JP3928036B2 - Inductive absorption material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction absorbing material. An induced absorption material is a material having induced absorption characteristics. In other words, a material that exhibits absorption characteristics that when the excitation light is incident, the light absorptivity (absorbance) of the material changes reversibly (increases / decreases) at a high speed at a wavelength different from that of the excitation light, depending on the intensity of the excitation light. It is.
[0002]
[Prior art]
When excitation light is incident, a material that exhibits a property that the light absorption rate (absorbance) of the material changes reversibly at high speed at the same wavelength as the excitation light or at a different wavelength depending on the intensity of the excitation light is light. Since it can be applied to various devices that control light, it is industrially important. Among these materials, materials that exhibit the property that the light absorption rate of the material changes reversibly at high speed at the same wavelength as the excitation light according to the intensity of the excitation light are collectively referred to as “nonlinear absorption materials”. The A material exhibiting nonlinear absorption characteristics also exhibits a refractive index change corresponding to the excitation light intensity, that is, a nonlinear refractive index change, based on the relationship between light absorption and refractive index.
[0003]
Among nonlinear absorbing materials, a material that exhibits the property that the light absorption rate of the material decreases reversibly at high speed at the same wavelength as the excitation light according to the intensity of the excitation light is called a “saturable absorber”. When a saturable absorber is combined with a half mirror to form a device such as a Fabry-Perot resonator or a ring resonator, the transmitted light intensity of the device responds to a slight increase in excitation light intensity to the device at high speed. A high-speed optical-optical switch function corresponding to an optical transistor that greatly increases or decreases is exhibited. In addition, a high-speed optical-optical memory function based on optical bistability obtained from the device structure based on such an optical switch function is exhibited.
[0004]
On the other hand, among non-linear absorption materials, a material that exhibits the property that the light absorption rate of the material increases reversibly at high speed at the same wavelength as the excitation light according to the intensity of the excitation light is called “reverse saturable absorber”. be called. The “reverse supersaturated absorber” can be applied as a material that exhibits an effect of suppressing the transmitted light intensity below a certain level only when weak light is transmitted well but strong light is incident, that is, a “light limiting material”.
[0005]
For materials that use excitation light and transmitted light of the same wavelength, such as “saturable absorbers” suitable for optical switches and memories, and “reverse saturable absorbers” suitable as light limiting materials, that is, nonlinear absorbing materials On the other hand, materials that exhibit the property that the light absorption rate of the material changes reversibly at high speed at a wavelength different from that of the excitation light according to the excitation light intensity are collectively referred to as an induced absorption material. Such a material using pumping light and transmitted light having different wavelengths is industrially important as a material having applicability to a high-speed optical switch material, a high-speed optical logic operation element, and the like.
[0006]
In the case of an induced absorption material in which light absorption increases reversibly at a wavelength different from that of excitation light when strong excitation light is incident, the relationship between excitation light intensity and transmitted light intensity at another wavelength Based on the above, it can be applied as a material for NOT type optical logic operation element.
[0007]
On the other hand, in the case of an inductive absorption material that absorbs strong excitation light and reversibly reduces light absorption at a wavelength different from that of the excitation light, the excitation light intensity and the transmitted light intensity at another wavelength. Based on this relationship, it can be applied as an AND type optical logic device material, a high-speed optical switch material, and the like.
[0008]
Necessary conditions for industrial applications include high-speed response that immediately responds when strong excitation light is input and reversibly express induced absorption, and large induced absorption. In addition, when strong excitation light is incident, the material does not undergo irreversible photoreaction, it is difficult to undergo thermal decomposition due to temperature rise, and when weak excitation light is incident, light is continuously irradiated for a long time. However, stability that does not change the light absorption characteristics is required.
[0009]
Conventionally, CdS, CdSe, and CdS are materials that exhibit relatively good induced absorption characteristics. _x Se _1-x Materials that consist only of semiconductors and materials in which semiconductor fine particles are dispersed and contained in transparent substances have been mainly researched and developed (for example, Masanori Ando, Chemistry and Industry, Vol. 4, No. 4, p. 621 (1997) )).
[0010]
However, such semiconductors are easily oxidized by oxygen in the atmosphere, and the induced absorption characteristics are likely to be reduced or deteriorated by the oxidation. In particular, when intense excitation light such as laser light is irradiated in an environment where oxygen is present, reduction and deterioration of induced absorption characteristics that are probably caused by photoreactions and thermal reactions are often accelerated. For example, even when the excitation light intensity to the material is lower than the destruction threshold of the material, there are phenomena such as the optical characteristics related to the induced absorption characteristics being gradually reduced or deteriorated by the laser irradiation for a long time. appear. The low stability of the optical characteristics related to the induced absorption characteristics is a problem (for example, Sakaguchi Takashi et al., The Review of Laser Engineering, Vol. 20, No. 2, p. 98 (1992)). .
[0011]
Thus, there is a demand for the development of a high-performance induction absorbing material that is more stable with respect to light irradiation in the atmosphere.
[0012]
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the prior art, and is less likely to cause irreversible characteristics change / deterioration due to photoreaction or temperature rise even when irradiated with intense laser light as excitation light. The main object of the present invention is to provide an induction absorbing material that can be used repeatedly and stably in the atmosphere for a long period of time.
[0013]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that the above object can be achieved by forming a thin film containing a specific metal oxide on a substrate, and have completed the present invention.
[0014]
That is, the present invention relates to the following induction absorbing material.
1. At least one selected from the group consisting of Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ru, In, Sn, Sb, Ta, W, Re, Os, Ir, and Bi An induction absorbing material formed from a metal oxide and a transparent substrate.
2. 2. The induction absorbing material according to 1 above, wherein the metal oxide is a thin film formed on a transparent substrate.
3. 3. The induction absorbing material according to 2 above, wherein the thin film further contains a transparent oxide or a transparent polymer.
4). 4. The induction absorbing material according to 3 above, wherein the metal oxide is fine particles, and a composite thin film in which the metal oxide fine particles are dispersed in a transparent oxide or a transparent polymer is formed on a transparent substrate.
5. The sol or gel obtained by hydrolyzing an organic solvent solution containing at least one compound selected from the group consisting of metal alkoxides and alkoxysilanes, and a group consisting of organic acid metal salts, inorganic acid metal salts and complexes Metal oxide fine particles in a transparent oxide obtained by adding a solution containing at least one selected from the above, applying the resulting mixture to a substrate, and heat-treating the applied substrate at 300 to 800 ° C. An induction absorbing material in which a composite thin film in which is dispersed is formed on a transparent substrate.
