Abstract: An object of the present invention is to provide an optical waveguide device in which absorption of light propagating through an optical waveguide by a control electrode is suppressed and in which peeling of a dielectric layer covering the optical waveguide is prevented.

Abstract: An optical waveguide device includes a low refractive index substrate 1 that includes a material having a lower refractive index than lithium niobate (LN), in which a thin film 2 including LN and having a thickness of 1 ?m or lower is disposed on a part of the low refractive index substrate 1, an optical waveguide 10 having a higher refractive index than the substrate 1 and including a material other than LN is disposed on the substrate 1, at least a part of the optical waveguide 10 is continuously disposed from the substrate 1 to the thin film 2, and in a region (transition region) where the optical waveguide 10 crosses an outer peripheral portion of the thin film 2, a thickness of the thin film 2 forms a slope shape and a gradient (tan?) of an edge is set to be 0.189 or lower.

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: An optical waveguide device including an optical waveguide formed on a substrate is provided, in which a directional coupler is disposed in a part of the optical waveguide, the directional coupler includes one center waveguide and two side waveguides disposed to interpose the center waveguide between the side waveguides, the side waveguides are disposed to come close to the center waveguide from a position where the side waveguides are separated from the center waveguide and then to be separated again from the center waveguide in a traveling direction of a light wave, and the center waveguide and the side waveguides are not in contact with each other.

Abstract: An optical waveguide device includes an optical waveguide formed on a substrate, in which a protuberant portion is formed on a surface of the substrate, the optical waveguide is disposed on the protuberant portion and is formed to have a larger width than a width of a part of the protuberant portion, and a low refractive index layer is disposed to cover the optical waveguide and to be in contact with at least a part of the protuberant portion, and has a lower refractive index than the optical waveguide.

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 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: 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: 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.