Abstract: An optical device includes a core formed on a substrate, a first source electrode and a second source electrode formed in contact with both side surfaces of the core interposed between the first source electrode and the second source electrode, and a drain electrode formed in contact with an upper surface of the core. The core, the first source electrode, and the second source electrode together form a plasmonic waveguide. The first source electrode and the second source electrode are Schottky coupled to the core.

Abstract: An enclosing-sealing apparatus includes a flap opener that opens a flap of an envelope while the envelope is conveyed to an enclosing position. A first envelope detector is disposed upstream from the flap opener in an envelope conveyance direction and detects both ends of the envelope in the envelope conveyance direction. A second envelope detector is disposed downstream from the flap opener in the envelope conveyance direction and detects both ends of the envelope in the envelope conveyance direction in an open state in which the flap opens. A controller determines the open state of the flap based on a first detection result sent from the first envelope detector and a second detection result sent from the second envelope detector. The controller performs troubleshooting for enclosing the enclosure into the envelope if the controller determines that the open state of the flap is faulty.

Abstract: A semiconductor laser includes a first optical waveguide including a first reflection unit and a second reflection unit, and a confinement portion. The first reflection unit and the second reflection unit are waveguide type reflection units each having a structure in which the refractive index is periodically modulated. The first reflection unit, the confinement portion, and the second reflection unit constitute a Fabry-Perot type optical resonator. The semiconductor laser also includes a second optical waveguide disposed along a first optical waveguide to extend from the confinement portion to the second reflection unit side. The second optical waveguide serves as an extraction optical waveguide. Further, a third reflection unit formed continuously with the second optical waveguide is provided at a location corresponding to the first reflection unit.

Abstract: A wavelength-tunable laser a circling waveguide having a circling structure; a first coupled waveguide coupled to the circling waveguide in one region; and a second coupled waveguide coupled to the circling waveguide in another region, wherein a first reflection region is connected in the light guiding direction of the first coupled waveguide, an active region and a second reflection region are sequentially connected in the light guiding direction of the second coupled waveguide, and the refractive index of at least part of the circling waveguide is modulated.

Abstract: A core and a slab layer that are formed on a lower clad layer are provided. The lower clad layer is formed on a substrate. The core is comprised of a semiconductor and has a rectangular shape in a cross-sectional view. The slab layer is comprised of a semiconductor. The core and the slab layer have a thickness that allows only up to a secondary mode of light to be present. Further, the core and the slab layer are laminated on the lower clad layer. Further, the core and the slab layer are disposed to be optically coupled to each other.

Abstract: A photoelectric conversion device includes a plurality of optical waveguides that are formed on a substrate and have the same waveguide direction, and a plurality of waveguide-type photoelectric conversion elements that are connected to the respective optical waveguides. The plurality of photoelectric conversion elements is arranged in the waveguide direction of the plurality of optical waveguides. In a planar view, the line segment connecting the photoelectric conversion elements adjacent to one another in the waveguide direction of the plurality of photoelectric conversion elements is inclined with respect to the waveguide direction.

Abstract: An optical semiconductor element includes, in order, a semiconductor laser, an optical waveguide, a loop waveguide, and a ring resonator optically coupled to the loop waveguide, in which a distance between the semiconductor laser and the ring resonator is 1 ?m or more and 200 ?m or less.

Abstract: A semiconductor photonic device includes a first cladding layer formed on a substrate formed with Si, a semiconductor layer formed on the first cladding layer, and a second cladding layer formed on the semiconductor layer. In the semiconductor layer, an active layer, and a p-type layer and an n-type layer disposed in contact with the active layer while sandwiching the active layer in a planar view are formed. A p-type electrode is electrically connected to the p-type layer, and an n-type electrode is electrically connected to the n-type layer. The active layer is formed in a core shape extending in a predetermined direction. This semiconductor photonic device also includes an optical coupling layer that is buried in the first cladding layer in such a manner as to be optically coupled to the active layer, and is formed in a core shape extending along the active layer.

Abstract: A semiconductor optical module includes a semiconductor laser element region having an active layer, a first cladding layer which is formed such that the active layer is embedded therein, a second cladding layer which is formed underneath the active layer and the first cladding layer, and a heater unit which produces a temperature change in a waveguide; an optical waveguide element region including a spot-size converter which converts a spot size of incident laser light, and an optical waveguide core layer which is formed such that the spot-size converter is embedded therein, the first cladding layer contains InP, the second cladding layer is made of a material lower in refractive index and higher in thermal conductivity than the first cladding layer, and a third cladding layer which is made of a material lower in refractive index and lower in thermal conductivity than the second cladding layer is formed underneath the spot-size converter and the heater unit.

Abstract: The optical modulator includes a lower cladding layer formed on a substrate, a core formed on the lower cladding layer, and an upper cladding layer formed on the core. The core is made of an InP-based semiconductor having a bandgap corresponding to a desired wavelength. Refractive indexes of the lower cladding layer and upper cladding layer are equal to or less than a refractive index of InP.

