Abstract: An integrated optical waveguide has a first optical waveguide, a second optical waveguide, and a groove. The second optical waveguide is coupled to the first optical waveguide and has a refractive index that is different from the first optical waveguide. The groove is disposed so as to traverse an optical path of the first optical waveguide and is separated from an interface between the first optical waveguide and the second optical waveguide by a predetermined spacing. The spacing from the interface and the width of the groove are determined such that reflection at a boundary between the first optical waveguide and the second optical waveguide is weakened. A semiconductor board may be disposed at a boundary between the first optical waveguide and the second optical waveguide.

Abstract: An integrated optical waveguide has a first optical waveguide, a second optical waveguide, and a groove. The second optical waveguide is coupled to the first optical waveguide and has a refractive index that is different from the first optical waveguide. The groove is disposed so as to traverse an optical path of the first optical waveguide and is separated from an interface between the first optical waveguide and the second optical waveguide by a predetermined spacing. The spacing from the interface and the width of the groove are determined such that reflection at a boundary between the first optical waveguide and the second optical waveguide is weakened. A semiconductor board may be disposed at a boundary between the first optical waveguide and the second optical waveguide.

Abstract: A process of producing a diamond thin-film includes implanting dopant into a diamond by an ion implantation technique, forming a protective layer on at least part of the surface of the ion-implanted diamond, and firing the protected ion-implanted diamond at a firing pressure of no less than 3.5 GPa and a firing temperature of no less than 600° C. A process of producing a diamond semiconductor includes implanting dopant into each of two diamonds by an ion implantation technique and superimposing the two ion-implanted diamonds on each other such that at least part of the surfaces of each of the ion-implanted diamonds makes contact with each other, and firing the ion implanted diamonds at a firing pressure of no less than 3.5 GPa and a firing temperature of no less than 600° C.

Abstract: In a conventional diamond semiconductor element, because of high density of crystal defects, it is impossible to reflect the natural physical properties peculiar to a diamond, such as high thermal conductivity, high breakdown field strength, high-frequency characteristics and the like, in the transistor characteristics. By slightly shifting surface orientation of a diamond substrate in a [001] direction, a significant reduction in crystal defects peculiar to a diamond is possible. The equivalent effects are also provided by shifting surface orientation of a single-crystal diamond thin-film or channel slightly from a [001] direction. It is possible to obtain a significantly high transconductance gm as compared with that in a transistor produced using conventional surface orientation.

Abstract: A process for producing a diamond thin-film includes forming a diamond crystal thin-film on a substrate and firing the diamond crystal thin-film at a sufficient temperature under high pressure under which a diamond is stable. A diamond single-crystal substrate having a diamond single-crystal thin-film formed thereon is placed in an ultra-high-pressure and high-temperature firing furnace to anneal the diamond single-crystal thin-film under the conditions of 1200° C. and 6 GPa.

Abstract: A process of producing a diamond thin-film includes implanting dopant into a diamond by an ion implantation technique, forming a protective layer on at least part of the surface of the ion-implanted diamond, and firing the protected ion-implanted diamond at a firing pressure of no less than 3.5 GPa and a firing temperature of no less than 600° C. A process of producing a diamond semiconductor includes implanting dopant into each of two diamonds by an ion implantation technique and superimposing the two ion-implanted diamonds on each other such that at least part of the surfaces of each of the ion-implanted diamonds makes contact with each other, and firing the ion implanted diamonds at a firing pressure of no less than 3.5 GPa and a firing temperature of no less than 600° C.

Abstract: An integrated optical waveguide has a first optical waveguide, a second optical waveguide, and a groove. The second optical waveguide is coupled to the first optical waveguide and has a refractive index that is different from the first optical waveguide. The groove is disposed so as to traverse an optical path of the first optical waveguide and is separated from an interface between the first optical waveguide and the second optical waveguide by a predetermined spacing. The spacing from the interface and the width of the groove are determined such that reflection at a boundary between the first optical waveguide and the second optical waveguide is weakened. A semiconductor board may be disposed at a boundary between the first optical waveguide and the second optical waveguide.

