Patent ID: 7817879

Claim:
An optical waveguide device, comprising: a dielectric substrate; a folded waveguide formed on the substrate, the folded waveguide including a first waveguide and a second waveguide, one part of the first waveguide being connected to one end of the second waveguide at a first coupling portion, the other end of the second waveguide being connected to another part of the first waveguide at a second coupling portion, the first waveguide being straight or curved with a radius of curvature larger than or equal to a first curvature radius, and the second waveguide being straight or curved with a radius of curvature smaller than the first curvature radius; an outer groove formed on the substrate along an outer peripheral of the folded waveguide; an input-side inner groove formed on the substrate near the first coupling portion and provided on an inner peripheral of the first waveguide; and an output-side inner groove discontinuous from the input-side inner groove and formed on the substrate near the second coupling portion and provided on an inner peripheral of the first waveguide, wherein the outer groove and the input-side inner groove near the first coupling portion, and the outer groove and the output-side inner groove near the second coupling portion both form ridge structures.