Patent ID: 7620275

Claim:
An apparatus, comprising: a 1×2 coupler in optical communication with an input optical waveguide, the 1×2 coupler configured to separate an input finite bandwidth optical signal provided from the input optical waveguide into two similar optical signals; input ends of first and second waveguide arms in optical communication with the 1×2 coupler and configured to each receive ones of the two similar optical signals, wherein an inherent birefringence of each of the first and second waveguide arms is substantially similar, and further wherein the first and second waveguide arms have different physical path lengths that differ by an amount (ΔL); and a 2×2 coupler in optical communication with an output end of the first and second waveguide arms, wherein the 2×2 coupler is configured to provide an interfered output transverse electric (TE) polarization and an interfered output transverse magnetic (TM) polarization.