Patent ID: 6510257
Filing Date: 2003-01-21
Classification: G01J,G02B,H04B

Abstract:
A method for monitoring the polarisation of a multi-wavelength light signal in an optical network comprising the steps of:beam splitting the light signal into two portions using a beam splitter having known optical characteristics, wherein the polarization of at least one of the two portions comprises both a TE and a TM component; demultiplexing a first signal portion of the two separated signal portions into a first plurality of signals within each of predetermined wavelength ranges corresponding to known channels using a first demultiplexer having known first polarisation-dependent characteristics; detecting a light intensity of each of the first plurality of signals and providing a first plurality of electrical signals in dependence thereupon; demultiplexing a second signal portion of the two separated signal portions into a second plurality of signals within each of the predetermined wavelength ranges corresponding to the known channels using a second demultiplexer having known second polarisation-dependent characteristics; detecting a light intensity of each of the second plurality of signals and providing a second plurality of electrical signals in dependence thereupon; converting the first and second plurality of electrical signals into a first and second plurality of digital data; and, using a processor, determining the polarisation of the light signal of each wavelength channel in dependence upon the first and second plurality of digital data and based on the known optical characteristics and first and second polarisation-dependent characteristics.