Sumitomo Osaka Cement Co., Ltd.

Yumi Murata

Yuki Kugimoto

Shingo Takano

Yu Kataoka

Katsutoshi Kondo

Provided is an optical waveguide element including spot size conversion means with suppressed optical insertion loss without complicating a manufacturing process. An optical waveguide element includes an optical waveguide substrate () having a rib-type optical waveguide () formed of a material having an electro-optic effect, and spot size conversion means for changing a mode field diameter of a light wave propagating through the optical waveguide at a position where an input end or an output end of the rib-type optical waveguide () is formed, in which the spot size conversion means includes a first configuration layer () that is connected to the rib-type optical waveguide () and includes a tapered portion () in which a width of the optical waveguide expands, a second configuration layer () that is laminated on the first configuration layer () and has a width narrower than a width of the first configuration layer (), and a third configuration layer () that is disposed to cover the second configuration layer () excluding a part of the second configuration layer () close to the rib-type optical waveguide and has a width wider than the width of the second configuration layer ().

Optical waveguide element, optical modulation device using optical waveguide element, and optical transmission device using optical waveguide element

An optical waveguide device including an optical waveguide substrate that has an electro-optic effect, is a crystal having anisotropy in thermal expansion rate, has a thickness set to 10 &#x3bc;m or lower, and includes an optical waveguide and a holding substrate that holds the optical waveguide substrate, the optical waveguide substrate and the holding substrate being joined to each other, in which the holding substrate is formed of a crystal having a lower dielectric constant than the optical waveguide substrate and having anisotropy in thermal expansion rate, and the optical waveguide substrate and the holding substrate are joined to each other such that differences in thermal expansion rate between the optical waveguide substrate and the holding substrate become small in different axial directions on a joint surface.

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Tokyo, Japan

Yumi Murata