JPH08313946A - Nonlinear optical thin film and its production - Google Patents

Abstract

PURPOSE: To obtain a large-size third-order nonlinear optical material by using composite fine particles. CONSTITUTION: Vapor deposition is performed on a quartz substrate in an argon gas atmosphere by using CdS, Ag, SiO2 , targets and a high frequency magnetron sputtering device while controlling the voltage applied on each target and vapor deposition time. In this method, a Ag thin film 2 is formed by vapor deposition, then CdS fine particles 1 are formed, further, a Ag thin film 2 is formed by vapor deposition to obtain composite fine particles having a structure of CdS fine particles/Ag layer, and then a SiO2 , layer 3 is formed by vapor deposition to obtain a laminar structure. This process is repeated to form 30 layers of the laminar structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a nonlinear optical thin film which is the basis of an optical device utilizing the third-order nonlinear optical effect.

[0002]

2. Description of the Related Art In recent years, nonlinear optical thin films have been considered for use as optical devices such as high-speed optical switches and harmonic generating elements. In particular, regarding a nonlinear optical thin film using a metal fine particle, a semiconductor fine particle, or an organic compound having a nonlinear optical property, which is the core of the thin film, development of a higher performance thin film, or an improved thin film and a manufacturing method thereof have been attracting attention. .

As a conventional technique in this field, Applied Physics A Vol. 47, 347 pages (Appl. Phy
s. A, Vol.47, 347 1988), there is a method for producing gold fine particle dispersed glass by a melting method. This method is based on the same melting and cooling method as the conventional filter-glass manufacturing method, and is a technique of precipitating gold ions dissolved in a glass matrix as fine gold particles by further heat treatment.

In addition, the journal of optical
Society of America Vol. 73 647 (J.
Opt. Soc. Am., Vol. 73 1983), a technique of using a cut-off filter glass in which CdS _x Se _1-x is dispersed in borosilicate glass for a nonlinear optical thin film has been proposed. . This cut-off filter glass is produced by putting a borosilicate glass raw material and CdS _x Se _1-x in a platinum crucible and melting at a temperature of about 1000 ° C.

[0005]

The method for producing a non-linear optical thin film in which metal fine particles are dispersed or semiconductor fine particles are dispersed in the above method has the following problems.

(1) In the case of fine metal particle-dispersed glass: The types of metals that can be melted by the melt cooling method are limited, and the third-order nonlinear optical constant is as small as 10 ^-11 esu. Moreover, since the solubility of the metal in glass is small, the amount of metal dispersed can be increased only by about 10 ⁻⁶ to 10 ⁻⁵ % by volume. Furthermore, in order to precipitate the metal dispersed in the glass as fine particles, 10
It must be heat-treated at a high temperature of 00 ° C. or higher for a long time. In addition, it is difficult to make a thin film, which is a promising device.

(2) Gold colloid solution: It is difficult to increase the gold colloid concentration, and the gold colloid aggregates at a concentration of 10 ^-6 % by volume or more. Also, the third-order nonlinear optical constant is as small as 10 ^-11 esu or less. Further, even if a low-concentration colloidal solution is prepared, it lacks long-term stability, and the solution composition gradually changes or the colloidal particle size increases with the passage of time.

(3) In the case of semiconductor fine particle dispersed glass: In the melt cooling method, a part of the constituent components of the semiconductor is evaporated during melting, the semiconductor composition changes, and the third-order nonlinear optical constant is also 10
There is a problem that it becomes as small as ^-11 to 10 ^-12 esu. Also,
It is difficult to make a thin film, which is a promising device.

According to the present invention, a semiconductor fine particle / metal layer, a semiconductor fine particle / semiconductor layer, or a composite fine particle composed of a metal fine particle / metal layer and exhibiting a third-order nonlinear optical effect is laminated with a glass or ceramic layer to form a tertiary layer. An object of the present invention is to provide a nonlinear optical thin film having an increased nonlinear optical susceptibility.

[0010]

To achieve the above object, the first non-linear optical thin film of the present invention comprises composite fine particles having a third-order non-linear optical effect having a structure in which the surface of semiconductor fine particles is coated with a metal layer. And a layer made of glass or ceramics that does not absorb light in the light absorption wavelength region of the layer made of the composite fine particles are sequentially laminated on the substrate.

The second nonlinear optical thin film of the present invention is
Glass having no light absorption in the light absorption wavelength range of a layer made of composite fine particles having a structure in which the surface of the semiconductor fine particles is coated with a semiconductor layer of a type different from that of the fine particles and exhibiting a third-order nonlinear optical effect, or A nonlinear optical thin film having a structure in which ceramic layers are sequentially laminated on a substrate.

