Abstract: An optical modulator includes an optical waveguide through which signal light passes, a split unit that splits the signal light that passes through the optical waveguide, and a pair of phase shifters each of which shifts a phase of signal light that is split by the split unit. Each of the phase shifters includes an in-shifter waveguide through which the signal light passes, and a heater electrode that heats the in-shifter waveguide in accordance with a driving voltage. The in-shifter waveguide includes an inbound waveguide for inputting the signal light coming from the split unit, an outbound waveguide for outputting the signal light, a folded waveguide that connects the inbound waveguide and the outbound waveguide. The heater electrode is arranged in the vicinity of the inbound waveguide and the outbound waveguide.

Abstract: An optical device includes a substrate, a dielectric substance laminated on the substrate, an optical waveguide surrounded by the dielectric substance, a heater electrode that is disposed above the optical waveguide and that is surrounded by the dielectric substance, and a trench. The trench includes a plurality of split trenches each of which is formed in a hollow segmented shape in the dielectric substance and in which the split trenches are disposed in parallel with the heater electrode. The split trenches are disposed in parallel with the heater electrode such that an area of the dielectric substance located between an end of each of the split trenches and a side surface of the heater electrode is gradually expanded.

Abstract: An optical device cut from a wafer into a chip by dicing, on the wafer, the optical device includes a plurality of optical waveguides; an optical circuit connected to the optical waveguide; and of the plurality of optical waveguides, a testing optical waveguide that guides test light to the optical circuit to be tested, by bypassing a non-connected optical waveguide portion at a terrace for mounting an optical chip component.

Abstract: An optical device includes a modulator and a tap coupler. The modulator includes an optical waveguide that is formed of a thin-film lithium niobate (LN) substrate and through which light passes, and an electrode that applies voltage to the optical waveguide, and modulates a phase of light that passes through the optical waveguide in accordance with an electric field in the optical waveguide, where the electric field corresponds to the voltage. The tap coupler includes at least a part formed of the thin-film LN substrate, and splits a part of the light that passes through an inside of the optical waveguide. The tap coupler includes a delayed interferometer that splits a part of the light that passes through the optical waveguide, at a split ratio corresponding to a phase difference of light that passes through an inside of the tap coupler from the optical waveguide.

Abstract: An optical device includes a rib optical waveguide that is a thin-film lithium niobate (LN) crystal formed of a thin-film LN substrate, and a buffer layer that is laminated on the optical waveguide. The optical device further includes an electrode that is laminated on the buffer layer, and sub electrodes that are arranged parallel to the electrode on the buffer layer, and attract a charge in the optical waveguide in accordance with electrification.

Abstract: An optical device includes an optical waveguide that is a rib type and that is formed of a thin film lithium niobate (LiNbO3: LN) substrate using a thin film LN crystal, and a buffer layer that is laminated on the optical waveguide. Furthermore, the optical device includes an electrode that is laminated on the buffer layer and that applies a voltage to the optical waveguide, and a gettering site that is disposed parallel to the optical waveguide and that traps an electric charge inside the optical waveguide.

Abstract: An optical device includes a rib waveguide that is a thin-film lithium niobate (LN) crystal, a buffer layer that is laminated on the rib waveguide, and an electrode that applies voltage to the rib waveguide. The buffer layer includes a thick-film part that is laminated on a rib of the rib waveguide, and thin-film parts that are laminated on slabs of the rib waveguide, where the slabs are located on both sides of the rib, and that have smaller thicknesses than a thickness of the thick-film part.

Abstract: An optical device includes a thin film Lithium Niobate (LN) layer, a first optical waveguide, and a second optical waveguide. The thin film LN layer is an X-cut or a Y-cut LN layer. The first optical waveguide is an optical waveguide that is formed on the thin film LN layer along a direction that is substantially perpendicular to a Z direction of a crystal axis of the thin film LN layer. The second optical waveguide is an optical waveguide that is routed and connected to the first optical waveguide. At least a part of a core of the first optical waveguide is made thicker than a core of the second optical waveguide.

Abstract: An optical device includes an optical waveguide, a buffer layer that is layered on the optical waveguide, and an electrode that is arranged on a surface of the buffer layer that is layered in a part near the optical waveguide and that applies an electric signal to the optical waveguide. The optical device further includes a slit that is formed in the buffer layer, that extends from the surface of the buffer layer to a vicinity of the optical waveguide, and that is filled with part of the electrode.

Abstract: An optical device includes an optical waveguide, a buffer layer that is layered on the optical waveguide, and an opening that is formed at least in the buffer layer above a part near a side surface of the optical waveguide. The optical device further includes an electrode that is layered in the opening and that is configured to apply a signal to the optical waveguide and a silicon layer that is layered on the buffer layer excluding the opening.

Abstract: Ultrasonic flowmeter includes fluid flow path through which a measurement target fluid flows and a pair of ultrasonic transducers that can transmit and receive an ultrasonic signal. The ultrasonic flowmeter further includes flow rate calculator that calculates a flow velocity or flow rate of a measurement target fluid. In addition, fluid flow path includes a main flow path including a plurality of divided flow paths obtained by dividing a flow path having a rectangular cross-section by the same width, and a sub flow path including an added flow path having the same width as that of the divided flow path and having a height lower than that of the divided flow path. Furthermore, flow rate calculator calculates the flow rate of the measurement target fluid flowing through the fluid flow path from the flow velocity or flow rate of the measurement target fluid obtained based on the propagation time.

