Abstract: There is provided a rare-earth gallium garnet ceramic having a high extinction ratio and a high light transmittance. The rare-earth gallium garnet ceramic contains, as a sintering aid, 5 mass ppm or more and 500 mass ppm or less of Ge calculated as metal, and 20 mass ppm or more and 250 mass ppm or less of Al calculated as metal.

Abstract: A semiconductor optical device that integrates photodiodes (PDs) and optical waveguides coupling with the PDs and a method of forming the semiconductor optical device are disclosed. The optical waveguides in a portion in the lower cladding layer thereof provides a modified layer that forms a conduction barrier of the lower cladding layer. The modified layer is formed by converting the conduction type thereof or implanting protons therein. The modified layer prevents the electrical coupling between PDs through the waveguides.

Abstract: The layout of character keys each having a plurality of characters allocated thereto is established on a virtual surface (first layer) including a detection position of a gesture that satisfies predetermined conditions, and when a gesture moving along the first layer is detected, a selection position with respect to the layout of character keys is moved in accordance with the gesture movement. When the movement direction of the gesture is switched to a direction away from the first layer under the condition that a prescribed character key in the layout is selected, each character allocated to the character key being selected is arranged outside the first layer at individually different positions relative to a virtual axis passing through the character key. Thereafter, in response to detection of a gesture moving toward any character, a character disposed at a moving destination is selected as an input character.

Abstract: A Mach-Zehnder modulator comprises first to third semiconductor structures provided on first to third areas of a primary surface of a conductive semiconductor region, respectively. The second semiconductor structure includes a semiconductor laminate and a first contact portion thereon. The third semiconductor structure includes the semiconductor laminate and a second contact portion thereon. The first and second contact portions constitute a contact layer. The second semiconductor structure has first and second waveguide sides. The first contact portion has an edge which terminates the contact layer and extends in a direction of a first reference plane on the top of the semiconductor laminate to reach the first waveguide side. The first reference plane and a top of the second semiconductor structure intersect with each other to define a line of intersection obliquely-crossed with an upper edge of the first waveguide side at a first angle different from a right angle.

Abstract: A semiconductor optical device includes a semiconductor substrate having first to fourth regions, a 90-degree optical hybrid provided in the third region on a principal surface of the semiconductor substrate, first and second waveguides provided in the first region and being optically coupled to the 90-degree optical hybrid, a photodiode provided in the fourth region, a third waveguide provided in the second region to optically couple the 90-degree optical hybrid to the photodiode, and a metal layer provided on a back surface of the semiconductor substrate. The metal layer includes a first part provided in the first region and a second part provided in the second region that is spaced apart from the first part by a distance. The 90-degree optical hybrid has a first length. The distance between the first and second parts is more than or equal to the first length.

Abstract: A semiconductor optical device includes a semiconductor substrate having first to fourth regions, a 90-degree optical hybrid provided in the third region on a principal surface of the semiconductor substrate, first and second waveguides provided in the first region being optically coupled to the 90-degree optical hybrid, a photodiode provided in the fourth region, a third waveguide provided in the second region to optically couple the 90-degree optical hybrid to the photodiode, and a metal layer provided on a back surface of the semiconductor substrate. The metal layer includes a first part provided in the first region and a second part provided in the second region spaced apart from the first region by a distance. The 90-degree optical hybrid has a first length. The distance between the first and second parts is more than or equal to the first length.

Abstract: A modulator including: a Mach-Zehnder modulator that includes an optical waveguide disposed on a substrate, the optical waveguide including an electrode thereon; a resin layer disposed on the substrate, the resin layer embedding the optical waveguide, the resin layer having a groove arranged besides the optical waveguide; a termination resistor disposed on the substrate in the groove of the resin layer; and a first wiring disposed on the resin layer, the first wiring being connected to the termination resistor and the electrode of the optical waveguide.

