Patent ID: 7171085

Claim:
A planar optical waveguide tap, in which polarization-dependent loss is substantially compensated from an input end to an output end, comprising: a first optical waveguide for supporting a first polarization mode and a second polarization mode when light is launched into the input end of said waveguide; a second optical waveguide having at least a coupling portion adjacent and proximate to the first optical waveguide for receiving a portion of light launched into the first optical waveguide into the second optical waveguide, said coupling portion coupling light in a first, substantially polarization-dependent manner, such that the first polarization mode couples significantly more strongly than the second polarization mode into the second optical waveguide from the first optical waveguide, so that light of the second polarization received into the second optical waveguide from the first optical waveguide experiences higher optical loss through said coupling portion than light of said first polarization mode; and, a bend portion of the second optical waveguide distinct from the coupling portion and positioned between the coupling portion and the output end, said bend portion having at least one predetermined bend therein having a prescribed size and shape that are effective to cause light to be transmitted through said band portion in a second substantially polarization-dependent manner, that is opposite to the said first, substantially polarization-dependent manner, so that the second polarization mode couples through said band portion significantly more strongly than the first polarization, whereby light of the first polarization mode radiates out of the bend portion of the waveguide into a cladding about the bend portion with greater efficiency, and therefore experiences higher optical loss in the bend, than light of the second polarization mode, so as to substantially compensate for a polarization-dependent loss that occurs from the coupling portion, for light which remains with the second optical waveguide after passing through the bend portion.