Abstract: A semiconductor optical device includes a substrate a spot-size converter, an optical detector, a core layer and a first III-V compound semiconductor layer, the core layer is disposed between the substrate and the first III-V compound semiconductor layer, the optical detector includes a light absorbing layer, a second III-V compound semiconductor layer, and an insulating film, the light absorbing layer is disposed between the substrate and the second III-V compound semiconductor layer, the second III-V compound semiconductor layer is disposed between the light absorbing layer and the insulating film, the light absorbing layer is optically coupled to the core layer, the spot-size converter has a first end face connected to the optical detector and a second end face opposite to the first end face, and the first III-V compound semiconductor layer is connected to the second III-V compound semiconductor layer and the insulating film at the first end face.

Abstract: A photo receiver includes a photo detector including a semiconductor substrate having a first main surface and a second main surface and a metal pattern layer provided on the second main surface; and a carrier including a supporting substrate having a third main surface facing the second main surface and a solder pattern layer provided on the third main surface. The solder pattern layer is bonded to the metal pattern layer. The first main surface is provided with a variable optical attenuator, an optical 90-degree hybrid device, and a plurality of photodiodes optically coupled to the variable optical attenuator via the optical 90-degree hybrid device. The solder pattern layer and the metal pattern layer are located in a peripheral area surrounding a central area where the variable optical attenuator and the optical 90-degree hybrid device are located when viewed in the normal direction of the first main surface.

Abstract: A light receiving device includes a semiconductor substrate having a first major surface and a second major surface opposite to the first major surface, and a metal pattern layer provided on the second major surface. The first major surface is provided with a first input port configured to receive an input of signal light, a second input port configured to receive an input of local oscillation light, a first light receiving element optically coupled to the first input port, an optical 90 degree hybrid element optically coupled to the first input port and the second input port, and a second light receiving element optically coupled to the optical 90 degree hybrid element. The metal pattern layer contains at least one of titanium or chromium.

Abstract: A semiconductor light receiving element includes a first semiconductor layer, a waveguide type photodiode structure, an optical waveguide structure, and a fourth semiconductor layer. The waveguide type photodiode structure is provided on the first semiconductor layer. The waveguide type photodiode structure includes an optical absorption layer, a second semiconductor layer, a multiplication layer, and a third semiconductor layer. The optical waveguide structure is provided on the first semiconductor layer. The optical waveguide structure includes an optical waveguiding core layer and a cladding layer. An end face of the waveguide type photodiode structure faces to an end face of the optical waveguide structure. The fourth semiconductor layer is located between the end face of the waveguide type photodiode structure and the end face of the optical waveguide structure. The fourth semiconductor layer contacts the multiplication layer at the end face of the waveguide type photodiode structure.

Abstract: An optical waveguide type photodetector includes a first semiconductor layer of a first conductive type, a multiplication layer of a first conductive type on the first semiconductor layer, an optical waveguide structure, and a photodiode structure. The photodiode structure has a third semiconductor layer of a second conductive type, an optical absorption layer of an intrinsic conductive type or of a second conductive type, and a second semiconductor layer of a second conductive type. The optical waveguide structure includes an optical waveguiding core layer and a cladding layer. An end face of the photodiode structure located in a second region of the first semiconductor layer and an end face of the optical waveguide structure located in a first region of the first semiconductor layer are in contact.

Abstract: A light-receiving device includes a first semiconductor layer having a first conductivity type, an optical waveguide structure on a first region of the first semiconductor layer, and a photodiode structure on a second region adjacent to the first region of the first semiconductor layer. The optical waveguide structure includes a core layer on the first semiconductor layer, and a cladding layer on the core layer. The photodiode structure includes a light-absorbing layer optically coupled with the core layer, and a second semiconductor layer having a second conductivity type on or above the light-absorbing layer. The light-absorbing layer includes a third semiconductor layer having a p-type, and a fourth semiconductor layer having a n-type or an i-type. The third semiconductor layer is disposed between the fourth semiconductor layer and a p-type layer that is one of the first semiconductor layer and the second semiconductor layer.

Abstract: A photo detector includes a variable optical attenuator provided on a substrate, an optical 90-degree hybrid device provided on the substrate, and a plurality of photodiodes provided on the substrate. The plurality of photodiodes are optically coupled to the variable optical attenuator via the optical 90-degree hybrid device. The variable optical attenuator includes an optical waveguide disposed on the substrate, a heater configured to heat the optical waveguide, and an insulating layer at least partially disposed between the substrate and the optical waveguide.

