Curved ridge optical waveguide, optical device, and method of manufacturing optical waveguide

An optical waveguide (1) is formed on a substrate (2) and includes a curved ridge structure (3), a curved optical path, and a buffer layer. The curved ridge structure is formed on the substrate so as to have a curvature in a longitudinal direction of the curved ridge structure. The curved optical path is formed along the curved ridge structure. The buffer layer (4) covers a side of the ridge structure and has a lower refractive index than a refractive index of the substrate.