Abstract: An optical semiconductor device includes: a substrate; an optical modulator including a semiconductor layer having a first conductivity type layer, an absorbing layer and a second conductivity type layer which are formed in this order on the substrate, a first electrode connected to the first conductivity type layer, and a second electrode connected to the second conductivity type layer; a first pad connected to the first electrode; and a second pad connected to the second electrode, wherein the semiconductor layer includes a waveguide, a first terrace and a second terrace positioned on opposite sides with respect to the waveguide, the first pad and the second pad are placed on the first terrace via an insulating film, and the first conductivity type layer is removed in the first terrace between the first pad and the second pad.

Abstract: An optical semiconductor device includes: a substrate; an optical modulator including a semiconductor layer having a first conductive type layer, an absorbing layer and a second conductive type layer which are formed in this order on the substrate, a first electrode connected to the first conductive type layer, and a second electrode connected to the second conductive type layer; a first pad connected to the first electrode; and a second pad connected to the second electrode, wherein the semiconductor layer includes a waveguide, a first terrace and a second terrace positioned on the opposite sides with respect to the waveguide, the first pad and the second pad are placed on the first terrace via an insulating film, and a groove is formed in the semiconductor layer between the first pad and the second pad.

Abstract: A semiconductor optical integrated device of the present disclosure includes: a substrate; a first EA modulator section formed on the substrate and comprising at least an n-type first semiconductor layer, a first modulation layer, and a p-type first semiconductor layer; and a second EA modulator section formed on the substrate and comprising at least an n-type second semiconductor layer, a second modulation layer having a width smaller than a width of the first modulation layer, and a p-type second semiconductor layer electrically connected to the n-type first semiconductor layer.

Abstract: An optical modulator integrated semiconductor laser of the present disclosure includes: a semiconductor laser section; a first connecting waveguide section; a first EA modulator section; a second connecting waveguide section; a second EA modulator section; and a first common electrode electrically connecting an n-type electrode of a first EA modulator provided in the first EA modulator section and a p-type electrode of a second EA modulator provided in the second EA modulator section.

Abstract: A semiconductor light-receiving device (100) of the present disclosure includes: a semiconductor substrate (1); an n-type buffer layer (2) formed above the semiconductor substrate (1); a multiplication layer (3) formed above the n-type buffer layer (2); a p-type electric field control layer (4) formed above the multiplication layer (3); and a light absorption layer (5) formed above the p-type electric field control layer (4), wherein any one, any two, or three of the n-type buffer layer (2), the multiplication layer (3), and the p-type electric field control layer (4) are composed of a digital alloy structure.

Abstract: A semiconductor light-receiving device according to the present disclosure includes: a semiconductor substrate; a multiplication layer formed above the semiconductor substrate; the multiplication layer composed of a digital alloy structure including a first semiconductor layer having a thickness of N times (1?N?20) a thickness of a monoatomic layer and a second semiconductor layer having a thickness of M times (1?M?20) the thickness of the monoatomic layer with a smaller bandgap energy than the first semiconductor layer in which the first semiconductor layer and the second semiconductor layer are alternately stacked a plurality of times therein; a light absorption layer formed above the multiplication layer; and an electric field relaxation layer formed between the multiplication layer and the light absorption layer; and a strain relaxation layer formed between the multiplication layer and the electric field relaxation layer.

Abstract: A semiconductor optical modulator is formed by stacking a plurality of semiconductor layers including an optical modulation layer on a semiconductor substrate and emits light by modulating an intensity or a phase of light incident on the optical modulation layer. The optical modulation layer is formed using a digital alloy in which the semiconductor layers having a layer thickness of two or more atomic layers and having different constituent elements or composition ratios are alternately and repeatedly stacked.

