JPH07248516A - Nonlinear optical material and its production - Google Patents

Abstract

PURPOSE:To produce a novel low-cost nonlinear optical material stably exhibiting a high nonlinear optical effect and excellent in safety. CONSTITUTION:A thin film of a substance contg. oxide of at least one kind of metal (A) selected from the group consisting of V, Cr Mn, Fe, Co, Ni and Cu is formed on a transparent substrate to obtain a tert. nonlinear optical material. A thin film of a composite obtd. by dispersing and depositing at least one kind of metal (B) selected from among Au, Ag and Cu as fine particles of <=500nm particle diameter in the interior or on the surface of a substance contg. oxide of the metal A is formed on a transparent substrate to obtain a tert. nonlinear optical material. A substance contg. oxide of the metal A is dispersed and deposited as fine particles of <=500nm particle diameter in a transparent substance to produce a tert. nonlinear optical material. A substance contg. oxide of the metal A and the metal B are dispersed and deposited as fine particles of <=500nm particle diameter in a transparent substance to produce a tert. nonlinear optical material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-linear optical material which is the basis of an optical device utilizing the non-linear optical effect and a method for producing the same, and more specifically, a metal oxide thin film and a metal fine particle having a large non-linear optical effect are dispersed and deposited. Metal oxide thin film,
The present invention also relates to a substance in which a metal oxide and / or a metal is made into fine particles and dispersed and precipitated in a transparent substance, and a method for producing them.

[0002]

[Prior Art and its Problems] CdS is a substance having a relatively large non-linear optical effect that has been found in the past.
Glass in which semiconductor fine particles such as are dispersed and deposited and glass in which precious metal fine particles such as Au are dispersed and deposited are known. In these substances, a large nonlinear optical effect can be obtained only when the semiconductor or the noble metal is made into fine particles.
When the particles are not made fine, almost no nonlinear optical effect is exhibited. Further, in those materials, glass only serves as a matrix for dispersing fine particles, and does not contribute to the increase of the nonlinear optical effect. Therefore, when a large amount of semiconductor or noble metal fine particles are contained in the glass, the nonlinearity is increased. The optical effect increases.

However, there is an upper limit for the ratio of such fine semiconductor particles or fine noble metal particles to be contained in the glass due to the nature of the substance and technical restrictions. Taking fine gold particles as an example, it is difficult to contain at least about 6.3 atom% (40% by weight) even by the technique using the ion implantation method capable of dispersing and depositing the largest amount in silica glass at present. . Therefore, the third-order nonlinear optical effect due to the fine gold particles is also limited to the amount of dispersion. Further, although the noble metal fine particle-dispersed glass has high stability, since the noble metal as a raw material is expensive, a nonlinear optical material using a cheaper raw material is desired. On the other hand, semiconductor fine particle-dispersed glass such as CdS is liable to cause a decrease in the nonlinear optical effect due to light irradiation and a blackening phenomenon, and those dispersed and precipitated in the porous glass undergo oxidative decomposition and liberate sulfur when left for a long time. There is a problem in stability because it may change over time, such as due to the presence of cadmium, which is harmful to the human body. Further, it is difficult to say that the productivity is high because a complicated process is required to disperse and precipitate the semiconductor or the noble metal in the form of fine particles in the glass and process it into a fiber or a thin film having an arbitrary shape. Therefore, the semiconductor fine particle-dispersed glass and the noble metal fine particle-dispersed glass have drawbacks as nonlinear optical materials.

[0004]

SUMMARY OF THE INVENTION In view of the current state of nonlinear optical materials, an object of the present invention is to provide a novel nonlinear optical material that stably exhibits a high nonlinear optical effect, is inexpensive, and is excellent in safety, and its It is to provide a manufacturing method.

[0005]

The present invention has been made in order to achieve the above object, and the third-order nonlinear optical material of the present invention comprises V, Cr, Mn, Fe, Co, Ni and Cu. A thin film containing an oxide of at least one metal selected from the group consisting of: is formed on a transparent substrate (hereinafter referred to as the first invention).

The "metal oxide" used in the first invention is not particularly limited with respect to the oxidation state of the metal, and for example, Cr ₂ O ₃ , MnO ₂ , Mn ₃ O ₄ , Fe ₂ O ₃ , Fe ₃ O. ₄ , CoO, Co ₃ O ₄ , Cu
Any of various oxidation states such as O is used, and particularly preferred metal oxides are Cr ₂ O ₃ , Mn ₃ O ₄ , Fe ₂ O ₃ ,
Examples include Co ₃ O ₄ and CuO. In addition, in the metal oxide,
Besides the single metal oxides mentioned above, MnCo ₂ O ₄ , NiC
Complex oxides such as o ₂ O ₄ and NiMnCo ₄ O ₈ are also included.

