Abstract: A disclosed optical device includes a first waveguide disposed between a branching portion and a multiplexing portion on a semiconductor substrate, and a second waveguide disposed between the branching portion and the multiplexing portion, the second waveguide being longer than the first waveguide. In the optical device, an optical confinement effect of the first waveguide is greater than an optical confinement effect of the second waveguide, the first waveguide has a curvature with a first curvature radius (Rs), the second waveguide has a curvature with a second curvature radius (Rl), and the first curvature radius is smaller than the second curvature radius.

Abstract: A method for manufacturing a core of a rotating electric machine includes arranging a permanent magnet in a receptacle of a core body and injecting an anchoring material into a gap between a wall surface of the receptacle and an outer surface of the permanent magnet. A liquid crystal polymer, more specifically, liquid crystal polyester is used as the anchoring material. The liquid crystal polymer is injected at a velocity of 100 to 300 millimeters per second.

Abstract: A wavelength tunable light source has a light source, a wavelength monitor circuit that receives a portion of light emitted from the light source, and a processor that controls a wavelength of the light emitted from the light source based upon an output value of the wavelength monitor circuit, wherein the wavelength monitor circuit has a wavelength filter that outputs four light components with optical phases shifted by 90 degrees from one another and multiple photo detectors that detects the four light components output from the wavelength filter, and wherein the processor selects at least one of the four light components, calculates a ratio of a monitor value of the selected light component to a total sum of monitor values of the four light components, and adjusts the wavelength of the light source so as to bring the ratio to be closer to a target ratio at a designated wavelength.

Abstract: A measurement unit includes a fluid inlet to let a fluid flow in, a fluid outlet to let the fluid flow out, and a single flow path connecting the fluid inlet with the fluid outlet. The measurement unit further includes a plurality of partition boards and a measuring instrument. The plurality of partition boards are disposed along a current of the fluid and between facing side surfaces of the flow path. The plurality of partition boards define M flow path segments (where M is an integer of 2 or greater) between the facing side surfaces. The measuring instrument measures a flow rate of the fluid flowing through N successively adjacent flow path segments (where N is an integer of 1 or greater and less than M).

Abstract: A wavelength tunable light source includes a light source, a wavelength monitor circuit configured to receive light emitted from the light source, and a processor that controls the light source based upon an output value of the wavelength monitor circuit, wherein the wavelength monitor circuit has a wavelength filter with a periodic transmission spectrum, and three photo detectors connected to outputs of the wavelength filter, and wherein the processor is configured to calculate a ratio of photo-detection normalized with two of three quantities of light received at the three photo detectors and control electric current input to the light source such that a calculated ratio of photo-detection approaches a target ratio at a designated wavelength.

Abstract: A light communication device further includes a rigid substrate, a package, and a flexible substrate. The rigid substrate includes a first terminal arranged on a surface thereof and a second terminal having a first hole opened at the surface. The package includes a third terminal and a fourth terminal being provided on a side wall thereof and being electrically coupled to a signal electrode and a ground electrode of the signal processor, respectively. The flexible substrate includes a fifth terminal and a sixth terminal being electrically coupled to the third terminal and the fourth terminal, respectively. The fifth terminal is electrically coupled to the first terminal on the surface, and the sixth terminal, with being placed into the first hole, is electrically coupled to the second terminal.

Abstract: An optical module has an optical modulator configured to perform phase modulation on each of divided light components of an input light and output at least two phase-modulated signal lights, a semiconductor optical amplifier configured to amplify the phased-modulated signal lights in a same polarization mode, and a polarization multiplexer configured to convert the amplified signal lights into two orthogonally polarized signal lights and multiplex the orthogonally polarized signal lights.

Abstract: An optical modulator includes an optical modulator chip configured to optically modulate an optical signal using an electrical signal input thereto; and a relay substrate configured to relay and couple the electrical signal to the optical modulator chip. The optical modulator chip includes a signal electrode and a ground electrode for the electrical signal, formed along a waveguide for the optical signal. One end of the optical modulator chip is arranged to face the relay substrate. An electrode connection portion coupling the electrical signal to the relay substrate by wire is provided at the one end. A distance between a tip of one end of the signal electrode in the electrode connection portion and the end of the optical modulator chip is less than a distance between a tip of an end of the ground electrode in the electrode connection portion and the end of the optical modulator chip.

