Abstract: There is provided an optical waveguide device including: a substrate; an optical waveguide formed on the substrate; and a working electrode that controls a light wave propagating through the optical waveguide, in which the working electrode includes a first base layer made of a first material, a first conductive layer on the first base layer, a second base layer made of a second material different from the first material, which is on the first conductive layer, and a second conductive layer on the second base layer, and an edge of the second base layer is covered with the second conductive layer, in a cross-section perpendicular to an extending direction of the optical waveguide.

Abstract: Provided is an optical waveguide element including spot size conversion means with suppressed optical insertion loss without complicating a manufacturing process.

Abstract: An optical waveguide element includes a substrate, an optical waveguide disposed inside the substrate or on the substrate, and an electrode provided along the optical waveguide, working on the optical waveguide to generate a phase change in a light wave propagating through the optical waveguide. The electrode is a traveling-wave electrode. In a modulation section where the light wave is controlled by the electrode, the electrode and the optical waveguide are configured so that the phase change generated in a first modulation section located within a predetermined distance range from a downstream side end portion along a propagation direction of a traveling wave of an electrical signal propagating through the electrode has a sign opposite to a sign of the phase change generated in a second modulation section located within a predetermined distance range from an input end of the electrical signal on an upstream side along the propagation direction.

Abstract: An optical waveguide element includes: a substrate on which an optical waveguide is formed; and an electrode that is formed on the substrate and controls a light wave propagating through the optical waveguide. The optical waveguide includes a protruding portion extending on the substrate, and the electrode includes a base layer made of Nb, and an upper layer formed on the base layer, the base layer being formed between the substrate and the upper layer.

Abstract: An optical waveguide device that can prevent fluctuations in electrical characteristics due to adhesion of foreign matter to electrodes without adversely affecting the degree of freedom in electrode design. The optical waveguide device includes a substrate, an optical waveguide formed on the substrate, an electrode for controlling a light wave propagating through the optical waveguide, and a first insulating layer disposed between two adjacent electrodes among the electrodes, in which the first insulating layer has a height from a surface of the substrate that is higher than heights of the two electrodes.

Abstract: An optical modulator with which electrical connection between a signal electrode and signal wiring of a wiring substrate can be reliably made even in a case where a width of the signal electrode in an action portion of an optical control substrate is narrow is provided.

Abstract: An optical waveguide element that suppresses insertion loss related to coupling to an optical fiber or the like while miniaturizing the optical waveguide element is provided. There is provided an optical waveguide element including: a rib optical waveguide (10) that is made of a material (1) having an electro-optic effect; and the reinforcing substrate (2) that supports the optical waveguide, in which one end of the optical waveguide forms a tapered portion (11) of which a width narrows toward an end surface of the reinforcing substrate, a structure (3) made of a material having a higher refractive index than a material constituting the reinforcing substrate is provided so as to cover the tapered portion, and a coating layer (4) made of a material having a lower refractive index than the material constituting the structure is disposed so as to cover the structure.

Abstract: An optical waveguide element includes a substrate and an optical waveguide that is disposed on the substrate. The optical waveguide has an effective refractive index change portion in which an effective refractive index of the optical waveguide related to a fundamental mode A parallel to a plane of polarization of a light wave propagated through the optical waveguide changes according to propagation of the light wave. In the effective refractive index change portion, a cross-sectional shape of the optical waveguide which is perpendicular to a propagation direction of the light wave is set such that the effective refractive index of the optical waveguide related to the fundamental mode A is higher than an effective refractive index of the optical waveguide related to another fundamental mode B perpendicular to the fundamental mode A.

Abstract: To provide an optical waveguide device in which damage to a thin plate, particularly damage to an optical waveguide, is prevented. An optical waveguide device includes: a thin plate 1 that has an electro-optic effect and that has a thickness of equal to or thinner than 10 ?m, an optical waveguide 2 being formed on the thin plate; and a reinforcing substrate that supports the thin plate, in which the thin plate 1 has a rectangular shape in a plan view, a dissimilar element layer 3, in which an element different from an element constituting the thin plate is disposed in the thin plate, is formed on at least a portion between an outer periphery of the thin plate and the optical waveguide 2, and a total length over which a cleavage plane of the thin plate traverses a region where the dissimilar element layer is formed, is equal to or longer than 5% of a width of the thin plate in a short side direction.

Abstract: Provided is an optical control element that can minimize an optical path difference between branched waveguides while reducing a difference in structure between the branched waveguides by disposing an input portion and an output portion of an optical waveguide on the same side of a substrate on which the optical waveguide is formed.

Abstract: There is provided an optical waveguide device including a substrate, an optical waveguide formed on the substrate, and a working electrode that controls a light wave propagating through the optical waveguide, in which the working electrode includes a first base layer made of a first material, and a first conductive layer on the first base layer, and a conductor pattern including a second base layer made of a second material different from the first material and a second conductive layer on the second base layer is formed in a region other than a path from an input end to an output end of the optical waveguide, in a region on the substrate.