The third nonlinear optical thin film of the present invention is
Glass having no light absorption in the light absorption wavelength range of a layer made of composite fine particles having a structure in which the surface of the metal fine particles is coated with a metal layer of a type different from that of the fine particles and exhibiting a third-order nonlinear optical effect, or A nonlinear optical thin film having a structure in which ceramic layers are sequentially laminated on a substrate.

In the nonlinear optical thin film of the present invention,
Semiconductor particles are ZnS, CdS, ZnSe, CdS
e, PbS, InP, InAs, GaAs, or Ga
It is preferably at least one selected from AlAs. Further, in the nonlinear optical thin film of the present invention,
The metal fine particles are preferably at least one selected from gold, platinum, silver, copper, tin, rhodium, palladium or iridium. Further, in the above-mentioned nonlinear optical thin film of the present invention, the semiconductor layer is ZnS, CdS, ZnS.
e, CdSe, PbS, InP, InAs, GaAs,
Alternatively, it is preferably at least one selected from GaAlAs. Further, in the nonlinear optical thin film of the present invention, the metal layer is preferably at least one selected from gold, platinum, silver, copper, tin, rhodium, palladium or iridium. Further, in the nonlinear optical thin film of the present invention, glass or ceramics,
Optically transparent SiO ₂ , TiO ₂ , and Al in a wide wavelength range
It is preferably at least one selected from ₂ O ₃ and SiN. Further, in the nonlinear optical thin film of the present invention, the substrate is SiO ₂ which is transparent in an optically wide wavelength range,
At least 1 selected from TiO ₂ , Al ₂ O ₃ and SiN
Preferably three.

Next, in the first method for producing a nonlinear optical thin film of the present invention, at least one selected from a metal, a semiconductor, a glass, or a ceramic is used for each target, and a metal is formed on the surface of semiconductor fine particles by a multi-source sputtering method. A layer made of composite fine particles having a third-order nonlinear optical effect, which has a layer-covered structure, and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially deposited on a substrate. It is equipped with the configuration.

In the second method for producing a non-linear optical thin film of the present invention, at least one selected from semiconductor, glass and ceramics is used for each target, and the fine particles are formed on the surface of the semiconductor fine particles by the multi-source sputtering method. Substrate in which a layer made of composite fine particles having a third-order nonlinear optical effect and having a structure of coating different types of semiconductor layers and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially formed. It has a structure of vapor deposition on top.

In the third method for producing a non-linear optical thin film of the present invention, at least one selected from metal, glass and ceramics is used for each target, and the fine particles are formed on the surface of the fine metal particles by the multi-source sputtering method. Substrate in which a layer made of composite fine particles having a third-order nonlinear optical effect having a structure in which different types of metal layers are coated and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially formed. It has a structure of vapor deposition on top.

[0017]

According to the first nonlinear optical material of the present invention,
It has a structure in which the surface of semiconductor particles is coated with a metal layer 3
Next, a nonlinear optical thin film having a structure in which a layer made of composite fine particles exhibiting a nonlinear optical effect and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially laminated on a substrate. As a result, it is possible to achieve a nonlinear optical thin film having a large third-order nonlinear optical susceptibility capable of increasing the nonlinear optical characteristics of semiconductor fine particles by the metal coating layer.

Further, according to the second nonlinear optical material of the present invention, a layer made of composite fine particles exhibiting a third-order nonlinear optical effect having a structure in which the surface of the semiconductor fine particles is coated with a semiconductor layer of a different type from the fine particles. The nonlinear optical characteristics of semiconductor fine particles are different by being a nonlinear optical thin film having a structure in which a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of composite fine particles is sequentially laminated on a substrate. It is possible to achieve a nonlinear optical thin film having a large third-order nonlinear optical susceptibility that can be increased by various types of semiconductor coating layers.

Further, according to the third nonlinear optical material of the present invention, a layer made of composite fine particles exhibiting a third-order nonlinear optical effect having a structure in which the surface of the metal fine particles is coated with a metal layer of a type different from the fine particles. The non-linear optical thin film having a structure in which a layer made of glass or ceramics having no light absorption in the light absorption wavelength range of the layer made of the composite fine particles is sequentially laminated on the substrate, and thus the non-linear optical characteristics of the metal fine particles are different. Non-linear optical thin films can be achieved that have a large third-order non-linear optical susceptibility that can be increased by a variety of metallization layers.

Further, the semiconductor fine particles are ZnS, CdS,
ZnSe, CdSe, PbS, InP, InAs, Ga
According to a preferred example of the present invention, which is at least one selected from As and GaAlAs, these semiconductors exhibit large nonlinear optical characteristics based on the quantum size effect, and can be easily atomized as compared with other semiconductors. It is also possible to realize a non-linear optical material having a larger third-order non-linear optical characteristic because it is less likely to be oxidized.

