Abstract: An optical modulator includes: a semiconductor chip; a waveguide in the semiconductor chip; a traveling wave electrode including an input portion and an output portion, to which a signal is applied for modulating light passing through the waveguide; a power supply line connected to the input portion via a first wire; and a termination resistor connected to the output portion via a second wire. Capacitance between the output portion and a grounding point is larger than capacitance between the input portion and the grounding point.

Abstract: An avalanche photodiode includes a substrate; an avalanche multiplying layer, a p-type electric field controlling layer, a light-absorbing layer, and a window layer sequentially laminated on the substrate. A p-type region is present in parts of the window layer and the light-absorbing layer. Carbon is the dopant of the electric field controlling layer. Zn is the dopant of the p-type region. A bottom face of the p-type region is closer to the substrate than is an interface between the light-absorbing layer and the window layer.

Abstract: A semiconductor optical integrated element includes: a substrate; and a laser diode and a modulator which are integrated on the substrate. The laser diode includes an embedded waveguide having a core layer, both sides of which are embedded in a semiconductor material. The modulator includes a high-mesa ridge waveguide having a core layer, neither side of which is embedded in the semiconductor material. The core layers in the laser diode and the modulator are stripe-shaped.

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.

Abstract: An optical modulator includes: a semiconductor chip; a waveguide in the semiconductor chip; a traveling wave electrode including an input portion and an output portion, to which a signal is applied for modulating light passing through the waveguide; a power supply line connected to the input portion via a first wire; and a termination resistor connected to the output portion via a second wire. Capacitance between the output portion and a grounding point is larger than capacitance between the input portion and the grounding point.

Abstract: A semiconductor optical integrated element includes: a substrate; and a laser diode and a modulator which are integrated on the substrate. The laser diode includes an embedded waveguide having a core layer, both sides of which are embedded in a semiconductor material. The modulator includes a high-mesa ridge waveguide having a core layer, neither side of which is embedded in the semiconductor material. The core layers in the laser diode and the modulator are stripe-shaped.

Abstract: A semiconductor photodetector comprises: a semiconductor substrate; a first multilayer reflective layer on a first surface of the semiconductor substrate and including semiconductor layers; a first optically-resonant layer on the first multilayer reflective layer; a second multilayer reflective layer on the first optically-resonant layer and including semiconductor layers; a light absorbing layer on the second multilayer reflective layer; a reflective film on the light absorbing layer; and an antireflective film on a second surface of the semiconductor substrate. The first optically-resonant layer has a larger thickness than the semiconductor layers of the first and second multilayer reflective layers. The combined optical thickness of the layers between the second multilayer reflective layer and the reflective film is not equal to the optical thickness of the first optically-resonant layer.

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: An optical semiconductor device comprises a distributed Bragg reflector layer of a first conductivity type, an optical absorption layer, and a semiconductor layer of a second conductivity type, sequentially formed on a semiconductor substrate; wherein said Bragg reflection layer of the first conductivity type has first semiconductor layers having a band gap wavelength larger than the wavelength of incident light, and second semiconductor layers having a band gap wavelength smaller than the wavelength of incident light; and an optical layer thickness of each of said first semiconductor layers is larger than the optical layer thickness of each of said second semiconductor layers.

Abstract: An optical semiconductor device includes a distributed Bragg reflection layer of a first conductivity type, a distortion elaxation layer of the first conductivity type, a light absorbing layer, and a semiconductor layer of a second conductivity type, sequentially arranged on a semiconductor substrate. The distortion relaxation layer the same material as the semiconductor substrate. The total optical length of layers between the distributed Bragg reflection layer and the light absorbing layer is an integer multiple of one-half the wavelength of incident light that is detected.

Abstract: A semiconductor light detecting element comprises: a semiconductor substrate having a first major surface and a second major surface opposite each other; a first reflective layer, an absorptive layer, a phase adjusting layer, and a second reflective layer sequentially disposed, from the semiconductor substrate, on the first major surface of the semiconductor substrate; and an anti-reflection film on the second major surface of the semiconductor substrate. The first reflective layer is a multilayer reflective layer including laminated semiconductor layers having different refractive indices; the absorptive layer has a band gap energy smaller than band gap energy of the semiconductor substrate; the phase adjusting layer has a band gap energy larger than the band gap energy of the absorptive layer; and the first reflective layer contacts the absorptive layer, without intervention of other layers.

Abstract: A semiconductor light detecting device includes an n-contact layer selectively disposed on an Fe—InP substrate. An optical waveguide layer is disposed on the n-contact layer and includes an n-cladding layer, a light absorption layer, and a p-cladding layer, laminated on one another over the n-contact layer, in that order. An Fe—InP current blocking layer is disposed on the n-cladding layer such that sides of the optical waveguide layer are buried in the Fe—InP current blocking layer. A p-electrode includes a contact electrode electrically connected to the p-cladding layer of the optical waveguide layer, a lead-out electrode portion extending on a side wall of the current blocking layer from the contact electrode and extending on the Fe—InP substrate, and an electrode pad disposed on a surface of the Fe—InP substrates with an SiN film between the electrode pad and the surface of the Fe—InP substrate and connected to the lead-out electrode portion.

