Abstract: A semiconductor optical device may include a semiconductor substrate; a mesa stripe structure that extends in a stripe shape in a first direction on the semiconductor substrate and includes a contact layer on a top layer; an adjacent layer on the semiconductor substrate and adjacent to the mesa stripe structure in a second direction orthogonal to the first direction; a passivation film that covers at least a part of the adjacent layer; a resin layer on the passivation film; an electrode that is electrically connected to the contact layer and extends continuously from the contact layer to the resin layer; and an inorganic insulating film that extends continuously from the resin layer to the passivation film under the electrode, is spaced apart from the mesa stripe structure, and is completely interposed between the electrode and the resin layer.

Abstract: An optical semiconductor device includes a substrate, a semiconductor multilayer which is formed on the substrate, and includes an optical functional layer, an insulating film formed on the semiconductor multilayer, and an electrode formed on a part of the insulating film. The insulating film covers the semiconductor multilayer except for a region in which the semiconductor multilayer and the electrode are electrically connected to each other. At least a part of a region of the insulating film that is overlapped with the electrode is thinner than a region of the insulating film that is not overlapped with the electrode.

Abstract: A semiconductor optical device includes: a lower mesa structure extending in a stripe shape and composed of some layers including an active layer; a buried layer configured to bury both sides of the lower mesa structure and made of indium phosphide; and an upper mesa structure extending in a stripe shape and composed of some layers including a bottom layer made of phosphorus-free materials, the bottom layer having a bottom surface protruding from a topmost layer of the lower mesa structure, the bottom surface being in contact with the lower mesa structure and the buried layer.

Abstract: A semiconductor optical device may include a semiconductor substrate; a mesa stripe structure that extends in a stripe shape in a first direction on the semiconductor substrate and includes a contact layer on a top layer; an adjacent layer on the semiconductor substrate and adjacent to the mesa stripe structure in a second direction orthogonal to the first direction; a passivation film that covers at least a part of the adjacent layer; a resin layer on the passivation film; an electrode that is electrically connected to the contact layer and extends continuously from the contact layer to the resin layer; and an inorganic insulating film that extends continuously from the resin layer to the passivation film under the electrode, is spaced apart from the mesa stripe structure, and is completely interposed between the electrode and the resin layer.

Abstract: A semiconductor optical device may include a semiconductor substrate; a mesa stripe structure that extends in a stripe shape in a first direction on the semiconductor substrate and includes a contact layer on a top layer; an adjacent layer on the semiconductor substrate and adjacent to the mesa stripe structure in a second direction orthogonal to the first direction; a passivation film that covers at least a part of the adjacent layer; a resin layer on the passivation film; an electrode that is electrically connected to the contact layer and extends continuously from the contact layer to the resin layer; and an inorganic insulating film that extends continuously from the resin layer to the passivation film under the electrode, is spaced apart from the mesa stripe structure, and is completely interposed between the electrode and the resin layer.

Abstract: An optical semiconductor device includes a multi-quantum well layer including well layers and barrier layers alternately overlapping with each other, an optical confinement layer, and a guide layer interposed between the multi-quantum well layer and the optical confinement layer. Each barrier layer is an undoped layer and an outermost layer is one of the barrier layers. The optical confinement layer has a refractive index that is greater than that of the outermost layer and a band gap that is smaller than that of the outermost layer. The guide layer includes a first adjacent layer in contact with the outermost layer and the guide layer is thinner than the optical confinement layer. Each of the optical confinement layer and the guide layer is an n-type semiconductor layer. The first adjacent layer of the guide layer has a band gap that is larger than that of the optical confinement layer.

Abstract: A semiconductor optical element is configured to emit or absorb light and includes a lower structure that includes a multiple quantum well layer; an upper mesa structure that is disposed on the lower structure; a current injection structure that is disposed on the upper mesa structure, when seen from an optical axis of the emitted or absorbed light, a width of a portion of the current injection structure in contact with the upper mesa structure is smaller than a width of the upper mesa structure, the portion of the current injection structure in contact with the upper mesa structure consisting of InP, and an average refractive index of the upper mesa structure is higher than a refractive index of the InP forming the current injection structure; and an insulating film covering both side surfaces of the upper mesa structure and a part of an upper surface of the upper mesa structure.

