Shin-etsu Chemical Co., Ltd.

Other

Hitachi Cable, Inc.

Jun Abe

Kazuo Koya

Seiki Ejima

Nobuyasu Mantoku

Masayuki Tanno

Yoshinori Kuwabara

Katsuyuki Imoto

Shinji Makikawa

Akira Ikushima

Koji Kato

Takumi Fujiwara

Masaaki Shirota

Masayasu Nagaoka

Tetsuya Otosaka

Hideo Hirasawa

Dai Inoue

Hiroshi Oyamada

Tsuneo Mori

Junichi Kushibiki

Sayuri Maeda

Provided is a method for producing a lithium tantalate single crystal substrate capable of suppressing increase in volume resistivity of the lithium tantalate single crystal substrate owing to reduction failure even when a lithium carbonate power is repeatedly used in heat treatment for the lithium tantalate single crystal substrate. The invention is a method for producing a lithium tantalate single crystal substrate having a volume resistivity of 1&#xd7;10&#x3a9;&#xb7;cm or more and less than 1&#xd7;10&#x3a9;&#xb7;cm, including a step of heat-treating a lithium tantalate single crystal substrate having a volume resistivity of 1&#xd7;10&#x3a9;&#xb7;cm or more and having a single-domain structure, under normal pressure and at a temperature of 350&#xb0; C. or higher but not higher than the Curie temperature thereof while burying it in a lithium carbonate powder having a BET specific surface area of 0.13 m/g or more, wherein the lithium carbonate powder is a used lithium carbonate powder that has been used in burying a lithium tantalate single crystal substrate in heat treatment for the lithium tantalate single crystal structure under normal pressure and at a temperature of 350&#xb0; C. or higher but not higher than the Curie temperature thereof, and in the heat treatment step, the heat treatment is carried out in a mixed gas atmosphere of an inert gas and a reducing gas at the start of the heat treatment, and after the heat treatment in the mixed gas atmosphere, the heat treatment is carried out in a single gas atmosphere of an inert gas.

Method for producing lithium tantalate single crystal substrate

[Object] It is an object of the present invention to provide a lithium tantalate single crystal substrate which undergoes only small warpage, is free from cracks and scratches, has better temperature non-dependence characteristics and a larger electromechanical coupling coefficient than a conventional Y-cut LiTaOsubstrate. [Means to solve the Problems] The lithium tantalate single crystal substrate of the present invention is a rotated Y-cut LiTaOsingle crystal substrate having a crystal orientation of 36&#xb0; Y-49&#xb0; Y cut characterized in that: the substrate is diffused with Li from its surface into its depth such that it has a Li concentration profile showing a difference in the Li concentration between the substrate surface and the depth of the substrate; and the substrate is treated with single polarization treatment so that the Li concentration is substantially uniform from the substrate surface to a depth which is equivalent to 5-15 times the wavelength of either a surface acoustic wave or a leaky surface acoustic wave propagating in the LiTaOsubstrate surface.

Lithium tantalate single crystal substrate, bonded substrate, manufacturing method of the bonded substrate, and surface acoustic wave device using the bonded substrate

A lithium tantalate single crystal substrate for a surface acoustic wave device that is a rotated Y-cut LiTaO3 substrate whose crystal orientation has a Y-cut angle of not smaller than 36&#xb0; and not larger than 49&#xb0; and which has such a Li concentration profile after diffusion of Li into the substrate from the surface thereof that the Li concentration at the surface of the substrate differs from that inside the substrate. A shear vertical type elastic wave whose main components are vibrations in the thickness direction and in the propagation direction and which is among those elastic waves which propagate in the X axis direction within the surface of this LiTaO3 substrate has an acoustic velocity of not lower than 3140 m/s and not higher than 3200 m/s.

Lithium tantalate single crystal substrate for a surface acoustic wave device and a device using the same, and a manufacturing method thereof and an inspection method thereof

[Object] An object of the present invention is to provide a method for manufacturing an oxide single crystal substrate having less dispersion in characteristics within the substrate surface. [Means to solve the Problems] In the manufacture method of the present invention, a powder containing a Li compound is dispersed in a medium to form a slurry, and heat is applied while the slurry is in contact with the surface of the oxide single crystal substrate, so as to diffuse Li into the substrate from the surface thereof to effect a modification of the substrate; or after the slurry is brought into contact with the surface of the oxide single crystal substrate, the oxide single crystal substrate is buried in a powder containing the Li compound, and heat is applied to effect the diffusion of Li in the substrate from the surface thereof whereby a modification of the substrate occurs.

Method of manufacturing an oxide single crystal substrate for a surface acoustic wave device

A method for manufacturing a preform having a core and a multilayer clad, includes covering a circumference of a rod including at least the core and an inner clad layer with a first tube including at least a high viscosity clad layer, and unifying the rod and the first tube by heating and contracting the first tube.

Optical fiber preform, method for manufacturing thereof, and optical fiber obtained by drawing thereof

A method for manufacturing a synthesized silica glass optical member, the method comprising: providing a porous silica glass body; heating the porous silica glass body in an atmosphere containing hydrogen or oxygen, and sintering the porous silica glass body in an atmosphere containing fluorine compound. Furthermore, a synthesized silica glass optical member manufactured by the method.