The fine metal particles are gold, platinum, silver, copper,
According to a preferred example of the present invention, which is at least one selected from tin, rhodium, palladium, and iridium, these metals exhibit nonlinear optical properties based on surface plasmon absorption and quantum size effect, and are superior to other metals. Since it is difficult to be affected by oxygen and other impurities and relatively pure metal fine particles can be deposited, it is possible to realize a nonlinear optical material having a larger third-order nonlinear optical characteristic.

The semiconductor layer is made of ZnS, CdS, Zn
Se, CdSe, PbS, InP, InAs, GaA
According to a preferred example of the present invention, which is at least one selected from s or GaAlAs, these semiconductors can be easily formed into a thin film as compared with other semiconductors by controlling vapor deposition conditions. Since it is difficult to oxidize, it is possible to easily coat different kinds of semiconductor fine particles and metal fine particles, and it is possible to realize a nonlinear optical material having a larger third-order nonlinear optical characteristic.

The metal layer is made of gold, platinum, silver, copper, tin,
According to the preferable example of the present invention, which is at least one selected from rhodium, palladium, and iridium, these metals can be easily formed into a thin film as compared with other metals by controlling vapor deposition conditions. Compared to other metals, it is less affected by oxygen and other impurities, different kinds of semiconductor fine particles and metal fine particles can be easily covered with a pure metal layer, and has a larger third-order nonlinear optical characteristic. It is possible to realize nonlinear optical materials.

According to a preferred example of the present invention in which the glass, ceramics or substrate is at least one selected from SiO ₂ , TiO ₂ , Al ₂ O ₃ and SiN, such glass, ceramics or substrate is used. But
Since it is chemically stable and optically transparent in a wide range, a nonlinear optical material having a large third-order nonlinear optical characteristic can be achieved.

Next, in the first method for producing a nonlinear optical thin film of the present invention, at least one selected from a metal, a semiconductor, glass, or a ceramic is used for each target, and a metal is formed on the surface of semiconductor fine particles by a multi-source sputtering method. A layer made of composite fine particles having a third-order nonlinear optical effect, which has a layer-covered structure, and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially deposited on a substrate. Since it is a method, it is possible to uniformly form a high concentration of composite fine particles having a third-order nonlinear optical effect having a structure in which the surface of semiconductor fine particles is coated with a metal layer, and a nonlinear optic having a large third-order nonlinear optical characteristic. The thin film can be easily manufactured. In the second method for producing a nonlinear optical thin film of the present invention, at least one selected from semiconductor, glass, and ceramics is used for each target, and the surface of the semiconductor fine particles is made of a different kind from the fine particles by the multi-source sputtering method. A layer composed of composite fine particles having a structure covering a semiconductor layer and exhibiting a third-order nonlinear optical effect, and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer composed of the composite fine particles are sequentially deposited on a substrate. Method, it is possible to uniformly form high-concentration composite fine particles having a third-order nonlinear optical effect having a structure in which different types of semiconductor layers are coated on the surface of the semiconductor fine particles, and to obtain large third-order nonlinear optical characteristics. It is possible to easily manufacture a nonlinear optical thin film having

In the third method for producing a nonlinear optical thin film of the present invention, at least one selected from metal, glass, and ceramics is used for each target, and the fine particles are formed on the surface of the fine metal particles by the multi-source sputtering method. Substrate in which a layer made of composite fine particles having a third-order nonlinear optical effect having a structure in which different types of metal layers are coated and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially formed. Since this is a method of vapor deposition on the upper surface, it is possible to uniformly form high-concentration composite fine particles having a third-order nonlinear optical effect, which has a structure in which different kinds of metal layers are coated on the surface of the metal fine particles, and a large third-order A non-linear optical thin film having non-linear optical characteristics can be easily manufactured.

[0027]

The present invention will be described more specifically with reference to the following examples.

Various combinations of the above-mentioned metal fine particles or semiconductor fine particles and metal layers or semiconductor layers are conceivable, but semiconductor fine particles / metal layer, semiconductor fine particles / semiconductor layer, or composite fine particles composed of metal fine particles / metal layer are preferable. In the case of composite fine particles composed of semiconductor fine particles / semiconductor layer, it is preferable that the band gap of the semiconductor fine particles is smaller than that of the semiconductor layer.

The dispersion amount of such composite fine particles is not particularly limited, but if it is too small, the nonlinear optical characteristics are not sufficiently obtained, and if it is too large, the light absorption increases and the light transmittance decreases. Or, since the aggregation of fine particles is likely to occur, it is preferably about 0.01 to 50 wt%, and more preferably 0.0 to 50 wt%.
1 to 30 wt% is preferable.

In the sputtering method used in the present invention, it is usually preferable to use argon gas, nitrogen gas or the like.
The gas pressure during sputtering is not particularly limited, but is usually in the range of 10 ^-2 to 10 ^-4 Torr.

