Patent ID: 7505648

Claim:
An optical device comprising a first filter, wherein said first filter comprises: a resonant element and a first waveguide, wherein: (a) said resonant element has a resonance at a first wavelength; and (b) said resonant element couples, onto said first waveguide, a first pair of spectral components, wherein: (i) each spectral component in said first pair have said first wavelength and a first polarization state; and (ii) said spectral components in said first pair propagate in different directions along said first waveguide; a first polarization rotator, wherein said first polarization rotator changes said first polarization state of one of said spectral components in said first pair to a second polarization state; a first polarization combiner, wherein said first polarization combiner receives said two spectral components and combines them to form a first filtered signal, wherein said first filtered signal has said first wavelength, said first polarization state, and said second polarization state; a polarization splitter, wherein said polarization splitter receives an optical signal and splits said optical signal into a first optical signal having said first polarization state and a second optical signal having said second polarization state, and wherein said first pair of spectral components are extracted from said first optical signal and said second optical signal; and a primary polarization rotator, wherein said primary polarization rotator changes said second polarization state of said second optical signal to said first polarization state.