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 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: 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 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: To provide an optical waveguide device that is small, has low optical loss, and has long-term stability. Provided is an optical waveguide device in which an optical waveguide A (20) is formed on a first substrate (2), an end portion of the first substrate has an input portion that inputs a light wave into the optical waveguide A or an output portion that outputs a light wave from the optical waveguide A, an optical waveguide B (10) is formed on a second substrate (1), the second substrate has an optical modulation portion that modulates a light wave propagating through the optical waveguide B, and at least a part of the optical waveguide A (20) has a conversion portion (20) that converts an optical mode field diameter.

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: In order to provides an optical waveguide element and an optical modulator that can prevent the damage to the substrate and the deterioration of the properties of the substrate that may occur due to the stress, by reducing the influence of stress on the substrate by the buffer layer, the optical waveguide 1 is provided with a substrate 5 having an electro-optical effect; an optical waveguide 10 formed on the substrate 5; a first buffer layer 9a provided on the substrate 5; and a second buffer layer 9b provided under the substrate 5, wherein the first buffer layer 9a and the second buffer layer 9b are composed of substantially the same material and have substantially the same thickness, and the first buffer layer 9a and the second buffer layer 9b are formed to be in contact with an upper surface and lower surface of the substrate 5, respectively.

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.

Abstract: An optical modulator according to the present invention comprises: a substrate which has electro-optic effects; an optical waveguide which is provided in the substrate; an optical fiber which is bonded to an end of the optical waveguide; a fixation member which is provided on an end part of the optical fiber; and an optical adhesive layer which bonds the optical fiber and the substrate to each other. The end of the optical waveguide is arranged in an end face of the substrate; the optical adhesive layer optically couples an end face of the optical fiber and an end of the optical waveguide with each other, while bonding the optical fiber, the fixation member and the substrate with each other; and the surface roughness of a surface of the fixation member, wherein the surface faces the end face of the substrate, is different from the surface roughness of an end face of the substrate, wherein the end face faces the surface of the fixation member.

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: 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 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: An optical modulator according to the present invention comprises: a substrate which has electro-optic effects; an optical waveguide which is provided in the substrate; an optical fiber which is bonded to an end of the optical waveguide; a fixation member which is provided on an end part of the optical fiber; and an optical adhesive layer which bonds the optical fiber and the substrate to each other. The end of the optical waveguide is arranged in an end face of the substrate; the optical adhesive layer optically couples an end face of the optical fiber and an end of the optical waveguide with each other, while bonding the optical fiber, the fixation member and the substrate with each other; and the surface roughness of a surface of the fixation member, wherein the surface faces the end face of the substrate, is different from the surface roughness of an end face of the substrate, wherein the end face faces the surface of the fixation member.

Abstract: The present invention relates to a method for producing titanium oxide particles, comprising a step of producing a mixed solution by mixing a hydrolysis product of a titanium alkoxide or a titanium metal salt and a compound having a five-membered ring containing nitrogen and a step of generating titanium oxide fine particles by heating and pressurizing the mixed solution, titanium oxide particles produced by the same production method, a dispersion solution of titanium oxide particles produced using the same titanium oxide particles, titanium oxide paste, a titanium oxide film, and a dye-sensitized solar cell.

Abstract: An optical device including a core layer that includes an EO polymer, and clad layers that are disposed on and beneath the core layer, in which a polymer polymerized in a composition containing a reactive ionic liquid is used in the clad layers.

Abstract: A method for producing titanium oxide particles of the present invention includes a step of producing a mixed solution by mixing a hydrolysis product of a titanium alkoxide or a titanium metal salt and a compound having a five-membered ring containing nitrogen and a step of generating titanium oxide fine particles by heating and pressurizing the mixed solution. Titanium oxide particles of the present invention are produced by the method for producing titanium oxide particles of the present invention. A dispersion solution of titanium oxide particles of the present invention includes the titanium oxide particles of the present invention. Titanium oxide paste of the present invention includes the titanium oxide particles of the present invention, a solvent, and a binder. A titanium oxide film of the present invention is obtained by applying and calcinating the titanium oxide paste of the present invention.

Abstract: A porous semiconductor layer contains anatase-type titanium oxide particles (A) which have an average primary particle size of 1 nm to 70 nm, and particles (B) obtained by coating surfaces of rutile-type titanium oxide particles, which have an average primary particle size of 100 nm to 1,000 nm, with an insulating material.

Abstract: An optical device including a core layer that includes an EO polymer, and clad layers that are disposed on and beneath the core layer, in which a polymer polymerized in a composition containing a reactive ionic liquid is used in the clad layers.