Patent ID: 6426816
Filing Date: 2002-07-30
Classification: H04J

Abstract:
A filter for reducing noise from a wavelength division multiplexing (WDM) signal to form a filter output signal, the filter comprising:a first stage that uses polarization based filtering to remove a portion of the noise to form a first reduced noise, and forms a first output signal from the WDM signal and the first reduced noise; a second stage that uses polarization based filtering to remove a portion of noise from the first reduced noise to form a second reduced noise, and forms a second output signal from the WDM signal and the second reduced noise; and a reflection stage that reflects the second output signal back into the second stage for further processing by the second stage; wherein the further processing by the second stage removes a portion of noise from the second reduced noise to form a third reduced noise, and forms a third output signal from the WDM signal and the third reduced noise; and the third output signal is provided to the first stage for further processing by the first stage that removes a portion of noise from the third reduced noise to form a fourth reduced noise, and forming the filter output signal from the WDM signal and fourth reduced noise.