Dynamically reconfigurable add/drop multiplexer with low coherent cross-talk for optical communication networks

A method of adding and/or dropping an optical channel in a wavelength division multiplexed system, comprising:

• directing a wavelength division multiplexed optical signal to a wavelength selective filter, said wavelength selective filter having a higher reflectivity for a first optical channel of said wavelength division multiplexed optical signal compared to a second optical channel of said wavelength division multiplexed optical signal;
• filtering said wavelength division multiplexed signal with said wavelength selective filter to produce a through channel substantially at a wavelength of said first optical channel and a drop channel substantially at a wavelength of said second optical channel;
• directing said through channel into a transmission path of said wavelength division multiplexed system and allowing said drop channel to pass therethrough;
• and
• monitoring said through channel with a wavelength tracker and stabilizer comprising an absolute wavelength reference,
• wherein said through channel is reflected by said wavelength selective filter to continue along a wavelength division multiplexed transmission path of said wavelength division multiplexed system.

A dynamically reconfigurable add-drop multiplexer, comprising:

• an optical signal input port;
• a tunable band-reflecting optical filter in optical communication with said optical signal input port;
• a wavelength tracker and stabilizer in optical communication with a reflected light path from said tunable band-reflecting optical filter,
• wherein said wavelength tracker and stabilizer comprises an optical channel monitor comprising an absolute wavelength and intensity reference, said wavelength tracker providing absolute wavelength and intensity information of light reflected by said tunable reflecting optical filter, and
• said band-reflecting optical filter reflects a wavelength channel to be sent as a through channel into said reflected light path and transmits a wavelength channel to be dropped.

A wavelength division multiplexed optical communication system, comprising:

• a plurality of transmitters;
• an add-drop multiplexer in communication with said plurality of transmitters;
• an optical transmission line in communication with said add-drop multiplexer;
• an optical demultiplexer in communication with the optical transmission line;
• and
• a plurality of receivers in communication with the optical demultiplexer;
• wherein said add-drop multiplexer comprises:
• 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 optical channels 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 comprising an absolute wavelength reference, said optical channel monitor providing absolute wavelength and intensity reference, said wavelength tracker providing absolute wavelength and intensity information of light reflected by said tunable reflecting optical filter.