The thin film of the substance containing the metal oxide of the first invention does not itself contribute to the nonlinear optical effect of the metal oxide, but by adding it, the thin film production of the metal oxide is facilitated. An additive component having a high optical transparency and a function of improving the structural stability and mechanical strength of the thin film may be added. Although such an additive component is not particularly limited, Al ₂ O ₃ , ZnO, ZrO _{2 and the} like are exemplified. The ratio of the number of metal atoms in the metal oxide to the number of metal atoms in the additive component is usually (1: 0.01) to (1: 0.
It is about 10).

As a transparent substrate to which the above thin film is applied,
Examples thereof include glass containing SiO ₂ as a main component, quartz, and sapphire containing Al ₂ O ₃ . These materials have a flat plate shape.

Further, the third-order nonlinear optical material of the present invention is
At least one selected from the group consisting of Au, Ag, and Cu is provided inside or on the surface of a substance containing an oxide of at least one metal selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, and Cu. A thin film of a composite in which fine particles of one kind of metal having a particle size of 500 nm or less are dispersed and deposited is formed on a transparent substrate (hereinafter referred to as a second invention).

In the second invention, the metal oxide and the transparent substrate are the same as those in the first invention.

Au, Ag, and Cu used in the second invention are usually used as a simple metal.

From the group consisting of Au, Ag, and Cu, the number of metal atoms in the substance containing the oxide of at least one metal selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, and Cu. The compounding ratio of the number of atoms of at least one selected metal is not particularly limited, but is preferably about (1: 0.05) to (1: 4), more preferably (1: 0.2) to (( It is about 1: 2). When at least one metal selected from the group consisting of oxides of the above metals and Au, Ag, Cu is within the above range, structural changes such as aggregation of metal fine particles due to heat during laser light irradiation Is less likely to occur and a desired nonlinear optical effect can be obtained, which is preferable.

The fine particles of at least one metal selected from the group consisting of Au, Ag and Cu used in the second invention have a particle size of 500 nm or less, preferably 5 to 100.
nm. In the second invention, V, Cr, Mn, Fe, Co,
The particle diameter of the oxide of at least one metal selected from the group consisting of Ni and Cu is arbitrary as long as the substance containing the oxide is a thin film, and even when the thin film is an aggregate of fine particles, the particles are The diameter is arbitrary.

Furthermore, the present invention relates to V, Cr, Mn, Fe, Co, N
A method for producing a third-order nonlinear optical material, characterized in that a substance containing an oxide of at least one metal selected from the group consisting of i and Cu is dispersed and precipitated as fine particles having a particle size of 500 nm or less in a transparent substance ( Hereinafter referred to as the third invention) and the third
It is also a third-order nonlinear optical material manufactured by the method of the invention.

As the metal oxide, there are the above-mentioned first and second metal oxides.
The same thing as the invention is used.

As the transparent material used in the third invention, all the materials used in the transparent substrate used in the first invention can be used. However, the shape is not limited.

The metal oxide used in the third invention is
The same thing as the first and second inventions is used, but its particle size is 500 nm or less, preferably 5 to 100.
nm.

Further, the present invention relates to V, Cr, Mn, Fe, Co, N
A substance containing an oxide of at least one metal selected from the group consisting of i and Cu, and at least one metal selected from the group consisting of Au, Ag, and Cu as fine particles having a particle size of 500 nm or less. It is also a third-order nonlinear optical material produced by the method for producing a third-order nonlinear optical material (hereinafter referred to as the fourth invention), which is characterized in that it is dispersed and precipitated in a transparent substance, and the method according to the fourth invention.

The first to fourth inventions will be described in detail below.

In the first aspect of the present invention, an oxide of at least one metal selected from V, Cr, Mn, Fe, Co, Ni and Cu is used as the main component of the nonlinear optical material. These oxides have the property of exhibiting a high third-order nonlinear optical effect under the irradiation of intense light such as laser light. The reason why such a phenomenon occurs is not clear, but it is presumed that it is due to the following principle. That is,
These metal oxides have continuous absorption bands in a wide wavelength range including ultraviolet, visible, and near infrared, and have semiconductor-like properties. Therefore, when the metal oxide is irradiated with laser light having a frequency near the band gap, the carrier density in the excited state remarkably increases, saturation absorption occurs, and the refractive index changes.
It is presumed that the second-order nonlinear optical effect appears. Further, it is considered that the change of the refractive index due to the temperature rise accompanying the irradiation of the laser beam also contributes to the expression of the third-order nonlinear optical effect.