The average radius of the fine particles used in the metal fine particles or the semiconductor fine particle layer varies depending on the type, but is preferably in the range of, for example, 1 nm to 50 nm in general, and the metal fine particles have a clear surface plasmon resonance absorption. It is preferable that the semiconductor fine particles have a large quantum size effect.

The composition ratio of the semiconductor fine particles / metal layer, the semiconductor fine particles / semiconductor layer, or the composite fine particles of metal fine particles / metal layer varies depending on the kind of combination, but is usually 0.5 to 0 in volume ratio. A range of 9.9 is preferred.

In the conventional structure, the fine particles are dispersed in the glass layer, but in the present invention, the semiconductor fine particles and the metal fine particles are covered with the metal layer or the semiconductor layer, and the composite layer and the glass layer are laminated. Therefore, the concentration of the electric field does not occur,
As a result, a nonlinear optical thin film having a high optical susceptibility can be formed.

Specific examples of the present invention will be described below. (Example 1) Cd having a diameter of 3 inches and a purity of 99.99%
Using S, Ag, and SiO ₂ targets in an argon gas atmosphere with a high-frequency magnetron sputtering device while controlling the applied power and deposition time of each target, each target was placed on a 0.5 mm thick quartz substrate. Deposition was performed. FIG. 1 shows a schematic sectional view of the produced thin film.

First, as shown in FIG. 1, an Ag thin film 2 was vapor-deposited on a quartz substrate 4 to a thickness of 10 nm (the substrate temperature at this time was 300 ° C.), and then CdS fine particles 1 were formed (the substrate at this time). (Temperature is 25 ° C), and then Ag thin film 2 is vapor-deposited to form CdS.
Composite fine particles composed of fine particles / Ag layer were formed. After that, the SiO ₂ layer 3 was vapor-deposited to laminate 30 layers (the substrate temperature at this time was 25 ° C.). Each size is
The average particle size of CdS is 5 nm, and the thickness of the Ag layer is 1.0 n.
m, the thickness of the SiO ₂ layer was 20 nm.

Since the band edge of the absorption spectrum of the thin film thus manufactured is blue-shifted as compared with 0.6 eV bulk CdS, the quantum size effect of the composite fine particle quantum was confirmed. Furthermore, front incidence type degeneration 4
The third-order nonlinear optical susceptibility by the light wave mixing method was 5 × 10 ⁻⁶ esu near the band edge.

Further, as a comparison with this example, a thin film having a structure in which 30 layers of CdS fine particles having no Ag layer and SiO ₂ layers were alternately laminated was prepared. In this thin film, the average particle size of the CdS fine particles was 5 nm, the thickness of the SiO ₂ layer was 20 nm, and the third-order nonlinear optical susceptibility by the front incidence degenerate four-wave mixing method was 7 × 10 ^−. It was ⁸ esu.

Therefore, when the Ag layer is used as the nonlinear optical thin film as in the present invention, the optical susceptibility is remarkably increased.

In the above structure, in addition to CdS fine particles / Ag layer, ZnS fine particles / Ag layer, ZnSe fine particles / Ag layer
Layer, CdSe fine particles / Ag layer, PbS fine particles / Ag layer,
InP fine particles / Ag layer, InAs fine particles / Ag layer, Ga
As fine particles / Ag layer or GaAlAs fine particles / Ag
The composite fine particles composed of layers were formed, and the third-order nonlinear optical susceptibility was 10 to 1000 times larger than that of the fine particles without Ag layer in the thin film having the same structure as in FIG.

Further, in place of SiO ₂ in this embodiment, T
Even if iO ₂ , Al ₂ O ₃ and SiN were used, a thin film showing almost the same characteristics was obtained.

Example 2 Diameter 3 inches, Purity 99.9
Using 9% CdTe, Au, SiO ₂ target,
Deposition was performed from each target on a 0.5 mm-thick quartz substrate while controlling the power applied to each target and the deposition time in an argon gas atmosphere using a high-frequency magnetron sputtering device. The structure of the produced thin film is the same as that shown in FIG. 1. In this example, the Au thin film 2 was vapor-deposited on the quartz substrate 4 in FIG. 1 (the substrate temperature at this time was 400 ° C.), and CdTe fine particles 1 are formed on the substrate (at a substrate temperature of 50 ° C. at this time), a thin film 2 of Au is further vapor deposited to form composite fine particles of CdTe fine particles / Au layer, and then a SiO ₂ layer 3 is vapor deposited to form a laminated structure. 30
The layers were laminated (the substrate temperature at this time was 50 ° C.). The size of each is such that the average particle size of the CdTe fine particles is 6 nm,
Layer thickness 1.2 nm, SiO ₂ layer thickness 20 nm
Met.

