Abstract: An optical device includes a first substrate, having first and second surfaces, and a second substrate having a third surface. The first substrate includes: a laser unit, having an active layer and emitting light into the first substrate from the active layer; a reflecting mirror, having a plane obliquely intersecting an optical axis of light emitted from the laser unit, and being formed on the first surface so as to reflect the light toward the second surface; and a convex lens, being formed in a region on the second surface, the region including an optical axis of the light reflected by the reflecting mirror. The second substrate is provided with a grating coupler and an optical waveguide on the third surface, the optical waveguide having light incident on the grating coupler propagating therethrough.

Abstract: A delay interferometer includes a half beam splitter and two pentagonal prisms disposed on a substrate. The half beam splitter branches light to be measured which travels substantially in parallel with the substrate into two branched light beams. The pentagonal prisms respectively reflect the respective branched light beams such that the optical axes of the branched light beams are moved in parallel in a direction substantially perpendicular to the substrate by reflection. The half beam splitter combines the branched light beams reflected by the pentagonal prisms to generate interference light beams.

Abstract: An optical module includes: an optical module main body including an optical connector to which a communication cable transferring optical signal is connected, and a terminal portion on which a plurality of terminal pads for transmitting and receiving an electric signal for communication using the optical signal are arranged; a lead array including a lead fixing portion that retains a plurality of metal leads arranged in parallel on and protruding from the lead fixing portion and electrically connected to the plurality of terminal pads of the terminal portion; and a flexible printed circuit including a plurality of holes through which the plurality of metal leads penetrate, and wires electrically connected to the metal leads.

Abstract: An optical receiver module capable of increasing the range in which the error in distance between a collecting lens and a light receiving section is allowed is provided. In the optical receiver module according to the invention, the optical receiver includes a semiconductor substrate to which the light from the collecting lens is input, and through which the light passes, and a light receiving section disposed on a side (a reverse side) of the semiconductor substrate, the side being further from the collecting lens, and adapted to receive the light transmitted through the semiconductor substrate, and then convert the light into an electrical signal. On a side (an obverse side) of the semiconductor substrate, the side being nearer to the collecting lens, there is formed a lens surface adapted to converge light from the collecting lens toward the light receiving section.

Abstract: A differential transmission circuit includes a pair of transmission line conductors and a ground conductor layer, wherein the pair of transmission line conductors include a first straight line region where both the pair of transmission line conductors extend in parallel to each other in a first direction with a first width in a first layer, a first cross region where one of the pair of transmission line conductors is formed in the first layer, the other thereof is formed in a second layer, and the pair of transmission line conductors cross the each other in a three-dimensional manner, the first cross region being disposed on the front side of the first straight line region, and wherein each of the widths of the pair of transmission line conductors in the first cross region is smaller than the first width.

Abstract: An optical module includes an electromagnetic wave absorption member. The electric connection member includes a floating portion which is in a floating state spaced apart from the housing and at a position away from a mounting portion by which the electric connection member is mounted on the housing in the direction opposite to the direction that the optical module is inserted into a cage. At least a portion of the electromagnetic wave absorption member is arranged between the housing and the floating portion. The floating portion is brought into contact with an inner side of the cage so as to establish the electrical connection with the inner side of the cage when the housing is inserted into the cage.

Abstract: In a delay line interferometer inside a demodulator, with respect to polarization states of two split beams of light to be interfered with each other, p polarization and s polarization are reversed by a half beam splitter and, further, again multiplexed by the half beam splitter used for splitting so that interference beams of light are generated.

Abstract: The present invention provides a nitride semiconductor light emitting device having an n-electrode that has an Au face excellent in ohmic contacts to an n-type nitride semiconductor and excellent in mounting properties, and a method of manufacturing the same. The nitride semiconductor light emitting device uses an n-electrode having a three-layer laminate structure that is composed of a first layer containing aluminum nitride and having a thickness not less than 1 nm or less than 5 nm, a second layer containing one or more metals selected from Ti, Zr, Hf, Mo, and Pt, and a third layer made of Au, from the near side of the n-type nitride semiconductor in order of mention. The n-electrode thus formed is then annealed to obtain ohmic contacts to the n-type nitride semiconductor.