Such a phenomenon does not appear in all metal oxides, but satisfies the two conditions of (a) having an absorption band at the wavelength of the irradiation laser beam and (b) having a semiconducting property. It is considered to be achieved only with metal oxides. The above-mentioned thin films of oxides of at least one metal selected from V, Cr, Mn, Fe, Co, Ni, and Cu all exhibit a high third-order nonlinear optical effect.

The thin film is usually formed on a transparent substrate such as glass, quartz or sapphire. The method for forming the thin film is not particularly limited, and a so-called vapor phase method such as a sputter deposition method, a vacuum vapor deposition method, a CVD method, or a solution of a metal alkoxide, a metal nitrate salt, an organic acid metal salt, or the like is applied on the substrate and thermally decomposed. How to do
Various known methods can be applied. The thickness of the thin film is not particularly limited, but when used as a nonlinear optical material by transmitting laser light to the thin film, if the thin film becomes too thick, the light transmission rate will decrease and the output light will be reabsorbed by the thin film. As a result, the usefulness as a nonlinear optical material is reduced. Usually, in the case of a dense thin film such as a thin film formed by the sputter deposition method, it is usually about 2 to 50 nm, preferably 5 to 20 nm is appropriate, and is formed by a method of applying a solution and thermally decomposing. Since the thin film is relatively not dense, it can be used as a nonlinear optical material even with a thicker film. On the other hand, when a thin film of a nonlinear optical material is formed on the surface of an optical waveguide and an evanescent wave exuding from the optical waveguide is used, there is no problem in using the thin film if it is too thick, but if the thin film is too thin, the nonlinear optical effect will occur. Since it is not an excellent material, the thickness of the thin film is
2nm or more, more preferably 2 ~ 100n
m, more preferably about 5 to 50 nm.

In the second aspect of the invention, fine particles of at least one metal selected from Au, Ag and Cu are dispersed and deposited in or on the surface of the thin film containing the above metal oxide as a main component. The purpose of mixing the metal fine particles in the composite material of the present invention is to enhance the nonlinear optical effect of the metal oxide thin film. Since the metal oxide thin film and the metal fine particles each have a high non-linear optical effect, the non-linear optical effect is enhanced as compared with a thin film containing only one of the components.

The method for forming such a metal fine particle-dispersed metal oxide composite film of the second invention is not particularly limited, and a metal oxide target and a metal target are used to deposit on the substrate by simultaneous sputtering or alternate sputtering. Method, a solution of a metal alkoxide, which is a precursor of a metal oxide, a metal nitrate, a metal salt of an organic acid, etc., and a solution of a substance, such as chloroauric acid, which is a precursor of metal fine particles, or a metal fine particle dispersion liquid. After forming a film on the substrate by spin coating, etc.,
A method of firing in an atmosphere containing oxygen such as air, a sputter deposition method on a porous or smooth metal oxide thin film,
A method of immobilizing metal fine particles by a method such as coating with a metal fine particle dispersion can be applied.

In the third invention, the transparent material is Si.
Glass matrix containing O _2, Al ₂ O _3, ZrO ₂ or the like can be mentioned fine particles of the metal oxide is 0.1% by weight or more transparent substance, preferably 2 to 80 wt%, more preferably 10 to 50 Dispersed and precipitated at a weight percentage. The metal oxide in the first invention is made into Cd by forming fine particles.
Similar to semiconductors such as S, due to the quantum size effect, when compared per unit number of atoms, it shows a larger nonlinear optical effect than thin-film metal oxides without atomization. Therefore, a material in which a certain amount or more of metal oxide fine particles are dispersed in a transparent matrix such as glass exhibits a larger nonlinear optical effect than a continuous metal oxide thin film which is not made into fine particles. The particle size of the metal oxide to be precipitated in the glass matrix is required to be 500 nm or less, in order to increase the nonlinear optical effect by the quantum size effect, preferably 5 to 100 nm, more preferably 5 to 50 nm. .

In the metal oxide-containing glass produced according to the third aspect of the invention, it is easy to increase the content concentration of the metal oxide fine particles, and the size of the metal oxide fine particles can be controlled. From a certain point, since there are many kinds of metal oxides that can be dispersed and precipitated, it is manufactured by using a porous glass matrix or by a sputter deposition method.

