Switchable wavelength router

  • US 5,694,233 A
  • Filed: 01/08/1997
  • Issued: 12/02/1997
  • Est. Priority Date: 07/23/1996
  • Status: Expired due to Term
First Claim
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1. A method for switching wavelength division multiplexed (WDM) optical signals comprising the steps of:

  • providing a first input/output (I/O) port for receiving the WDM optical signal;

    providing a second I/O port;

    providing a third I/O port;

    spatially decomposing the WDM optical signal received from said first I/O port into first and second beams having orthogonal polarizations with respect to each other;

    rotating the polarization of said first beam to substantially match the polarization of said second beam;

    demultiplexing said first and second beams of same polarization through a first wavelength filter having a polarization dependent optical transmission function such that said first beam decomposes into third and fourth beams with their polarizations orthogonal to each other, and said second beam decomposes into fifth and sixth beams with their polarizations orthogonal to each other, wherein said third and fifth beams carry a first predetermined spectral band at a first polarization and said fourth and sixth beams carry a second predetermined spectral band at a second polarization, wherein said first and second spectral bands are substantially complementary and said first and second polarizations are orthogonal;

    spatially routing said third, fourth, fifth and sixth beams based upon their polarizations;

    passing said routed third, fourth, fifth and sixth beams through a second wavelength filter having substantially the same transmission function as said first wavelength filter, wherein second wavelength filter rotates said third, fourth, fifth, and sixth beams back to the same polarization state as said second beam before it enters said first wavelength filter;

    rotating the polarizations of said fifth and sixth beams such that they are orthogonal to said third and fourth beams;

    spatially recombining said third and fifth beams containing said first spectral band, and spatially recombining the said fourth and sixth beams containing said second spectral band; and

    coupling said first spectral band to said second I/O port and said second spectral band to said third I/O port.

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