Abstract: An optical functional device includes: first and second optical couplers each including a multi-mode interferometer waveguide portion having a first end portion and a second end portion, two units of first input/output ports and two units of second input/output ports; and first and second arc-shaped waveguides each optically connecting one of the first and second input/output ports of the first and second optical coupler and one of the first and second input/output ports of the second optical coupler, respectively. Further, the first optical coupler, the second optical coupler, the first arc-shaped waveguide, and the second arc-shaped waveguide constitute a ring resonator, and each of the multi-mode waveguide portions of the first optical coupler and the second optical coupler have a narrow portion, an average width of the narrow portion in a longitudinal direction being narrower than widths at the first end portion and the second end portion.

Abstract: A reflection filter device includes: a ring resonator filter including a ring-shaped waveguide and two arms, each of the two arms being optically coupled to the ring-shaped waveguide; and a dual-branch portion including a light input/output port and two branch ports, the light input/output port being configured to allow input and output of light, the two branch ports being configured to allow output of the light input from the light input/output port, the light being split into two, the two arms being connected to the two branch ports, respectively, at least one of the two arms being equipped with a phase adjuster.

Abstract: The present technology provides a surface emitting laser capable of suppressing a decrease in luminous efficiency. The present technology provides a surface emitting laser including: first and second multilayer film reflectors; a plurality of active layers laminated together between the first and second multilayer film reflectors; a tunnel junction disposed between two active layers adjacent to each other in a lamination direction among the plurality of active layers; and an oxide confinement layer disposed between one active layer of the two adjacent active layers and the tunnel junction. According to the present technology, it is possible to provide a surface emitting laser capable of suppressing a decrease in luminous efficiency.

Abstract: A surface emitting laser according to one embodiment of the present disclosure includes: a substrate having a convex part provided on a surface thereof; and a vertical resonator structure formed on the substrate, and including an active layer, a first semiconductor layer, and a current blocking layer. The first semiconductor layer is a semiconductor layer of a first conductivity type having a step structure part having a shape conforming to the convex part at a location facing the convex part. The current blocking layer is a semiconductor layer of a second conductivity type different from the first conductivity type and having an opening in which an inner peripheral surface is in contact with an outer peripheral surface of the step structure part.

Abstract: An optical waveguide structure includes a lower cladding layer positioned on a substrate; an optical guide layer positioned on the lower cladding layer; an upper cladding layer positioned on the optical guide layer; and a heater positioned on the upper cladding layer. The lower cladding layer, the optical guide layer, and the upper cladding layer constitute a mesa structure. The optical guide layer has a lower thermal conductivity than the upper cladding layer. An equation “Wwg?Wmesa?3×Wwg” is satisfied, wherein Wmesa represents a mesa width of the mesa structure, and Wwg represents a width of the optical guide layer. The optical guide layer occupies one-third or more of the mesa width in a width direction of the mesa structure.

Abstract: An optical functional device includes: first and second optical couplers each including a multi-mode interferometer waveguide portion having a first end portion and a second end portion, two units of first input/output ports and two units of second input/output ports; and first and second arc-shaped waveguides each optically connecting one of the first and second input/output ports of the first and second optical coupler and one of the first and second input/output ports of the second optical coupler, respectively. Further, the first optical coupler, the second optical coupler, the first arc-shaped waveguide, and the second arc-shaped waveguide constitute a ring resonator, and each of the multi-mode waveguide portions of the first optical coupler and the second optical coupler have a narrow portion, an average width of the narrow portion in a longitudinal direction being narrower than widths at the first end portion and the second end portion.

Abstract: A semiconductor device includes: a mesa portion that has a semiconductor layered structure, and that extends in a predetermined direction; an extending portion that extends along the mesa portion and that is separated by trench grooves arranged respectively on both sides of the mesa portion; insulating portions that are made from an insulating material, and are arranged in the respective trench grooves; and a conductive portion that is arranged on an upper side of the mesa portion. Further, at least one of the insulating portions adheres intimately to the mesa portion, and forms a gap between the at least one of the insulating portions and the extending portion in at least a part of an extending direction of the mesa portion, and the conductive portion is arranged across at least one of the insulating portions and the mesa portion.