Conventionally, a method has been disclosed in which a dispersion of metal oxide fine particles is infiltrated into a porous glass matrix, dried, and then heated to 1500 ° C. in an atmosphere containing oxygen to prepare a nonlinear optical material (Japanese Patent Laid-Open No. Hei 10 (1999) -242242). 2-44031). However, in this method, only a porous glass matrix having a pore size larger than the diameter of the metal oxide fine particles can be used, and the type of metal oxide and the metal oxide fine particles from which the metal oxide fine particle dispersion liquid can be obtained. There is a drawback that the size of is limited. Therefore, there is a demand for a method in which the type and size of the metal oxide fine particles can be selected and dispersed and precipitated in the porous glass matrix with a high degree of freedom according to the purpose.

In order to solve such problems, when the glass containing a metal oxide of the third invention is produced using a porous glass matrix, for example, vanadyl isopropoxide or vanadyl ethoxide is added to the porous glass matrix. Impregnated with a solution of metal alkoxides such as, metal nitrates such as manganese nitrate, cobalt nitrate, ferrous nitrate, and copper nitrate, organic acid metal salts such as vanadium octylate, nickel octylate, chromium naphthenate, and copper naphthenate. The method of thermal decomposition after drying is used.

In carrying out the method for producing the metal oxide-containing glass of the third invention by using the sputter deposition method, for example, a silica glass target and a metal oxide target are used and the substrate is subjected to simultaneous sputtering or alternating sputtering, Alternatively, it is possible to adopt a method of depositing on the glass having different refractive indexes forming the optical waveguide.

In the fourth aspect of the present invention, the glass matrix is contained in a proportion of 0.1% by weight or more, preferably 2 to 80% by weight, more preferably 10 to 50% by weight, together with the above-mentioned metal oxide fine particles. Dispersed and precipitated in a transparent substance such as. The purpose of mixing the metal fine particles in the composite material of the present invention is to enhance the nonlinear optical effect of the metal oxide fine particles. Since both the metal oxide fine particles and the metal fine particles have a high non-linear optical effect, the non-linear optical effect is enhanced as compared with a material in which only one of the single components is dispersed and precipitated in the transparent substance. The grain size of the metal oxide and the grain size of the metal to be precipitated in the transparent substance is 50 because the quantum size effect increases the nonlinear optical effect.
It must be 0 nm or less. The ratio of the metal oxide and the metal to be precipitated in the transparent substance is not particularly limited, but the ratio of the metal oxide and the metal to the transparent substance is 0.
If it is less than 1% by weight, a metal oxide / metal-containing glass having an excellent non-linear optical effect cannot be obtained. Therefore, the ratio of the metal oxide and the metal is preferably 0.1% by weight or more.

In the metal oxide / metal-containing glass produced according to the fourth aspect of the invention, it is easy to increase the concentration of the metal oxide / metal fine particles, and the size of the metal oxide / metal fine particles is large. The porous glass matrix is used for the production, or the sputter deposition method is used because of the large amount of metal oxides and metals that can be dispersed and precipitated.

When a metal oxide / metal-containing glass is produced by using the porous glass matrix according to the method of the fourth aspect of the invention, for example, a metal alkoxide or a metal nitrate, which is a precursor of the metal oxide, is added to the porous glass matrix. A method of impregnating with a solution of an organic acid metal salt or the like and a solution of a substance such as chloroauric acid serving as a metal precursor, drying and then thermally decomposing it can be used.

When the metal oxide / metal-containing glass is produced by the sputter deposition method according to the method of the fourth aspect of the invention, for example, a silica glass target, a metal oxide target, and a metal target are used to perform a co-sputtering method or It is possible to adopt a method of depositing on the substrate or on the glass constituting the optical waveguide having different refractive indexes by the alternate sputtering method.

In the first to fourth inventions, these metal oxides can be used alone or in combination. Also,
It may be used not only as an oxide of a single component metal element but also as a composite oxide.

In the third and fourth inventions, in order to reduce the scattering of light due to the voids remaining in the porous glass and to improve the non-linear optical effect, the manufactured material is adjusted to 600
Post-treatment such as heat treatment at a high temperature of ℃ or more may be performed.

[0036]

According to the present invention, it is possible to provide a novel nonlinear optical material which stably exhibits a high nonlinear optical effect, is inexpensive, and is excellent in safety, and a method for producing the same.

[0037]

EXAMPLES Hereinafter, examples of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A copper naphthenate film was formed on a glass substrate (one surface) by a spin coating method, and baked at 380 ° C. for 2 hours to prepare a light brown transparent copper oxide (CuO) thin film having a thickness of about 35 nm. did. The third-order nonlinear susceptibility (χ ⁽³⁾ ) of this copper oxide thin film was 5x10 ^-8 esu as measured by the degenerate four-wave mixing method (DFWM) at a wavelength of 532 nm, and it has high performance that can be used as a nonlinear optical material. all right.

