JPH0695184A - Organic nonlinear optical material and optical functional element using that - Google Patents

Abstract

PURPOSE:To obtain an org. nonlinear optical material having large nonlinear optical characteristicas and excellent transparency by incorporating a specified compd. CONSTITUTION:3-(p-t-butylphenyl)-3-hydroxy-1-(p-methoxyphenyl)-2-prope ne-1-on (called as MHMPO) is used as a nonlinear optical medium. Namely, the org. nonlinear optical material BHMPO containing a compd. expressed by formula is prepared as a single crystal of >=1mm square, or the optical material is dispersed in a transparent high mol.wt. polymer material and oriented in a large electric field. Each dispersion body is maintained in an optical resonator. As the transparent polymer material to disperse the org. nonlinear optical material, polymer obtd. by polymn. of monomers, such as acylic acid, methylacrylate, ethylacrylate, butyl acrylate, styrene, is used.

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 an optical functional element using the same.

[0002]

2. Description of the Related Art Non-linear optical materials are materials that exhibit second-order and third-order non-linear responses 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 device functions such as a switch, it has been attracting attention as a laser wavelength conversion device and an optical computing device.

Conventionally, non-linear optical materials have been lithium niobate (LiNbO ₃ ), potassium dihydrogen phosphate (KD).
Inorganic materials such as P) and gallium arsenide (GaAs) and semiconductor materials have been mainly studied. However, inorganic and semiconductor materials have many problems in terms of compound modification, deliquescent property, and response speed.

On the other hand, organic compounds are easy to modify, have a large nonlinear optical constant in terms of nonlinearity, and there is a possibility that a material having a high response speed can be obtained. Research and development of optical materials have become popular. Examples of organic nonlinear optical materials include methylparanitroaniline (MNA) and methylparanitro-
Materials having excellent non-linear optical properties such as N-oxide pyridine (POM) have already been found.

[0005]

In developing a second-order organic nonlinear optical material, it is important that the nonlinearity of the molecule itself, that is, the supramolecular polarizability β is large. Therefore, the design and synthesis of compounds in which various electron-donating groups and electron-withdrawing groups are introduced into a molecule having a π-electron conjugated system have been performed.

However, for the second-order nonlinear optical material, it is necessary that the crystal structure of the material does not have an inversion symmetry center. However, by introducing an electron-donating group or an electron-withdrawing group into the π-electron conjugated system. When the dipole moment of the molecule is increased, the crystal tends to have a structure having an inversion symmetry center.
That is, in designing the organic nonlinear optical material, not only the supramolecular polarizability β must be increased, but also the crystal structure must be sufficiently considered.

Further, when a second-order nonlinear optical material is used as the material for the wavelength conversion element, the transparency in the harmonic generation region becomes a problem.

The wavelength of the present semiconductor laser light is about 850
Since it is ~ 750 nm, the absorption wavelength edge of the nonlinear optical material is the second harmonic generation region of the laser, that is, about 430 nm.
Although it is desirable that the wavelength be less than or equal to nm, shortening the absorption wavelength edge leads to a decrease in the supramolecular polarizability β,
It is difficult to solve both the nonlinearity and the transmittance problem in the second harmonic generation region at the same time.

Further, regarding the crystal structure, it is difficult to predict the crystal structure of a compound at the stage of molecular design. Paranitroaniline, 4-dimethylamino-4′-nitrostilbene, paranitro-N-oxide pyridine, and the like have a large supramolecular polarizability β, but the crystal has a structure with an inversion symmetry center. Is an example of a compound showing no non-linearity.

An object of the present invention is to provide an organic nonlinear optical material having a large nonlinear optical characteristic and excellent transparency.

Another object of the present invention is to provide an optical functional element using the above nonlinear optical material.

[0012]

In order to achieve the above object, the organic material represented by the formula [1] was examined. As a result, 3- (pt-butylphenyl) -3-
It was found that by using hydroxy-1- (p-methoxyphenyl) -2-propen-1-one (hereinafter referred to as BHMPO) as a non-linear optical medium, a highly functional optical functional device can be obtained. The gist of the present invention is as follows.

(1) An organic nonlinear optical material containing a compound represented by the formula [1].

[0014]

[Chemical 6]

(2) The organic nonlinear optical material BHMPO described in the above formula [1] is a single crystal of 1 mm square or more, or
An optical functional device comprising the organic nonlinear optical material dispersed in a transparent polymer and oriented in a strong electric field, the dispersion being held in an optical resonator.

