Patent ID: 7349628

Claim:
A device for multiplexing or demultiplexing M optical signals, M being an integer and greater than or equal to 2, and each of the signals being carried by a different wavelength λ m , said device comprising: a multi-mode interference (MMI) waveguide having at a first side, a number N of access terminals for connection of N access waveguides, each of the access waveguides having a tapered part leading to the MMI waveguide, and said MMI waveguide having a tapered part where the access waveguides connect leading to a second part of the MMI waveguide, said MMI waveguide having dimensions such that each of the optical signals propagating into the MMI waveguide at the i:th access waveguide, where i≦N, produces N self-images inside the MMI waveguide at a respective distance I m from the access terminals, where N is an integer greater than or equal to 2; M wavelength selective reflection means arranged in the second part of the MMI waveguide, each of which is arranged in proximity of a respective one of the distances I m , wherein the m:th wavelength selective reflection means is arranged to reflect the optical signal carried by the m:th wavelength, where 2≦m≦M; M phase adjusting means arranged in the second part of the MMI waveguide, each of which is arranged in relation to a corresponding wavelength selective reflection means, wherein the m:th phase adjusting means is arranged to adjust the phase of the self-images of the optical signal carried by the m:th wavelength to create a single self-image at a selected output access waveguide when reflected by the m:th wavelength selective reflection means; and wherein the m:th wavelength selective reflective means is reflective to the m:th wavelength λ m , and substantially transparent to all wavelengths λ k , where λ k ≠λ m .