Patent ID: 7397995
Filing Date: 2008-07-08
Classification: G02B

Abstract:
1. An optical waveguide, comprising: a substantially planar waveguide substrate; a lower waveguide core; an upper waveguide core positioned above and substantially parallel to the lower waveguide core along overlapping portions of their respective lengths; lower cladding between the substrate and the lower waveguide core; upper cladding above the upper waveguide core; and middle cladding between the overlapping portions of the lower and upper waveguide cores, the middle cladding having a non-planar upper surface arising from its deposition onto the lower waveguide core and the lower cladding by a process exhibiting a non-negligible degree of conformality, wherein: refractive indices of the lower, middle, and upper claddings are each less than refractive indices of the lower and upper waveguide cores; widths of the upper and lower waveguide cores are substantially larger than their respective thicknesses, so that the non-planar upper surface of the middle cladding includes a substantially flat rortion above the lower waveguide core; the upper and lower waveguide cores are arranged so as to jointly support at least one propagating optical waveguide mode along the overlapping portions of their respective lengths; and the upper and lower waveguide cores are arranged along the overlapping portions of their respective lengths so that the supported optical mode is substantially confined bilaterally by the lower and upper waveguide cores, from below by the lower waveguide core, and from above by the upper waveguide core.