Abstract: An embodiment photodetector includes a clad layer formed on a substrate, a first semiconductor layer formed on the clad layer, and a second semiconductor layer and a third semiconductor layer with the first semiconductor layer interposed therebetween formed on the clad layer. The photodetector includes a light absorbing layer made of an n-type III-V compound semiconductor formed on the first semiconductor layer through an insulating layer.

Abstract: An embodiment semiconductor optical device includes an optical waveguide including a core, and an active layer extending in the waveguide direction of the optical waveguide for a predetermined distance and arranged in a state in which the active layer can be optically coupled to the core. The core and the active layer are arranged in contact with each other. The core is formed of a material with a refractive index of about 1.5 to 2.2, such as SiN, for example. In addition, the core is formed to a thickness at which a higher-order mode appears. The higher-order mode is an E12 mode, for example.

Abstract: There are included: a second semiconductor layer of a second conduction-type formed to be on and in contact with the active layer; and a third semiconductor layer of a second conduction-type formed on the second semiconductor layer, the third semiconductor layer is arranged above a formation region of the active layer, a bottom surface of the third semiconductor layer is arranged in the formation region of the active layer, and a width of the third semiconductor layer, on the active layer side, in a direction perpendicular to a waveguide direction and parallel to a plane of a substrate is set to be smaller than a width of the active layer in the same direction.

Abstract: An optical device includes a first reflecting section, a second reflecting section, and a confining section. The first reflecting section is constituted of a thin-wire waveguide-type one-dimensional photonic crystal. The second reflecting section is constituted of a thin-wire waveguide-type one-dimensional photonic crystal of which a lattice constant differs from that of the first reflecting section. The confining section is sandwiched between the first reflecting section and the second reflecting section. A Fabry-Perot optical resonator is constituted by the first reflecting section, the confining section, and the second reflecting section.

Abstract: A difference ?1 between an equivalent refractive index of a first reflecting section and an equivalent refractive index of a core in a first region that corresponds to the first reflecting section and a difference between an equivalent refractive index of a second reflecting section and an equivalent refractive index of the core in a second region that corresponds to the second reflecting section is set so as to be greater than a difference between an equivalent refractive index of a confining section and an equivalent refractive index of the core in a third region that corresponds to the confining section.

Abstract: A first burying layer burying a side of a first ridge structure is formed by selective growth using a first selective growth mask and a third selective growth mask. The first burying layer is formed by regrowth from a surface of a second semiconductor layer on a side of the first ridge structure. At the same time, by selective growth using a second selective growth mask and a fourth selective growth mask, a second burying layer burying a side of a second ridge structure is formed. The second burying layer is formed by regrowth from a surface of a fourth semiconductor layer on a side of the second ridge structure.

Abstract: A semiconductor laser is provided with: an active layer that excites a transverse electric (TE) mode and a transverse magnetic (TM) mode of light and constitutes at least a part of a resonator guiding the TE mode and the TM mode of light; and a diffraction grating as a frequency difference setting structure that sets the difference in oscillation frequency between the TE mode and the TM mode of light higher than a relaxation-oscillation frequency.

Abstract: In an optical device, a first semiconductor layer and a second semiconductor layer are formed to be thinner than a core, an active layer has a shape with an end in a waveguide direction tapers toward a tip end, the first semiconductor layer having a trapezoidal shape with a width thereof decreases toward a side of a third semiconductor layer from a side of the core in a plan view and a width thereof decreases as one end in the waveguide direction recedes from a central portion of the active region, and the second semiconductor layer having a trapezoidal shape with a width thereof decreases toward a side of a fourth semiconductor layer from the side of the core in a plan view and a width thereof decreases as one end in the waveguide direction recedes from the central portion of the active region.

Abstract: A direct modulation laser includes a distributed feedback type laser active region and an optical feedback region optically connected to one end of the laser active region in a waveguide direction. The direct modulation laser performs laser oscillation by using photon-photon resonance (PPR) that occurs depending on a frequency difference between a frequency of light generated (oscillated) in the laser active region and a frequency of an FP mode in the optical feedback region.

Abstract: A semiconductor optical device includes a light emitting layer that emits light in a state of current injection; an optical waveguide in which a width or a thickness in an extending direction (y) of the light emitting layer varies along the extending direction; and a uniform diffraction grating having constant cycle, width and depth, wherein the light emitting layer, the optical waveguide and the uniform diffraction grating are arranged at positions where the light emitting layer, the optical waveguide, and the uniform diffraction grating are optically coupled to one another, the uniform diffraction grating is arranged above the light emitting layer, the optical waveguide is arranged below the light emitting layer, and the optical waveguide includes, in the extending direction, a first portion having a predetermined width, a second portion having a larger width than the width of the first portion, and a third portion having the same width as the width of the first portion.