Abstract: An optical waveguide element includes a substrate having an electro-optic effect, an optical waveguide formed in the substrate, and a control electrode arranged on the substrate to modulate a light wave propagating through the optical waveguide. The control electrode includes a signal electrode and a ground electrode. The signal electrode and the ground electrode are arranged along a modulation effect portion of the optical waveguide that performs modulation. In a shape of a bottom surface of the ground electrode facing the substrate, a slit separating the ground electrode into a first ground electrode close to the signal electrode and a second ground electrode far from the signal electrode is formed in a range corresponding to the modulation effect portion.

Abstract: A method of roughening the upper surface of the slab waveguide includes a method of locally forming roughness using an electron beam and a method of roughening the upper surface via etching. As an etching condition for the rough surface, processing is performed under a condition in which roughness is generated compared to a processing condition for the rib top portion. Particularly, since the surface can be simply locally roughened by etching, the rough surface can be formed much more simply than that of the unnecessary light beam removing unit in Patent Literature No. 1. Roughness of the rough surface is preferably 10 nm or larger in arithmetic average roughness Ra.

Abstract: The purpose of the present invention is to provide an optical modulator in which propagation loss related to transmission of a high-frequency signal is reduced. An optical modulator, in which an electro-optical conversion element E/OC and a driver circuit DRV for driving the electro-optical conversion element are housed in the same case CA, includes: a multiplexer MUX that converts an input modulation signal, which is input from an outside of the case, into an output modulation signal having a higher frequency than the input modulation signal, and supplies the output modulation signal to the driver circuit, in which the multiplexer is housed in the case CA.

Abstract: An optical waveguide device that enables a location in which an optical loss such as a propagation loss or a coupling loss occurs to be easily specified is provided. An optical waveguide device includes a substrate 1 on which an optical waveguide 2 is formed, and a grating 6 formed in a part of the optical waveguide 2 or a grating 6 connected to a monitoring optical waveguide 5 that merges with or branches from a part of the optical waveguide 2, in which inputting a light wave into the optical waveguide or outputting at least a part of the light wave propagating through the optical waveguide is performed through the grating 6.

Abstract: An optical modulator that can suppress crosstalk of a modulation signal even in a case where a wiring substrate is disposed to overlap with a modulation substrate is provided. An optical modulator includes a modulation substrate 1 that includes an optical waveguide and a modulation electrode 10 for modulating a light wave which propagates through the optical waveguide, and a wiring substrate 2 provided with wiring 22 for relaying a modulation signal to be applied to the modulation electrode 10, in which the wiring substrate is disposed to overlap with the modulation substrate to cover an action portion on which modulation is performed by the modulation electrode, and an electromagnetic wave absorption member SH is disposed at at least a part of a position facing the action portion in the wiring substrate.

Abstract: It is possible to provide an optical modulator in which a transmission loss from a driver circuit element to a modulation substrate is reduced. An optical modulator includes a modulation substrate (1) that includes an optical waveguide (200) and a modulation electrode (10) for modulating a light wave propagating through the optical waveguide, a driver circuit element (2) that generates a modulation signal to be applied to the modulation electrode (10), and a case (3) that accommodates the modulation substrate (1) and the driver circuit element (2), in which an output terminal (20?) that outputs the modulation signal is provided on an upper surface side of the driver circuit element (2), and a wiring substrate (4) including a wiring that electrically connects the output terminal (20?) and the modulation electrode (10) is disposed above the driver circuit element (2) and the modulation substrate (1) to straddle both the driver circuit element (2) and the modulation substrate (1).

Abstract: An optical waveguide element includes a substrate having an electro-optic effect, an optical waveguide formed in the substrate, and a control electrode arranged on the substrate to modulate a light wave propagating through the optical waveguide. The control electrode includes a signal electrode and a ground electrode. The signal electrode and the ground electrode are arranged along a modulation effect portion of the optical waveguide that performs modulation. In a shape of a bottom surface of the ground electrode facing the substrate, a slit separating the ground electrode into a first ground electrode close to the signal electrode and a second ground electrode far from the signal electrode is formed in a range corresponding to the modulation effect portion.

