Patent ID: 6744943
Filing Date: 2004-06-01
Classification: G02B,H04J

Abstract:
Au add-drop optical filter for removing a drop signal from a target wavelength channel of a multi-channel input signal and adding an add signal into the target wavelength channel, comprising:input means for receiving the multi-channel input signal, the input signal comprising a plurality of input signals in a plurality of corresponding channels and the drop signal in the target wavelength channel; adding means for delivering the add signal at said target wavelength to the input signal; first polarization splitter means, connected to said input port and to said adding means, for splitting each of the input, drop, and add signals into two corresponding input, drop, and add signal polarized components; first polarization changing means for changing polarization of the add and drop signals at said target wavelength and passing all signals at other wavelengths therethrough; a first line for delivering a first portion of said input, drop, and add signal polarized components to said first polarization changing means, such that said input signal polarized components pass through said first polarization changing means, wherein polarizations of said add and drop signal polarized components is changed; second polarization changing means for changing polarization of the add and drop signals at said target wavelength and passing all signals at other wavelengths therethrough; a second line for delivering a second portion of said input, drop, and add signal polarized components to said second polarization changing means, such that said input signal polarized components pass through said second polarization changing means, wherein polarization of said add and drop signal polarized components is changed; output means for transmitting, to a first external destination, an output signal comprising a plurality of Input signals in a plurality of corresponding channels and the add signal in the target wavelength charnel; drop means for transmitting the drop signal in the target wavelength channel to a second external destination; and second polarization splitter means, connected to said first and second polarization changing means and to said output and drop means, for directing the input and add signal polarized components to said output means and for directing said drop signal polarized components to said drop means.