Abstract: There is provided an optical waveguide device including: a substrate; an optical waveguide formed on the substrate; and a working electrode that controls a light wave propagating through the optical waveguide, in which the working electrode includes a first base layer made of a first material, a first conductive layer on the first base layer, a second base layer made of a second material different from the first material, which is on the first conductive layer, and a second conductive layer on the second base layer, and an edge of the second base layer is covered with the second conductive layer, in a cross-section perpendicular to an extending direction of the optical waveguide.

Abstract: An optical waveguide element includes: a substrate; and a plurality of optical waveguides causing light to turn between a first direction and a second direction that is an opposite direction of the first direction in a plane of the substrate, the plurality of optical waveguides includes first portions extending in the first direction with a predetermined distance therebetween, second portions extending in a third direction that is different from the first direction, and third portions extending in the second direction, and each of the plurality of optical waveguides except for the optical waveguide in which the second portion extending in the third direction is located on an innermost side in the first direction intersects, at the third portion, another optical waveguide in which the second portion extending in the third direction is located further inward in the first direction.

Abstract: An optical waveguide device includes a substrate, an optical waveguide formed on the substrate, two electrodes disposed at positions sandwiching the optical waveguide from both sides in a plane of the substrate; and a dielectric layer covering a top of the optical waveguide, wherein the dielectric layer extends in a width direction of the optical waveguide to an extent including edges of the two electrodes, facing the optical waveguide, and is disposed to partially cover each of the two electrodes.

Abstract: Provided is an optical waveguide element that prevents leaked light generated at a forking section from entering a downstream optical waveguide such as another forking section, thereby affording minimal degradation of optical characteristics. The optical waveguide is characterized in that: at least one of two fork waveguides (20a, 20b) forking from a first forking section (20) comprises a second forking section (21, 22); slab waveguides (3c-1 to 3c-3) are formed between the two fork waveguides; and between the first forking section and the second forking section, slits (41, 42) are formed that partition the slab waveguides into a first slab waveguide area (3c-1) close to the first forking section and second slab waveguide areas (3c-2, 3c-3) close to the second forking section(s).

Abstract: An optical waveguide device including a rib-type optical waveguide 2 formed of a material having an electro-optic effect, and a reinforcing substrate 1 that supports the rib-type optical waveguide, one end of the rib-type optical waveguide 2 has a tapered portion 20, structures 4 are provided that are disposed apart from the tapered portion so as to sandwich the tapered portion and are disposed on the reinforcing substrate 1, an upper substrate is disposed above the tapered portion and the structures, and an adhesive layer is disposed in a space sandwiched between the upper substrate and the structures.

Abstract: In an optical waveguide element, performance deterioration due to recoupling of unnecessary light leaking from an optical waveguide with the optical waveguide is prevented. An optical waveguide element includes an optical substrate on which an optical waveguide is formed, and a support substrate that is bonded to the optical substrate, on a bonded surface of the support substrate bonded to the optical substrate, a recess portion along the optical waveguide on the optical substrate is formed directly under the optical waveguide, a portion of the support substrate from an upper surface of the support substrate to at least a depth of a bottom surface of the recess portion has a refractive index higher than a substrate refractive index of the optical substrate, and the recess portion is filled with a substance having a refractive index lower than the substrate refractive index.

Abstract: In order to provide an optical waveguide element that is capable of reducing coupling loss at a coupling portion with an optical fiber and of reducing propagation loss in an optical waveguide, the optical waveguide element comprises a supporting substrate and a waveguide layer consisting of a material having an electro-optic effect stacked on the supporting substrate, wherein a rib portion for forming an optical waveguide is provided protruding on an upper surface of the waveguide layer; a groove portion is formed on an upper surface of the supporting substrate directly below a part of the rib portion; and the groove portion is filled with a material having an effective refractive index comparable to that of the waveguide layer.

Abstract: An optical waveguide element includes a substrate and an optical waveguide that is disposed on the substrate. The optical waveguide has an effective refractive index change portion in which an effective refractive index of the optical waveguide related to a fundamental mode A parallel to a plane of polarization of a light wave propagated through the optical waveguide changes according to propagation of the light wave. In the effective refractive index change portion, a cross-sectional shape of the optical waveguide which is perpendicular to a propagation direction of the light wave is set such that the effective refractive index of the optical waveguide related to the fundamental mode A is higher than an effective refractive index of the optical waveguide related to another fundamental mode B perpendicular to the fundamental mode A.

Abstract: An optical waveguide element includes an optical waveguide which is formed on one surface of a substrate, an incidence part for light to be incident on the optical waveguide or an emission part for emitting light from the optical waveguide which is disposed in an end portion of the substrate, and a dielectric film which is formed on the optical waveguide of at least one of the incidence part and the emission part, and the vicinity thereof. Regarding the dielectric film, dielectric films including a dielectric film formed of a first material having an index of refraction higher than an index of refraction of the substrate and a dielectric film formed of a second material having an index of refraction lower than the index of refraction of the substrate are alternately laminated.