Abstract: A first semiconductor layer is of a first conductive type. A multiplication layer is of a first conductive type and is provided on the first semiconductor layer. An optical waveguide structure has an end face provided on a first region of the multiplication layer. A photodiode structure has an end face and provided on a second region of the multiplication layer. The photodiode structure has a third semiconductor layer being of a second conductive type, an optical absorption layer being of an intrinsic conductive type or of a second conductive type, and a second semiconductor layer being of a second conductive type which are arranged in this order. The optical waveguide structure includes an optical waveguiding core layer and a cladding layer. The end face of the waveguide type photodiode structure and the end face of the optical waveguide structure are in contact.

Abstract: A semiconductor light receiving element includes a first semiconductor layer, a waveguide type photodiode structure, an optical waveguide structure, and a fourth semiconductor layer. The waveguide type photodiode structure is provided on the first semiconductor layer. The waveguide type photodiode structure includes an optical absorption layer, a second semiconductor layer, a multiplication layer, and a third semiconductor layer. The optical waveguide structure is provided on the first semiconductor layer. The optical waveguide structure includes an optical waveguiding core layer and a cladding layer. An end face of the waveguide type photodiode structure faces to an end face of the optical waveguide structure. The fourth semiconductor layer is located between the end face of the waveguide type photodiode structure and the end face of the optical waveguide structure. The fourth semiconductor layer is contacted with the multiplication layer of the end face of the waveguide type photodiode structure.

Abstract: A photo receiver includes a photo detector including a semiconductor substrate having a first main surface and a second main surface and a metal pattern layer provided on the second main surface; and a carrier including a supporting substrate having a third main surface facing the second main surface and a solder pattern layer provided on the third main surface. The solder pattern layer is bonded to the metal pattern layer. The first main surface is provided with a variable optical attenuator, an optical 90-degree hybrid device, and a plurality of photodiodes optically coupled to the variable optical attenuator via the optical 90-degree hybrid device. The solder pattern layer and the metal pattern layer are located in a peripheral area surrounding a central area where the variable optical attenuator and the optical 90-degree hybrid device are located when viewed in the normal direction of the first main surface.

Abstract: A photo detector includes a variable optical attenuator provided on a substrate, an optical 90-degree hybrid device provided on the substrate, and a plurality of photodiodes provided on the substrate. The plurality of photodiodes are optically coupled to the variable optical attenuator via the optical 90-degree hybrid device. The variable optical attenuator includes an optical waveguide disposed on the substrate, a heater configured to heat the optical waveguide, and an insulating layer at least partially disposed between the substrate and the optical waveguide.

Abstract: A photodiode (PD) device that monolithically integrates a PD element with a waveguide element is disclosed. The PD device includes a conducting layer with a first region and a second region next to the first region, where the PD element exists in the first region, while, the waveguide element exists in the second region and optically couples with the PD element. The waveguide element includes a core layer and a cladding layer on the conducting layer, which forms an optical confinement structure. The PD element includes an absorption layer on the conducting layer and a p-type cladding layer on the absorption layer, which form another optical confinement structure. The absorption layer has a length at least 12 ?m measured from the interface against the core layer.

Abstract: An optical semiconductor device comprises a semiconductor substrate, an optical 90-degree hybrid circuit provided on the substrate, a plurality of input optical waveguides provided on the substrate, and a plurality of output optical waveguides provided on the substrate. The plurality of input optical waveguides is optically coupled to input ends of the optical 90-degree hybrid circuit. The plurality of output optical waveguides is optically coupled to output ends of the optical 90-degree hybrid circuit. Each of the plurality of input optical waveguides includes a first curving portion and a first straight portion adjacent to the first curving portion, and each of the plurality of output optical waveguides includes a second curving portion. A central axis of the first curving portion is inwardly offset with respect to a central axis of the first straight portion, and a central axis of the second curving portion follows a raised sine curve.