Synthesized silica glass optical member and method for manufacturing the same

There is disclosed a method for producing a base material for optical fiber having a deformed first clad consisting of at least a core, a first clad and a second clad, comprising a step of deforming a shape of a section of the first clad so that it may have at least one linear part when the first clad is formed around the core, a step of depositing porous glass fine particles as the second clad made of the same material as that of the first clad on a glass rod having the deformed first clad to form a porous glass base material, and a step of forming the second clad having a round section by vitrifying it. There can be provided a method for producing a base material for optical fiber wherein a lot of breakages or cracks on the surface of the base material can be prevented in a step of depositing porous glass fine particles for the second clad on the first clad, and base material for optical fiber having no defects, and an optical fiber having an efficient effect of being excited with excitation light.

Method for producing base material for optical fiber having deformed first clad, base material for optical fiber and optical fiber

A grating optical fiber comprises a core, a first clad layer formed around the core, and a second clad layer formed around the first clad. Germanium is doped in the core, while germanium and fluorine are doped in the first clad layer. Gratings are formed on both the core and the first clad layer. The difference between the indexes of refraction between the first and second clad layers is smaller than the difference between the indexes of refraction between the core and the first clad layer.

Grating optical fiber, and optical fiber base material suitable for grating

There is disclosed second-order nonlinear glass material wherein a part having second-order nonlinearity contains Ge, H and OH and has second-order nonlinear optical constant d of 1 pm/V or more, and a method for producing second-order nonlinear glass material comprising treating a porous glass material containing Ge with hydrogen, sintering it and subjecting it to a ultraviolet poling treatment. There can be provided second-order nonlinear glass material having second-order nonlinearity which is a sufficiently high and has a sufficiently long lifetime for a practical purpose, in use of the glass material for optical functional elements or the like.

Method for producing a second-order nonlinear glass material

There is disclosed second-order nonlinear glass material wherein a part having second-order nonlinearity contain Ge, H and OH and second-order nonlinear optical constant d of 1 pm/V or more, and a method for producing second-order nonliner glass material comprising treating a porous class material containing Ge with hydrohen, sintering it and subjecting it to a ultraviolet poling treatment. There can be provided second-order nonlinger glass material having second-order nonlinearity which is a sufficiently high and has a sufficiently long lifetime for a practical purpose, in use of the glass material for optical elements or the like.

Second-order nonlinear glass material

A mask having a center hole for passing through a center fiber, which is one of multiple fibers, and multiple surrounding holes for passing through surrounding fibers, which are the remainder of the multiple fibers, and a stress adjusting unit for holding stresses generated in the center fiber and surrounding fibers to a desired constant value, respectively, are installed. The surrounding fibers are rotated around the center fiber by rotating the mask. The center fiber and the surrounding fibers that have been twisted around the center fiber are heated with a heating apparatus and drawn. The center fiber and the surrounding fibers are fixed using a clamp installed between the stress adjusting unit and the heating apparatus.

Apparatus and method for making multi-branching optical coupler

Grating optical fiber, and optical fiber base material suitable for

A rare earth element-doped multiple-core optical fiber has an outer cladding layer and a plurality of cores each covered with a primary cladding layer. The cores are positioned substantially on a central axis of the outer cladding layer and separated with a predetermined spacing S from each other by the primary cladding layer. The outer cladding layers are made of SiO.sub.2, or SiO.sub.2 added with a dopant like F, Ge, etc. The primary cladding layer is made of SiO.sub.2 doped with Er, or SiO.sub.2 doped with Er and F together and formed to have a predetermined thickness of 1.0 .mu.m.about.1.5 .mu.m to form the predetermined spacing S. The Soot glass rods for cores and primary cladding layers are immersed in an Er-compound solution, then picked up, dried and consolidated to form Er--Al co-doped SiO.sub.2 --GeO.sub.2 transparent glass rods. The glass rods are inserted into a quartz tube and collapsed by heat to fabricate an optical fiber preform rod, then heated to be drawn to provide an Er-doped multiple-core optical fiber.

Rare earth element-doped multiple-core optical fiber and method for

An Er-doped multiple-core optical fiber amplifier has an Er-doped multiple-core optical fiber. A signal light of 1.5 .mu.m wavelength band is input through an optical isolator at front stage, and excitation lights of 0.98 .mu.m or 1.48 .mu.m wavelength emitted from excitation light sources are injected through a WDM coupler at front stage and a WDM coupler at rear stage, respectively. An amplified signal light is output through optical isolator at rear stage. A length L.sub.M of the Er-doped multiple-core optical fiber is set to obtain a substantially maximum saturated output power of the amplified signal light.

Rare earth element-doped optical fiber amplifier

The object of the present invention is to provide a wide-band optical fiber coupler whose light-branching ratio is independent of the wavelength of light rays to be transmitted therethrough as well as a method for preparing the wide-band optical fiber coupler. When an optical fiber 1 having zero-dispersion at 1.55 .mu.m band and an optical fiber 2 having zero-dispersion at 1.3 .mu.m band are fused and drawn to form a coupled portion 3, a light beam 15 is incident upon the optical fiber 2 and the intensity of the light beam outgoing through either of these optical fibers 2 or 1 is measured to detect the light-branching ratio observed at the coupled portion 3. The drawing operation is interrupted at an instance when the detected light-branching ratio falls within the range of 50.+-.5%.

Growing community of inventors

Annaka, Japan

Jun Abe