6). 6. The above 4 or 5 wherein the ratio of the number of non-oxygen atoms in the transparent oxide to the number of metal atoms in the metal oxide or the total number of monomer units constituting the transparent polymer is 1: 1 to 100. Inductive absorption material.
7). 3. The ratio of the number of non-oxygen atoms in the transparent oxide to the number of metal atoms in the metal oxide or the total number of monomer units constituting the transparent polymer is from 1: 0.01 to 1. Inductive absorption material.
8). 2. The induction absorbing material according to 1 above, wherein the metal oxide is fine particles and dispersedly contained in the transparent substrate.
9. 9. The induction absorbing material according to 8 above, wherein a transparent oxide or a transparent polymer is further dispersed in the transparent substrate.
10. 9. The ratio of the number of non-oxygen atoms in the transparent oxide to the number of metal atoms in the metal oxide or the total number of monomer units constituting the transparent polymer is from 1: 0.01 to 1. Inductive absorption material.
11. 11. The induction absorbing material according to any one of 8 to 10 above, wherein the transparent substrate is porous glass.
12 Transparent oxide is SiO ₂ , Al ₂ O _Three , ZrO ₂ , HfO ₂ , ThO ₂ , ZnO and Ta ₂ O _Five The induced absorption material according to any one of 3 to 7 and 9 to 11 selected from the group consisting of:
13. 13. The induction absorbing material according to any one of 3 to 7 and 9 to 12, wherein the transparent polymer is at least one selected from the group consisting of acrylic resins, polycarbonate resins, polystyrene resins and polyvinyl resins.
14 14. The induction absorbing material according to any one of 1 to 13, wherein the metal oxide is fine particles, and the average particle size of the metal oxide fine particles is 1000 nm or less.
15. Metal oxide is TiO, Ti ₂ O _Three , TiO ₂ , CrO, Cr ₂ O _Three , CrO ₂ , Cr ₂ O _Five , CrO _Three , CrO _Five , MnO, Mn _Three O _Four , Mn ₂ O _Three , MnO ₂ , MnO _Three , Mn ₂ O ₇ , FeO, Fe _Three O _Four , Fe ₂ O _Three , CoO, Co ₂ O _Three , Co _Three O _Four , CoO ₂ , NiO, Ni _Three O _Four , Ni ₂ O _Three , NiO ₂ , Cu ₂ O, CuO, ZnO, NbO, Nb ₂ O _Three , NbO ₂ , Nb ₂ O _Five , MoO, Mo ₂ O _Three , MoO ₂ , Mo ₂ O _Five , MoO _Three , RuO, Ru ₂ O _Three , RuO ₂ , RuO _Four , In ₂ O, In ₂ O _Three , SnO, SnO ₂ , Sb ₂ O _Three , Sb ₂ O _Four , Sb ₂ O _Five , TaO ₂ , Ta ₂ O _Three , Ta ₂ O _Five , WO ₂ , W ₂ O _Five , WO _Three , Re ₂ O, ReO, Re ₂ O _Three , ReO ₂ , Re ₂ O _Five , ReO _Three , Re ₂ O ₇ , OsO, Os ₂ O _Three , OsO ₂ , OsO _Three , OsO _Four , Ir ₂ O _Three , IrO ₂ , BiO, Bi ₂ O _Three And Bi ₂ O _Five 15. The induction absorbing material according to any one of 1 to 14, which is at least one selected from the group consisting of:
16. Metal oxide is XCr ₂ O _Four (X is any one of Mg, Zn, Cu, Mn, Fe, Co and Ni), Na ₂ SnO _Three , Pb ₂ SnO _Four , Bi ₂ Sn ₂ O ₇ , Bi ₂ O _Three ・ AMoO3 (a is 4, 3, 2, 1, 1/2, 1/3 or 1/10), Bi ₂ O _Three ・ BWO _Three (b is 2-3, 1, 1 / 2-1 / 5 or 1/10), cBi ₂ O _Three ・ Sb ₂ O _Five (c is 1 or 3), Bi ₉ PMo ₁₂ O ₅₂ , Fe ₂ (MoO _Four ) _Three , (MoO _Three ) _1.0 (Cr ₂ O _Three ) _0.75 , A _d WO _Three (0 <d <1, A is any one of H, Li, K, Na, Rb, Ca, Cu, Ag, In, Tl, Sn, Pb and rare earth elements), LiTi ₂ O _Four , MnCo ₂ O _Four , NiCo ₂ O _Four And NiMnCo _Four O ₈ 15. The induction absorbing material according to any one of 1 to 14, which is at least one selected from the group consisting of:
17. A high-speed optical switch using the induction absorbing material according to any one of 1 to 16 above.
18. A high-speed optical logic device using the induction absorbing material according to any one of 1 to 16 above.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The induced absorption material of the present invention is composed of Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ru, In, Sn, Sb, Ta, W, Re, Os, Ir, and Bi. It is formed from an oxide of at least one metal selected from the group and a transparent substrate.
[0016]
The induction absorbing material of the present invention may contain a transparent oxide or a transparent polymer (hereinafter, these may be referred to as “transparent components”).
[0017]
The induced absorption material of the present invention can have the following structure.
1) A thin film made of only a metal oxide is formed on a transparent substrate.
2) A composite thin film containing a metal oxide and a transparent oxide or a transparent polymer is formed on a transparent substrate.
3) Metal oxide fine particles are dispersed in the transparent substrate.
4) Metal oxide fine particles and transparent oxide or transparent polymer are dispersed in the transparent substrate.
[0018]
The thin film made of only the metal oxide may be a thin film formed by aggregation of metal oxide fine particles or a continuous film.
[0019]
When a composite thin film containing a metal oxide and a transparent oxide or transparent polymer is formed on a transparent substrate, (a) a transparent oxide or transparent polymer is added to the metal oxide Either a composite thin film or (b) a composite thin film in which metal oxide fine particles are dispersed in a transparent oxide or a transparent polymer may be used. (a) The metal oxide in the composite thin film in which a transparent oxide or a transparent polymer is added to the metal oxide may be fine particles, and a continuous film is formed together with the transparent oxide or polymer. It may be formed.
[0020]
The metal oxide used in the present invention may be a single metal oxide, a complex oxide, or a mixture thereof.