Since the band edge of the absorption spectrum of the thin film thus produced is blue-shifted as compared with 0.8 eV bulk CdTe, the quantum size effect of the composite fine particle quantum was confirmed. Furthermore, the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method was 7 × 10 ⁻⁶ esu near the band edge.

Further, as a comparison with this example, a thin film having a structure in which 30 layers of CdTe fine particles without an Au layer and SiO ₂ layers were alternately laminated was prepared. In this thin film, the average particle size of the CdTe fine particles was 6 nm, the thickness of the SiO ₂ layer was 20 nm, and the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method was 3 × 10 ^−. It was ⁸ esu.

Therefore, when the Au layer is used as the nonlinear optical thin film as in the present invention, the optical susceptibility is remarkably increased.

In the above structure, CdTe fine particles / Au
In addition to the layers, ZnS particles / Au layer, ZnSe particles / A
u layer, CdSe fine particles / Au layer, PbS fine particles / Au
Layer, InP fine particles / Au layer, InAs fine particles / Au layer,
GaAs particles / Au layer, or GaAlAs particles /
The composite fine particles made of the Au layer were formed, and the third-order nonlinear optical susceptibility was 10 to 100 times larger than that of the fine particles having no Au layer in the thin film having the same structure as in FIG.

Further, T is used instead of SiO ₂ in this embodiment.
Even if iO ₂ , Al ₂ O ₃ and SiN were used, a thin film showing almost the same characteristics was obtained.

Example 3 Diameter 3 inches, Purity 99.9
Using 9% CdS, PbS, SiO ₂ target,
Deposition was performed from each target on a 0.5 mm thick quartz substrate while controlling the power applied to each target and the deposition time in an argon atmosphere using a high frequency magnetron sputtering device. The structure of the produced thin film is the same as that shown in FIG. 1. In this example, the PbS thin film 2 was vapor-deposited on the quartz substrate 4 in FIG. 1 (the substrate temperature at this time was 350 ° C.), and CdS fine particles 1 are formed on the substrate (the substrate temperature at this time is 25 ° C.), and the PbS thin film 2 is further formed.
Was vapor-deposited to form composite fine particles composed of CdS fine particles / PbS layer, and then SiO ₂ layer 3 was vapor-deposited to form 30 laminated layers (at this time, the substrate temperature was 25 ° C.). Regarding the respective sizes, the average particle diameter of the CdS fine particles was 4 nm, the thickness of the PbS layer was 0.8 nm, and the thickness of the SiO ₂ layer was 20 nm.

Since the band edge of the absorption spectrum of the thin film thus manufactured is blue-shifted as compared with 0.4 eV bulk CdS, the quantum size effect of the composite fine particle quantum was confirmed. Furthermore, front incidence type degeneration 4
The third-order nonlinear optical susceptibility by the light wave mixing method was 7 × 10 ⁻⁷ esu near the band edge.

Further, as a comparison of this example, a thin film having a structure in which 30 CdS fine particles without PbS layers and SiO ₂ layers were alternately laminated was prepared. In this thin film, the average grain size of CdS was 4 nm, the thickness of the SiO ₂ layer was 20 nm, and the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method was 3 × 10 ^{−8 in the} vicinity of the band edge. It was esu.

Therefore, when the PbS layer is used as the nonlinear optical thin film as in the present invention, the optical susceptibility is remarkably increased.

In the above structure, CdS fine particles / PbS
In addition to the layers, ZnS particles / PbS layer, ZnSe particles /
PbS layer, CdS fine particles / CdSe layer, ZnS fine particles /
The composite fine particles made of CdSe were formed, and the third-order nonlinear optical susceptibility was 10 to 100 times higher than that of the fine particles without the semiconductor coating layer in the thin film having the same structure as in FIG.

Further, in place of SiO ₂ in this embodiment, T
Even if iO ₂ , Al ₂ O ₃ and SiN were used, a thin film showing almost the same characteristics was obtained.

Example 4 Diameter 3 inches, Purity 99.9
9% GaAs, GaAlAs, and SiO ₂ targets were used, and the power applied to each target was adjusted using a high-frequency magnetron sputtering device in an argon atmosphere.
Deposition was performed from each target on a quartz substrate having a thickness of 0.5 mm while controlling the deposition time. The structure of the produced thin film is the same as that shown in FIG. 1, and in this embodiment,
In FIG. 1, a GaAlAs thin film 2 is vapor-deposited on a quartz substrate 4 (at this time, the substrate temperature is 280 ° C.), then GaAs fine particles 1 are formed (at this time, the substrate temperature is 25 ° C.), and the GaAlAs thin film 2 is further formed. Vapor deposition of GaAs fine particles / GaA
After forming the composite fine particles composed of the 1As layer, the SiO ₂ layer 3 was vapor-deposited to form 30 laminated layers (at this time, the substrate temperature was 25 ° C.). The average size of the GaAs particles is 4 nm and the thickness of the GaAlAs layer is 0.8.
nm, and the thickness of the SiO ₂ layer was 20 nm.

