Abstract: A composite substrate capable of maintaining high resistance after processing at 300° C. and a method of manufacturing the composite substrate are provided. The composite substrate according to the present invention is manufactured by bonding a silicon (Si) wafer having an interstitial oxygen concentration of 2 to 10 ppma to a piezoelectric material substrate as a support substrate, and thinning the piezoelectric material substrate after the bonding. The piezoelectric material substrate is particularly preferably a lithium tantalate wafer (LT) substrate or a lithium niobate (LN) substrate.

Abstract: Provided is a high-performance composite substrate for surface acoustic wave device which has good temperature characteristics and in which spurious caused by the reflection of a wave on a joined interface between a piezoelectric crystal film and a support substrate is reduced. The composite substrate for surface acoustic wave device includes: a piezoelectric single crystal substrate; and a support substrate, where, at a portion of a joined interface between the piezoelectric single crystal substrate and the support substrate, at least one of the piezoelectric single crystal substrate and the support substrate has an uneven structure, a ratio of an average length RSm of elements in a cross-sectional curve of the uneven structure to a wavelength ? of a surface acoustic wave when the substrate is used as a surface acoustic wave device is equal to or more than 0.2 and equal to or less than 7.0.

Abstract: [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.

Abstract: Provided is a composite substrate for surface acoustic wave device which does not cause peeling of an entire surface of a piezoelectric single crystal film even when heating the film to 400° C. or higher in a step after bonding. The composite substrate is formed by providing a piezoelectric single crystal substrate and a support substrate, forming a film made of an inorganic material on at least one of the piezoelectric single crystal substrate and the support substrate, and joining the piezoelectric single crystal substrate with the support substrate so as to sandwich the film made of the inorganic material.

Abstract: To provide a method for producing a composite wafer capable of reducing a spurious arising by reflection of an incident signal on a joint interface between a lithium tantalate film and a supporting substrate, in the composite wafer including a supporting substrate having a low coefficient of thermal expansion, and a lithium tantalate film having a high coefficient of thermal expansion stacked on the supporting substrate. The method for producing a composite wafer is a method for producing a composite wafer that produces a composite wafer by bonding a lithium tantalate wafer having a high coefficient of thermal expansion to a supporting wafer having a low coefficient of thermal expansion, wherein prior to bonding together, ions are implanted from a bonding surface of the lithium tantalate wafer and/or the supporting wafer, to disturb crystallinity near the respective bonding surfaces.

Abstract: A composite substrate includes a single crystal support substrate containing first element as a main component; an oxide single crystal layer provided on the single crystal support substrate and containing a second element (excluding oxygen) as a main component; and an amorphous layer provided in between the single crystal support substrate and the oxide single crystal layer and containing a first element, a second element, and Ar, the amorphous layer having a first amorphous region in which proportion of the first element is higher than proportion of the second element, and a second amorphous region in which the proportion of the second element is higher than the proportion of the first element, concentration of Ar contained in the first amorphous region being higher than concentration of Ar contained in the second amorphous region and being 3 atom % or more.

Abstract: [Object] An object of the present invention is to provide a bonded substrate which is excellent in temperature characteristics and suppresses unnecessary response due to reflection of an elastic wave at a bonding interface. [Means to Solve the Problems] The present invention is unique in that a bonded substrate is constructed by bonding a LiTaO3 substrate and a base plate wherein a Li concentration at a base plate-bonding face of the LiTaO3 substrate is higher than that at a LiTaO3 substrate-side end face of the bonded substrate, that the difference between the Li concentration at the base plate-bonding face of the LiTaO3 substrate and the Li concentration at the LiTaO3 substrate-side end face of the bonded substrate is 0.1 mol % or greater, that the Li concentration at the base plate-bonding face of the LiTaO3 substrate satisfies an equation Li/(Li+Ta)×100=(50+?) mol %, where ? is in the range of ?1.2<?<0.

Abstract: [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 LiTaO3 substrate.

Abstract: The lithium tantalate single crystal substrate is a rotated Y-cut LiTaO3 single crystal substrate having a crystal orientation of 36° Y-49° 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 LiTaO3 substrate surface.

Abstract: 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° and not larger than 49° 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.

Abstract: [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.

Abstract: An optical isolator comprsing at least two parts of a Faraday rotator obtained from a garnet crystal and an analyzer, which is small in size, can be mounted directly to a semiconductor laser. The garnet crystal is grown, by a liquid-phase epitaxial growth technique, on the substrate of a garnet with a lattice constant of 12.514±0.015 Å, and consists of the following composition formula: (Tb1−(a+b+c+d)LnaBibM1cEud)3(Fe1−eM2e)5O12 where Ln is an element selected from rare-earth elements excluding Tb and Eu, and Y; M1 is an element selected from elements Ca, Mg, and Sr; M2 is an element selected from elements of Al, Ga, Sc, In, Ti, Si, and Ge; a, b, c, d, and e are defined as 0≦a≦0.5, 0.3<b≦0.6, 0≦c≦0.02, 0<d≦0.3, and 0.01<e≦0.3, respectively.

Abstract: A Faraday rotator whose Faraday's rotational angle has low temperature-dependency; a method for efficiently preparing the same; a magneto-optical element which makes use of the Faraday rotator and whose characteristic properties are not susceptive to temperature changes; and an optical isolator, which can be provided at a low price. A Faraday rotator consists of a garnet crystal represented by the following compositional formula and having a lattice constant of 12.470 ±0.013 Å: (Tb1−(a+b+c)LnaBibM1c)3(Fe1−dM2d)5O12 in the formula, Ln is an element selected from the group consisting of rare earth elements other than Tb; M1 represents an element selected from the group consisting of Ca, Mg and Sr; M2 is an element selected from the group consisting of Al, Ti, Si and Ge; and a to d are numerals satisfying the following relations: 0≦a≦0.5, 0<b≦0.2, 0≦c≦0.02 and 0≦d≦0.1.

