JPH052199A - Wavelength conversion element - Google Patents

Abstract

PURPOSE:To control the solid orientation of an org. material and to obtain high efficiency by constituting the above-mentioned element of an org. crystal having nonlinear optical characteristics and a base having the refractive index lower than the refractive index of this crystal. CONSTITUTION:This wavelength conversion element of a waveguide type consists of the org. crystal 1 having the nonlinear optical characteristics and the base 2 having the refractive index lower than the refractive index of this crystal 1. This wavelength conversion element is made incident with basic waves on the crystal part, converts the wavelength of the incident light to a second harmonic wave and guides this wave to generate 1/2 wavelength of the incident light. The nonlinear optical crystal to be used here is adequately the optically active amine salt of the carboxylic acid expressed by formula I. In the formula I, (n) is 0, 1 or 2; Ar is 5 to 14C arom. group; R1- is a functional group selected from an amino group expressed by R2R3N-, ether group expressed by R4-O-, thioether group expressed by R5-S-, nitrile group, -COOR6, ester group expressed by -OCOR7 (R2 to R7 is 1 to 8C hydrocarbon group or hydrogen atom), etc.

Description

Detailed Description of the Invention

[0001]

The present invention relates to the field of optical information transmission technology,
The present invention relates to an optical wavelength conversion element in the field of optical recording technology.

[0002]

2. Description of the Related Art In recent years, it has been known that the nonlinear optical characteristics of organic substances are larger than those of existing inorganic compounds. On the other hand, in the field of optical recording, recording / reading or shortening of the writing wavelength has been required from the viewpoint of high density recording. For this purpose, the second harmonic generation (a phenomenon in which light having a wavelength half the wavelength of the incident light is emitted), which is one of the nonlinear optical characteristics, has been studied in detail. A. YARIV, Kunio Tada, Takeshi Kamiya translation (Maruzen Co., Ltd.) p250-259 is generally used. However, the mechanism of wavelength conversion in such a state is a phenomenon that the activity becomes high only when the phase matching condition utilizing the birefringence of the crystal is satisfied, and in order to arrange this condition,
Very complicated operations are required, such as determining the space layout,
In addition, the behavior of birefringence often changes depending on the external temperature and humidity, which is a problem in practical use.

As a method for solving the above problems,
Cherenkov radiation has been studied for making a waveguide type device and facilitating generation of the second harmonic in a certain direction.

In this case, in particular, the form of the material that causes the nonlinear optical phenomenon has a great effect on the generation of the second harmonic, and this control is an essential technique for improving the conversion efficiency. Especially, since the wavelength conversion efficiency is proportional to the power density of the laser light,
It is necessary to devise to confine incident light as much as possible. In addition, an organic material, which is generally said to have better nonlinear optical characteristics than an inorganic material, may not fully exhibit its original performance due to a change in the spatial arrangement of molecules in the solid structure. The present invention aims to provide a wavelength conversion element having a high efficiency by controlling a solid orientation of an organic material by using a novel material having a large non-linear optical property and eliminating such a defect.

[0005]

That is, the present invention relates to a waveguide type wavelength conversion element comprising an organic crystal having nonlinear optical characteristics and a support having a refractive index lower than that of the crystal. The wavelength conversion element of the present invention is characterized in that a fundamental wave is incident on a crystal part, the incident light wavelength is converted into a second harmonic, and the second harmonic is guided. The nonlinear optical crystal used in the present invention has the following general formula (1).
An optically active amine salt of a carboxylic acid represented by

R ₁ -Ar- (CH = CH) _n -CH = C (CN) -COOH (1) [where n represents 0, 1 or 2] Ar has 5 carbon atoms
~ 14 aromatic groups. R ₁ -is an amino group represented by R ₂ R ₃ N-, an ether group represented by R ₄ -O-, R
₅ -thio group represented by -S-, nitrile group, -C
An ester group represented by OOR ₆ and -OCOR ₇ , -CO
NR ₈ R _9, amido group represented by -NR ₁₀ COR _11, -
A hydrocarbon group represented by R ₁₂ (R _{2 to} R ₁₂ are functional groups selected from the same or different hydrocarbon groups having 1 to 8 carbon atoms, or a hydrogen atom)] Used in the present invention The optically active amines are 1-phenylethylamine, 1-
It is preferably one selected from α-naphthylamine, 1-phenyl-2-methylethylamine, 1-phenyl-2-aminopropane and brucine.

L-(-)-phenylethylamine salt of 4-dimethylaminophenylpentadienenoic acid is preferable as the carboxylic acid amine salt having nonlinear optical characteristics.

