Coating processes – Direct application of electrical – magnetic – wave – or... – Polymerization of coating utilizing direct application of...
Reexamination Certificate
1998-08-04
2001-03-20
Speer, Timothy M. (Department: 1775)
Coating processes
Direct application of electrical, magnetic, wave, or...
Polymerization of coating utilizing direct application of...
C427S498000, C427S585000
Reexamination Certificate
active
06203860
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thin film of potassium niobate, a process for producing the thin film, and an optical device using the thin film. Particularly, the present invention relates to a thin film of a perovskite-type transparent potassium niobate which can be used in the field of optical devices, electronic devices, and the like. More particularly, the present invention relates to a thin film of a perovskite-type potassium niobate which is formed on an amorphous substrate, has excellent transparency, and is or is not (
110
) oriented, a process for producing the thin film, and an optical device using the thin film.
PRIOR ART OF THE INVENTION
Heretofore, thin films of potassium niobate have been prepared on crystalline substrates of KTaO
3
, MgAl
2
O
4
, and (100) MgO by process (Appl. Phys. Lett., Volume 61, Page 373 (1992), and Appl. Phys. Lett., Volume 65, Page 1073 (1994)), and on cyrstalline substrates of (100) MgO and (0001) sapphire by a sol-gel process (J. Am. Ceram. Soc., Volume 77, Page 820 (1994)).
When a thin film of potassium niobate is prepared on a crystalline substrate, the thin film grows only on a specific surface of the crystal. Therefore, free selection of the refractive index of the substrate is impossible when the substrate is used as a part of a cladding of an optical waveguide. Moreover, preparation of a finely processed surface with high precision is not easy because the specific surface of the crystalline substrate should be exposed.
SUMMARY OF THE INVENTION
The present invention has an object of providing a thin film of the perovskite-type potassium niobate which has excellent transparency, can be (
110
) oriented, and can be used for optical devices, such as an optical waveguide, a second harmonic generating device, and an optical switching device.
As the result of extensive studies by the present inventors to achieve the above object, it was discovered that a thin film of a transparent perovskite-type potassium niobate can be prepared on a substrate when the thin film of potassium niobate is prepared on an amorphous substrate, and that a transparent oriented thin film of a perovskite-type potassium niobate is easily prepared on an amorphous substrate when the amorphous substrate has a specific composition. The present invention has been completed on the basis of above mentioned discoveries.
Accordingly, the present invention provides:
(1) A thin film of a perovskite-type transparent potassium niobate formed on an amorphous substrate;
(2) The thin film of a perovskite-type transparent potassium niobate described in (1), wherein the thin film formed on an amorphous substrate is (
110
) oriented;
(3) The thin film of a perovskite-type transparent potassium niobate described in (1), wherein the amorphous substrate is a glass substrate containing at least one element selected from the group consisting of alkaline earth metal elements, rare earth elements, Bi, Pb, Nb, Co, Ni, and W;
(4) The thin film of a perovskite-type transparent potassium niobate described in (2) wherein the amorphous substrate is a glass substrate containing at least one element selected from the group consisting of alkaline earth metal elements, rare earth elements, Bi, Pb, and Nb;
(5) The thin film of a perovskite-type transparent potassium niobate described in (1), wherein the amorphous substrate is a composite amorphous substrate comprising an amorphous layer which contains at least one element selected from the group consisting of alkaline earth metal elements, rare earth elements, Bi, Pb, Nb, Co, Ni, and W, and is formed on a crystalline, amorphous, or crystalline-amorphous composite substrate;
(6) The thin film of a perovskite-type transparent potassium niobate described in (2), wherein the amorphous substrate is a composite amorphous substrate comprising an amorphous layer which contains at least one element selected from the group consisting of alkaline earth metal elements, rare earth elements, Bi, Pb, and Nb, and is formed on a crystalline, amorphous, or crystalline-amorphous composite substrate;
(7) The thin film of a perovskite-type transparent potassium niobate described in any of (3) and (4), wherein the glass substrate has a pattern of fine grooves or ridges;
(8) The thin film of a perovskite-type transparent potassium niobate described in any of (5) and (6), wherein the composite amorphous substrate comprises the amorphous layer formed on a patterned substrate in which a fine pattern of strips of metal electrodes is formed on a crystalline, amorphous, or crystalline-amorphous composite substrate by patterning;
(9) The thin film of a perovskite-type transparent potassium niobate described in any of (5) and (6), wherein the composite amorphous substrate comprises the amorphous layer formed on a crystalline, amorphous, or crystalline-amorphous composite substrate having a pattern of fine grooves or ridges;
(10) A process for producing a thin film of a perovskite-type transparent potassium niobate comprising preparing the thin film of a perovskite-type transparent potassium niobate on an amorphous substrate by a physical vapor deposition process;
(11) The process for producing a thin film of a perovskite-type transparent potassium niobate described in (10), wherein the physical vapor deposition process is a sputtering process;
(12) The process for producing a thin film of a perovskite-type transparent potassium niobate described in any of (10) and (11), wherein the thin film prepared on an amorphous substrate is (
110
) oriented;
(13) The process for producing a thin film of a perovskite-type transparent potassium niobate described in any of (10) and (11), wherein the amorphous substrate is a glass substrate containing at least one element selected from the group consisting of alkaline earth metal elements, rare earth elements, Bi, Pb, Nb, Co, Ni, and W;
(14) The process for producing a thin film of a perovskite-type transparent potassium niobate described in (12), wherein the amorphous substrate is a glass substrate containing at least one element selected from the group consisting of alkaline earth metal elements, rare earth elements, Bi, Pb, and Nb;
(15) The process for producing a thin film of a perovskite-type transparent potassium niobate described in any of (10) and (11), wherein the process comprises preparing the thin film of a perovskite-type transparent potassium niobate on a composite amorphous substrate comprising an amorphous layer which contains at least one element selected from the group consisting of alkaline earth metal elements, rare earth elements, Bi, Pb, Nb, Co, Ni, and W, and is formed on a crystalline, amorphous, or crystalline-amorphous composite substrate by a process selected from the group consisting of a physical vapor deposition process, a sol-gel process, a chemical vapor deposition process, a liquid phase deposition process, and a thick film printing process;
(16) The process for producing a thin film of a perovskite-type transparent potassium niobate described in (12), wherein the process comprises preparing the thin film of a perovskite-type transparent potassium niobate on a composite amorphous substrate comprising an amorphous layer which contains at least one element selected from the group consisting of alkaline earth metal elements, rare earth elements, Bi, Pb, and Nb, and is formed on a crystalline, amorphous, or crystalline-amorphous composite substrate by a process selected from the group consisting of a physical vapor deposition process, a sol-gel process, a chemical vapor deposition process, a liquid phase deposition process, and a thick film printing process;
(17) An optical device comprising the thin film of a perovskite-type transparent potassium niobate prepared on an amorphous substrate described in any of (1) to (9);
(18) The optical device described in (17), wherein the optical device is an optical waveguide;
(19) The optical device described in (17), wherein the optical device is a second harmonic generating device; and
(20) The optical device described in (17), wherein the optical d
Hashima Hidekazu
Kawai Hideki
Nakajima Sadao
Speer Timothy M.
Yamamura Glass Co. Ltd.
Young & Thompson
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