As the transparent high molecular weight polymer in which the organic nonlinear optical material is dispersed, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, styrene, etc. A high molecular polymer obtained by polymerizing a representative monomer is used. Especially, the wavelength is 400 nm
Polymers that do not absorb the above light are desirable. And
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 a strong electric field while orienting the non-linear material.
Further, it can also be obtained by polymerizing a monomer in which the above-mentioned non-linear material is dispersed, and then heating the polymer to a temperature not lower than the glass transition temperature of the polymer and gradually cooling it under a strong electric field.

(3) The organic nonlinear optical material BHMP
The optical functional element according to claim 1, wherein a single crystal or dispersion of O forms an optical waveguide surrounded by a cladding layer.

(4) An optical functional element having an optical waveguide formed on a substrate, wherein the optical waveguide is a single crystal or dispersion of the organic nonlinear optical material.

(5) 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 wave. A light wavelength conversion device, wherein a single crystal of an organic nonlinear optical material represented by the above formula [1] or a dispersion dispersed in a transparent high molecular weight polymer is provided in the optical path of the harmonic generation means. An optical wavelength conversion device having.

(6) An electro-optical element for switching or modulating an optical signal by the electro-optical effect, wherein the optical path of the optical element is a single crystal of the organic nonlinear optical material represented by the above formula [1] or An electro-optical element having a dispersion dispersed in a transparent polymer.

1 to 3 are schematic perspective views of an optical functional element using the organic nonlinear optical material of the present invention.
In FIGS. 1 and 2, the nonlinear optical material 2 is surrounded by the cladding layer 1. In FIG. 3, the nonlinear optical material 2 is formed on the substrate 3.

4 to 6 are schematic configuration diagrams of an optical wavelength conversion device to which the optical functional element of the present invention is applied. In the figure,
The wavelength of the laser light from the light source 5 is converted by the optical functional element 6 of the present invention and the semitransparent mirror 4. In addition, 5 indicates a polarizing plate, 6 indicates incident light, and 7 indicates output light. Further, 10 is a reflecting mirror, 11 is return light, and 12 is other incident light.

FIG. 7 is a schematic diagram showing an example of the configuration of an optical wavelength conversion device to which the optical functional element of the present invention is applied. A laser beam 26 (GaAl) from a laser diode 21 is added to an SHG element 25 having a core of the organic nonlinear material single crystal or a polymer dispersion thereof and a clad layer surrounding the core.
As semiconductor laser light: wavelength 0.88 to 0.75 μm) collimator 22, anamorphic prism pair 23
And by transmitting through the condenser lens 24,
The second harmonic of blue light (wavelength 0.44 to 0.37 μm) can be obtained. By using the SHG element 25 of the present invention, an optical wavelength conversion device having a short cutoff wavelength and excellent laser light resistance can be obtained.

Further, the BHMPO of the present invention can be applied to second-order nonlinear devices such as optical rectification, optical mixing and parametric amplifier.

The BHMPO of the present invention is a third harmonic generation,
It can be applied to a third-order nonlinear device such as a car shutter, light mixing, an optical memory utilizing optical bistability, and an optical arithmetic element.

The BHMPO of the present invention is used as a wavelength conversion element by producing a single crystal by a method of precipitating a crystal from an organic solvent, Bridgman method, Czochralski method, sublimation method, etc., and cutting and polishing the single crystal. Can be used. It can also be used as a Cherenkov type or quasi phase matching type non-linear device.

[0027]

The organic nonlinear optical material BHMPO is considered to be extremely effective as a second-order nonlinear optical material because it has a non-centrosymmetric crystal structure as shown in FIG. 8 due to its unique molecular structure.

[0028]

【Example】

[Example 1] The BHMPO was recrystallized from each solution of methanol, acetonitrile, hexane, toluene, acetone, chloroform, and ethyl acetate, and the SHG (second harmonic generation) intensity of each powder was measured.

The measurement was carried out by S.M. K. Kurtz, T .; T. It carried out according to the method of Perry (J. Appl. Phys., 39 , 3798). A Q-switch YAG laser (wavelength 1064 nm) was used as a light source for the measurement. The powder sample was irradiated with laser light, and the generated second harmonic was collected and detected. The SHG intensity is shown in the table as a relative value with respect to the SHG intensity of the urea powder measured in the same manner.