Abstract: An optical modulator includes a substrate on which an optical waveguide and a modulation electrode that modulates a light wave propagating through the optical waveguide are formed, and a case housing the substrate, the optical waveguide includes at least an optical branching part that branches one light wave into two light waves or an optical combining part that combines two light waves into one light wave, the modulation electrode has a signal electrode and a ground electrode, and a part of the signal electrode is disposed so as to cross the optical branching part or the optical combining part, and the optical modulator is provided with a suppressing unit that suppresses changes in an intensity ratio of the light waves branched at the optical branching part or an intensity ratio of the light waves combined at the optical combining part, by the signal electrode.

Abstract: An optical modulator includes a substrate on which an optical waveguide and a modulation electrode that modulates a light wave propagating through the optical waveguide are formed, and a case housing the substrate, the optical waveguide includes at least an optical branching part that branches one light wave into two light waves or an optical combining part that combines two light waves into one light wave, the modulation electrode has a signal electrode and a ground electrode, and a part of the signal electrode is disposed so as to cross the optical branching part or the optical combining part, and the optical modulator is provided with a suppressing unit that suppresses changes in an intensity ratio of the light waves branched at the optical branching part or an intensity ratio of the light waves combined at the optical combining part, by the signal electrode.

Abstract: A transmission line has a signal electrode formed on one surface of a flexible printed circuit, and a ground electrode formed on the other surface of the flexible printed circuit. A connection terminal has signal terminals formed on both the surfaces of the flexible printed circuit and electrically connected to each other through a via hole, and ground terminals formed on both the surfaces of the flexible printed circuit and electrically connected to each other through the via hole. The signal terminal on the surface, on which the ground electrode is formed, is formed such that at least a width in an end portion on the transmission line side is narrower than a width of a part of the signal terminal on the surface, on which the signal electrode is formed, to be at the same position when the flexible printed circuit is seen in a plan view.

Abstract: An optical waveguide device module includes an optical waveguide device and a connection substrate provided outside the optical waveguide device, and these are housed in a housing. The optical waveguide device has a control electrode including a signal electrode and ground electrodes disposed to interpose the signal electrode between the ground electrodes. A signal line, ground lines disposed so as to interpose the signal line between the ground lines, and a back surface ground electrode disposed on a surface of the connection substrate are provided on the connection substrate. The ground line and the back surface ground electrode are electrically connected through a via hole passing through the connection substrate. Electrical connection means for electrically connecting the ground line and the ground electrode is provided. A connection portion of the electrical connection means on the ground line side is in the vicinity of the via hole of the ground line.

Abstract: In a light modulation element that modulates light by controlling light waves that propagate through an optical waveguide, the realization of the additional broadening of the bandwidth by improving the degree of freedom in the design of the electrode is enabled. A light modulation element which includes optical waveguides formed on a substrate and a control electrode and modulates light by controlling light waves that propagate through the optical waveguide by conducting electricity in the control electrode, in which the control electrode includes radio frequency electrodes that configure a signal line through which radio frequency signals propagate and a bias electrode to which a bias voltage is applied, and the radio frequency electrode has a conductive layer made of copper or a copper alloy.

Abstract: An optical modulator includes a substrate, an optical waveguide, a control electrode applying a high frequency signal in order to modulate light waves propagating through the optical waveguide, and a relay substrate provided with a relay line to transfer the high frequency signal to the control electrode. The control electrode and the relay line together have a coplanar line structure inclusive of at least electrical connection portions of both the control electrode and the relay line. The control electrode includes an electrical connection portion and a routing portion positioned between the electrical connection portion and an active portion applying an electrical field to the optical waveguide. The routing portion has a coplanar line structure. A distance between ground electrodes sandwiching a signal electrode in the electrical connection portion of the control electrode is substantially equal to a distance between ground electrodes sandwiching a signal electrode of the routing portion.

