Patent ID: 7720334

Claim:
An optical apparatus, comprising: a first cladding layer; a second cladding layer; a first guiding layer between the first and second cladding layers, and having a core sublayer; and a second guiding layer between the first and second cladding layers, and having a grating stripe that includes a set of diffractive elements, wherein the grating stripe has a higher refractive index relative to the core sublayer and wherein the grating stripe is configured to establish discretized signal modes that propagate along an extended direction of the grating stripe and to bound the signal modes transversely, wherein: the first and second cladding layers and the first guiding layer are arranged so as to form a slab waveguide that supports a plurality of slab waveguide optical modes and that substantially confines in one transverse dimension optical signals propagating in two dimensions in the slab waveguide optical modes; the first and second cladding layers and the second guiding layer are arranged so as to form a channel waveguide that supports one or more channel waveguide optical modes and that substantially confines in two transverse dimensions optical signals propagating in one dimension in the channel waveguide optical modes; and the diffractive elements are arranged so as to couple at least one of the slab waveguide optical modes and at least one of the channel waveguide optical modes so as to enable transfer of a first optical signal from the at least one slab waveguide optical modes to the at least one channel waveguide optical modes thus coupled and transfer of a second optical signal from the at least one channel waveguide optical modes to the at least one slab waveguide optical modes thus coupled.