Since the band edge of the absorption spectrum of the thin film thus manufactured is blue-shifted as compared with 0.7 eV bulk GaAs, the quantum size effect of the composite fine particle quantum was confirmed. Furthermore, the third-order nonlinear optical susceptibility obtained by the front incidence type degenerate four-wave mixing method was 9 × 10 ⁻⁷ esu near the band edge.

Further, as a comparison of this embodiment, GaAlAs
A thin film having a structure in which 30 layers of GaAs fine particles having no layers and SiO ₂ layers were alternately laminated was prepared. In this thin film, Ga
The average particle size of As is 4 nm, and the thickness of the SiO ₂ layer is 20 nm.
And the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method is 6 × 10 ⁻⁸ esu near the band edge.
Met.

Therefore, when the GaAlAs layer is used as the nonlinear optical thin film as in the present invention, the optical susceptibility is remarkably increased.

In the above structure, GaAs fine particles / Ga
In addition to the AlAs layer, composite fine particles composed of InP fine particles / InAs layer were formed, and the third-order nonlinear optical susceptibility was 10 to 100 times larger than the fine particles without the semiconductor coating layer in the thin film having the same structure as in FIG. .

Further, T is used instead of SiO ₂ in this embodiment.
Even if iO ₂ , Al ₂ O ₃ and SiN were used, a thin film showing almost the same characteristics was obtained.

Example 5 Diameter 3 inches, Purity 99.9
Using a 9% Au, Ag, and SiO ₂ target in an argon atmosphere with a high-frequency magnetron sputtering device, controlling the applied power and deposition time of each target, each target was placed on a 0.5 mm thick quartz substrate. The vapor deposition was performed from. The structure of the produced thin film is similar to that of the schematic cross-sectional view shown in FIG. 1. In this embodiment, the Au thin film 2 is vapor-deposited on the quartz substrate 4 in FIG. 1 (the substrate temperature at this time is 400 ° C.). Then, Ag fine particles 1 are formed (at this time, the substrate temperature is 25 ° C.), a thin film 2 of Au is further deposited to form composite fine particles composed of Ag fine particles / Au layer, and then a SiO ₂ layer 3 is deposited. Thirty layers of the laminated structure were laminated (the substrate temperature at this time was 25 ° C.). Each size is
The average particle size of the Ag particles is 3 nm, and the thickness of the Au layer is 1.
The thickness was 2 nm, and the thickness of the SiO ₂ layer was 20 nm.

In the absorption spectrum of the thin film thus produced, a peak due to the surface plasmon absorption of Ag particles was found at 430 nm. Furthermore, the third-order nonlinear optical susceptibility measured by the front incidence type degenerate four-wave mixing method was 3 × 10 ⁻⁷ esu at each surface plasmon absorption wavelength.

Further, as a comparison with this example, a thin film having a structure in which 30 Ag layers without an Au layer and 30 SiO ₂ layers were alternately laminated was prepared. In this thin film, the average particle diameter of Ag was 3 nm, the thickness of the SiO ₂ layer was 20 nm, and the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method was
It was 9 × 10 ⁻⁹ esu in the vicinity of the band edge.

Therefore, when the Au layer is used as the nonlinear optical thin film as in the present invention, the optical susceptibility is remarkably increased.

Further, in place of SiO ₂ in this embodiment, T
Even if iO ₂ , Al ₂ O ₃ and SiN were used, a thin film showing almost the same characteristics was obtained.

In the above structure, in addition to the combination of Ag particles / Au layer, Ag particles / Pt layer, Cu particles / Au.
Layer, Sn / Au layer, Rh / Au layer, Pd / Au layer, I
The composite fine particles composed of the r / Au layer were formed, and the third-order nonlinear optical susceptibility was 10 to 100 times larger than that of the metal fine particles without the metal coating layer in the thin film having the same structure as in FIG.

(Embodiment 6) An optical bistable device was manufactured using the material shown in the above-mentioned embodiment 1, and a wavelength of 440 was applied to this device.
Laser light of nm was incident with a spot diameter of 5 μm, and the relationship between the intensity of the incident light and the intensity of the emitted light was measured at room temperature (25 ° C.), and bistable characteristics were exhibited at each wavelength.

(Embodiment 7) An optical bistable device was manufactured using the materials shown in the above-mentioned embodiment 5, and a wavelength 430 was applied to this device.
Laser light of nm was incident with a spot diameter of 5 μm, and the relationship between the intensity of the incident light and the intensity of the emitted light was measured at room temperature (25 ° C.), and bistable characteristics were exhibited at each wavelength.

