Provided is an optical waveguide device in which both signal electrode collapse and signal electrode peeling/damage can be prevented. An optical waveguide device in which an optical waveguide is formed on a substrate and a control electrode for controlling a light wave propagating through the optical waveguide is disposed on the substrate, is characterized in that, the control electrode includes a signal electrode, and the signal electrode has a narrow portion, where a width of the signal electrode on a substrate side is narrow, and a wide portion, where a width of the signal electrode on an upper portion side of the signal electrode is wide, a prevention film that is disposed in contact with the narrow portion of the signal electrode and that prevents the signal electrode from collapsing, is provided on the substrate, and at a position of the signal electrode where the narrow portion and the wide portion are connected, a surface of the prevention film is formed as a curved surface protruding toward the signal electrode, and a side surface of the signal electrode is formed along the curved surface.

An electro-optic modulator includes an optical structure and an electrical structure. The optical structure includes an input waveguide, a beam splitter, a first waveguide arm, a second waveguide arm, a beam combiner, and an output waveguide; each of the first waveguide arm and the second waveguide arm includes a conventional waveguide region. The first waveguide arm further includes a first modulating region, a second modulating region, and a third modulating region. The second waveguide arm further includes a fourth modulating region, a fifth modulating region, and a sixth modulating region; the electrical structure includes a traveling wave electrode including a signal-ground-signal electrode structure. The traveling wave electrode further includes a signal input region, a modulating electrode region, and a matched resistor region. The modulating electrode region includes a first signal electrode, a ground electrode, and a second signal electrode.

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.

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.

An optical device including a waveguide and an electrode is described. The waveguide includes at least one optical material having an electro-optic effect. The electrode includes a channel region and extensions protruding from the channel region. The extensions are closer to a portion of the waveguide than the channel region is.

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.

A electronic method, includes receiving, by a graphene structure, a SPP mode of a particular frequency. The electronic method includes receiving, by the graphene structure, a driving microwave voltage. The electronic method includes generating, by the graphene structure, an entanglement between optical and voltage fields.

In an optical waveguide element which uses a rib type optical waveguide, light propagating in the rib type optical waveguide is monitored stably and accurately. The optical waveguide element includes a rib type optical waveguide provided on a optical waveguide substrate and configured of a convex portion protruding in a thickness direction of the optical waveguide substrate and extending in a plane direction of the optical waveguide substrate, and a light receiving element configured of a light receiving part formed on a light receiving element substrate disposed on the rib type optical waveguide and configured to receive at least a part of light propagating through the rib type optical waveguide, and the light receiving element substrate is supported by at least one first convex portion having the same height as that of the rib type optical waveguide provided on the optical waveguide substrate.

To provide an optical modulation element whereby reduced drive voltage and suppression of DC drift can be obtained at the same time. An optical modulation element includes: a substrate; and an optical waveguide formed of an electrooptic material film formed on the substrate and having a ridge part which is a protruding portion, and a slab part having a smaller film thickness than the ridge part 11r. The optical waveguide includes a first waveguide part having a first ridge width and a first slab film thickness and to which an RF signal is applied, and a second waveguide part having a second ridge width and a second slab film thickness different from the first slab film thickness and to which a DC bias is applied.

An optical device includes an optical waveguide that is a rib type and that is formed of a thin film lithium niobate (LiNbO.sub.3: 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.