Abstract: A semiconductor integrated optical device includes: a supporting base including semi-insulating semiconductor; a first photoelectric convertor having first photodiode mesas; a second photoelectric convertor having second photodiode mesas; a first 90° optical hybrid having at least one first multimode waveguide mesa; a second 90° optical hybrid having at least one second multimode waveguide mesa; an optical divider mesa; first and second input waveguide mesas coupling the first and second 90° optical hybrids with the optical divider mesa, respectively; a conductive semiconductor region disposed on the supporting base, the conductive semiconductor region mounting the first photodiode mesas, the second photodiode mesas, the first multimode waveguide mesas, the second multimode waveguide mesas, and the optical divider mesa; a first island semiconductor mesa extending between the first and second multimode waveguide mesas; and a first groove extending through the first island semiconductor mesa and the conductive

Abstract: A photodiode (PD) device that monolithically integrates a PD element with a waveguide element is disclosed. The PD device includes a conducting layer with a first region and a second region next to the first region, where the PD element exists in the first region, while, the waveguide element exists in the second region and optically couples with the PD element. The waveguide element includes a core layer and a cladding layer on the conducting layer, which forms an optical confinement structure. The PD element includes an absorption layer on the conducting layer and a p-type cladding layer on the absorption layer, which form another optical confinement structure. The absorption layer has a length at least 12 ?m measured from the interface against the core layer.

Abstract: A photodiode (PD) device that monolithically integrates a PD element with a waveguide element is disclosed. The PD device includes a conducting layer with a first region and a second region next to the first region, where the PD element exists in the first region, while, the waveguide element exists in the second region and optically couples with the PD element. The waveguide element includes a core layer and a cladding layer on the conducting layer, which forms an optical confinement structure. The PD element includes an absorption layer on the conducting layer and a p-type cladding layer on the absorption layer, which form another optical confinement structure. The absorption layer has a length at least 12 ?m measured from the interface against the core layer.

Abstract: An optical semiconductor device comprises a semiconductor substrate, an optical 90-degree hybrid circuit provided on the substrate, a plurality of input optical waveguides provided on the substrate, and a plurality of output optical waveguides provided on the substrate. The plurality of input optical waveguides is optically coupled to input ends of the optical 90-degree hybrid circuit. The plurality of output optical waveguides is optically coupled to output ends of the optical 90-degree hybrid circuit. Each of the plurality of input optical waveguides includes a first curving portion and a first straight portion adjacent to the first curving portion, and each of the plurality of output optical waveguides includes a second curving portion. A central axis of the first curving portion is inwardly offset with respect to a central axis of the first straight portion, and a central axis of the second curving portion follows a raised sine curve.

Abstract: A functional optical device applicable to a coherent optical communication system as a front end device is disclosed. The functional optical device includes a pair of light-receiving elements of a type of waveguide photodiode (PD), a pair of signal pads, a pair of ground pads, a bias pad, and a substrate that monolithically integrates those elements thereon. The light-receiving elements generate a photocurrent complementary to each other in respective anodes thereof; while, receive biases through the bias pad common to the light-receiving elements. Those pads are disposed along an edge of the substrate such that the signal pads put the bias pads therebetween, and the ground pads put the signal pads and the bias pad therebetween.

Abstract: A photodiode (PD) device that monolithically integrates a PD element with a waveguide element is disclosed. The PD device includes a conducting layer with a first region and a second region next to the first region, where the PD element exists in the first region, while, the waveguide element exists in the second region and optically couples with the PD element. The waveguide element includes a core layer and a cladding layer on the conducting layer, which forms an optical confinement structure. The PD element includes an absorption layer on the conducting layer and a p-type cladding layer on the absorption layer, which form another optical confinement structure. The absorption layer has a length at least 12 ?m measured from the interface against the core layer.

Abstract: A semiconductor integrated optical device includes: a supporting base including semi-insulating semiconductor; a first photoelectric convertor having first photodiode mesas; a second photoelectric convertor having second photodiode mesas; a first 90° optical hybrid having at least one first multimode waveguide mesa; a second 90° optical hybrid having at least one second multimode waveguide mesa; an optical divider mesa; first and second input waveguide mesas coupling the first and second 90° optical hybrids with the optical divider mesa, respectively; a conductive semiconductor region disposed on the supporting base, the conductive semiconductor region mounting the first photodiode mesas, the second photodiode mesas, the first multimode waveguide mesas, the second multimode waveguide mesas, and the optical divider mesa; a first island semiconductor mesa extending between the first and second multimode waveguide mesas; and a first groove extending through the first island semiconductor mesa and the conductive