Patent ID: 7450811

Claim:
A device provided with an optical waveguide comprising: a core formed on a substrate having a relatively high refractive index; and a cladding arranged to cover said core and having a relatively low refractive index, wherein said cladding includes a multi-layer structure portion which is formed by laminating, in a direction away from said core, one or more low refractive index layers formed using a material with a refractive index lower than that of said core and one or more high refractive index layers formed using a material with a refractive index higher than that of said core, and a lamination cycle of said low refractive index layer and said high refractive index layer in said multi-layer structure portion set to be shorter than a distance to which a polarization mode for guiding said core leaks out to a single-layer cladding on the assumption that said single-layer cladding is formed using the material constituting said low refractive index layer.