Abstract: A semiconductor optical device has a substrate including a primary surface with first to fourth areas; a first conductivity-type semiconductor layer disposed on the third and fourth areas; a first semiconductor laminate disposed on the first conductivity-type semiconductor layer and the third area; a resin body disposed on the second to fourth areas; a first electrode connected with the first semiconductor laminate through a first opening of the resin body in the third area; a first pad electrode disposed on the first area; and a wiring conductor extending on a first side and a top of the resin body in the second and third areas and on the first area to connect the first electrode to the first pad electrode. The first side of the resin body is disposed in the second area. The first semiconductor laminate includes a second conductivity-type semiconductor region being in contact with the first electrode.

Abstract: An optical semiconductor device including: a substrate having a principal surface; first and second optical waveguides disposed on the principal surface of the substrate, the first and second optical waveguides extending in a first direction, the second optical waveguide being arranged adjacent to the first optical waveguide in a second direction intersecting with the first direction; first and second signal electrodes disposed on the first and second optical waveguides; a resistor disposed on the principal surface, the resistor being arranged between the first optical waveguide and the second optical waveguide, the resistor being electrically connected to the first signal electrode and the second signal electrode; a resin layer disposed on the principal surface, top surfaces of the first and second signal electrodes, and the resistor; and a capacitor disposed on the resin layer, the capacitor being electrically connected to the resistor through an opening of the resin layer.

Abstract: A semiconductor optical device that integrates photodiodes (PDs) and optical waveguides coupling with the PDs and a method of forming the semiconductor optical device are disclosed. The optical waveguides in a portion in the lower cladding layer thereof provides a modified layer that forms a conduction barrier of the lower cladding layer. The modified layer is formed by converting the conduction type thereof or implanting protons therein. The modified layer prevents the electrical coupling between PDs through the waveguides.

Abstract: A semiconductor optical modulator includes a substrate having a principal surface; a waveguide disposed on the principal surface of the substrate, the waveguide extending in a first direction; a first electrode disposed on the waveguide, the first electrode being in contact with an upper surface of the waveguide; a first wiring connected to the first electrode, the first wiring extending in a second direction intersecting the first direction; a build-up portion connected to the first wiring; a second wiring connected to the build-up portion, the second wiring extending in a plane parallel to the principal surface of the substrate; and a resin layer disposed on the substrate, the resin layer embedding the first wiring and the build-up portion. The build-up portion extends along a third direction, the third direction intersecting perpendicularly to the principal surface of the substrate. The second wiring is disposed on the resin layer.

Abstract: A semiconductor optical device includes a substrate including first and second regions arranged in a first direction, a photodiode disposed on the first region, an optical waveguide disposed on the second region, and a buried layer disposed on a side surface of the photodiode. The side surface of the photodiode extends in the first direction. The photodiode has a first end surface intersecting with the first direction, and the optical waveguide is in direct contact with the first end surface. The buried layer is composed of a III-V compound semiconductor doped with a transition metal. The photodiode includes a stacked semiconductor layer including a first cladding layer, a light-absorbing layer and a second cladding layer stacked in that order on the substrate. The light-absorbing layer has a side surface having at least a portion recessed with respect to a side surface of the first cladding layer.

Abstract: A semiconductor optical device comprises a substrate including a primary surface with first to fourth areas; a first conductivity-type semiconductor layer disposed on the third and fourth areas; a first semiconductor laminate disposed on the first conductivity-type semiconductor layer and the third area; a resin body disposed on the second to fourth areas; a first electrode connected with the first semiconductor laminate through a first opening of the resin body in the third area; a first pad electrode disposed on the first area; and a wiring conductor extending on a first side and a top of the resin body in the second and third areas and on the first area to connect the first electrode to the first pad electrode. The first side is disposed in the second area. The first semiconductor laminate includes a second conductivity-type semiconductor region being in contact with the first electrode.

Abstract: A Mach-Zehnder modulator comprises first to third semiconductor structures provided on first to third areas of a primary surface of a conductive semiconductor region, respectively. The second semiconductor structure includes a semiconductor laminate and a first contact portion thereon. The third semiconductor structure includes the semiconductor laminate and a second contact portion thereon. The first and second contact portions constitute a contact layer. The second semiconductor structure has first and second waveguide sides. The first contact portion has an edge which terminates the contact layer and extends in a direction of a first reference plane on the top of the semiconductor laminate to reach the first waveguide side. The first reference plane and a top of the second semiconductor structure intersect with each other to define a line of intersection obliquely-crossed with an upper edge of the first waveguide side at a first angle different from a right angle.

