Patent ID: 6850364

Claim:
An optical device for processing optical signals which include an odd set of channels and an even act of channels, the optical device comprising: a fundamental filter cell for filtering optical signals propagating on a first leg and a second leg of an optical loop, wherein the first leg and the second leg of the optical loop pass through the fundamental filter cell, the fundamental filter cell operating as a full waveplate to the odd set of channels and a half waveplate to the even set of channels on the first leg of the optical loop and as a half waveplate to the odd set of channels and a full waveplate to the even set of channels on the second leg of the optical loop; a retro reflector optically coupled with the fundamental filter cell to reflect the optical signals from the first leg to the second leg to form the optical loop through the fundamental filter cell; and a splitter/combiner optically coupled between the fundamental filter cell and the retro reflector to split or combine the odd set of channels and the even set of channels depending on the propagation direction of the optical signals along the optical loop.