Patent ID: 8594503

Claim:
An optical device comprising: a first waveguide pair that includes a first dielectric waveguide formed on a substrate and a second dielectric waveguide formed on the substrate; a second waveguide pair that includes a third dielectric waveguide formed on the substrate and a fourth dielectric waveguide formed on the substrate, wherein the first waveguide pair and the second waveguide pair intersect at an intersection; and a diffraction grating structure formed at the intersection and configured to couple in and couple out light of a first predetermined wavelength and light of a second predetermined wavelength at substantially a same time, wherein: the diffraction grating structure is adapted for diffracting light of the first predetermined wavelength from the first waveguide pair in a coupling direction; the diffraction grating structure is adapted for diffracting light of the second predetermined wavelength to the second waveguide pair to substantially the coupling direction; the coupling direction depends on the first predetermined wavelength and the second predetermined wavelength, and is substantially different from a normal direction on an average plane defined by the diffraction grating structure; and the first predetermined wavelength and the second predetermined wavelength are substantially different.