Patent ID: 6441960
Filing Date: 2002-08-27
Classification: G02B,H04J

Abstract:
An optical apparatus comprising:a ) a first birefrigent element for receiving a wavelength division multiplexed (WDM) signal and decomposing said WDM signal into a first beam and a second beam that are orthogonally polarized and spatially separated; b) a first wavelength filter optically coupled to receive said first and second beams from said first birefrigent element, wherein said first wavelength filter decomposes said first beam into third and fourth beams with orthogonal polarizations and said second beam into fifth and sixth beams with orthogonal polarizations, wherein said third and fifth beams carry a first spectral set of wavelengths and said fourth and sixth beams carry a second spectral set of wavelengths, and wherein said first and second spectral sets are substantially complementary; c) a second birefrigent element optically coupled to receive said third, forth, fifth, and sixth beams from said first wavelength filter, wherein said third, fourth, fifth, and sixth beams are spatially separated into four polarized components, wherein said third, fourth, fifth, and sixth beams are spatially positioned such that they can be construed as traveling along four corners of an imaginary â€œrectangular propagation pipeâ€ , with said third beam positioned diagonally relative to said fifth beam and said fourth beam positioned diagonally relative to said sixth beam; d) a beam-swapping element optically coupled to receive two or more of said third, fourth, fifth, and sixth beams from said second birefrigent element, wherein upon emerging from said beam-swapping element said third and fifth beams become positioned such that they can be construed as falling on a first side-plane of said imaginary â€œrectangular propagation pipeâ€ , and said fourth and sixth beams become positioned such that they can be construed as falling on a second side-plane of said imaginary â€œrectangular propagation pipeâ€ , and wherein said first and second side-planes are parallel to each other; and e) a third birefrigent element optically coupled to receive said third, forth, fifth, and sixth beams from said beam-swapping element, wherein upon emerging from said third birefrigent element said third and fifth beams are spatially combined into a first output signal carrying said first spectral set, and said fourth and sixth beams are spatially combined into a second output signal carrying said second spectral set.