Abstract: A testing method of a wavelength-tunable laser having a resonator including wavelength selection portions having wavelength property different from each other includes a first step of controlling the wavelength-tunable laser so as to oscillate at a given wavelength according to an initial setting value, a second step of tuning the wavelength property of the wavelength selection portions and detecting discontinuity point of gain-condition-changing of the wavelength-tunable laser, and a third step of obtaining a stable operating point of the wavelength selection portion according to a limiting point of an oscillation condition at the given wavelength, the limiting point being a point when the discontinuity point is detected.

Abstract: An optical semiconductor device includes an optical semiconductor element, a metal pattern and at least one thermal conductive material. The optical semiconductor element has a first optical waveguide region and a second optical waveguide region. The second optical waveguide region is optically coupled to the first optical waveguide region and has a heater for changing a refractive index of the second optical waveguide region. The metal pattern is provided on an area to be thermally coupled to a temperature control device. The thermal conductive material couples the metal pattern with an upper face of the first optical waveguide region of the optical semiconductor element. The thermal conductive material is electrically separated from the first optical waveguide region.

Abstract: An optical semiconductor device has a heater, an optical waveguide layer, a first electrode and a second electrode. The heater is provided on a first semiconductor region and has more than one heater segment coupled or separated to each other. The optical waveguide layer is provided in the first semiconductor region and receives heat from the heater. The first electrode is coupled to a connecting point of the heater segments adjacent to each other. The second electrodes are electrically common and are coupled to other ends of the heater segments in opposite side of the connecting point respectively.

Abstract: An optical device includes an optical element, a detector and a controller. The optical element has an optical waveguide. Refractive index of the optical waveguide is controlled by a heater. A temperature of the optical element is controlled by a temperature control device. The detector detects a current flowing in the heater and/or a voltage applied to the heater. The controller controls an electrical power provided to the heater so as to be kept constant according to the detection result of the detector.

Abstract: A method of controlling a semiconductor laser that has a plurality of wavelength selection portions having a different wavelength property from each other and is mounted on a temperature control device, including: a first step of correcting a temperature of the temperature control device according to a detected output wavelength of the semiconductor laser; and a second step of controlling at least one of the wavelength selection portions so that changing amount differentials between each wavelength property of the plurality of the wavelength selection portions is reduced, the changing amount differential being caused by correcting the temperature of the temperature control device.

Abstract: A method of controlling a semiconductor laser having a wavelength selection portion, a refractive index of the wavelength selection portion being controllable with a heater including: a starting sequence including a first step for adjusting a heat value of the heater until the heat value of the heater reaches a given value; and a wavelength control sequence including a second step for correcting a wavelength of the semiconductor laser according to a detection result of an oscillation wavelength of the semiconductor laser after the starting sequence.

Abstract: An optical semiconductor device includes an optical semiconductor element, a metal pattern and at least one thermal conductive material. The optical semiconductor element has a first optical waveguide region and a second optical waveguide region. The second optical waveguide region is optically coupled to the first optical waveguide region and has a heater for changing a refractive index of the second optical waveguide region. The metal pattern is provided on an area to be thermally coupled to a temperature control device. The thermal conductive material couples the metal pattern with an upper face of the first optical waveguide region of the optical semiconductor element. The thermal conductive material is electrically separated from the first optical waveguide region.

Abstract: An optical semiconductor device includes a wavelength-tunable semiconductor laser chip, a mount carrier, a first temperature sensor and a wire. The wavelength-tunable semiconductor laser chip has a first optical waveguide and a second optical waveguide. The second optical waveguide has a heater on a surface thereof and is optically coupled to the first optical waveguide. The mount carrier is for mounting the wavelength-tunable semiconductor laser chip, and has a first area arranged at a surface of the mount carrier of the first optical waveguide side when the wavelength-tunable semiconductor laser chip is mounted. The first temperature sensor is mounted on the first area. The wire couples between the heater and a second area arranged at a surface of the mount carrier of the second optical waveguide side when the wavelength-tunable semiconductor laser chip is mounted.

Abstract: A new guanidine compound which is a bisguanidine compound represented by the formula (1): (wherein X represents hydrogen or a substituent; the benzene ring may have the same or different substituents bonded thereto; and R1's are the same or different hydrocarbon groups) and has a symmetrical structure. This compound can be a new functional substance such as, e.g., an aid for asymmetric synthesis.

Abstract: An optical semiconductor device includes a wavelength-tunable semiconductor laser chip, a mount carrier, a first temperature sensor and a wire. The wavelength-tunable semiconductor laser chip has a first optical waveguide and a second optical waveguide. The second optical waveguide has a heater on a surface thereof and is optically coupled to the first optical waveguide. The mount carrier is for mounting the wavelength-tunable semiconductor laser chip, and has a first area arranged at a surface of the mount carrier of the first optical waveguide side when the wavelength-tunable semiconductor laser chip is mounted. The first temperature sensor is mounted on the first area. The wire couples between the heater and a second area arranged at a surface of the mount carrier of the second optical waveguide side when the wavelength-tunable semiconductor laser chip is mounted.

Abstract: An optical semiconductor device includes an optical semiconductor element, a metal pattern and at least one thermal conductive material. The optical semiconductor element has a first optical waveguide region and a second optical waveguide region. The second optical waveguide region is optically coupled to the first optical waveguide region and has a heater for changing a refractive index of the second optical waveguide region. The metal pattern is provided on an area to be thermally coupled to a temperature control device. The thermal conductive material couples the metal pattern with an upper face of the first optical waveguide region of the optical semiconductor element. The thermal conductive material is electrically separated from the first optical waveguide region.