Abstract: A laser device includes a wavelength-tunable laser including plural wavelength selectors in an optical resonator; a semiconductor optical amplifier that amplifies the laser light input thereto; a light intensity variation detector that detects variation in intensity of the laser light output from the wavelength-tunable laser before the laser light is input to the semiconductor optical amplifier; a wavelength dithering generation unit that generates a resonator mode wavelength dithering to modulate a resonator mode of the resonator; a wavelength dithering feedback controller that performs, on the resonator mode wavelength dithering, feedback control based on the variation in intensity detected by the light intensity variation detector; a light intensity detector that detects an intensity of the laser light output from the semiconductor optical amplifier; and a semiconductor optical amplifier feedback controller that performs feedback control on the semiconductor optical amplifier based on the intensity detecte

Abstract: A reflection filter device includes: a ring resonator filter including a ring-shaped waveguide and two arms, each of the two arms being optically coupled to the ring-shaped waveguide; and a dual-branch portion including a light input/output port and two branch ports, the light input/output port being configured to allow input and output of light, the two branch ports being configured to allow output of the light input from the light input/output port, the light being split into two, the two arms being connected to the two branch ports, respectively, at least one of the two arms being equipped with a phase adjuster.

Abstract: An optical waveguide structure includes a lower cladding layer positioned on a substrate; an optical guide layer positioned on the lower cladding layer; an upper cladding layer positioned on the optical guide layer; and a heater positioned on the upper cladding layer. The lower cladding layer, the optical guide layer, and the upper cladding layer constitute a mesa structure. The optical guide layer has a lower thermal conductivity than the upper cladding layer. An equation “Wwg?Wmesa?3×Wwg” is satisfied, wherein Wmesa represents a mesa width of the mesa structure, and Wwg represents a width of the optical guide layer. The optical guide layer occupies one-third or more of the mesa width in a width direction of the mesa structure.

Abstract: A laser device includes a wavelength-tunable laser including plural wavelength selectors in an optical resonator; a semiconductor optical amplifier that amplifies the laser light input thereto; a light intensity variation detector that detects variation in intensity of the laser light output from the wavelength-tunable laser before the laser light is input to the semiconductor optical amplifier; a wavelength dithering generation unit that generates a resonator mode wavelength dithering to modulate a resonator mode of the resonator; a wavelength dithering feedback controller that performs, on the resonator mode wavelength dithering, feedback control based on the variation in intensity detected by the light intensity variation detector; a light intensity detector that detects an intensity of the laser light output from the semiconductor optical amplifier; and a semiconductor optical amplifier feedback controller that performs feedback control on the semiconductor optical amplifier based on the intensity detecte

Abstract: A wavelength tunable laser device includes: a laser cavity formed of a grating and a reflecting mirror including a ring resonator filter; a gain portion; and a phase adjusting portion. The grating creates a first comb-shaped reflection spectrum. The ring resonator filter includes a ring-shaped waveguide and two arms and creates a second comb-shaped reflection spectrum having peaks of a narrower full width than peaks in the first comb-shaped reflection spectrum at a wavelength interval different from that of the first comb-shaped reflection spectrum. One of the peaks in the first comb-shaped reflection spectrum and one of the peaks in the second comb-shaped reflection spectrum are overlapped on a wavelength axis, and a spacing between cavity modes is narrower than the full width at half maximum of the peaks in the first comb-shaped reflection spectrum.

Abstract: A wavelength tunable laser device includes: a laser cavity formed of a grating and a reflecting mirror including a ring resonator filter; a gain portion; and a phase adjusting portion. The grating creates a first comb-shaped reflection spectrum. The ring resonator filter includes a ring-shaped waveguide and two arms and creates a second comb-shaped reflection spectrum having peaks of a narrower full width than peaks in the first comb-shaped reflection spectrum at a wavelength interval different from that of the first comb-shaped reflection spectrum. One of the peaks in the first comb-shaped reflection spectrum and one of the peaks in the second comb-shaped reflection spectrum are overlapped on a wavelength axis, and a spacing between cavity modes is narrower than the full width at half maximum of the peaks in the first comb-shaped reflection spectrum.

Abstract: A semiconductor laser includes a semiconductor substrate, an active region provided over the semiconductor substrate and having an active layer and a first diffraction grating, and a guiding region provided over the semiconductor substrate and having a guiding layer continuously extending from the active layer in an optical axis direction and a second diffraction grating continuously extending from the first diffraction grating in the optical axis direction. A grating period of the second diffraction grating is uniform, the first diffraction grating has a first part in which a grating period becomes uneven, and a grating formation density of the first diffraction grating is smaller than the grating formation density of the second diffraction grating.

Abstract: A semiconductor laser includes a semiconductor substrate, an active region provided over the semiconductor substrate and having an active layer and a first diffraction grating, and a guiding region provided over the semiconductor substrate and having a guiding layer continuously extending from the active layer in an optical axis direction and a second diffraction grating continuously extending from the first diffraction grating in the optical axis direction. A grating period of the second diffraction grating is uniform, the first diffraction grating has a first part in which a grating period becomes uneven, and a grating formation density of the first diffraction grating is smaller than the grating formation density of the second diffraction grating.