Patent ID: 6959153

Claim:
An add-drop multiplexer, comprising: an optical transmission signal input port adapted to receive a wavelength division multiplexed optical transmission signal; an optical transmission signal output port adapted to output at least a portion of said wavelength division multiplexed optical transmission signal; an add-drop optical channel port adapted to receive an optical add channel and output an optical drop channel; a wavelength selective optical filter arranged between said optical transmission signal input port, said optical transmission signal output port and said optical add-drop channel port; and a wavelength tracker and stabilizer in optical communication with said wavelength selective optical filter, wherein said wavelength selective optical filter reflects an optical channel that will continue through said add-drop multiplexer along a transmission line to said optical transmission signal output port and permits an optical channel that is to be dropped to pass therethrough, and said wavelength tracker and stabilizer comprises an optical channel monitor having an absolute wavelength reference, said optical channel monitor providing absolute wavelength and intensity information of the optical channel reflected by said wavelength selective optical filter.