[0067]

As described above, according to the first non-linear optical material of the present invention, a layer of composite fine particles having a third-order non-linear optical effect having a structure in which the surface of semiconductor fine particles is coated with a metal layer The non-linear optical thin film has a structure in which a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of a layer made of composite fine particles is sequentially laminated on a substrate, so that the non-linear optical characteristics of semiconductor fine particles are metal-coated. It is possible to provide a nonlinear optical thin film having a large third-order nonlinear optical susceptibility that can be increased by layers.

According to the second nonlinear optical material of the present invention, a layer made of composite fine particles having a third-order nonlinear optical effect, which has a structure in which the surface of semiconductor fine particles is coated with a semiconductor layer of a different type from the fine particles, The nonlinear optical characteristics of semiconductor fine particles are different by being a nonlinear optical thin film having a structure in which a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of composite fine particles is sequentially laminated on a substrate. It is possible to provide a nonlinear optical thin film having a large third-order nonlinear optical susceptibility that can be increased by various types of semiconductor coating layers.

According to the third nonlinear optical material of the present invention, a layer made of composite fine particles having a third-order nonlinear optical effect, which has a structure in which the surface of the metal fine particles is coated with a metal layer of a different type from the fine particles, The non-linear optical thin film having a structure in which a layer made of glass or ceramics having no light absorption in the light absorption wavelength range of the layer made of the composite fine particles is sequentially laminated on the substrate, and thus the non-linear optical characteristics of the metal fine particles are different. It is possible to provide a non-linear optical thin film having a large third-order non-linear optical susceptibility that can be increased by various kinds of metal coating layers.

The semiconductor fine particles are ZnS, CdS,
ZnSe, CdSe, PbS, InP, InAs, Ga
According to a preferred example of the present invention, which is at least one selected from As and GaAlAs, these semiconductors exhibit large nonlinear optical characteristics based on the quantum size effect, and can be easily atomized as compared with other semiconductors. It is also possible to provide a non-linear optical material having a larger third-order non-linear optical characteristic because it is less likely to be oxidized.

The metal fine particles are gold, platinum, silver, copper,
According to a preferred example of the present invention, which is at least one selected from tin, rhodium, palladium, and iridium, these metals exhibit nonlinear optical properties based on surface plasmon absorption and quantum size effect, and are superior to other metals. Since it is less susceptible to oxygen and other impurities and relatively fine metal particles can be deposited, it is possible to provide a nonlinear optical material having a larger third-order nonlinear optical characteristic.

The semiconductor layer is made of ZnS, CdS, Zn
Se, CdSe, PbS, InP, InAs, GaA
According to a preferred example of the present invention, which is at least one selected from s or GaAlAs, these semiconductors can be easily formed into a thin film as compared with other semiconductors by controlling vapor deposition conditions. Since it is difficult to oxidize, it is possible to easily coat different kinds of semiconductor fine particles and metal fine particles, and it is possible to provide a nonlinear optical material having a larger third-order nonlinear optical characteristic.

The metal layer is made of gold, platinum, silver, copper, tin,
According to the preferable example of the present invention, which is at least one selected from rhodium, palladium, and iridium, these metals can be easily formed into a thin film as compared with other metals by controlling vapor deposition conditions. Compared to other metals, it is less affected by oxygen and other impurities, different kinds of semiconductor fine particles and metal fine particles can be easily covered with a pure metal layer, and has a larger third-order nonlinear optical characteristic. A non-linear optical material can be provided.

According to a preferred example of the present invention in which the glass, ceramics or substrate is at least one selected from SiO ₂ , TiO ₂ , Al ₂ O ₃ and SiN, such glass, ceramics or substrate is used. But
Since it is chemically stable and optically transparent in a wide range, it is possible to provide a nonlinear optical material having a large third-order nonlinear optical characteristic.

Next, in the first method for producing a nonlinear optical thin film of the present invention, at least one selected from a metal, a semiconductor, glass, or a ceramic is used for each target, and a metal is formed on the surface of semiconductor fine particles by a multi-source sputtering method. A layer made of composite fine particles having a third-order nonlinear optical effect, which has a layer-covered structure, and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially deposited on a substrate. Since it is a method, it is possible to uniformly form a high concentration of composite fine particles having a third-order nonlinear optical effect having a structure in which the surface of semiconductor fine particles is coated with a metal layer, and a nonlinear optic having a large third-order nonlinear optical characteristic. A thin film can be easily provided.

In the second method for producing a nonlinear optical thin film of the present invention, at least one selected from semiconductor, glass, or ceramics is used for each target, and the fine particles are formed on the surface of the semiconductor fine particles by the multi-source sputtering method. Substrate in which a layer made of composite fine particles having a third-order nonlinear optical effect and having a structure of coating different types of semiconductor layers and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially formed. Since this is a method of vapor deposition on the upper surface, it is possible to uniformly form high-concentration composite fine particles having a third-order nonlinear optical effect having a structure in which semiconductor layers of different types are coated on the surface of the semiconductor fine particles, and to obtain a large third-order It is possible to easily provide a nonlinear optical thin film having nonlinear optical characteristics.