Abstract: A connector which is detachably connected to a cylindrical section is prevented from unintentionally disconnecting and breaking. The connector has inner and outer cylinder members. The inner cylinder member has an engagement plate protruding from the inner peripheral surface of an inner cylinder body and engaging with a recess formed in the outer peripheral surface of the cylindrical section, and also has slits arranged radially and extending from the engagement plate to a part of the inner cylinder body. The engagement between the recess and the engagement plate restricts the axial movement of the inner cylinder member relative to the cylindrical section. When the outer cylinder member is mounted on the inner cylinder member, the inner peripheral surface of the outer cylinder member is in contact with the outer peripheral surface of the inner cylinder member, and the displacement of the engagement plate in the diameter expansion direction is restricted.

Abstract: An integrated optical semiconductor device includes a substrate including first and second regions; a plurality of light receiving devices disposed in the second region; a multimode interference coupler disposed in the first region, the multimode interference coupler including output optical waveguides optically coupled to the corresponding light receiving devices; first and second conductive layers disposed on a back surface of the substrate in the first and second regions, respectively; and a plurality of capacitors disposed in the second region, each of the capacitors including a first electrode connected to one of the light receiving devices and a second electrode connected to the second conductive layer. The second conductive layer is electrically insulated from the first conductive layer. The substrate is made of a semi-insulating semiconductor. The multimode interference coupler and the light receiving devices include the same n-type semiconductor layer disposed on a principal surface of the substrate.

Abstract: A method for producing optical semiconductor devices includes: forming a stacked semiconductor layer on a device substrate to provide an epitaxial substrate having a size corresponding to a section arrangement; forming, on the epitaxial substrate, a mask having a pattern for a semiconductor mesa and for a trench of at least one optical semiconductor device, a width of the trench in the pattern being determined according to a trench width map in which trench width is based upon an in-plane distribution of the thickness of a resin layer of the at least one device, and upon a correlation between the thickness of the resin layer and the trench width; forming a trench structure including the semiconductor mesa and the trench by etching the stacked semiconductor layer using the mask; forming a resin layer on the trench structure; and forming an opening on the semiconductor mesa by etching the resin layer.

Abstract: A semiconductor Mach-Zehnder modulator includes a substrate having a main surface including first, second and third regions sequentially arranged along a direction; a waveguide mesa including first and second waveguide arms provided on the second region, first and second optical couplers provided on the first and third regions, respectively; a first semiconductor protective layer provided on side surfaces of the first and second waveguide arms; a buried layer provided on side surfaces of the waveguide mesa and on the main surface, the buried layer including a material having a dielectric constant lower than that of the first protective layer; and first and second upper electrodes provided on the first and second waveguide arms, respectively. The first and second optical couplers are connected to the first and second waveguide arms. Above the second region, the buried layer is provided on the first protective layer.

Abstract: A method for producing a semiconductor optical device includes the steps of forming first and second optical waveguides; forming a first resin layer on the first and the second optical waveguides; forming an opening in the first resin layer; forming a first electrode in the opening; forming a second resin layer on the first electrode and the first resin layer; forming a groove in the second resin layer on the first electrode; forming a second electrode on the second resin layer, a side surface of the groove, and the top surface of the first electrode; and forming a third electrode on the second electrode. The second and third electrodes have a region in which the second and third electrodes pass over the second optical waveguide, and, in the region, the first and second resin layers are disposed between the second electrode and the second optical waveguide.

Abstract: A method for manufacturing a semiconductor modulator includes the steps of preparing a substrate having a main surface including first and second areas; forming a stacked semiconductor layer on the main surface; forming an optical waveguide mesa by etching the stacked semiconductor layer using a mask, the optical waveguide mesa including an optical modulation portion; applying a resin on a top surface and a side surface of the optical waveguide mesa and on the substrate; forming a first opening in the resin on the second area of the substrate; forming an underlayer structure on the second area of the substrate in contact with the substrate; and forming a pad electrode on the underlayer structure in contact with the underlayer structure through the first opening of the resin. The underlayer structure includes an insulating layer made of a dielectric material.