Regarding the preparation of such a material, as shown in, for example, Japanese Patent Application Laid-Open No. 1-245230 (published on September 29, 1991), α-obtained by the reaction of an aromatic aldehyde with an active methylene compound. It can be prepared by reacting a cyanoacrylic acid compound with the optically active amine described above. The optically active salt of a carboxylic acid represented by the above general formula can be formed into crystals by a slow evaporation method in which a solvent is slowly evaporated after being dissolved in a polar solvent. In the production of the wavelength conversion element according to the present invention, these crystals can be produced separately in another space and then mounted on a support whose refractive index is smaller than this crystal. , By using the capillary phenomenon in the gap between the two substrates with the spacing of several μ adjusted, the solution is allowed to stand still,
By evaporating the solvent, a molded product integrated with the substrate can be obtained. As the support material, it is essential that it is smaller than the refractive index of the nonlinear optical material, and various glass materials, particularly silica borate glass, are preferably used. Forming grooves in advance on the surface of the support in contact with the nonlinear optical material may facilitate the integration of molding.

[0009]

When the wavelength of the incident light is single, the wavelength conversion element described in the present invention generates the second harmonic wave in which the wavelength of the incident light is halved. For example, 800 mμ used in CD reading. If a semiconductor laser having a light emission wavelength in the vicinity is used as an input light source, light emission of 400 mμ occurs, and the conventional reading density can be improved 3 to 4 times.
Further, if two types of incident light sources having different wavelengths are used, it can be used as an optical element which emits light having a wavelength which is a reciprocal of the sum of the reciprocals of both wavelengths, generally a long wavelength.

[0010]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 L-(-)-phenylethylamine salt of 4-dimethylaminophenylpentadienenoic acid was used as a carboxylic acid amine salt having non-linear optical characteristics, and a solution was prepared by dissolving 500 mg of this powder in 10 ml of methanol. Then, as shown in FIG. 1, one side is dipped in two pieces of silicoborate glass (refractive index: 1.46) sandwiching a 20 micron polyethylene terephthalate film in this solution. The two substrates with the solution rising due to the capillary phenomenon sandwiched therein were allowed to stand at room temperature for about 7 days. About 2 mm in the gap between the boards
Precipitation of plate-like crystals of about × 10 mm was observed. As shown in FIG. 2, when a YAG laser having a wavelength of 1.06 μ was incident on this portion, green light was observed from the other end face. The spectrum of this emission was measured by a wavelength scan with a multi-channel photo detector, and the result is shown in FIG. From this figure, it was confirmed that this emission consists of 1/2 wavelength of the incident light and is not phosphorescence or fluorescence accompanying excitation.

[0011]

Example 2 As a carboxylic acid amine salt having a non-linear optical characteristic, 1-α-naphthylamine salt of α-cyano-p-dimethylaminocinnamic acid was used, and two pieces of silicoboric acid glass were used as in Example 1. Crystallization was performed in the gap to prepare an element sandwiching a plate crystal having a size of about 2 mm × 8 mm. When a laser beam of 1.06 μm was incident on this end face, green light emission was observed from the other end faces.

[0012]

Example 3 Using 1-α-naphthylamine salt of α-cyano-p-methoxyphenylpropenoic acid as a carboxylic acid amine salt having nonlinear optical properties, two pieces of silicoboric acid were used in the same manner as in Example 1. Crystallization was carried out in the gaps between the glass to prepare an element sandwiching a plate crystal having a size of about 3 mm × 5 mm. When 0.83μ of laser light was incident on this end face, the emission of light from the other end face was measured by wavelength scanning with a multi-channel photodetector. As a result, it was confirmed that the wavelength was 0.42μ.

[Brief description of drawings]

FIG. 1 shows a concept of a method for producing a wavelength conversion element.

FIG. 2 is a conceptual diagram showing a mechanism of a wavelength conversion element.

FIG. 3 shows an emission spectrum of the wavelength conversion element in Example 1.

[Explanation of symbols]

1 Non-linear optical crystal 2 Support substrate 3 Non-linear material solution 10 incident light 11 Outgoing light 12 Laser light source 13 Condensing lens

Claims (3)

[Claims] 1. A waveguide type wavelength conversion element comprising an organic crystal having nonlinear optical characteristics and a support having a refractive index lower than that of the crystal. 2. The organic crystal having the non-linear optical characteristics is represented by the following general formula (1) R ₁ -Ar- (CH = CH) _n -CH = C (CN) -COOH (1) [where n is 0 , 1 or 2 is represented. Ar has 5 carbon atoms
~ 14 aromatic groups. R ₁ -is an amino group represented by R ₂ R ₃ N-, an ether group represented by R ₄ -O-, R
₅ -thio group represented by -S-, nitrile group, -C
An ester group represented by OOR ₆ and -OCOR ₇ , -CO
NR ₈ R _9, amido group represented by -NR ₁₀ COR _11, -
A hydrocarbon group represented by R ₁₂ (R _{2 to} R ₁₂ are functional groups selected from the same or different hydrocarbon groups having 1 to 8 carbon atoms, or a hydrogen atom)] The wavelength conversion element according to claim 1, which is an optically active amine salt of an acid. 3. The optically active amine according to claim 2, selected from 1-phenylethylamine, 1-α-naphthylamine, 1-phenyl-2-methylethylamine, 1-phenyl-2-aminopropane and brucine. The wavelength conversion element according to claim 2, wherein the wavelength conversion element is one type.