In the third method for producing a nonlinear optical thin film of the present invention, at least one selected from metal, glass, and ceramics is used for each target, and the fine particles are formed on the surface of the metal fine particles by the multi-source sputtering method. Substrate in which a layer made of composite fine particles having a third-order nonlinear optical effect having a structure in which different types of metal layers are coated and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially formed. Since this is a method of vapor deposition on the upper surface, it is possible to uniformly form high-concentration composite fine particles having a third-order nonlinear optical effect, which has a structure in which different kinds of metal layers are coated on the surface of the metal fine particles, and a large third-order It is possible to easily provide a nonlinear optical thin film having nonlinear optical characteristics.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a nonlinear optical thin film according to an embodiment of the present invention.

[Explanation of symbols]

 1 fine particles 2 coating layer 3 glass 4 substrate

Claims (12)

[Claims] 1. A composite fine particle layer having a structure in which semiconductor fine particles are covered with a metal layer and exhibiting a third-order nonlinear optical effect, and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the composite fine particle layer. A non-linear optical thin film in which and are alternately laminated on a substrate. 2. A composite fine particle layer having a structure in which semiconductor fine particles are covered with a semiconductor layer of a type different from that of said semiconductor fine particles, and showing a third-order nonlinear optical effect; and a light absorption wavelength range of said composite fine particle layer. A non-linear optical thin film in which layers made of non-glass or ceramics are alternately laminated on a substrate. 3. A composite fine particle layer having a structure in which metal fine particles are coated with a metal layer of a type different from that of said metal fine particles and exhibiting a third-order nonlinear optical effect, and a light absorption wavelength range of said composite fine particle layer. A non-linear optical thin film in which layers made of non-glass or ceramics are alternately laminated on a substrate. 4. The semiconductor fine particles are ZnS, CdS, ZnS.
e, CdSe, PbS, InP, InAs, GaAs,
Alternatively, the nonlinear optical thin film according to claim 1 or 2, wherein the nonlinear optical thin film is at least one selected from GaAlAs. 5. The nonlinear optical thin film according to claim 3, wherein the fine metal particles are at least one selected from gold, platinum, silver, copper, tin, rhodium, palladium and iridium. 6. The semiconductor layer comprises ZnS, CdS, ZnSe,
The nonlinear optical thin film according to claim 2, which is at least one selected from CdSe, PbS, InP, InAs, GaAs, and GaAlAs. 7. The nonlinear optical thin film according to claim 1, wherein the metal layer is at least one selected from gold, platinum, silver, copper, tin, rhodium, palladium and iridium. 8. A layer made of glass or ceramics,
Nonlinear optical thin film according to any one of claims 1 to 3, wherein the _{SiO 2, TiO 2, Al 2} O 3, is at least one selected from SiN. 9. The substrate is SiO ₂ , TiO ₂ , Al ₂ O ₃ or S.
At least one selected from iN, The nonlinear optical thin film in any one of Claims 1-3. 10. A target made of metal, semiconductor, glass,
Alternatively, by using at least one selected from ceramics, the light of the layer composed of the composite particles and the layer composed of the composite particles, which has a third-order nonlinear optical effect and has a structure in which the surface of the semiconductor particles is coated with a metal layer by the multi-source sputtering method. Layers made of glass or ceramics that do not absorb light in the absorption wavelength range are sequentially deposited on the substrate by stacking, and the substrate temperature at the time of coating the metal layer is the substrate temperature at the time of forming the semiconductor fine particles. A method for manufacturing a non-linear optical thin film, characterized by being higher than the above. 11. A third-order nonlinear structure having a structure in which at least one selected from semiconductor, glass, and ceramics is used for each target, and the surface of semiconductor fine particles is coated with a semiconductor layer of a different type from the fine particles by a multi-source sputtering method. A layer made of composite fine particles exhibiting an optical effect and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially laminated on the substrate, and the semiconductor layer is formed. A method for producing a non-linear optical thin film, wherein the substrate temperature at the time of coating is higher than the substrate temperature at the time of forming the semiconductor fine particles. 12. A third-order nonlinear structure in which at least one selected from metal, glass, and ceramics is used for each target, and the surface of metal fine particles is coated with a metal layer of a different type from the fine particles by a multi-source sputtering method. A layer made of composite fine particles exhibiting an optical effect and a layer made of glass or ceramics that does not absorb light in the light absorption wavelength range of the layer made of the composite fine particles are sequentially laminated on the substrate, and the metal layer is formed. A method for producing a non-linear optical thin film, characterized in that the substrate temperature at the time of coating is higher than the substrate temperature at the time of forming the metal fine particles.