Abstract: A method for manufacturing a semiconductor light emitting device includes forming a lower cladding layer over a GaAs substrate; forming a quantum dot active layer over the lower cladding layer; forming a first semiconductor layer over the quantum dot active layer; forming a diffraction grating by etching the first semiconductor layer; forming a second semiconductor layer burying the diffraction grating; and forming an upper cladding layer having a conductive type different from that of the lower cladding layer over the second semiconductor layer, wherein the processes after forming the quantum dot active layer are performed at a temperature not thermally deteriorating or degrading quantum dots included in the quantum dot active layer.

Abstract: An active layer (18) is formed over a semiconductor substrate having a pair of facets (15A, 15B) mutually facing opposite directions. An upper cladding layer (19) is formed on the active layer, having a refractive index lower than that of the active layer. A diffraction grating (25) is disposed in the upper cladding layer on both sides of a distributed feedback region in a waveguide region (22), the waveguide region extending from one facet to the other of the semiconductor substrate. End regions (22B) are defined at both ends of the waveguide region and the distributed feedback region (22A) is disposed between the end regions. Low refractive index regions (26) are disposed in the upper cladding layer on both sides of each of the end regions of the waveguide region, the low refractive index regions having a refractive index lower than that of the upper cladding layer.

Abstract: An optical semiconductor device includes a silicon oxide layer configured to be formed on a substrate; an optical waveguide part configured to be formed on the silicon oxide layer; a cladding layer configured to be formed covering the optical waveguide part; and a semiconductor laser configured to be disposed on the substrate. Laser light emitted from the semiconductor laser enters the optical waveguide part. The optical waveguide part increases transmittance of light when the wavelength becomes greater within an oscillation wavelength range of the semiconductor laser.

Abstract: The invention relates to a spot-size converter, a manufacturing method thereof, and an integrated optical circuit device, and ensures easier coupling to the optical fiber and higher accuracy in manufacturing the spot-size converter. A first core that is extended from a first end configured to input/output light toward a second end, and a second core that is formed by a plurality of cores, and formed at a position to be evanescent-coupled to the first core, and moreover extended along a direction from the first end toward the second end are provided, and, on the second core, a third core that has a taper unit and is formed at a position to be evanescent-coupled to the second core in a lamination direction is provided.

Abstract: A spot-size converter includes a substrate, a first core provided over the substrate, and second and third cores provided over the substrate and over or under the first core with a cladding layer sandwiched therebetween and extending in parallel to the substrate and the first core.

Abstract: An optical waveguide includes a substrate, a first core provided over the substrate and having a first taper region that extends from one side toward the other side and has a sectional area that decreases toward the other side, and a plurality of second cores provided over the substrate and over or under the first core with a first cladding layer sandwiched therebetween and extending in parallel to the substrate and the first core.

Abstract: A semiconductor light emitting device includes a lower cladding layer, an active layer, and an AlGaAs upper cladding layer mounted on a GaAs substrate. The semiconductor light emitting device has a ridge structure including the AlGaAs upper cladding layer. The semiconductor light emitting device further includes an InGaAs etching stop layer provided in contact with the lower side of the AlGaAs upper cladding layer. The InGaAs etching stop layer has a band gap greater than that of the active layer.

Abstract: An optical semiconductor device includes a substrate; and an active layer disposed on the substrate, wherein the active layer includes a first barrier layer containing GaAs, a quantum dot layer, which is disposed on the first barrier layer, which includes a quantum dot containing InAs, which includes a side barrier layer which covers at least a part of the quantum dot and a side surface of the quantum dot, and having an elongation strain inherent therein, and a second barrier layer disposed on the quantum dot layer.

Abstract: A semiconductor light emitting device includes a lower cladding layer, an active layer, and an AlGaAs upper cladding layer mounted on a GaAs substrate. The semiconductor light emitting device has a ridge structure including the AlGaAs upper cladding layer. The semiconductor light emitting device further includes an InGaAs etching stop layer provided in contact with the lower side of the AlGaAs upper cladding layer. The InGaAs etching stop layer has a band gap greater than that of the active layer.

Abstract: A method for manufacturing a semiconductor light emitting device includes forming a lower cladding layer over a GaAs substrate; forming a quantum dot active layer over the lower cladding layer; forming a first semiconductor layer over the quantum dot active layer; forming a diffraction grating by etching the first semiconductor layer; forming a second semiconductor layer burying the diffraction grating; and forming an upper cladding layer having a conductive type different from that of the lower cladding layer over the second semiconductor layer, wherein the processes after forming the quantum dot active layer are performed at a temperature not thermally deteriorating or degrading quantum dots included in the quantum dot active layer.

Abstract: An optical semiconductor device includes: a substrate of semiconductor; an array having a plurality of active regions arranged on the substrate so as to emit light to the same direction, the plurality of active regions being arranged more densely at ends of the array than in the center of the array in a direction crossing the light emitting direction; and electrodes which inject current to the plurality of active regions.