Abstract: Provided is an optical module in which a temperature of a semiconductor element to be subjected to temperature control is controlled to fall within a desired operating temperature range regardless of whether an environmental temperature is outside or inside the operating temperature range of the semiconductor element, and which is stably operated with low power consumption. A control section 30 determines, based on the environmental temperature having a temperature range of from a first temperature to a second temperature, a target temperature from a predetermined operating temperature range of from a third temperature to a fourth temperature. The control unit 30, an ATC circuit 34, a TEC control IC 12, and a TEC 24 control the temperature of a laser module 20 to become the target temperature. The first temperature is lower than the third temperature, and the second temperature is higher than the fourth temperature.

Abstract: A differential transmission circuit includes a grounded conductive layer, a pair of transmission line conductors, a conductive film and a via hole which connects the grounded conductive layer to the conductive film. The differential transmission circuit further includes a straight-line region which is present in the differential transmission circuit through which a differential transmission signal output by a driving circuit is transmitted and in which the pair of transmission line conductors extends parallel so as to have a first width, and a band rejection filter region in which the pair of transmission line conductors planarly overlaps the conductive film and extends parallel so as to have a second width narrower than the first width and a common mode of the differential transmission signal is attenuated at one of the frequencies which are natural number multiples of a frequency corresponding to the predetermined bit rate.

Abstract: A printed circuit board includes a substrate, a signal output circuit formed on the substrate for outputting a clock signal, a shield for covering the signal output circuit, a power supply wiring for connecting the signal output circuit and a power source, and a trap filter provided to the power supply wiring and provided inside the shield, for attenuating a frequency component corresponding to a frequency of clock signal. The trap filter includes a resonance circuit having one portion of the power supply wiring, an inner-layer wiring of the substrate located below the one portion of the power supply wiring, an inner-layer ground wiring of the substrate located below the inner-layer wiring, and a via hole for connecting the one portion of the power supply wiring and the inner-layer wiring.

Abstract: A polarization diversity optical system device includes: a polarization split unit that splits a first coherent light into a first split light and a second split light whose polarization components are orthogonal to each other, and splits a second coherent light into a third split light and a fourth split light whose polarization components are orthogonal to each other; and a light combining unit that combines the first split light with one of the third split light and the fourth split light, and combines the second split light with the other of the third split light and the fourth split light.

Abstract: A differential transmission circuit includes a pair of transmission line conductors and a ground conductor layer, wherein the pair of transmission line conductors include a first straight line region where both the pair of transmission line conductors extend in parallel to each other in a first direction with a first width in a first layer, a first cross region where one of the pair of transmission line conductors is formed in the first layer, the other thereof is formed in a second layer, and the pair of transmission line conductors cross the each other in a three-dimensional manner, the first cross region being disposed on the front side of the first straight line region, and wherein each of the widths of the pair of transmission line conductors in the first cross region is smaller than the first width.

Abstract: An optical phase shifter according to the invention includes the thermo-optical element of which a refractive index with respect to an input optical signal changes dependently on temperature; a temperature change section, having contact with one end of the thermo-optical element and of which a temperature changes so that a temperature of the thermo-optical element becomes a desired temperature; a heat dissipation section being disposed on an opposite side of the thermo-optical element with respect to the temperature change section and going into a state of thermal equilibrium at a temperature different from the temperature of the temperature change section; and a temperature buffer section, being disposed between the temperature change section and the heat dissipation section, having contact with the temperature change section and the heat dissipation section, and having a heat resistance greater than that of the heat dissipation section.