Abstract: A semiconductor optical device may include a semiconductor substrate; a mesa stripe structure that extends in a stripe shape in a first direction on the semiconductor substrate and includes a contact layer on a top layer; an adjacent layer on the semiconductor substrate and adjacent to the mesa stripe structure in a second direction orthogonal to the first direction; a passivation film that covers at least a part of the adjacent layer; a resin layer on the passivation film; an electrode that is electrically connected to the contact layer and extends continuously from the contact layer to the resin layer; and an inorganic insulating film that extends continuously from the resin layer to the passivation film under the electrode, is spaced apart from the mesa stripe structure, and is completely interposed between the electrode and the resin layer.

Abstract: A semiconductor optical element is configured to emit or absorb light and includes a lower structure that includes a multiple quantum well layer; an upper mesa structure that is disposed on the lower structure; a current injection structure that is disposed on the upper mesa structure, when seen from an optical axis of the emitted or absorbed light, a width of a portion of the current injection structure in contact with the upper mesa structure is smaller than a width of the upper mesa structure, the portion of the current injection structure in contact with the upper mesa structure consisting of InP, and an average refractive index of the upper mesa structure is higher than a refractive index of the InP forming the current injection structure; and an insulating film covering both side surfaces of the upper mesa structure and a part of an upper surface of the upper mesa structure.

Abstract: Provided is an optical semiconductor device which has long-term reliability since a threshold current is small, and a relaxation oscillation frequency is high. An optical semiconductor device includes an InP semiconductor substrate, a lower mesa structure that is disposed above the InP semiconductor substrate, and includes a multiple quantum well layer, an upper mesa structure that is disposed on the lower mesa structure, and includes a cladding layer, a buried semiconductor layer that buries both side surfaces of the lower mesa structure, and an insulating film that covers both side surfaces of the upper mesa structure by being in contact with both side surfaces of the upper mesa structure, in which the lower mesa structure includes a first semiconductor layer, above the multiple quantum well layer, and the upper mesa structure includes a second semiconductor layer which is different from the cladding layer in composition, below the cladding layer.

Abstract: An optical semiconductor device includes an InP substrate; an active layer disposed above the InP substrate; a n-type semiconductor layer disposed below the active layer; and a p-type clad layer disposed above the active layer, wherein the p-type clad layer includes one or more p-type In1-xAlxP layers, the Al composition x of each of the one or more p-type In1-xAlxP layers is equal to or greater than a value corresponding to the doping concentration of a p-type dopant, and the absolute value of the average strain amount of the whole of the p-type clad layer is equal to or less than the absolute value of a critical strain amount obtained by Matthews' relational expression, using the entire layer thickness of the whole of the p-type clad layer as a critical layer thickness.

Abstract: In an optical transmitter module for combining three or more optical signals different in intensity with an optical multiplexer to generate a PAM signal, the influence of the beat noise and the chromatic dispersion due to the difference in wavelength is reduced. The optical transmitter module includes first through third optical signal sources adapted to output respective optical signals binary intensity modulated with different amplitude from each other, and a combining section. The combining section has a wavelength multiplexer adapted to wavelength-multiplex a plurality of input optical signals having different wavelengths from each other while keeping the respective polarization states, and a polarization multiplexer adapted to polarization-multiplex a pair of input optical signals having respective polarization states perpendicular to each other, and the combining section combines the input optical signals from the first through third optical signal sources with each other to generate a PAM8 signal.

Abstract: To provide an optical transmitter module with simplified control of a voltage to be applied to an optical modulator. An optical transmitter module includes a semiconductor laser for irradiating a laser beam; a demultiplexer for branching the laser beam to output branched light beams; optical modulators for modulating an optical amplitude of each of the branched light beams into a first optical amplitude or a second optical amplitude, depending on an input level at two levels; and a multiplexer for multiplexing output light beams from the optical modulators. The optical transmitter module may include optical waveguides for connecting the optical modulators and the multiplexer, and the optical waveguides may include a first optical waveguide for causing a first phase difference and a second optical waveguide for causing a second phase difference different from the first phase difference.

Abstract: A semiconductor optical device includes: a first conductive type semiconductor layer; an active layer; a second conductive type semiconductor layer including a ridge portion; a pair of first grooves, formed on bottom surfaces of both sides of the ridge portion and dividing the active layer; an optical functioning part including the first and second conductive type semiconductor layers, converting a state of light, and having a height higher than a height of the bottom surface of the ridge portion; and a second groove, at least a part thereof being formed on the optical functioning part, an end portion thereof being connected to the first groove, the second conductive type semiconductor layer being divided, and the maximum height of an inner wall surface thereof being higher than the maximum height of an inner wall surface of the first groove.