Abstract: An optical modulator including an optical modulation element mounted inside a housing, in which at least a portion of an electric line is connected to an external circuit board through a flexible printed circuit, and which is disposed on the external circuit board. A recess portion that mounts the flexible printed circuit is formed on an outer bottom surface of the housing and at a part where the flexible printed circuit is connected, and a device for preventing a resonance mode is provided such that a resonance mode of a microwave and a millimeter wave or a parallel plate mode is prevented from being generated among a surface A of the recess portion facing the flexible printed circuit, an electric wiring part B provided on the flexible printed circuit overlapping the surface A when seen in a plan view, an electric wiring part C provided on the external circuit board overlapping the surface A when seen in a plan view.

Abstract: The objective of the present invention is to provide an optical modulator adapted for use with various modulating units and various modulation regions, and with which variability in optical losses is limited as far as possible.

Abstract: Provided is an optical waveguide device in which destabilization of a DC bias which is applied to an optical waveguide, due to a bias electrode picking up electric noise, is reduced and an operating characteristic is stable. An optical waveguide device includes: a substrate having an electro-optic effect; an optical waveguide formed on the substrate; a modulation electrode for applying an electric field corresponding to a modulation signal to the optical waveguide; and a bias electrode for applying an electric field corresponding to a DC bias to the optical waveguide, in which in order to reduce capture of electric noise by the bias electrode, with respect to at least a part of the bias electrode, a plurality of electrode portions (b11, b12) are formed in at least one (B1) of the pair of electrodes by folding back one electric line.

Abstract: An optical modulator includes a substrate, an optical waveguide, a control electrode applying a high frequency signal in order to modulate light waves propagating through the optical waveguide, and a relay substrate provided with a relay line to transfer the high frequency signal to the control electrode. The control electrode and the relay line together have a coplanar line structure inclusive of at least electrical connection portions of both the control electrode and the relay line. The control electrode includes an electrical connection portion and a routing portion positioned between the electrical connection portion and an active portion applying an electrical field to the optical waveguide. The routing portion has a coplanar line structure. A distance between ground electrodes sandwiching a signal electrode in the electrical connection portion of the control electrode is substantially equal to a distance between ground electrodes sandwiching a signal electrode of the routing portion.

Abstract: An optical waveguide device module includes an optical waveguide device and a connection substrate provided outside the optical waveguide device, and these are housed in a housing. The optical waveguide device has a control electrode including a signal electrode and ground electrodes disposed to interpose the signal electrode between the ground electrodes. A signal line, ground lines disposed so as to interpose the signal line between the ground lines, and a back surface ground electrode disposed on a surface of the connection substrate are provided on the connection substrate. The ground line and the back surface ground electrode are electrically connected through a via hole passing through the connection substrate. Electrical connection means for electrically connecting the ground line and the ground electrode is provided. A connection portion of the electrical connection means on the ground line side is in the vicinity of the via hole of the ground line.

Abstract: Provided is an optical modulator including: a relay substrate; a first transmission line that is provided on a flat surface of the relay substrate, and transmits an electrical signal along the flat surface; a second transmission line that is provided separately from the relay substrate, is electrically connected to the first transmission line, and transmits, to the first transmission line, the electrical signal that has been input from an outer side in a direction that is not included in the flat surface; a modulation unit that modulates an optical signal by using the electrical signal that is transmitted by the first transmission line and the second transmission line; and a shield that shields a radiation component of the electrical signal that is radiated from the second transmission line.

Abstract: An optical modulator including an optical modulation element mounted inside a housing, in which at least a portion of an electric line is connected to an external circuit board through a flexible printed circuit, and which is disposed on the external circuit board. A recess portion that mounts the flexible printed circuit is formed on an outer bottom surface of the housing and at a part where the flexible printed circuit is connected, and a device for preventing a resonance mode is provided such that a resonance mode of a microwave and a millimeter wave or a parallel plate mode is prevented from being generated among a surface A of the recess portion facing the flexible printed circuit, an electric wiring part B provided on the flexible printed circuit overlapping the surface A when seen in a plan view, an electric wiring part C provided on the external circuit board overlapping the surface A when seen in a plan view.