Abstract: A semiconductor optical integrated device comprises a semiconductor amplifier and a plurality of semiconductor lasers, wherein the semiconductor amplifier and the semiconductor lasers are monolithically integrated on a semiconductor substrate, an n-side cladding layer of the semiconductor amplifier and an n-side cladding layer of each of the semiconductor lasers are electrically insulated by an insulating layer formed between the semiconductor substrate and the n-side cladding layer of the semiconductor lasers and an insulating layer formed between the n-side cladding layer of the semiconductor amplifier and the n-side cladding layer of the semiconductor lasers, the n-side cladding layer of the semiconductor lasers and the p-side cladding layer of the semiconductor amplifier is configured to be electrically connected, and the semiconductor amplifier and each semiconductor laser of the plurality of semiconductor lasers are electrically connected in series.

Abstract: A multiplication layer on a semiconductor substrate of n-type contains Al atoms. An electric field control layer on the multiplication layer is of p-type, and includes a high-concentration area, and a low-concentration area lower in impurity concentration than the high-concentration area which is formed outside the high-concentration area. An optical absorption layer on the electric field control layer is lower in impurity concentration than the high-concentration area. A window layer of n-type formed on the optical absorption layer is larger in band gap than the optical absorption layer. A light-receiving area of p-type is formed apart from an outer edge of the window layer, and at least partly faces the high-concentration area through the window layer and the optical absorption layer. The guard ring area of p-type which the window layer separates from the light-receiving area penetrates through the window layer to extend into the optical absorption layer.

Abstract: A semiconductor optical integrated device is a semiconductor optical integrated device in which a first optical element, a monitoring light waveguide and a second optical element, through which light propagates, are formed on a common semiconductor substrate; wherein the monitoring light waveguide is joined to the first optical element, and the second optical element is joined to the monitoring light waveguide. The monitoring light waveguide includes a light scattering portion for scattering a part of the light, which is composed of a combination of light waveguides having different mode field diameters or having different centers of mode field diameters; and a light detector for receiving scattered light scattered by the light scattering portion, is placed on an outer periphery of the monitoring light waveguide, or on a back surface of the semiconductor substrate on its side opposite to that facing the light scattering portion.

Abstract: A semiconductor optical integrated device is a semiconductor optical integrated device in which a first optical element, a monitoring light waveguide and a second optical element, through which light propagates, are formed on a common semiconductor substrate; wherein the monitoring light waveguide is joined to the first optical element, and the second optical element is joined to the monitoring light waveguide. The monitoring light waveguide includes a light scattering portion for scattering a part of the light, which is composed of a combination of light waveguides having different mode field diameters or having different centers of mode field diameters; and a light detector for receiving scattered light scattered by the light scattering portion, is placed on an outer periphery of the monitoring light waveguide, or on a back surface of the semiconductor substrate on its side opposite to that facing the light scattering portion.

Abstract: A semiconductor optical integrated device comprises a semiconductor amplifier and a plurality of semiconductor lasers, wherein the semiconductor amplifier and the semiconductor lasers are monolithically integrated on a semiconductor substrate, an n-side cladding layer of the semiconductor amplifier and an n-side cladding layer of each of the semiconductor lasers are electrically insulated by an insulating layer formed between the semiconductor substrate and the n-side cladding layer of the semiconductor lasers and an insulating layer formed between the n-side cladding layer of the semiconductor amplifier and the n-side cladding layer of the semiconductor lasers, the n-side cladding layer of the semiconductor lasers and the p-side cladding layer of the semiconductor amplifier is configured to be electrically connected, and the semiconductor amplifier and each semiconductor laser of the plurality of semiconductor lasers are electrically connected in series.

Abstract: A multiplication layer on a semiconductor substrate of n-type contains Al atoms. An electric field control layer on the multiplication layer is of p-type, and includes a high-concentration area, and a low-concentration area lower in impurity concentration than the high-concentration area which is formed outside the high-concentration area. An optical absorption layer on the electric field control layer is lower in impurity concentration than the high-concentration area. A window layer of n-type formed on the optical absorption layer is larger in band gap than the optical absorption layer. A light-receiving area of p-type is formed apart from an outer edge of the window layer, and at least partly faces the high-concentration area through the window layer and the optical absorption layer. The guard ring area of p-type which the window layer separates from the light-receiving area penetrates through the window layer to extend into the optical absorption layer.