Abstract: An optical semiconductor device includes an InP substrate; an active layer disposed above the InP substrate; a n-type semiconductor layer disposed below the active layer; and a p-type clad layer disposed above the active layer, wherein the p-type clad layer includes one or more p-type In1-xAlxP layers, the Al composition x of each of the one or more p-type In1-xAlxP layers is equal to or greater than a value corresponding to the doping concentration of a p-type dopant, and the absolute value of the average strain amount of the whole of the p-type clad layer is equal to or less than the absolute value of a critical strain amount obtained by Matthews' relational expression, using the entire layer thickness of the whole of the p-type clad layer as a critical layer thickness.

Abstract: In an optical transmitter module for combining three or more optical signals different in intensity with an optical multiplexer to generate a PAM signal, the influence of the beat noise and the chromatic dispersion due to the difference in wavelength is reduced. The optical transmitter module includes first through third optical signal sources adapted to output respective optical signals binary intensity modulated with different amplitude from each other, and a combining section. The combining section has a wavelength multiplexer adapted to wavelength-multiplex a plurality of input optical signals having different wavelengths from each other while keeping the respective polarization states, and a polarization multiplexer adapted to polarization-multiplex a pair of input optical signals having respective polarization states perpendicular to each other, and the combining section combines the input optical signals from the first through third optical signal sources with each other to generate a PAM8 signal.

Abstract: Provided is an optical semiconductor device which has long-term reliability since a threshold current is small, and a relaxation oscillation frequency is high. An optical semiconductor device includes an InP semiconductor substrate, a lower mesa structure that is disposed above the InP semiconductor substrate, and includes a multiple quantum well layer, an upper mesa structure that is disposed on the lower mesa structure, and includes a cladding layer, a buried semiconductor layer that buries both side surfaces of the lower mesa structure, and an insulating film that covers both side surfaces of the upper mesa structure by being in contact with both side surfaces of the upper mesa structure, in which the lower mesa structure includes a first semiconductor layer, above the multiple quantum well layer, and the upper mesa structure includes a second semiconductor layer which is different from the cladding layer in composition, below the cladding layer.

Abstract: A semiconductor optical device includes: a first conductive type semiconductor layer; an active layer; a second conductive type semiconductor layer including a ridge portion; a pair of first grooves, formed on bottom surfaces of both sides of the ridge portion and dividing the active layer; an optical functioning part including the first and second conductive type semiconductor layers, converting a state of light, and having a height higher than a height of the bottom surface of the ridge portion; and a second groove, at least a part thereof being formed on the optical functioning part, an end portion thereof being connected to the first groove, the second conductive type semiconductor layer being divided, and the maximum height of an inner wall surface thereof being higher than the maximum height of an inner wall surface of the first groove.

Abstract: Provided is a semiconductor optical device, an arrayed semiconductor optical device, an optical module having a structure to reduce the parasitic capacitance as well as a high design degree of freedom and having a multilayer structure in which a semi-insulating substrate, a first semiconductor layer having one conductive type, an active layer having light emission function, a second semiconductor layer having the other conductive type, an insulating layer, and a conductive layer are stacked in order from the bottom. The multilayer structure includes a light emitting structure, a first electrode structure, and a second electrode structure. In the semi-insulating substrate and the first semiconductor layer, a first grove which separates the second electrode structure from a remaining portion and approaches the second electrode structure with a non-linear shape rather than a linear shape in its entirety is formed.

Abstract: To provide an optical transmitter module with simplified control of a voltage to be applied to an optical modulator. An optical transmitter module includes a semiconductor laser for irradiating a laser beam; a demultiplexer for branching the laser beam to output branched light beams; optical modulators for modulating an optical amplitude of each of the branched light beams into a first optical amplitude or a second optical amplitude, depending on an input level at two levels; and a multiplexer for multiplexing output light beams from the optical modulators. The optical transmitter module may include optical waveguides for connecting the optical modulators and the multiplexer, and the optical waveguides may include a first optical waveguide for causing a first phase difference and a second optical waveguide for causing a second phase difference different from the first phase difference.