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Birefringent optical wavelength multiplexer/demultiplexer

  • US 4,566,761 A
  • Filed: 09/13/1984
  • Issued: 01/28/1986
  • Est. Priority Date: 09/13/1984
  • Status: Expired due to Fees
First Claim
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1. A birefringent optical wavelength multiplexer/demultiplexer comprisingfirst polarization beam splitting means for splitting an applied collimated beam of light into two linearly polarized beams whose directions of propagation are perpendicular to one another;

  • first reflecting means for reflecting one of said linearly polarized beams parallel to the other polarized beam;

    a birefringent element having a pair of opposed parallel surfaces, with an optical axis oriented nominally parallel to said surfaces, said element being oriented with said parallel surfaces perpendicular to the direction of propagation of said linearly polarized beams, said optical axis being oriented half way between the two polarized beams incident upon said element, 45°

    from the polarization axis of each said beam, whereinone electric field component of each of said polarized beams which is parallel to an "extraordinary" axis of said element propagates at a different rate of speed, dependent upon the material of said element, than the other electric field component which is parallel to an "ordinary" axis of said element;

    second reflecting means for reflecting the other of said linearly polarized beams, following propagation of said other beam through said element, in a direction perpendicular to that of said one of said polarized beams following propagation of said one polarized beam through said element; and

    second polarization beam splitting means oriented to receive both said reflected other beam and the propagated one beam, wherein(1) when the propagated other beam and the propagated one beam have polarization states which are linearly polarized parallel to said respective applied polarized beams, said reflected other beam is transmitted by said second polarization beam splitting means, and said propagated one beam is reflected by said second polarization beam splitting means, whereby said reflected other beam and said propagated one beam are combined and transmitted outwardly from a first port; and

    (2) when the propagated other beam and the propagated one beam have polarization states which are linearly polarized perpendicular to said respective applied polarized beams, said reflected other beam is reflected by said second polarization beam splitting means, and said propagated one beam is transmitted by said second polarization beam splitting means, whereby said reflected other beam and said propagated one beam are combined and transmitted outwardly from a second port.

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