[0030]

[Table 1]

Example 2 A wavelength conversion element was manufactured using BHMPO. In order to manufacture a wavelength conversion element, BHMPO was first highly purified by recrystallization from a solvent and zone melting. Next, when the purified material is kept in a molten state and a hollow glass capillary is introduced into the molten material from one end, the hollow portion of the glass capillary is filled with BHMPO by a capillary phenomenon. The glass capillary was slowly pulled out to a temperature region lower than the melting point of the organic material to fill the hollow portion of the glass capillary with a single crystal or polycrystal of BHMPO.

When the filled BHMPO is in a polycrystalline state, the glass capillary is heated again to a temperature higher than the melting point of BHMPO and then pulled out to a temperature region lower than the melting point to single crystallize the BHMPO. Laser light was made to enter the wavelength conversion element thus manufactured, and emission of light having a half wavelength of the laser light was confirmed.

[0033]

The BHMPO of the present invention has excellent nonlinear optical characteristics, and the nonlinear optical effect can be applied to various optical functional devices.

[Brief description of drawings]

FIG. 1 is a schematic view of an optical functional element using the organic nonlinear optical material of the present invention.

FIG. 2 is a schematic view of another optical functional element using the organic nonlinear optical material of the present invention.

FIG. 3 is a schematic view of another optical functional element using the organic nonlinear optical material of the present invention.

FIG. 4 is a schematic configuration diagram of an optical wavelength conversion device to which the optical functional element of the present invention is applied.

FIG. 5 is a schematic configuration diagram of another optical wavelength conversion device to which the optical functional element of the present invention is applied.

FIG. 6 is a schematic configuration diagram of another optical wavelength conversion device to which the optical functional element of the present invention is applied.

FIG. 7 is a schematic configuration diagram of an optical wavelength conversion device to which the nonlinear optical element of the present invention is applied.

FIG. 8 is a crystal structure diagram of an organic nonlinear optical material BHMPO of the present invention.

[Explanation of symbols]

1 ... Clad layer, 2 ... Non-linear optical material, 3 ... Substrate, 4 ...
Semi-transmissive mirror, 5 ... Light source, 6 ... Optical functional element, 7 ... Polarizing plate,
8 ... Incident light, 9 ... Output light, 10 ... Reflector, 11 ... Return light, 12 ... Other incident light, 21 ... Laser diode, 2
2 ... Collimator, 23 ... Anamorphic prism pair, 24 ... Condensing lens, 25 ... SHG element, 26 ... Laser light.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Miwa Kato 4026 Kuji-machi, Hitachi City, Ibaraki Prefecture, Hitate Manufacturing Co., Ltd.Hitachi Laboratory Ltd. Hitachi Research Laboratory (72) Inventor Tomoyuki Hamada 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd.

Claims (8)

[Claims] 1. An organic nonlinear optical material containing a compound represented by the formula [1]. [Chemical 1] 2. An optical function, wherein the organic nonlinear optical material comprises a 1 mm square or larger single crystal of the compound represented by the formula [1], and the single crystal is held in an optical resonator. Sex element. [Chemical 2] 3. The organic nonlinear optical material is a compound represented by the formula [1], and the compound is a dispersion dispersed in a transparent high molecular polymer and oriented in a strong electric field. An optical functional element characterized by being held in an optical resonator. [Chemical 3] 4. The optical functional device according to claim 3, wherein the transparent high molecular weight polymer in which the organic nonlinear optical material is dispersed is a polymer that does not absorb light having a wavelength of 400 nm or more. 5. The optical functional device according to claim 2, wherein the single crystal or dispersion of the organic nonlinear optical material forms an optical waveguide surrounded by a cladding layer. 6. An optical functional element having an optical waveguide formed on a substrate, wherein the optical waveguide is made of a single crystal or dispersion of the organic nonlinear optical material. Sex element. 7. A light comprising 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 wave. A wavelength conversion device, wherein the formula [1] is provided in the optical path of the harmonic generating means.
An optical wavelength conversion device comprising a single crystal of an organic nonlinear optical material represented by or a dispersion dispersed in a transparent high molecular weight polymer. [Chemical 4] 8. An electro-optical element for switching or modulating an optical signal by an electro-optical effect, wherein the optical path of the optical element is a single crystal or a transparent organic non-linear optical material represented by the formula [1]. An electro-optical element having a dispersion dispersed in a high molecular polymer. [Chemical 5]