[0021]
The oxidation state of the metal contained in the metal oxide is not particularly limited. For example, TiO, Ti as single metal oxide ₂ O _Three , TiO ₂ , CrO, Cr ₂ O _Three , CrO ₂ , Cr ₂ O _Five , CrO _Three , CrO _Five , MnO, Mn _Three O _Four , Mn ₂ O _Three , MnO ₂ , MnO _Three , Mn ₂ O ₇ , FeO, Fe _Three O _Four , Fe ₂ O _Three , CoO, Co ₂ O _Three , Co _Three O _Four , CoO ₂ , NiO, Ni _Three O _Four , Ni ₂ O _Three , NiO ₂ , Cu ₂ O, CuO, ZnO, NbO, Nb ₂ O _Three , NbO ₂ , Nb ₂ O _Five , MoO, Mo ₂ O _Three , MoO ₂ , Mo ₂ O _Five , MoO _Three , RuO, Ru ₂ O _Three , RuO ₂ , RuO _Four , In ₂ O, In ₂ O _Three , SnO, SnO ₂ , Sb ₂ O _Three , Sb ₂ O _Four , Sb ₂ O _Five , TaO ₂ , Ta ₂ O _Three , Ta ₂ O _Five , WO ₂ , W ₂ O _Five , WO _Three , Re ₂ O, ReO, Re ₂ O _Three , ReO ₂ , Re ₂ O _Five , ReO _Three , Re ₂ O ₇ , OsO, Os ₂ O _Three , OsO ₂ , OsO _Three , OsO _Four , Ir ₂ O _Three , IrO ₂ , BiO, Bi ₂ O _Three , Bi ₂ O _Five Examples thereof include metal oxides in various oxidation states. As a preferred metal oxide, TiO ₂ , Cr ₂ O _Three , Mn _Three O _Four , MnO ₂ , Fe _Three O _Four , Fe ₂ O _Three , CoO, Co _Three O _Four , NiO, Cu ₂ O, CuO, Nb ₂ O _Three , RuO ₂ , In ₂ O _Three , SnO ₂ , Ta ₂ O _Five , WO _Three , Re ₂ O ₇ , OsO ₂ , IrO ₂ , Bi ₂ O _Three As a particularly preferred metal oxide, Cr ₂ O _Three , Mn _Three O _Four , MnO ₂ , Fe _Three O _Four , Fe ₂ O _Three , CoO, Co _Three O _Four , Cu ₂ O, CuO, In ₂ O _Three , SnO ₂ , WO _Three , IrO ₂ , Bi ₂ O _Three Etc.
[0022]
As composite oxide, for example, XCr ₂ O _Four (X is any one of Mg, Zn, Cu, Mn, Fe, Co and Ni), Na ₂ SnO _Three , Pb ₂ SnO _Four , Bi ₂ Sn ₂ O ₇ , Bi ₂ O _Three ・ AMoO3 (a is 4, 3, 2, 1, 1/2, 1/3 or 1/10), Bi ₂ O _Three ・ BWO _Three (b is 2-3, 1, 1 / 2-1 / 5 or 1/10), cBi ₂ O _Three ・ Sb ₂ O _Five (c is 1 or 3), Bi ₉ PMo ₁₂ O ₅₂ , Fe ₂ (MoO _Four ) _Three , (MoO _Three ) _1.0 (Cr ₂ O _Three ) _0.75 , A _d WO _Three (0 <d <1, A is any one of H, Li, K, Na, Rb, Ca, Cu, Ag, In, Tl, Sn, Pb and rare earth elements), LiTi ₂ O _Four , MnCo ₂ O _Four , NiCo ₂ O _Four , NiMnCo _Four O ₈ Etc. can be illustrated.
[0023]
When the metal oxide is a fine particle, the average particle diameter is not particularly limited as long as the induced absorption characteristics are obtained, but is usually about 1000 nm or less, preferably about 1 to 200 nm, more preferably about 1 to 100 nm. It is. The particle size distribution of the metal oxide fine particles is not particularly limited, but about 95% or more of the fine particles are usually distributed in the range of about 2 to 500 nm, preferably about 2 to 200 nm. In addition, the value of an average particle diameter and a particle diameter is a measured value by a X ray diffraction method or an electron microscope.
[0024]
The transparent component that may be included in the material of the present invention itself does not need to exhibit large induced absorption characteristics. When a transparent component and a metal oxide are used in combination,
Easier to manufacture thin films,
The induced absorption properties of the metal oxide are improved, or
An effect is obtained that the structural stability and mechanical strength of the thin film are improved (for example, the thin film is less likely to be damaged by irradiation with strong excitation laser light).
[0025]
The transparent oxide is not particularly limited as long as it is an oxide that does not exhibit induced absorption characteristics when formed into a single component thin film, for example. That is, it is not particularly limited as long as it is other than the metal oxide such as Ti described above. As a transparent oxide, for example, SiO ₂ , Al ₂ O _Three , ZrO ₂ , HfO ₂ , ThO ₂ , ZnO, Ta ₂ O _Five Etc. can be illustrated. SiO ₂ As glass (e.g. SiO ₂ And glass), quartz and the like. Al ₂ O _Three As sapphire (e.g. Al ₂ O _Three And white sapphire).
[0026]
The transparent polymer is not particularly limited, and examples thereof include acrylic resins such as polymethyl methacrylate; polycarbonate resins such as polycarbonate; polystyrene resins such as polystyrene; and polyvinyl resins such as polyvinyl alcohol.
[0027]
When the transparent component is included, the ratio between the metal oxide and the transparent component is not particularly limited. For example, the ratio of the number of non-oxygen atoms in the transparent oxide to the number of metal atoms in the metal oxide or the total number of monomer units constituting the polymer is usually about 1: 0.01 to 100, preferably Is about 1: 0.1-10. The total number of monomer units constituting the polymer is a value obtained by summing the number of moles of monomers constituting the polymer for all the polymers contained in the material. Alternatively, the weight ratio of the transparent oxide or the transparent polymer to the metal oxide is usually about 1: 0.005 to 200, preferably about 1: 0.05 to 20.
[0028]
For example, when a composite thin film in which a transparent component is added to a metal oxide is formed on the substrate, the number of non-oxygen atoms in the transparent oxide relative to the number of metal atoms in the metal oxide or a transparent polymer is formed. The ratio of the total number of monomer units is preferably about 1: 0.01 to 1, more preferably about 1: 0.02 to 1, and particularly preferably about 1: 0.04 to 1. In this case, the total number of non-oxygen atoms in the transparent oxide or the number of monomer units constituting the transparent polymer may be smaller than 1 with respect to the number of metal atoms in the metal oxide. Alternatively, the weight ratio of the transparent oxide or transparent polymer to the metal oxide is usually about 1: 0.005 to 2, preferably about 1: 0.01 to 2, more preferably about 1: 0.02 to 2.
