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Means for Reducing Crosstalk Between Optical Waveguides Through the Use Of Wavelength Division

IP.com Disclosure Number: IPCOM000101513D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 91K

Publishing Venue

IBM

Related People

Dono, NR: AUTHOR [+5]

Abstract

Optical signals carried in parallel adjacent and crisscrossing optical waveguides are subject to optical crosstalk noise due to dispersion of optical energy in waveguides. Although most of the energy of an optical signal is trapped in a waveguide, some energy couples into nearby adjacent waveguides. If the adjacent waveguide runs parallel to a given waveguide for a considerable distance, then the amount of energy coupled between waveguides can be large enough to hamper the communication of information on the waveguides.

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Means for Reducing Crosstalk Between Optical Waveguides Through the Use Of Wavelength Division

       Optical signals carried in parallel adjacent and
crisscrossing optical waveguides are subject to optical crosstalk
noise due to dispersion of optical energy in waveguides.  Although
most of the energy of an optical signal is trapped in a waveguide,
some energy couples into nearby adjacent waveguides.  If the adjacent
waveguide runs parallel to a given waveguide for a considerable
distance, then the amount of energy coupled between waveguides can be
large enough to hamper the communication of information on the
waveguides.

      A similar effect occurs when two waveguides, carrying different
optical signals, cross each other.  At the intersection of the two
waveguides, energy from one waveguide can couple into the crossing
waveguide because of reflections and dispersion at the intersection
of the waveguides.  We describe a means for isolating optical signals
in parallel adjacent and crossing optical waveguides in order to
reduce the effects of both such sources of signal degradation.

      Multiple Wavelengths for Crosstalk Reduction
      The mechanism of interest has two parts:
           1.  A means for isolating waveguides running in
               one direction.
           2.  A means for isolating waveguides arranged as a
              crisscrossing grid in two directions.

      Parallel Adjacent Waveguides Running in One Direction

      The idea is to use two different wavelengths for optical
communication.  Number the waveguides consecutively as Waveguide 1,
Waveguide 2, ..., Waveguide N.  Use wavelength go to transmit
information on even-numbered wave guides, and wavelength g1 to
transmit information on odd-numbered waveguides.  Energy that couples
from one waveguide to the next will cause transmissions at one
optical wavelength to be contaminated by optical energy at the other
wavelength.  However, the optical receivers are tuned to the
wavelength of the specific waveguide to which they are coupled, and,
in essence, they filter out the unwanted energy of the other
wavelength.  The tuning can be any one of several means, including by
means of an optical grating or by means of a...