An optical waveguide apparatus includes an optical waveguide, such as an
optical sheet of a two-dimensional slab waveguide, and an
appropriately-shaped plated structure provided in the optical waveguide.
Typically, the plated structure is constructed so as to serve as an
optical-path converting unit for optically coupling the optical waveguide
and an optical device, which is to be provided on or in the vicinity of
the optical waveguide, or as at least a part of a via penetrating the
optical waveguide.