Patent ID: 8478083

Claim:
An apparatus, comprising: a substrate; an input waveguide provided on the substrate, the input waveguide receiving an optical signal, the optical signal having a first polarization in the input waveguide; a first waveplate waveguide provided on the substrate, the first waveplate waveguide receiving the optical signal, the first waveplate waveguide having first and second waveplate eigen modes, which are oriented along first and second directions, respectively; a delay waveguide provided on the substrate, the first waveplate waveguide supplying the optical signal to the first delay waveguide, the delay waveguide having first and second delay eigen modes, which are oriented along third and fourth directions, respectively; a second waveplate waveguide provided on the substrate, the second waveplate waveguide receiving the optical signal from the first delay waveguide, the second waveplate waveguide having the first and second waveplate eigen modes; and an output waveguide provided on the substrate, the output waveguide supplying the optical signal, such that the optical signal in the output waveguide has a second polarization different than the first polarization wherein the delay waveguide is one of a plurality of delay waveguides provided along an optical path in which the optical signal propagates from the input waveguide to the output waveguide.