Abstract: An optical device includes: a first cladding layer; a core layer disposed on the first cladding layer and, with increase in its sectional area, extending from a first end which receives/outputs light along a direction from the first end toward a second end; a slab layer disposed on the first cladding layer and extending to the second end along the direction from the first end toward the second end; a rib layer disposed on the slab layer and, with decrease in its sectional area, extending to the second end along the direction from the first end toward the second end; and a second cladding layer disposed on the core layer and the rib layer. The core layer and both of the slab and rib layers are optically coupled in a part in which the sectional are of the core and rib layers is the maximum.

Abstract: A semiconductor light emitting device includes a lower cladding layer, an active layer, and an AlGaAs upper cladding layer mounted on a GaAs substrate. The semiconductor light emitting device has a ridge structure including the AlGaAs upper cladding layer. The semiconductor light emitting device further includes an InGaAs etching stop layer provided in contact with the lower side of the AlGaAs upper cladding layer. The InGaAs etching stop layer has a band gap greater than that of the active layer.

Abstract: A semiconductor light-emitting device includes a GaAs substrate; and an active layer provided over the GaAs substrate, the active layer including: a lower barrier layer lattice-matched to the GaAs substrate; a quantum dot provided on the lower barrier layer; a strain relaxation layer covering a side of the quantum dot; and an upper barrier layer contacting the top of the quantum dot, at least a portion of the upper barrier layer contacting the top of the quantum dot being lattice-matched to the GaAs substrate, and having a band gap larger than a band gap of the quantum dot and smaller than a band gap of GaAs.

Abstract: An active layer having a p-type quantum dot structure is disposed over a lower cladding layer made of semiconductor material of a first conductivity type. An upper cladding layer is disposed over the active layer. The upper cladding layer is made of semiconductor material, and includes a ridge portion and a cover portion. The ridge portion extends in one direction, and the cover portion covers the surface on both sides of the ridge portion. A capacitance reducing region is disposed on both sides of the ridge portion and reaching at least the lower surface of the cover portion. The capacitance reducing region has the first conductivity type or a higher resistivity than that of the ridge portion, and the ridge portion has a second conductivity type. If the lower cladding layer is an n-type, the capacitance reducing region reaches at least the upper surface of the lower cladding layer.

Abstract: An optical semiconductor device includes a substrate; and an active layer disposed on the substrate, wherein the active layer includes a first barrier layer containing GaAs, a quantum dot layer, which is disposed on the first barrier layer, which includes a quantum dot containing InAs, which includes a side barrier layer which covers at least a part of the quantum dot and a side surface of the quantum dot, and having an elongation strain inherent therein, and a second barrier layer disposed on the quantum dot layer.

Abstract: An active layer (18) is formed over a semiconductor substrate having a pair of facets (15A, 15B) mutually facing opposite directions. An upper cladding layer (19) is formed on the active layer, having a refractive index lower than that of the active layer. A diffraction grating (25) is disposed in the upper cladding layer on both sides of a distributed feedback region in a waveguide region (22), the waveguide region extending from one facet to the other of the semiconductor substrate. End regions (22B) are defined at both ends of the waveguide region and the distributed feedback region (22A) is disposed between the end regions. Low refractive index regions (26) are disposed in the upper cladding layer on both sides of each of the end regions of the waveguide region, the low refractive index regions having a refractive index lower than that of the upper cladding layer.

Abstract: A semiconductor light-emitting device includes a GaAs substrate; and an active layer provided over the GaAs substrate, the active layer including: a lower barrier layer lattice-matched to the GaAs substrate; a quantum dot provided on the lower barrier layer; a strain relaxation layer covering a side of the quantum dot; and an upper barrier layer contacting the top of the quantum dot, at least a portion of the upper barrier layer contacting the top of the quantum dot being lattice-matched to the GaAs substrate, and having a band gap larger than a band gap of the quantum dot and smaller than a band gap of GaAs.

Abstract: An active layer (18) is formed over a semiconductor substrate having a pair of facets (15A, 15B) mutually facing opposite directions. An upper cladding layer (19) is formed on the active layer, having a refractive index lower than that of the active layer. A diffraction grating (25) is disposed in the upper cladding layer on both sides of a distributed feedback region in a waveguide region (22), the waveguide region extending from one facet to the other of the semiconductor substrate. End regions (22B) are defined at both ends of the waveguide region and the distributed feedback region (22A) is disposed between the end regions. Low refractive index regions (26) are disposed in the upper cladding layer on both sides of each of the end regions of the waveguide region, the low refractive index regions having a refractive index lower than that of the upper cladding layer.

Abstract: An optical semiconductor device includes: a waveguide structure including layers grown over a semiconductor substrate, having a width defined by sidewalls formed by etching the layers, and including a wide, a narrow, and an intermediate width portion, formed along a propagation direction; and a diffraction grating formed on the sidewalls of at least one of the wide and narrow width portions of the waveguide structure, the diffraction grating having vertical grooves periodically disposed along the propagation direction and defining a wavelength of propagation light, wherein the narrow width portion is formed in such a manner that a loss of 50% or more is given to a higher order transverse mode. An optical semiconductor device having a vertical diffraction grating is provided which can suppress generation of a higher order transverse mode and an increase in a device resistance.