US Patent 7796846 Optical integrated device and method of manufacturing the same

An optical integrated device comprises a substrate and a waveguide formed on a surface of the substrate. The waveguide includes a lower clad layer, a core layer formed on the lower clad layer and having a refractive index greater than that of the lower clad layer, and an upper clad layer formed on the core layer and having a refractive index smaller than that of the core layer. The waveguide further includes a straight waveguide part and a bending waveguide part curved in a plane parallel to the surface of the substrate. The lower clad layer in the bending waveguide part projects from the substrate by a projection height greater than that of the lower clad layer in the straight waveguide part.