Abstract: A magnetostatic wave device includes a Gd3Ga5O12 substrate off-angled from a {110} plane. A magnetic thin film including a crystal of garnet is formed on the Gd3Ga5O12 substrate by liquid-phase epitaxy. A transducer operates for exciting magnetostatic wave in the magnetic thin film in response to an RF electric signal. A bias magnetic field is applied to the magnetic thin film. There is a relation as 20°≦|&thgr;1+&thgr;2|≦35°, where “&thgr;1” denotes an angle between a longitudinal direction of the transducer and a <001> orientation of the crystal in the magnetic thin film, and “&thgr;2” denotes an angle between a transverse direction of the transducer and a specified direction.

Abstract: An improvement is proposed relating to an optical isolator for bonding of the polarizer and analyzer of polarizing glass to the respective holder rings for position adjustment. The improvement comprises: (a) forming a metallized layer of a specific composition over at least two of the side surfaces of each of the polarizer and analyzer on the area of the surface excepting for the linear areas of 50 to 150 .mu.m width from the top and bottom surfaces of the polarizer or analyzer; and (b) bonding the polarizer and analyzer to the respective holder rings by soldering using a solder alloy with intervention of the metallized layer between the polarizer or analyzer and the holder ring. The invention further provides an optical part having, on at least one of the surfaces, a heat-resistant anti-reflection coating film which is a double-layered film consisting of a thin film of the titanium oxide TiO.sub.x (x=1.9 to 2.

Abstract: A magnetostatic wave device includes a Gd.sub.3 Ga.sub.5 O.sub.12 substrate off-angled from a {110} plane. A magnetic thin film including a crystal of garnet is formed on the Gd.sub.3 Ga.sub.5 O.sub.12 substrate by liquid-phase epitaxy. A transducer is operative for exciting magnetostatic wave in the magnetic thin film in response to an RF electric signal. A bias magnetic field is applied to the magnetic thin film. There is a relation as 20.degree..ltoreq..vertline..theta..sub.1 +.theta..sub.2 .vertline..ltoreq.35.degree., where ".theta..sub.1 " denotes an angle between a longitudinal direction of the transducer and a <001> orientation of the crystal in the magnetic thin film, and ".theta..sub.2 " denotes an angle between a direction of the bias magnetic field and a transverse direction of the transducer which is perpendicular to the longitudinal direction thereof.

Abstract: A reflection-type S/N enhancer includes a Gd.sub.3 Ga.sub.5 O.sub.12 substrate off-angled from a {110} plane. A magnetic thin film including a crystal of garnet is formed on the Gd.sub.3 Ga.sub.5 O.sub.12 substrate by liquid-phase epitaxy. The magnetic thin film has a saturation magnetization in a range of 500 G to 1,100 G. A transducer is operative for exciting magnetostatic wave in the magnetic thin film in response to an RF electric signal. A bias magnetic field is applied to the magnetic thin film. There is a relation as .vertline..theta..sub.1 +.theta..sub.2 .vertline.<45.degree., where ".theta..sub.1 " denotes an angle between a longitudinal direction of the transducer and a <001> orientation of the crystal in the magnetic thin film, and ".theta..sub.2 " denotes an angle between a direction of the bias magnetic field and a transverse direction of the transducer in a horizontal plane. The transverse direction of the transducer is perpendicular to the longitudinal direction thereof.

Abstract: An improvement is proposed relating to an optical isolator for bonding of the polarizer and analyzer of polarizing glass to the respective holder rings for position adjustment. The improvement comprises: (a) forming a metallized layer of a specific composition over at least two of the side surfaces of each of the polarizer and analyzer on the area of the surface excepting for the linear areas of 50 to 150 .mu.m width from the top and bottom surfaces of the polarizer or analyzer; and (b) bonding the polarizer and analyzer to the respective holder rings by soldering using a solder alloy with intervention of the metallized layer between the polarizer or analyzer and the holder ring. The invention further provides an optical part having, on at least one of the surfaces, a heat-resistant anti-reflection coating film which is a double-layered film consisting of a thin film of the titanium oxide TiO.sub.x (x=1.9 to 2.

Abstract: Proposed is an improvement in a magnetostatic surface wave device such as an S/N enhancer comprising a thin film chip of a magnetic oxide garnet, e.g., gallium-substituted YIG epitaxially grown on the surface of a substrate, e.g., GGG, to which a magnetic field is applied within the plane of the thin film. The low-pass cut-off frequency of the microwaves can be decreased to 400 MHz or lower and the half-value width of magnetic resonance .DELTA.H can be small enough when the principal plane of the thin film of the magnetic oxide garnet is the (110) plane and the magnetic field applied thereto is in such a direction that the angle between the direction of the magnetic field and the direction of the <100> axis of the thin film within the (110) plane is in the range from .+-.27.degree. to .+-.33.degree..

Abstract: Proposed is an improvement in the method for the preparation of a chip of an oxide garnet film epitaxially having a specific chemical composition as grown on the surface of a GGG substrate wafer having a crystallographic plane orientation of (111), which is useful as a working element in a magnetostatic wave device such as high-frequency filters, signal noise enhancers, isolators and the like with decreased temperature dependence of the properties. The epitaxially grown single crystal film is adjusted to have such dimensions that the thickness h and the smallest dimension L within the plane of the film satisfy the relationship that the ratio h/L is in the range from 0.001 to 0.25.