Abstract: An optical device includes an optical waveguide that is a projected section and that is disposed at a predetermined portion on a thin film substrate, a buffer layer that is formed on the thin film substrate and the optical waveguide, and an electrode that is formed on the buffer layer and that applies a voltage to the optical waveguide. The electrode covers a step portion of the buffer layer formed on side walls of the optical waveguide.

Abstract: An optical device includes a substrate W, a RF modulating unit, and a phase adjustment unit 220. The RF modulating unit is provided on the substrate W and modulates light in accordance with a RF signal. The phase adjustment unit 220 is provided on the substrate W and adjusts the phase of an optical signal modulated by the RF modulating unit. The phase adjustment unit 220 includes a heater 2200 and a to-be-heated optical waveguide 2201. The to-be-heated optical waveguide 2201 is provided between a thin film LN substrate 32 and a buffer layer 33 of the substrate W, and is formed of a material having a thermo-optical effect. The heater 2200 is provided at a position opposite the to-be-heated optical waveguide 2201, with the buffer layer 33 therebetween on the substrate W, and heats the to-be-heated optical waveguide 2201.

Abstract: An optical device includes a substrate, a layered structure provided on the substrate and including an intermediate layer, an optical waveguide formed of a thin crystal film having an electro-optic effect, and a buffer layer stacked in this order, and an electrode provided on or above the buffer layer and configured to apply a direct current voltage to the optical waveguide. The resistivity of the intermediate layer is higher than the resistivity of the buffer layer.

Abstract: An optical device includes a plurality of first Si waveguides that split and output an optical signal received from an input unit, plurality of LN waveguides that are included in a LN modulator and that transmit the optical signals that are split and output by the first Si waveguides, and a plurality of second Si waveguides that multiplex and output the associated optical signals that are output from the plurality of respective LN waveguides. The device includes an output unit that outputs the optical signal multiplexed by the second Si waveguides, and a plurality of Mach-Zehnder interferometers disposed on each of waveguides connected by the first Si waveguides, the LN waveguides, and the second Si waveguides, respectively. When there are differences among waveguide lengths of the LN waveguides, the device is configured such that the optical path lengths of the waveguides for the respective Mach-Zehnder interferometers are equalized.

Abstract: An optical device has a silicon (Si) substrate, a ground electrode, a lithium niobate (LN) optical waveguide, and a signal electrode. The ground electrode is an electrode that is at ground potential and that is layered on the Si substrate. The LN optical waveguide is an optical waveguide that is formed by a thin film LN substrate that is layered on the ground electrode. The signal electrode is an electrode that is disposed at a position opposite the ground electrode with the LN optical waveguide interposed therebetween and that applies a high-frequency signal.

Abstract: The present disclosure relates to a heat treatment method and a heat treatment furnace that enable characteristics on an equal level to those when bluing processing is performed to be obtained without the bluing processing being performed in stress-relief annealing of a motor core. A heat treatment method according to one aspect is a heat treatment method in stress-relief annealing of a motor core. The heat treatment method includes an annealing step of annealing the motor core by using an exothermic converted gas as a furnace atmospheric gas, and a cooling step of cooling the motor core obtained in the annealing step, by using an exothermic converted gas as a furnace atmospheric gas, in a temperature range from a temperature in the annealing step to 500° C. at a cooling rate exceeding 600° C. per hour.

Abstract: An optical device includes: a substrate; an optical waveguide that forms a Mach-Zehnder interferometer; a signal electrode; and a ground electrode. The optical waveguide is placed between the signal electrode and the ground electrode. An electric field is generated in a direction along a surface of the substrate when a voltage is applied between the signal electrode and the ground electrode. The optical waveguide includes a first waveguide through which input light propagates, a curved waveguide which is optically coupled to the first waveguide, and a second waveguide which is optically coupled to the curved waveguide. The signal electrode includes first and second electrodes that are respectively placed near the first and second waveguides. An electric signal is supplied to the first electrode, and an inverted electric signal is supplied to the second electrode.

Abstract: An optical device includes an optical modulator formed on an optical IC chip. A shape of the IC chip is a rectangle or a parallelogram. The optical modulator includes an interferometer, wiring patterns, a first polymer pattern, and a second polymer pattern. The interferometer includes an optical waveguide that is formed in a direction from a first edge to a second edge of the optical IC chip. The wiring patterns are formed parallel to the optical waveguide. The first polymer pattern is formed along the first edge or the second edge. The second polymer pattern is connected to the first polymer pattern and formed on the optical waveguide without overlapping the wiring patterns.

Abstract: An optical device is formed on an optical IC chip. The shape of the optical IC chip is rectangular or parallelogram. The optical device induces: an optical device circuit; a first optical waveguide that is coupled to the optical device circuit; a pad that is electrically connected to the optical device circuit; a grating coupler; and a second optical waveguide that is coupled to the grating coupler. The pad is formed in a region close to a first side of the optical IC chip. The grating coupler is formed in a specified region, which is not close to the first side, on the optical IC chip. The first optical waveguide and the second optical waveguide are respectively extended to an edge of the optical IC chip.