[0029]
When a composite thin film in which metal oxide fine particles are dispersed and contained in a transparent component is formed on a transparent substrate, the number of non-oxygen atoms in the transparent oxide relative to the number of metal atoms in the metal oxide or a transparent polymer Is preferably about 1: 1 to 100, more preferably about 1: 1 to 50, and particularly preferably about 1: 1 to 20. Alternatively, the weight ratio of the transparent oxide or transparent polymer to the metal oxide is usually about 1: 0.5 to 200, preferably about 1: 0.5 to 100, and more preferably about 1: 0.5 to 40.
[0030]
When the metal oxide fine particles and the transparent component are dispersed and contained in the transparent substrate, the number of non-oxygen atoms in the transparent oxide relative to the number of metal atoms in the metal oxide or the monomer constituting the transparent polymer The ratio of the total number of units is preferably about 1: 0.01 to 1, more preferably about 1: 0.02 to 1, and particularly preferably about 1: 0.04 to 1. Alternatively, the weight ratio of the transparent oxide or transparent polymer to the metal oxide is usually about 1: 0.005 to 2, preferably about 1: 0.01 to 2, more preferably about 1: 0.02 to 2.
[0031]
By setting it as the above range, the effect by using a transparent component together is acquired more reliably. When the ratio of the transparent component is too large, the degree of characteristic improvement accompanying the increase in the ratio of the transparent component is reduced.
[0032]
The substrate used in the present invention is transparent and is not particularly limited as long as it can be used as an induction absorbing material. When the substrate used in the present invention has a desired thickness, the light transmittance is usually about 1 to 95% at a wavelength of about 300 to 200 nm. The thickness of the substrate can be appropriately set according to the application, transparency of the material, etc., but is usually about 0.05 to 5 mm, preferably about 0.1 to 3 mm. As the material of the substrate, for example, SiO ₂ , Al ₂ O _Three , ZnO, ZrO ₂ , Ta ₂ O _Five , HfO ₂ , ThO ₂ Transparent oxides such as acrylic resins, polycarbonate resins, polystyrene resins, polyvinyl resins, etc .; ZnSe, MgF ₂ Etc. SiO ₂ As glass (e.g. SiO ₂ And glass), quartz and the like. Al ₂ O _Three As sapphire (e.g. Al ₂ O _Three And white sapphire). The transparent substrate may be a porous body, for example, porous glass (e.g., SiO ₂ For example, a porous glass containing as a main component). Regardless of whether the thin film is formed on the transparent substrate or the metal oxide fine particles are dispersed in the transparent substrate, a porous body can be used as the transparent substrate.
[0033]
The light transmittance of the induction absorbing material of the present invention can be appropriately selected according to the specific application, but is usually about 2 to 90%.
[0034]
The method for producing the induction absorbing material of the present invention is not particularly limited. In the case of an induction absorbing material in which a thin film containing a metal oxide or the like is formed on a transparent substrate, a known method such as a method of forming a thin film on a substrate can be used. When metal oxide fine particles and the like are dispersed in the transparent substrate, for example, a known method such as a method of impregnating a metal oxide precursor or the like into a porous substrate and baking it may be used. it can.
[0035]
The method for forming a thin film made of only a metal oxide on a substrate is not particularly limited. For example, gas phase methods such as sputter deposition, vacuum deposition, laser MBE, and CVD; metal alkoxide, metal nitrate, organic Method of applying acid metal salt solution on substrate and thermally decomposing; Method of applying metal oxide fine particle dispersion directly on substrate by spin coating method, dip coating method, spraying method, etc., drying and post-processing A well-known thin film forming method such as can be used.
[0036]
A method for forming a composite thin film containing a metal oxide and a transparent component on a substrate is not particularly limited. For example, in a known thin film formation method, a composite thin film having a desired composition can be obtained by appropriately selecting a metal oxide or a precursor thereof, a transparent component or a target containing the precursor, a solution, a dispersion, or the like. it can. For example, a method in which a solution of metal alkoxide, metal nitrate, organic acid metal salt or the like is applied to the surface of a smooth substrate or porous substrate and thermally decomposed; a metal oxide fine particle dispersion is spin-coated or dip-coated Examples of known methods such as coating, drying, and post-treatment on the surface of a substrate having a smooth surface or a porous substrate directly by a spray method or the like.
[0037]
As a method for forming a composite thin film in which metal oxide fine particles are dispersed in a transparent oxide on a transparent substrate, for example, an organic solvent solution containing at least one compound selected from the group consisting of metal alkoxides and alkoxysilanes A solution containing at least one selected from the group consisting of an organic acid metal salt, an inorganic acid metal salt and a complex is added to the sol or gel obtained by hydrolyzing the solution, and the resulting mixture is applied to a substrate. A method of heat-treating the coated substrate at 300 to 800 ° C. can also be applied. This method is a novel method.
[0038]
As a method of forming a composite thin film containing a metal oxide and a transparent polymer on a substrate, for example, a metal oxide solution or a metal oxide fine particle dispersion is mixed with a transparent organic polymer or a precursor solution thereof. Then, after coating on a transparent substrate, a method of reacting as necessary, drying, removing the solvent, and the like can be exemplified. As the solvent, a solvent in which a metal oxide is dispersed and a transparent organic polymer is dissolved is preferable. For example, both an organic solvent and water can be used. Examples of the organic solvent include halogenated hydrocarbons such as chloroform and dichloromethane; lower alcohols such as ethanol and butanol; ketones such as acetone and the like. An organic solvent can be used individually by 1 type, and these mixed solvents may be sufficient.
[0039]
The thickness of the thin film consisting only of the metal oxide is not particularly limited, and the thin film forming method, application, and density (total amount of metal oxide, transparent oxide, and transparent polymer other than the voids in the thin film) The volume ratio can be appropriately set. For example, a dense thin film obtained by a sputter deposition method, a laser MBE method, or the like generally has a density of about 0.7 to 1. In this case, the film thickness is usually about 5 to 500 nm, preferably 10 to 200 nm. On the other hand, in the case of a relatively non-dense thin film obtained by a method of applying a solution and thermally decomposing, a method of applying a metal oxide fine particle dispersion directly on a substrate, etc., the density is generally about 0.3 to 0.9. . In this case, even if the film thickness is made thicker, it can be suitably used as an induction absorbing material, and can be usually about 5 to 1000 nm, preferably about 10 to 400 nm. By setting the film thickness in the above range, it is possible to obtain an induction absorbing material with more favorable light transmittance.
