0028]

[Table 1]

Examples 7 to 14 Table 3 shows the results of calculation of the nonlinear optical characteristics of various compounds of the present invention as in Examples 1 to 6. Examples 7 to 11 are nitro groups (NO ₂ ).
Alternatively, the results are obtained by using an amino group (NH ₂ ).
Nos. 14 to 14 are results when two kinds of substituents are used in combination.
As shown in the table, all of the compounds of the present invention show a marked increase in nonlinearity as compared with the unsubstituted molecule.

[0030]

[Table 2]

[0031]

The organic nonlinear optical material of the present invention has excellent nonlinearity.

By using the organic nonlinear optical material and combining it with a semiconductor laser, a laser beam having a wavelength in the visible region can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a wavelength conversion device using the compound of the present invention.

FIG. 2 is a schematic configuration diagram of a wavelength conversion device using the compound of the present invention.

FIG. 3 is a schematic configuration diagram of a wavelength conversion device using the compound of the present invention.

FIG. 4 is a schematic view of a specific example of an optical wavelength conversion device to which the nonlinear optical element of the present invention is applied.

[Explanation of symbols] 1 ... Light source, 2, 4, 8, 9 ... Semi-transmissive mirror, 5 ... Polarizing plate,
6, 7 ... Incident light and output light, 10 ... Reflector, 11 ... Return light, 12 ... Other incident light, 13 ... Laser diode, 1
4 ... Laser light, 15 ... Collimator, 16 ... Anamorphic prism pair, 17 ... Condensing lens, 18 ... SHG
Element, 19 ... SHG light.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Tsunoda 4026 Kuji Town, Hitachi City, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hiritsu Manufacturing Co., Ltd.

Claims (8)

[Claims] 1. An organic nonlinear optical material comprising a quinoline compound represented by the following general formula [1]. [Chemical 1] [In the formula, X, Y and Z are hydrogen or an electron-donating or electron-accepting substituent, and the case where X, Y and Z are all hydrogen is excluded. ] 2. The organic nonlinear optical material according to claim 1, wherein X, Y and Z in the general formula [1] are composed of a quinoline-based compound which is any one of hydrogen, halogen, amino group and nitro group. .. 3. A quinoline compound represented by the following general formula [2] is formed into a single crystal or a film dispersed in a polymer, and the single crystal or film is used as an optical waveguide. A nonlinear optical element characterized by the above. [Chemical 2] [In the formula, X, Y and Z are hydrogen or an electron-donating or electron-accepting substituent, and the case where X, Y and Z are all hydrogen is excluded. ] 4. The non-linear optical element according to claim 3, wherein the film dispersed in the polymer is oriented in a strong electric field. 5. The non-linear optical element according to claim 3, wherein the high molecular polymer is a polymer having no absorption at 400 nm or more. 6. An optical waveguide comprising a clad layer and a core portion, wherein the core portion is a single crystal of a quinoline compound represented by the following general formula [3] or a film dispersed in a high molecular polymer. An optical waveguide characterized by being formed. [Chemical 3] [In the formula, X, Y and Z are hydrogen or an electron-donating or electron-accepting substituent, and the case where X, Y and Z are all hydrogen is excluded. ] 7. A nonlinear optical element including an optical waveguide comprising a clad layer and a core portion, wherein the core portion is a single crystal of a quinoline compound represented by the following general formula [4] or a high molecular polymer. Non-linear optical element characterized by being a dispersion of. [Chemical 4] [In the formula, X, Y and Z are hydrogen or an electron-donating or electron-accepting substituent, and the case where X, Y and Z are all hydrogen is excluded. ] 8. A light wavelength having a light source, a condensing means for condensing the light from the light source, and a harmonic generating means for receiving the light condensed by the condensing means to generate a second harmonic. A conversion device, wherein the second harmonic generation means is provided with a single crystal of a quinoline compound represented by the following general formula [5] or a dispersion in a polymer in an optical path. Characteristic optical wavelength converter. [Chemical 5] [In the formula, X, Y and Z are hydrogen or an electron-donating or electron-accepting substituent, and the case where X, Y and Z are all hydrogen is excluded. ]