Patent ID: 8032027

Claim:
An optical device comprising: a splitter device configured to split an input spectrum among a plurality of output ports, and a combiner device configured to combine at least a portion of the split input spectrum into a single output port, each of the splitter and combiner devices having respective first and second input ports, respective first and second output ports, and a respective transfer matrix; a first optical path optically coupling the first output port of the splitter device and the first input port of the combiner device; a second optical path optically coupling the second output port of the splitter device and the second input port of the combiner device; and an optical filter optically coupled to at least one of the first and the second optical paths, wherein the first and second optical paths are configured to introduce, at least at a wavelength of the input spectrum, a phase shift of π radians to the optical radiation propagating through the first optical path with respect to the optical radiation propagating through the second optical path, said transfer matrix of the combiner device is a diagonal transpose of the transfer matrix of the splitter device, the splitter device is configured to split the input spectrum into the first and second optical paths such that (i) at a first wavelength of the input spectrum, a ratio of a portion of an input signal transferred to the first optical path to a portion of the input signal transferred to the second optical path is greater than 10 and (ii) at a second wavelength of the input spectrum, the ratio of the portion of the input signal transferred to the first optical path to the portion of the input signal transferred to the second optical path is less than 0.1, and a wavelength spacing between the first wavelength and the second wavelength is less than 100 nanometers.