[0040]
The thickness of the composite thin film when the composite thin film in which the metal oxide fine particles are dispersed in the transparent component or the composite thin film in which the transparent component is added to the metal oxide is formed on the substrate is not particularly limited. If the thickness is too thick, the light transmission rate becomes too small, and the usefulness as the induction absorbing material may be reduced. The preferable film thickness in the composite thin film is proportionally increased in accordance with the content ratio of the transparent component as compared with the metal oxide single thin film. For example, when the ratio between the number of metal atoms in the metal oxide and the number of non-oxygen atoms in the oxide in the transparent component or the total number of monomer units constituting the polymer is 1: 1, About twice the preferable film thickness in the case of the oxide single thin film is preferable, and in the case of 1:10, about 10 times the preferable film thickness in the case of the metal oxide single thin film is preferable. The thickness of the composite thin film is not particularly limited, and examples thereof include a thickness at which the light transmittance is usually about 1 to 95%, preferably about 2 to 90% at a wavelength of about 300 to 2000 nm. The appropriate film thickness increases in proportion to the content ratio of the transparent component, but is usually about 10 nm to 10 mm, preferably about 20 nm to 5 mm.
[0041]
When metal oxide fine particles and the like are dispersed and contained in a transparent substrate, for example, a porous glass substrate is impregnated with a metal oxide fine particle dispersion or a metal oxide precursor solution, dried, and then oxidized with oxygen or the like. A method of heating in an atmosphere can be exemplified. The metal oxide precursor is not particularly limited as long as it is a compound that generates a metal oxide by heat treatment in an oxidizing atmosphere, and examples thereof include inorganic acid metal salts and organic acid metal salts. Examples of inorganic acid metal salts include metal nitrates such as manganese nitrate, cobalt nitrate, ferrous nitrate, and copper nitrate. Examples of organic acid metal salts include carboxylates such as cobalt octylate, iron octylate, manganese octylate, nickel octylate, chromium naphthenate, and copper naphthenate.
[0042]
As a manufacturing method in the case of dispersing a metal oxide and a transparent metal oxide in a substrate, for example, a metal oxide fine particle dispersion or a solution of a metal oxide precursor and a transparent metal oxide fine particle dispersion or Examples include a method of mixing a transparent metal oxide precursor solution, impregnating the mixed solution with a porous glass substrate, drying, and heating in an oxidizing atmosphere such as oxygen.
[0043]
As a manufacturing method in the case where a metal oxide and a transparent polymer are dispersed in a substrate, for example, a metal oxide fine particle dispersion and a transparent polymer solution are mixed, and a porous glass substrate is added to the mixed solution. Examples of the method include impregnation and drying.
[0044]
When a porous glass substrate is used as the substrate, post-treatment such as heat treatment of the obtained material at a high temperature of about 600 ° C. or higher may be performed. By performing post-treatment, voids remaining in the porous glass can be reduced, so that light scattering by the voids can be reduced, and loss of excitation light intensity can be reduced.
[0045]
Since the material of the present invention has high induced absorption characteristics, it is useful as a high-speed optical switch, a high-speed optical logic operation element, or the like.
[0046]
The material of the present invention has a property that light absorption increases or decreases in response to irradiation excitation light at a high speed at a wavelength different from irradiation excitation light, in other words, the light transmittance decreases as the irradiation excitation light intensity increases. Or it has an increasing property. For example, in the case of an induced absorption material in which the light absorption of a material at a wavelength different from that of the excitation light increases reversibly at high speed when strong excitation light is incident, the excitation light intensity and the transmitted light intensity at a different wavelength are used. Based on the above relationship, it can be suitably used as a NOT type optical logic element material. On the other hand, when a strong excitation light is incident, the light absorption of the material at a wavelength different from that of the excitation light is reversibly reduced at high speed. In the case of an induced absorption material, the excitation light intensity and the transmitted light intensity at a different wavelength are used. Based on this relationship, it can be suitably used as a material for an AND type optical logic operation element, a material for a high-speed optical switch, or the like.
[0047]
Examples of the method of using the induced absorption material of the present invention include a method of directly irradiating both the excitation light and the monitor light directly on the induced absorption material and detecting an absorption change at the time of the excitation light irradiation at the wavelength of the monitor light. be able to. The excitation light and the monitor light are different in intensity and wavelength, and the excitation light is stronger than the monitor light. The intensity of the excitation light can be set as appropriate according to the specific application, etc., but is usually 100 W / cm ² Above, preferably 1kW / cm ² ~ 1GW / cm ² Degree. The intensity ratio of the two kinds of light is not particularly limited, but the value of the intensity of the monitor light / the intensity of the excitation light is usually about 1/10 or less, preferably about 1/1000 or less.
[0048]
The wavelength of the excitation light is not particularly limited as long as the induction absorbing material absorbs light. In many cases, the induced absorption material of the present invention increases the light absorption at the excitation light wavelength and its nearby wavelengths, further reduces the light absorption at a wavelength slightly away from the excitation light wavelength, and further greatly away from the excitation light wavelength. It shows the behavior that light absorption is increased at a different wavelength. Therefore, the wavelength of the monitor light can be appropriately determined according to the type of the absorption material to be used, the specific application, and the like. The wavelengths of the excitation light and the monitor light are usually about 300 to 2000 nm.
[0049]
As a light source of excitation light, for example, a laser such as a pulse laser or a continuous wave laser can be used. When a pulse laser is used, the pulse width is usually about 5 fs to 20 ns, preferably about 10 fs to 10 ns.
[0050]
As a monitor light source, for example, a xenon lamp, a halogen lamp, or the like can be used.
[0051]
[Action]
The reason why the material of the present invention exhibits induced absorption characteristics is not clear, but is presumed to be based on the following principle.
[0052]
For example, the metal oxide thin film used in the present invention has a broad absorption spectrum. When this metal oxide thin film is irradiated with excitation light, the transmittance is reversibly decreased or increased at a high speed at various wavelengths different from the excitation light. The reason why the transmittance change depending on the excitation light intensity at various wavelengths different from the excitation light wavelength occurs is that two-photon absorption at the excitation light wavelength and the resulting electrons in the metal oxide right object having the semiconductor droplet property. It is conceivable that the transmittance changes at various wavelengths different from the excitation light wavelength due to density change. In general, when the excitation light to a substance is weak, only one-photon absorption is usually observed, and the two-photon absorption is very small. However, the two-photon absorption is proportional to the square of the excitation light intensity. In the strong case, two-photon absorption is also generated in addition to one-photon absorption and is observed.
