Abstract: Provided is a waveguide-type polarization beam splitter in which deterioration of a polarization extinction ratio due to temperature change and wavelength change is suppressed. The waveguide-type polarization beam splitter includes: input optical waveguides; a first multimode interference optical coupler; a pair of optical waveguide arms; a second multimode interference optical coupler; and output optical waveguides. A quarter wavelength delay is provided in one of the pair of optical waveguide arms, a groove is formed to extend across both of the pair of optical waveguide arms, and two quarter wave plates are provided in the groove to extend respectively across the arms. Polarization axes of the respective quarter wave plates are orthogonal to each other.

Abstract: Provided is a waveguide-type polarization beam splitter in which deterioration of a polarization extinction ratio due to temperature change and wavelength change is suppressed. A groove is formed to extend across a pair of optical waveguide arms and two quarter wave plates are provided in the groove to extend respectively across the arms. Polarization axes of the quarter wave plates are orthogonal to each other. A first optical coupler which gives a phase difference of 0° or 180° between coupled or split light beams and a second optical coupler which gives a phase difference of 90° or ?90° between coupled or split light beams are used in combination.

Abstract: A low cost photocurrent monitoring circuit is provided. A photocurrent monitoring circuit, which performs monitoring by converting photocurrents output from a plurality of photodiodes (PD1 to PDn) into voltage, includes: a multiplexer circuit (MUX) for selecting one of input terminals to establish a connection of the selected input terminal to an output terminal, wherein the photodiodes (PD1 to PDn) are respectively connected to the input terminals; and an amplifier (LA) for converting a photocurrent which flows from a selected photodiode via the multiplexer circuit (MUX) into a voltage, and for outputting the voltage.

Abstract: A low-cost optical module with highly consistent properties. The optical module includes, in a housing, an optical waveguide array, an optical functional element array, lens optics using one or a plurality of lenses for optically coupling the optical waveguide array and the optical functional element array, and a mirror disposed so as to convert the propagation direction of optical beams transmitted by the lens optics such that the optical beams are incident on the optical incidence ports of the optical functional element array. The optical functional element array is affixed to the housing, and the angle of the mirror is fixed in place after the angle of the mirror is adjusted such that the optical waveguide array and the optical functional element array are optically coupled.

Abstract: In an integrated optical receiver or transmitter, both the displacement of an optical axis caused by thermal changes and the property degradation of an optical functional circuit are inhibited. A planar lightwave circuit having a substrate and a waveguide-type optical functional circuit formed thereon composed of a material different from that of the substrate, and includes a waveguide region formed only of an optical wavelength that is in contact with a side forming an emission-end face of the optical waveguide for propagating the light emitted from the optical functional circuit or an incident-end face of an optical waveguide for propagating the light incident on the optical functional circuit. The planar lightwave circuit is fixed to a fixing mount only at the bottom of the substrate where the waveguide region is formed.

Abstract: An optical module including a flat-plate-shaped base having a predetermined thickness, an optical semiconductor package which is mounted on a plane of the flat-plate-shaped base to air-tightly seal an active optical element, a waveguide optical element which wave-guides light from an optical fiber or to an optical fiber and which is mounted on the plane of the flat-plate-shaped base, an optical lens which connects the optical semiconductor package and the waveguide optical element and which is mounted on the plane of the flat-plate-shaped base, and a frame-equipped lid which covers the optical semiconductor package, the waveguide optical element, and the optical lens and which is fixed onto the plane of the flat-plate-shaped base.

Abstract: A rubber composition that can improve in good balance the fuel economy, wet-grip performance, and abrasion resistance, and a pneumatic tire that uses this rubber composition are provided. This rubber composition contains a rubber component, and carbon black and/or silica, wherein based on 100% by mass of the rubber component, the rubber component contains 5 to 50% by mass of natural rubber, 0.3 to 10% by mass of an epoxidized natural rubber, and at least 5% by mass of a conjugated diene polymer that has a constituent unit based on a conjugated diene and a constituent unit represented by formula (I) below, at least one terminal of the polymer being modified, and wherein a total content of the carbon black and the silica is 3 to 100 parts by mass per 100 parts by mass of the rubber component.

Abstract: A low cost photocurrent monitoring circuit is provided. A photocurrent monitoring circuit, which performs monitoring by converting photocurrents output from a plurality of photodiodes (PD1 to PDn) into voltage, includes: a multiplexer circuit (MUX) for selecting one of input terminals to establish a connection of the selected input terminal to an output terminal, wherein the photodiodes (PD1 to PDn) are respectively connected to the input terminals; and an amplifier (LA) for converting a photocurrent which flows from a selected photodiode via the multiplexer circuit (MUX) into a voltage, and for outputting the voltage.

Abstract: An optical waveguide and an optical waveguide circuit having polarization insensitivity or a required low-level polarization dependence without degradation of the optical characteristics and reliability are disclosed, and a fabricating method of an optical waveguide and an optical waveguide circuit having polarization insensitivity or a required low-level polarization dependence without increasing the fabricating burden and the cost are disclosed. The optical waveguide comprises a planar substrate; a lower cladding which is provided on the planar substrate, where the lower cladding has a ridge; a core, provided on the ridge of the lower cladding, for transmitting light; and an upper cladding provided in a manner such that the core is covered with the upper cladding. The ridge has a shape predetermined so as to decrease polarization dependence of the optical waveguide to a required low level.

Abstract: An optical waveguide and an optical waveguide circuit having polarization insensitivity or a required low-level polarization dependence without degradation of the optical characteristics and reliability are disclosed, and a fabricating method of an optical waveguide and an optical waveguide circuit having polarization insensitivity or a required low-level polarization dependence without increasing the fabricating burden and the cost are disclosed. The optical waveguide comprises a planar substrate; a lower cladding which is provided on the planar substrate, where the lower cladding has a ridge; a core, provided on the ridge of the lower cladding, for transmitting light; and an upper cladding provided in a manner such that the core is covered with the upper cladding. The ridge has a shape predetermined so as to decrease polarization dependence of the optical waveguide to a required low level.