Patent ID: 8676009

Claim:
An optical device, comprising: a first waveguide slab located over a planar optical substrate and having a first plane of symmetry; first and second input port couplers extending from said first waveguide slab and having a first input coupler pair axis located about midway between said first and second input port couplers and offset at a nonzero first distance from said first plane of symmetry; and first and second output port couplers extending from said first waveguide slab and having a first output coupler pair axis located about midway between said first and second output port couplers and offset at a nonzero second distance from said first plane of symmetry, wherein the nonzero second distance is different from the nonzero first distance wherein said first waveguide slab, said input port couplers and said output port couplers are formed in a single mode passive waveguide stack, and further comprising a dilute waveguide stack located between said optical substrate and said waveguide slab.