[0053]
The two-photon absorption process, for example, is fast enough to follow the rising speed of a nanosecond pulse laser or picosecond pulse laser, so that the electronic state of the material changes rapidly with the incidence of strong laser excitation light, and excitation In a wide wavelength range different from light, an increase or decrease in light absorption is caused.
[0054]
In general, the influence of the temperature rise of the material accompanying the excitation light irradiation is almost negligible until a few tens of picoseconds after the start of light irradiation. Therefore, when the pulse laser light having a pulse width of the order of picoseconds is irradiated, It is estimated that the induced absorption characteristics observed in the oxide are mainly due to the above-described two-photon absorption. When a pulse laser or continuous wave laser with a pulse width of nanoseconds or more is irradiated, in addition to the above-described induced absorption characteristics due to two-photon absorption, induced absorption characteristics due to the temperature rise of the material accompanying excitation light irradiation Are also expressed. Many metal oxide semiconductors increase the carrier concentration that causes light absorption in the ultraviolet-visible-near-infrared region as the temperature rises, so the increase in light absorption accompanying the rise in temperature that occurs when absorbing excitation light was used. Induced absorption characteristics can be developed.
[0055]
It is considered that the induced absorption characteristic does not appear in all metal oxides, but is achieved only in metal oxides that satisfy at least the following three conditions.
(B) Having an absorption band at the wavelength of the laser beam irradiated as excitation light,
(B) having an absorption band at a wavelength different from that of the excitation light; and
(C) Having semiconductor properties.
[0056]
All of the metal oxides contained in the material of the present invention satisfy the above three conditions and exhibit large induced absorption characteristics.
[0057]
Moreover, it is considered that the induction absorption characteristics of the metal oxide are improved by using the transparent component in combination for the following reason. In general, metal oxides have a large light absorption. Therefore, when a very strong laser beam is irradiated onto a thin film made of only metal oxides, a rapid temperature rise occurs and the metal oxides have excellent heat resistance. May be damaged.
[0058]
On the other hand, when a transparent component that absorbs less light than the metal oxide is used in combination, the temperature rise is small even when a very strong laser beam is irradiated. In addition, the heat generated by the metal oxide is quickly conducted and diffused to the transparent component, and the time during which the metal oxide is exposed to a high temperature can be shortened, and an excessive temperature rise is suppressed. As a result, as compared with a thin film made of only the metal oxide, the composite thin film is less susceptible to damage even when irradiated with a stronger laser beam.
[0059]
【The invention's effect】
The material of the present invention expresses a large reversible induced absorption characteristic at a high speed at a wavelength different from that of the excitation light as the intensity of the excitation light increases and decreases.
[0060]
The material of the present invention is very stable in the atmosphere and can be used repeatedly over a long period of time.
[0061]
According to the present invention, an induction absorbing material having excellent heat resistance can be provided. When the transparent component is used in combination, a material having particularly excellent heat resistance can be provided. The material of the present invention is very stable and highly reproducible, for example, even when the excitation light having an intensity lower than the breakdown threshold is irradiated in the atmosphere for a long time, the induced absorption characteristics are not gradually reduced or deteriorated. Expresses absorption characteristics. In addition, when irradiated with strong excitation laser light, it is difficult to be subjected to irreversible characteristic change / deterioration due to photoreaction or temperature rise.
[0062]
Many conventional inductive absorption materials made of semiconductors contain cadmium which is harmful to the human body. The material of the present invention does not contain cadmium.
[0063]
Conventional absorption materials made of semiconductors must be synthesized under an inert atmosphere, and their operations are relatively complicated. On the other hand, the material of the present invention can be easily produced.
[0064]
The material of the present invention can be manufactured at low cost.
[0065]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples of the present invention together with comparative examples. The present invention is not limited to the following examples.
[0066]
Example 1
Cobalt oxide (Co) with brown color on glass substrate (one side) using magnetron RF sputtering method _Three O _Four ) A thin film was produced. Excitation laser light with a wavelength of 355 nm and a pulse width of 10 ns is incident on this cobalt oxide thin film, and the wavelength of the monitor light (light source: xenon lamp) is changed from 400 to 850 nm to measure the change in absorbance of the cobalt oxide thin film at 400 to 850 nm. did. Furthermore, using an ND filter, the incident laser light intensity (I ₀ ) And the change in absorbance of the cobalt oxide thin film at 400 to 850 nm was measured at each light intensity.
[0067]
As a result, I ₀ The absorbance of the cobalt oxide thin film changed reversibly at high speed in the time within the pulse of the excitation laser beam. I ₀ > 0.2MW / cm ² In the case of reversible, especially at high speed. I ₀ = 0.6MW / cm ² The induced absorption exhibited by the cobalt oxide thin film at that time was a small decrease in absorption at a wavelength of 400 to 480 nm and a large increase in absorption at a wavelength of 540 to 850 nm. The increase in absorption was maximum at a wavelength of 810 nm. Thus, it was found that this cobalt oxide thin film has high performance as an induction absorbing material. I ₀ = 0.4MW / cm ² The induced absorption characteristics did not change even after irradiating the above excitation laser with 200 pulses or more, and showed good reproducibility, stability against light irradiation and long-term stability.
[0068]
Example 2
Excitation laser light having a wavelength of 532 nm and a pulse width of 10 ns is incident on the cobalt oxide thin film manufactured in Example 1, and the incident laser light intensity (I ₀ ) Was changed, the wavelength of the monitor light was changed from 400 to 850 nm, and the change in absorbance of the cobalt oxide thin film at a wavelength of 400 to 850 nm was measured.
[0069]
As a result, I ₀ The absorbance of the cobalt oxide thin film changed reversibly at high speed in the time within the pulse of the excitation laser beam. I ₀ > 0.2MW / cm ² In particular, it changed reversibly at high speed. I ₀ = 0.6MW / cm ² The induced absorption exhibited by the cobalt oxide thin film was a small decrease in absorption at a wavelength of 400 to 460 nm and a large increase in absorption at a wavelength of 490 to 850 nm. The increase in absorption was greatest at a wavelength of 840 nm. Thus, it was found that this cobalt oxide thin film has high performance that can be used as an induction absorbing material. I ₀ = 0.4MW / cm ² The stimulated absorption characteristics did not change even after irradiation of more than 200 pulses of the excitation laser, showing good reproducibility, stability against light irradiation and long-term stability.