Abstract: A semiconductor light detecting element having a mesa structure comprises: a first semiconductor layer having n-type conductivity located on a semiconductor substrate, a light absorbing layer located on the first semiconductor layer, and a second semiconductor layer located on the light absorbing layer; a burying layer burying peripheries of the light absorbing layer and the second semiconductor layer. The burying layer has a band gap larger than the band gap of the light absorbing layer. The second semiconductor layer has a first region having p-type conductivity, and a second region having i-type or n-type conductivity and located between the first region and the burying layer.

Abstract: A transmitted light absorption/recombination layer, a barrier layer, a wavelength selection/absorption layer, and an InP window layer having a p-type region are supported by an n-type substrate and arranged in that order. Light with a wavelength of 1.3 ?m reaches the wavelength selection/absorption layer through the InP window layer. Then, the light is absorbed by the wavelength selection/absorption layer and drawn from the device as an electric current signal. Light with a wavelength of 1.55 ?m reaches the transmitted light absorption/recombination layer through the barrier layer. Then, the light is absorbed by the transmitted light absorption/recombination layer, generating electrons and holes. These electrons and holes recombine with each other and, hence, disappear.

Abstract: A semiconductor photosensitive element comprises: a semiconductor substrate of a first conductivity type; a first light absorption layer, a first semiconductor layer of a second conductivity type, a first semiconductor layer of the first conductivity type, a second light absorption layer, and a second semiconductor layer of a second conductivity type, arranged in this order on the semiconductor substrate; a first electrode connected the second semiconductor layer of the second conductivity type; a second electrode connected to the semiconductor substrate; and a third electrode electrically connecting the first semiconductor layer of the first conductivity type to the first semiconductor layer of the second conductivity type. The third electrode is located outside a light detection region for detecting optical signals.

Abstract: An n-type InGaAs light absorbing layer and an n-type InP layer (first conductivity type semiconductor layer), which is a window layer, and a multiplication layer are multilayered one atop another on an n-type InP substrate. By selectively diffusing impurities and implanting ions, a p-type InP region second conductivity type semiconductor region) is formed on a part of the top surface of the n-type InP layer. The top surfaces of the n-type InP layer and p-type InP region are covered with a surface protection film. A cathode electrode (first electrode) is connected to the underside of the n-type InP substrate. A ring-shaped anode electrode (second electrode) is connected to the top surface of the p-type InP region. A low-voltage electrode surrounds the anode electrode. A voltage lower than that of the cathode electrode his applied to this low-voltage electrode.

Abstract: A semiconductor light detecting element having a mesa structure comprises: a first semiconductor layer having n-type conductivity located on a semiconductor substrate, a light absorbing layer located on the first semiconductor layer, and a second semiconductor layer located on the light absorbing layer; a burying layer burying peripheries of the light absorbing layer and the second semiconductor layer. The burying layer has a band gap larger than the band gap of the light absorbing layer. The second semiconductor layer has a first region having p-type conductivity, and a second region having i-type or n-type conductivity and located between the first region and the burying layer.

Abstract: An avalanche photodiode comprises: a substrate; a semiconductor layer of a first conductivity type on the substrate; and an avalanche multiplication layer, a light absorption layer, and a window layer which are sequentially formed on the semiconductor layer, wherein apart of the window layer is a region of a second conductivity type, and the light absorption layer includes a first light absorption layer, and a second light absorption layer which has higher electric conductivity than electric conductivity of the first light absorption layer.

Abstract: Provided is a photodiode array that is capable of outputting an electric signal with a large electric power and an optical microwave transmission system receiver that supplies an electric power with the aid of an optical fiber and does not require the electric power line from the external. An input modulation light is branched and input to a plurality of photodiode elements (1), electric output terminals (5) of the plurality of photodiode elements (1) are connected in parallel to each other, and a combined electric output is extracted. The electric output terminal (5) of the photodiode array configured as described above is connected to an antenna (7) without an intermediation of an amplifier circuit.

Abstract: A semiconductor light-receiving device and its manufacturing method are provided which are capable of suppressing dark current and deterioration. Semiconductor crystals were sequentially grown over an n-type InP substrate, including an n-type InP buffer layer, an undoped GaInAs light absorption layer, an undoped InP diffusion buffer layer, and a p-type InP window layer. Next, a first mesa was formed by removing a part from the p-type InP window layer to the n-type InP buffer layer with a Br-based etchant having low etching selectivity, so as to form a sloped “normal” mesa structure. Next, a second mesa having a smaller diameter than the first mesa was formed by dry etching, by precisely removing a part from the p-type InP window layer to a certain mid position of the undoped InP diffusion buffer layer.