Abstract: An integrated optical waveguide has a first optical waveguide, a second optical waveguide, and a groove. The second optical waveguide is coupled to the first optical waveguide and has a refractive index that is different from the first optical waveguide. The groove is disposed so as to traverse an optical path of the first optical waveguide and is separated from an interface between the first optical waveguide and the second optical waveguide by a predetermined spacing. The spacing from the interface and the width of the groove are determined such that reflection at a boundary between the first optical waveguide and the second optical waveguide is weakened. A semiconductor board may be disposed at a boundary between the first optical waveguide and the second optical waveguide.

Abstract: An integrated optical waveguide has a first optical waveguide, a second optical waveguide, and a groove. The second optical waveguide is coupled to the first optical waveguide and has a refractive index that is different from the first optical waveguide. The groove is disposed so as to traverse an optical path of the first optical waveguide and is separated from an interface between the first optical waveguide and the second optical waveguide by a predetermined spacing. The spacing from the interface and the width of the groove are determined such that reflection at a boundary between the first optical waveguide and the second optical waveguide is weakened. A semiconductor board may be disposed at a boundary between the first optical waveguide and the second optical waveguide.

Abstract: In a conventional diamond semiconductor element, because of high density of crystal defects, it is impossible to reflect the natural physical properties peculiar to a diamond, such as high thermal conductivity, high breakdown field strength, high-frequency characteristics and the like, in the transistor characteristics. By slightly shifting surface orientation of a diamond substrate in a [001] direction, a significant reduction in crystal defects peculiar to a diamond is possible. The equivalent effects are also provided by shifting surface orientation of a single-crystal diamond thin-film or channel slightly from a [001] direction. It is possible to obtain a significantly high transconductance gm as compared with that in a transistor produced using conventional surface orientation.

Abstract: In a conventional diamond semiconductor element, because of high density of crystal defects, it is impossible to reflect the natural physical properties peculiar to a diamond, such as high thermal conductivity, high breakdown field strength, high-frequency characteristics and the like, in the transistor characteristics. By slightly shifting surface orientation of a diamond substrate in a [001] direction, a significant reduction in crystal defects peculiar to a diamond is possible. The equivalent effects are also provided by shifting surface orientation of a single-crystal diamond thin-film or channel slightly from a [001] direction. It is possible to obtain a significantly high transconductance gm as compared with that in a transistor produced using conventional surface orientation.

Abstract: An integrated optical waveguide has a first optical waveguide, a second optical waveguide, and a groove. The second optical waveguide is coupled to the first optical waveguide and has a refractive index that is different from the first optical waveguide. The groove is disposed so as to traverse an optical path of the first optical waveguide and is separated from an interface between the first optical waveguide and the second optical waveguide by a predetermined spacing. The spacing from the interface and the width of the groove are determined such that reflection at a boundary between the first optical waveguide and the second optical waveguide is weakened. A semiconductor board may be disposed at a boundary between the first optical waveguide and the second optical waveguide.

Abstract: An integrated optical waveguide has a first optical waveguide, a second optical waveguide, and a groove. The second optical waveguide is coupled to the first optical waveguide and has a refractive index that is different from the first optical waveguide. The groove is disposed so as to traverse an optical path of the first optical waveguide and is separated from an interface between the first optical waveguide and the second optical waveguide by a predetermined spacing. The spacing from the interface and the width of the groove are determined such that reflection at a boundary between the first optical waveguide and the second optical waveguide is weakened. A semiconductor board may be disposed at a boundary between the first optical waveguide and the second optical waveguide.

Abstract: An integrated optical waveguide has a first optical waveguide, a second optical waveguide, and a groove. The second optical waveguide is coupled to the first optical waveguide and has a refractive index that is different from the first optical waveguide. The groove is disposed so as to traverse an optical path of the first optical waveguide and is separated from an interface between the first optical waveguide and the second optical waveguide by a predetermined spacing. The spacing from the interface and the width of the groove are determined such that reflection at a boundary between the first optical waveguide and the second optical waveguide is weakened. A semiconductor board may be disposed at a boundary between the first optical waveguide and the second optical waveguide.