[0070]
Example 3
Octyl acid, which is a raw material for metal oxide fine particles, is obtained by hydrolyzing a solution containing silicon alkoxide and zirconium alkoxide on a glass substrate (one side) using metal alkoxide and metal salt as raw materials. Cobalt oxide (Co) having a particle size of about 5 to 20 nm is added by a method in which a solution containing cobalt is added, and the resulting solution is coated on a substrate and heat-treated at 380 ° C. _Three O _Four ) A composite thin film having a brown color with fine particles dispersed in silica-zirconia glass was prepared. An excitation laser beam having a wavelength of 355 nm and a pulse width of 10 ns is incident on this composite thin film, and the incident laser beam intensity (I ₀ ) Was changed, the wavelength of the monitor light was changed from 400 to 850 nm, and the change in absorbance of the composite thin film at a wavelength of 400 to 850 nm was measured.
[0071]
As a result, I ₀ Increasing the absorbance changed reversibly at high speed. Especially I ₀ > 0.2MW / cm ² In the case of, the absorbance of the composite thin film reversibly changed with the time within the pulse of the excitation laser beam. I ₀ = 0.6MW / cm ² Thus, the induced absorption exhibited by the composite thin film was a small decrease in absorption at a wavelength of 400 to 420 nm and a large increase in absorption at a wavelength of 440 to 850 nm. The increase in absorption was greatest at a wavelength of 780 nm. Thus, it was found that this composite thin film has high performance that can be used as an induction absorbing material. I ₀ = 1MW / cm ² The induced absorption characteristics did not change even after irradiation of more than 200 pulses of the excitation laser, and showed excellent reproducibility, especially high stability against light irradiation, and long-term stability.
[0072]
Example 4
Cobalt oxide (Co _Three O _Four ) Excitation laser light with a wavelength of 532 nm and a pulse width of 10 ns is incident on a thin film containing fine particles dispersed in silica-zirconia glass, and the incident laser light intensity (I ₀ ) Was measured, and the change in absorbance of the composite thin film at a wavelength of 400 to 850 nm was measured.
[0073]
As a result, I ₀ Increasing the absorbance changed reversibly at high speed. Especially I ₀ > 0.2MW / cm ² Thus, the absorbance of the composite thin film reversibly changed with time within the pulse of the excitation laser beam. I ₀ = 0.6MW / cm ² Thus, the induced absorption exhibited by the composite thin film was a small decrease in absorption at a wavelength of 400 to 440 nm and a large increase in absorption at a wavelength of 480 to 850 nm. The increase in absorption was greatest at a wavelength of 850 nm. Thus, it was found that this composite thin film has high performance that can be used as an induction absorbing material. I ₀ = 1MW / cm ² The induced absorption characteristics did not change even after irradiation of more than 200 pulses of the excitation laser, and showed excellent reproducibility, especially high stability against light irradiation, and long-term stability.
[0074]
Example 5
Manganese octylate film is formed on glass substrate (single side) by spin coating method and baked at 380 ° C. _Three O _Four ) A thin film was prepared. Excitation laser light with a wavelength of 355 nm or 532 nm and a pulse width of 10 ns is incident on this manganese oxide thin film, and the incident laser light intensity (I ₀ ) Was measured, and the change in absorbance of the manganese oxide thin film at a wavelength of 400 to 850 nm was measured. As a result, I ₀ Especially when I increase ₀ > 0.2MW / cm ² Thus, the absorbance of the manganese oxide thin film reversibly changed rapidly at the time within the pulse of the excitation laser beam. I ₀ = 0.6MW / cm ² In both cases where the excitation light wavelengths were 355 nm and 532 nm, the induced absorption exhibited by the manganese oxide thin film was increased in the wavelength range of 400 to 850 nm. The increase in absorption was greatest at a wavelength of 400 nm and then large at a wavelength of 600 nm. Thus, it was found that this manganese oxide thin film has high performance that can be used as an induction absorbing material. I ₀ = 0.4MW / cm ² The induced absorption characteristics did not change even after irradiation of more than 200 pulses of the excitation laser, and showed good reproducibility, stability to light irradiation and long-term stability.
[0075]
Example 6
An iron octylate film is formed on a glass substrate (one side) by spin coating, baked at 380 ° C., and iron oxide (Fe ₂ O _Three ) A thin film was prepared. Excitation laser light with a wavelength of 355 nm or 532 nm and a pulse width of 10 ns is incident on this iron oxide thin film, and the incident laser light intensity (I ₀ ) Was measured, and the change in absorbance of the iron oxide thin film at a wavelength of 400 to 850 nm was measured.
[0076]
As a result, I ₀ Especially when I increase ₀ > 0.2MW / cm ² Thus, the absorbance of the iron oxide thin film changed reversibly at high speed in the time within the pulse of the excitation laser beam. I ₀ = 0.6MW / cm ² In both cases where the excitation light wavelengths were 355 nm and 532 nm, the induced absorption exhibited by the iron oxide thin film was a large increase in absorption at a wavelength of 420 to 600 nm. The increase in absorption was greatest at a wavelength of 560 nm. Thus, it was found that this iron oxide thin film has high performance that can be used as an induction absorbing material. I ₀ = 0.4MW / cm ² The induced absorption characteristics did not change even after irradiation of more than 200 pulses of the excitation laser, and showed good reproducibility, stability to light irradiation and long-term stability.
[0077]
Example 7
A copper naphthenate film was formed on a glass substrate (one side) by a spin coat method and baked at 380 ° C. to prepare a brown copper oxide (CuO) thin film. Excitation laser light with a wavelength of 355 nm or 532 nm and a pulse width of 10 ns is incident on this copper oxide thin film, and the incident laser light intensity (I ₀ ) Was measured, and the change in absorbance of the copper oxide thin film at a wavelength of 400 to 850 nm was measured. As a result, I ₀ Especially when I increase ₀ > 0.2MW / cm ² Thus, the absorbance of the copper oxide thin film changed reversibly at high speed in the time within the pulse of the excitation laser beam. I ₀ = 0.6MW / cm ² In both cases where the excitation light wavelengths were 355 nm and 532 nm, the induced absorption exhibited by the copper oxide thin film was decreased at wavelengths of 450 to 490 nm, and increased significantly at wavelengths of 400 to 420 nm and 560 to 850 nm. The increase in absorption was greatest at a wavelength of 790 nm. Thus, it was found that this copper oxide thin film has high performance that can be used as an induction absorbing material. I ₀ = 0.4MW / cm ² The induced absorption characteristics did not change even after irradiation of more than 200 pulses of the excitation laser, and showed good reproducibility, stability to light irradiation and long-term stability.