Abstract: According to the present invention, a semiconductor device includes a substrate comprising a front end face, a rear end face and side faces, a plurality of semiconductor lasers provided on the substrate, a forward optical multiplexer to multiplex forward output light of the plurality of semiconductor lasers and output the multiplexed light to the front end face, a backward optical multiplexer to multiplex backward output light of the plurality of semiconductor lasers and output the multiplexed light to the rear end face and a plurality of backward waveguides connected to an output section of the backward optical multiplexer, wherein the plurality of backward waveguides includes a main waveguide disposed at a center of the output section and a plurality of lateral waveguides disposed on both sides of the main waveguide to bend toward the side faces and output light from the side faces diagonally to the side faces.

Abstract: In an avalanche photodiode provided with a substrate including a first electrode and a first semiconductor layer, formed of a first conductivity type, which is connected to the first electrode, the configuration is in such a way that, at least an avalanche multiplication layer, a light absorption layer, and a second semiconductor layer having a bandgap that is larger than that of the light absorption layer are layered on the substrate; a second conductivity type conductive region is formed in the second semiconductor layer; and the second conductivity type conductive region is arranged so as to be connected to a second electrode. With the foregoing configuration, an avalanche photodiode having a small dark current and a high long-term reliability can be provided with a simple process.

Abstract: A first arm portion and a second arm portion are provided so as to have a distance therebetween greater than a distance between input ends of two output waveguides and greater than a distance between an output end of a first output portion and an output end of a second output portion, the first arm portion forming a traveling path of light from one of the two output waveguides to the first output portion through a first optical amplifier, the second arm portion forming a traveling path of light from another one of the two output waveguides to the second output portion through a second optical amplifier. The first optical amplifier and the second optical amplifier have curved portions in which the first output portion and the second output portion are curved in a direction toward each other, and the first optical amplifier and the second optical amplifier respectively output light from the output end of the first output portion and the output end of the second output portion.

Abstract: A first arm portion and a second arm portion are provided so as to have a distance therebetween greater than a distance between input ends of two output waveguides and greater than a distance between an output end of a first output portion and an output end of a second output portion, the first arm portion forming a traveling path of light from one of the two output waveguides to the first output portion through a first optical amplifier, the second arm portion forming a traveling path of light from another one of the two output waveguides to the second output portion through a second optical amplifier. The first optical amplifier and the second optical amplifier have curved portions in which the first output portion and the second output portion are curved in a direction toward each other, and the first optical amplifier and the second optical amplifier respectively output light from the output end of the first output portion and the output end of the second output portion.

Abstract: An optical semiconductor device includes: a resonator end face; an optical waveguide; a window structure located between the resonator end face and the optical waveguide; and a vernier on the window structure and allowing measurement of length of the window structure along an optical axis direction.

Abstract: A wavelength variable light source according to the present invention includes: an MMI that includes an input side and an output side, the input side connecting to one end of each of a plurality of MMI input waveguides, and the output side connecting to a plurality of MMI output waveguides, the MMI multiplexing light input from each of the MMI input waveguides and outputting the multiplexed light to each of the MMI output waveguides; a plurality of DFB-LDs connected to the other end of each of the MMI input waveguides, each of the MMI output waveguides performing a single mode oscillation at a different wavelength; and two SOAs respectively connected to two MMI output waveguides of the MMI output waveguides, and having different gains from each other.

Abstract: An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; an optical amplifying section amplifying output light of the wave coupling section; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a light intensity lowering section located in each of the first optical waveguides and lower light intensity of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the respective semiconductor lasers; to decrease line width of the light output by the semiconductor lasers.