Example 2 A cobalt oxide (Co ₃ O ₄ ) thin film having a thickness of about 60 nm and showing a transparent light brown color was prepared on a glass substrate (one surface) by a sputtering method.
The third-order nonlinear susceptibility (χ ⁽³⁾ ) of this cobalt oxide thin film was 4 × 10 ^-8 esu as measured by the degenerate four-wave mixing method (DFWM) at a wavelength of 532 nm.

Example 3 A toluene solution of iron naphthenate and a toluene dispersion of fine gold particles having an average particle size of 10 nm were mixed, and this solution was spin-coated on a glass substrate (one surface) to form iron naphthenate and fine gold particles. A mixed film was formed. This mixed film was baked at 380 ° C. for 2 hours to prepare an iron oxide (Fe ₂ O ₃ ) -gold fine particle composite thin film having a thickness of about 30 nm and exhibiting reddish purple and light brown transparency. The third-order nonlinear susceptibility (χ ⁽³⁾ ) of this composite thin film degenerates at a wavelength of 532 nm 4
The measurement result by the optical wave mixing method (DFWM) was 1x10 ^-7 esu, and the performance as a nonlinear optical material was improved by compounding.

Example 4 A mixed toluene solution of manganese nitrate and cobalt nitrate was impregnated into a porous glass matrix having an average pore diameter of 4 nm, a porosity of 28% and a specific surface area of 200 m ² / g, and dried and then dried at 380 ° C. for 2 hours. A brown material was prepared by firing to fix the manganese-cobalt composite oxide in the pores of the porous glass. The third-order nonlinear susceptibility (χ ⁽³⁾ ) of this manganese-cobalt composite oxide fine particle-dispersed glass has a degenerate four-wave mixing method (DFW) at a wavelength of 532 nm.
The result measured by M) was 10 ^-10 esu.

Example 5 Chloroauric acid was added to and dissolved in a toluene / butanol mixed solution of cobalt octylate, and the resulting mixed solution was subjected to porosity having an average pore diameter of 4 nm, a porosity of 28% and a specific surface area of 200 m ² / g. The glass matrix was impregnated, dried, and then baked at 380 ° C. for 2 hours to prepare a purple-brown material in which cobalt oxide and gold were immobilized in the pores of the porous glass. The third-order nonlinear susceptibility (χ ⁽³⁾ ) of the cobalt oxide fine particle / gold fine particle-dispersed glass was 10 ^-9 esu as measured by the degenerate four-wave mixing method (DFWM) at a wavelength of 532 nm.

[Brief description of drawings]

FIG. 1 is a diagram showing light absorption characteristics of a thin film manufactured in a first example of the present invention.

FIG. 2 is a diagram showing light absorption characteristics of a thin film manufactured in a third embodiment of the present invention.

FIG. 3 is a diagram showing a process of a fifth embodiment of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sakaguchi Ryo 1-831 Midorigaoka, Ikeda City, Osaka Prefecture Industrial Technology Institute, Osaka Institute of Industrial Technology (72) Inventor Masaru Miya, 1-8, Midorigaoka, Ikeda, Osaka Prefecture No. 31 Industrial Technology Institute Osaka Institute of Technology

Claims (6)

[Claims] 1. A third-order nonlinearity obtained by forming a thin film of a substance containing an oxide of at least one metal selected from the group consisting of V, Cr, Mn, Fe, Co, Ni and Cu on a transparent substrate. Optical material. 2. A group consisting of Au, Ag and Cu inside or on the surface of a substance containing an oxide of at least one metal selected from the group consisting of V, Cr, Mn, Fe, Co, Ni and Cu. A third-order nonlinear optical material comprising a transparent substrate and a thin film of a composite in which fine particles of at least one kind of metal selected from the group having a particle size of 500 nm or less are dispersed and deposited. 3. A substance containing an oxide of at least one metal selected from the group consisting of V, Cr, Mn, Fe, Co, Ni and Cu, dispersed and precipitated in a transparent substance as fine particles having a particle size of 500 nm or less. A method of manufacturing a third-order nonlinear optical material, comprising: 4. A product manufactured by the method according to claim 3.
Non-linear optical material. 5. A substance containing an oxide of at least one metal selected from the group consisting of V, Cr, Mn, Fe, Co, Ni and Cu,
Also, a method for producing a third-order nonlinear optical material, characterized in that at least one metal selected from the group consisting of Au, Ag, and Cu is dispersed and precipitated as fine particles having a particle size of 500 nm or less in a transparent substance. 6. A device manufactured by the method according to claim 5.
Non-linear optical material.