[0078]
Example 8
A chromium naphthenate film is formed on a glass substrate (one side) by spin coating, baked at 380 ° C., and chrome oxide (Cr ₂ O _Three ) A thin film was prepared. An excitation laser beam having a wavelength of 355 nm or 532 nm and a pulse width of 10 ns is incident on this chromium oxide thin film, and the incident laser beam intensity (I ₀ ) Was changed, and the change in absorbance of the chromium oxide thin film at a wavelength of 400 to 850 nm was measured.
[0079]
As a result, I ₀ Especially when I increase ₀ > 0.2MW / cm ² Thus, the absorbance of the chromium oxide thin film changed reversibly at high speed in the time within the pulse of the excitation laser beam. I ₀ = 0.6MW / cm ² In both cases where the excitation light wavelengths were 355 nm and 532 nm, the induced absorption exhibited by the chromium oxide thin film was a large increase in absorption at the wavelength of 400 nm. The increase in absorption was greatest at a wavelength of 400 nm. Thus, it was found that this chromium oxide thin film has high performance that can be used as an induction absorbing material. I ₀ = 0.4MW / cm ² The induced absorption characteristics did not change even after irradiation of more than 200 pulses of the excitation laser, and showed good reproducibility, stability to light irradiation and long-term stability.
[0080]
Example 9
Nickel oxide (NiO) obtained by spin-coating nickel octylate, zinc octylate, indium octylate, tin octylate, and bismuth octylate on a quartz substrate (one side) and firing at 450 ° C. , Zinc oxide (ZnO), indium oxide (In ₂ O _Three ), Tin oxide (SnO ₂ ), Bismuth oxide (Bi ₂ O _Three Each of the thin films in (1) becomes an induction absorbing material in a wavelength region included in a wavelength region of 400 to 850 nm when an excitation laser beam having a wavelength of 355 nm or 532 nm and a pulse width of 10 ns is incident.
[0081]
Example 10
Molybdenum oxide (MoO) obtained by forming an organometallic salt or organometallic complex compound on a glass substrate (one side) by spin coating and firing at 400 ° C _Three ), Ruthenium oxide (RuO ₂ ), Antimony oxide (Sb ₂ O _Three ), Tungsten oxide (WO _Three ), Rhenium oxide (Re ₂ O ₇ ), Osmium oxide (OsO ₂ ), Iridium oxide (IrO ₂ Each of the thin films in (1) becomes an induction absorbing material in a wavelength region included in a wavelength region of 400 to 850 nm when an excitation laser beam having a wavelength of 355 nm or 532 nm and a pulse width of 10 ns is incident.
[0082]
Example 11
Titanium oxide (TiO2) obtained by magnetron RF sputtering method on a glass substrate (one side) ₂ ), Niobium oxide (Nb ₂ O _Five ), Tantalum oxide (Ta ₂ O _Five ), Tungsten oxide (WO _Three ), Iridium oxide (IrO ₂ Each of the thin films in (1) becomes an induction absorbing material in a wavelength region included in a wavelength region of 400 to 850 nm when an excitation laser beam having a wavelength of 355 nm or 532 nm and a pulse width of 10 ns is incident.
[Brief description of the drawings]
FIG. 1 shows a thin film manufactured in Example 1 having a wavelength of 355 nm, a pulse width of 10 ns, and I ₀ = 0.6MW / cm ² It is a figure which shows the wavelength characteristic of the induced absorption which a thin film shows when the excitation laser beam of this is incident.
FIG. 2 shows that the thin film manufactured in Example 1 has a wavelength of 532 nm, a pulse width of 10 ns, and I ₀ = 0.6MW / cm ² It is a figure which shows the wavelength characteristic of the induced absorption which a thin film shows when the excitation laser beam of this is incident.
FIG. 3 shows that the thin film manufactured in Example 3 has a wavelength of 355 nm, a pulse width of 10 ns, and I ₀ = 0.6MW / cm ² It is a figure which shows the wavelength characteristic of the induced absorption which a thin film shows when the excitation laser beam of this is incident.
4 shows a thin film manufactured in Example 3 having a wavelength of 532 nm, a pulse width of 10 ns, I ₀ = 0.6MW / cm ² It is a figure which shows the wavelength characteristic of the induced absorption which a thin film shows when the excitation laser beam of this is incident.

Claims (14)

_{Mn 3 O 4, Fe 2 O} 3, Co 3 O 4 and induced absorption material formed from at least one of gold Shokusan product and a transparent substrate selected from the group consisting of CuO. NiO, In ₂ O _Three , SnO ₂ Or Bi ₂ O _Three An induction absorbing material formed from a transparent substrate. TiO ₂ , RuO ₂ , Sb ₂ O _Three , Ta ₂ O _Five , Re ₂ O ₇ , OsO ₂ Or IrO ₂ An induction absorbing material formed from a transparent substrate. Induced absorption material according to claim 1 to 3 metal oxide is a thin film formed on a transparent substrate. Thin film, further, induction absorbing material according to claim 4 comprising a transparent oxide. Induction absorbing material according to the metal oxide is particulate, claim 5 composite thin film in which the metal oxide fine particles are dispersed in the transparent oxide is formed on a transparent substrate. The induction absorbing material according to claim 6 , wherein the ratio of the total number of non-oxygen atoms in the transparent oxide to the number of metal atoms in the metal oxide is 1: 1 to 100. 6. The induction absorbing material according to claim 5 , wherein the ratio of the total number of non-oxygen atoms in the transparent oxide to the number of metal atoms in the metal oxide is 1: 0.01 to 1. The induction absorbing material according to any one of claims 1 to 3 , wherein the metal oxide is fine particles and dispersedly contained in the transparent substrate. The induction absorbing material according to claim 9 , wherein a transparent oxide is further dispersed in the transparent substrate. The induction absorbing material according to claim 10 , wherein the ratio of the total number of non-oxygen atoms in the transparent oxide to the number of metal atoms in the metal oxide is 1: 0.01 to 1. The induction absorbing material according to claim 9 , wherein the transparent substrate is porous glass. Transparent oxide is derived absorbent material according to any one of SiO ₂ der Ru claims 5-8 and 10-12. 14. The induction absorbing material according to claim 1, wherein the metal oxide is fine particles, and the average particle size of the metal oxide fine particles is 1000 nm or less.

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