Abstract: A disclosed optical device includes a first waveguide disposed between a branching portion and a multiplexing portion on a semiconductor substrate, and a second waveguide disposed between the branching portion and the multiplexing portion, the second waveguide being longer than the first waveguide. In the optical device, an optical confinement effect of the first waveguide is greater than an optical confinement effect of the second waveguide, the first waveguide has a curvature with a first curvature radius (Rs), the second waveguide has a curvature with a second curvature radius (Rl), and the first curvature radius is smaller than the second curvature radius.

Abstract: The invention relates to a tunable laser source, and the reduction in the loss and the size can both be achieved in a tunable laser source having a power monitor and a wavelength locker function. A tunable laser is formed of a semiconductor optical amplifier and a resonator, and one of the two output light beams split from part of the light within the tunable laser by a 2×2 type optical splitter is incident into a light intensity monitor, and the other is incident into a wavelength locker.

Abstract: An optical module includes an optical modulator that includes a cutout portion and a first terminal projecting to the inside of the cutout portion, and is configured to perform optical modulation by using an electrical signal input to the first terminal; a driver, at least a part of the driver being housed inside the cutout portion, that is configured to generate an electrical signal; an electrode pattern that extends from the driver inside the cutout portion, and is configured to transmit the electrical signal generated by the driver; and a flexible board having flexibility, one end of the flexible board being electrically connected with the first terminal inside the cutout portion, another end of the flexible board extending in the direction away from the driver, the flexible board being connected with the electrode pattern and configured to input the electrical signal transmitted by the electrode pattern to the first terminal.

Abstract: An optical module includes an optical modulator that modulates light by using an electrical signal input from a first surface to a plurality of electrodes; and a flexible substrate that has a plurality of wiring patterns electrically connected to the plurality of electrodes, respectively, on the first surface. The optical modulator has a bulging part that bulges out from the first surface opposed to the flexible substrate toward the flexible substrate and is in contact with the flexible substrate.

Abstract: A method for producing poly(dimethyl vinylphosphonate) from a monomer component mainly containing dimethyl vinylphosphonate by anionic polymerization in the presence of an anionic polymerization initiator, the method being characterized in that an aliphatic ether is used as a polymerization solvent, and a method for producing poly(vinylphosphonic acid) characterized in that the poly(dimethyl vinylphosphonate) obtained by the former method is hydrolyzed in the presence of an acid are provided. The methods make it possible to easily produce a poly(dimethyl vinylphosphonate) which has a high molecular weight and in which the molecular weight is controlled, and make it possible to produce a poly(vinylphosphonic acid) which has a high molecular weight and in which the molecular weight is controlled corresponding to the poly(dimethyl vinylphosphonate).

Abstract: An optical module includes: a driver; an optical modulator; a connector that is electrically connected to either the driver or the optical modulator and is provided with an input/output terminal; and a flexible substrate that has flexibility, is connected to the connector, and transfers an electrical signal generated by the driver to the optical modulator, wherein in an end part connected to the connector, the flexible substrate has, on a first surface facing the input/output terminal, a signal-purpose wiring pattern used for transferring the electrical signal and a ground-purpose wiring pattern formed along the signal-purpose wiring pattern, and has, on a second surface that is different from the first surface, a ground electrode that partially covers the second surface and has a shorter electrical distance to the signal-purpose wiring pattern than an electrical distance between the signal-purpose wiring pattern and the ground-purpose wiring pattern.

Abstract: A core has accommodating slots each accommodating a permanent magnet. A fixing agent is injected into the space between the inner surface of each accommodating slot and the outer surface of the associated permanent magnet. A liquid-crystal polymer is used as the fixing agent. More specifically, liquid-crystal polyester is used.

Abstract: An optical module includes a package, a substrate, a lead pin, and a ground pattern. The substrate is accommodated in the package, includes a signal line pattern that transmits an electric signal, extends toward a side wall of the package beyond an end of the signal line pattern, and has a through hole between the end of the signal line pattern and the side wall of the package. The lead pin is inserted into the through hole in the substrate and inputs the electric signal to the end of the signal line pattern. The ground pattern is provided in at least a part of regions surrounding the through hole on the substrate.

Abstract: Disclosed is an optical modulator module including an optical modulator configured to have a signal electrode and a ground electrode; a conductive package configured to accommodate the optical modulator and have electrical continuity with the ground electrode of the optical modulator; a substrate configured to have a ground electrode on a first surface thereof electrically connected to the package by solder or a conductive adhesive and have a signal electrode on another surface thereof; and a lead pin configured to electrically connect the signal electrode of the optical modulator to the signal electrode of the substrate.