Abstract: An optical semiconductor device has a semiconductor substrate, a semiconductor region and heater. The semiconductor region has a stripe shape demarcated with a top face and a side face thereof. The stripe shape has a width smaller than a width of the semiconductor substrate. An optical waveguide layer is located in the semiconductor region. A distance from a lower end of the side face of the semiconductor region to the optical waveguide layer is more than half of the width of the semiconductor region. The heater is provided above the optical waveguide layer.

Abstract: An optical semiconductor device has a semiconductor substrate, an optical semiconductor region and a heater. The optical semiconductor region is provided on the semiconductor substrate and has a width smaller than that of the semiconductor substrate. The heater is provided on the optical semiconductor region. The optical semiconductor region has a cladding region, an optical waveguide layer and a low thermal conductivity layer. The optical waveguide layer is provided in the cladding region and has a refractive index higher than that of the cladding region. The low thermal conductivity layer is provided between the optical waveguide layer and the semiconductor substrate and has a thermal conductivity lower than that of the cladding region.

Abstract: An optical semiconductor device has a heater, an optical waveguide layer, a first electrode and a second electrode. The heater is provided on a first semiconductor region and has more than one heater segment coupled or separated to each other. The optical waveguide layer is provided in the first semiconductor region and receives heat from the heater. The first electrode is coupled to a connecting point of the heater segments adjacent to each other. The second electrodes are electrically common and are coupled to other ends of the heater segments in opposite side of the connecting point respectively.

Abstract: In a III group nitride compound semiconductor wherein light that has been emitted in a light emitting portion formative layer is reflected by a multilayered reflection layer that is provided between the light emitting portion formative layer and sapphire substrate, it is desirable, for increasing the reflection efficiency of the light that has been emitted in the light emitting portion formative layer, that the multilayered reflection layer be provided at a position that is as near to the light emitting portion as possible. However, since the multilayered reflection layer is high in resistance value and also high in power consumption, locating the multilayered reflection layer near the light emitting portion formative layer results in that the resistance value in the vicinity of a relevant cathode electrode becomes increased. This raises the problem that emission of light occurs only in part of the light emitting portion formative layer.

Abstract: A gain-coupled DFB laser diode includes a multiple quantum well active layer and a pair of cladding layers sandwiching the multiple quantum well active layer vertically, wherein the multiple quantum well active layer includes a plurality of gain regions aligned in a direction of propagation of a laser beam and repeated periodically, each of the gain regions having a multiple quantum well structure, and a buried layer fills a gap between a pair of adjacent gain regions, wherein the buried layer includes a plurality of high-refractive index layers and a plurality of low-refractive index layers, each of the high-refractive index layers is formed of a first semiconductor material having a first bandgap, while each of the low-refractive index layers is formed of a second semiconductor material having a second, larger bandgap.

Abstract: In a III group nitride compound semiconductor wherein light that has been emitted in a light emitting portion formative layer is reflected by a multilayered reflection layer that is provided between the light emitting portion formative layer and sapphire substrate, it is desirable, for increasing the reflection efficiency of the light that has been emitted in the light emitting portion formative layer, that the multilayered reflection layer be provided at a position that is as near to the light emitting portion as possible. However, since the multilayered reflection layer is high in resistance value and also high in power consumption, locating the multilayered reflection layer near the light emitting portion formative layer results in that the resistance value in the vicinity of a relevant cathode electrode becomes increased. This raises the problem that emission of light occurs only in part of the light emitting portion formative layer.

Abstract: A method of manufacturing a distributed feedback semiconductor laser, has the steps of: growing on a semiconductor substrate a lamination of alternately stacked lower barrier layer and lower well layer having a band gap narrower than the lower barrier layer, to form a lower quantum well structure; growing an intermediate layer on an uppermost lower well layer, the intermediate layer having a band gap broader than the lower well and a thickness thicker than the lower barrier layer; growing on the intermediate layer a lamination of alternately stacked upper well layer and upper barrier layer having a band gap broader than the upper well layer and a thickness thinner than the intermediate layer, to form an upper quantum well structure; forming a mask on the upper quantum well structure, the mask having periodical pattern; by using the mask as an etching mask, etching the upper quantum well structure in a periodical shape by using the intermediate layer as an etching margin layer; and removing the mask.

Abstract: An integrated semiconductor device is provided that has pads with less input signal attenuation. When J-FET (2) is driven by an input signal, the current passing through it varies. The parasitic capacitance (4) is charged or discharged by the input/output signal of the buffer circuit (6) following the varying current. Thus, since the voltage across the parasitic capacitance (3) varies in phase and at the same level, the parasitic capacitance (3) can be ignored. This effect allows attenuation of an input signal due to the parasitic capacitance (3) to be prevented.

Abstract: In a data transmission, a driving circuit 14 drives a light receiving element 15 in accordance with data from an external control circuit. In accordance with IrDA or remote control communication, driving capability of the driving circuit is changed. In a data reception, received data is transferred to a first or a second signal processing circuit in accordance with the IrDA or remote control communication and processed according to each communication format. In this configuration, a single light emitting or light receiving element permits data communication in different kinds of data communication formats.