Patent ID: 6907156

Claim:
A device comprising: a first bidirectional optical coupler having first and second arms; a second bidirectional optical coupler having first and second arms; an optical demultiplexer having an input and plural outputs; a plurality of phase shifters; an optical multiplexer having plural inputs and an output; a first waveguide optically connecting the first arm of the first bidirectional coupler to the input of the optical demultiplexer, the first waveguide being coupled with a first all-pass optical filter; the plurality of phase shifters being optically interposed between the plural outputs of the optical demultiplexer and the plural inputs of the optical multiplexer, and the output of the optical multiplexer connected to the first arm of the second bidirectional optical coupler; a second waveguide optically connecting the second arms of the first and second bidirectional optical couplers, the second waveguide being coupled with an second all-pass optical filter.