INTERFEROMETRIC ELEMENT, INTERFEROMETRIC N-STAGE TREE ELEMENT, AND METHOD OF PROCESSING A FIRST OPTICAL INPUT SIGNAL AND A SECOND OPTICAL INPUT SIGNAL SO AS TO PROVIDE A PLURALITY OF ORTHOGONAL OUTPUT SIGNALS

摘要

The invention relates to an interferometric element comprising a first interferometer of the Mach-Zehnder type and a second interferometer of the Mach-Zehnder type, said first interferometer comprising a first input coupling element and a first output coupling element, and said second interferometer comprising a second input coupling element and a second output coupling element, said input coupling elements being optically connected to the output coupling elements by means of transmission lines, such that for each of the output coupling elements at least one delayed transmission line from among the respective associated transmission lines is designed for providing a frequency-dependent phase shift that differs from the frequency-dependent phase shift of the or each of the other, non-delayed transmission lines connected to the relevant output coupling element, while at least one of the transmission lines in the interferometric element is designed for providing an additional, frequency-independent phase shift, wherein the first and the second interferometer are optically coupled to one another cross-wise such that at least one transmission line of the first input coupling element is connected to the second output coupling element, and that at least one transmission line of the second input coupling element is connected to the first output coupling element. Furthermore, the invention relates to an N-stage tree element comprising the interferometric elements and to the use of the element.