Abstract: Provided is a semiconductor electroluminescent device with an InGaAlAs-based well layer having tensile strain, or a semiconductor electroluminescent device with an InGaAsP-based well layer having tensile strain and with an InGaAlAs-based barrier layer which is high-performance and highly reliable in a wide temperature range. In a multiple-quantum well layer of the semiconductor electroluminescent device, a magnitude of interface strain at an interface between the well layer and the barrier layer is smaller than a magnitude of critical interface strain determined by a layer thickness value which is larger one of a thickness of the well layer and a thickness of the barrier layer.

Abstract: Provided are an optical semiconductor which includes a pyroelectric first substrate having an optical waveguide formed in a surface thereof and a second substrate connected to the first substrate via an insulating adhesive layer and which inhibits a pyroelectric effect caused therein, and an optical module. The optical semiconductor includes: a first substrate which has an electro-optic effect and is pyroelectric, the first substrate having an optical waveguide formed in an upper surface thereof; a second substrate connected the first substrate via an insulating adhesive layer; a first conductive film formed on a lower surface of the first substrate; and a second conductive film formed on at least one side surface of the first substrate and the second substrate, in which the first conductive film is electrically connected to the second conductive film.

Abstract: Provided is a backside illuminated semiconductor light-receiving device enhancing a frequency characteristic without deteriorating assembling operability. The light-receiving device includes a rectangular substrate; a light receiving mesa portion formed on a center portion of one side on a front surface of the substrate and includes a PN junction portion; a P-type electrode formed on the light receiving mesa portion and conductive with one side of the PN junction portion; an N-type electrode mesa portion formed on one corner portion of the one side; an N-type electrode pulled out to the N-type electrode mesa portion and conductive with the other side of the PN junction portion; a P-type electrode mesa portion and a dummy electrode mesa portion formed in a region including three other corner portions; and a dummy electrode formed on the dummy electrode mesa portion.

Abstract: In an optical semiconductor device related to the present invention, a first light source outputting light having a first polarization, a second light source outputting light having a second polarization, a first optical modulator being optically connected to an output side of the first light source and modulating the light that is output from the first light source to output a light signal, a second optical modulator being optically connected to an output side of the second light source and modulating the light that is output from the second light source to output a light signal, and an optical multiplexer coupling the light signal that is output from the first optical modulator with the light signal that is output from the second optical modulator to output a coupled light signal, are integrated on a semiconductor substrate together.

Abstract: In a BH laser which uses InGaAlAs-MQW in an active layer, Al-based semiconductor multi-layer films including an InP buffer layer and an InGaAlAs-MQW layer, and an InGaAsP etching stop layer are formed in a mesa shape, and a p type InP burial layer is buried in side walls of the mesa shape. An air ridge mesa-stripe of a lateral center that is substantially the same as that of the mesa shape is formed on the mesa shape. According to the present structure, a leakage current can be considerably reduced, the light confinement coefficient can be made to be larger than in a BH laser in the related art, and thereby it is possible to implement a semiconductor laser with a low leakage current and a high relaxation oscillation frequency.

Abstract: Within a semiconductor laser device, mounting a semiconductor laser element array of multi-beam structure on a sub-mount, the semiconductor laser element array of multi-beam structure comprises one piece of a semiconductor substrate 11; a common electrode 1, which is formed on a first surface of the semiconductor substrate; a semiconductor layer 2, which is formed on the other surface of the semiconductor substrate, and has a plural number of light emitting portions 7 within an inside thereof; a plural number of anode electrodes 3 of a second conductivity type, which are formed above the plural number of light emitting portions, respectively; and a supporting portion 25, which is provided outside a region of forming the light emitting portions, wherein on one surface of the sub-mount is connected an electrode 3 of the semiconductor laser element array through a solder 4, and that solder 4 is formed to cover a supporting portion and an electrode neighboring thereto, and further on the electrode 3 is formed a g