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.

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.

Abstract: An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a phase regulator regulating phase of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the semiconductor lasers; a second optical waveguide optically connecting the wave coupling section to the phase regulator; an optical amplifying section amplifying output light of the phase regulator; and a third optical waveguide optically connecting an output of the phase regulator to the optical amplifying section. The phase regulator adjusts the phase of reflected light that returns to the semiconductor lasers to decrease line width of the light output by the semiconductor lasers.

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; first optical waveguides respectively optically connecting respective semiconductor lasers to the wave coupling section; a phase regulator regulating phase of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the semiconductor lasers; a second optical waveguide optically connecting the wave coupling section to the phase regulator; an optical amplifying section amplifying output light of the phase regulator; and a third optical waveguide optically connecting an output of the phase regulator to the optical amplifying section. The phase regulator adjusts the phase of reflected light that returns to the semiconductor lasers to decrease line width of the light output by the semiconductor lasers.

Abstract: An avalanche photodiode including a first electrode; and a substrate including a first semiconductor layer of a first conduction type electrically connected to the first electrode, in which at least an avalanche multiplication layer, a light absorption layer, and a second semiconductor layer of a second conduction type with a larger band gap than the light absorption layer are deposited on the substrate. The second semiconductor layer is separated into inner and outer regions by a groove formed therein, the inner region electrically connected to a second. With the configuration, the avalanche photodiode has a low dark current and high long-term reliability. In addition, the outer region includes an outer trench, and at least the light absorption layer is removed by the outer trench to form a side face of the light absorption layer. With the configuration, the dark current can be further reduced.

Abstract: A semiconductor light detecting element includes: an InP substrate; and a semiconductor stacked structure on the InP substrate and including at least a light absorbing layer, wherein the light absorbing layer includes an InGaAsBi layer lattice-matched to the InP substrate.