Patent ID: 7003194
Filing Date: 2006-02-21
Classification: G02B

Abstract:
1. An optical multiplexer and demultiplexer comprising (i) a multimode waveguide (ii) a first coupling waveguide which communicates with the multimode waveguide at a first longitudinal position therealong; and (iii) two second coupling waveguides which communicate with the multimode waveguide at respective second longitudinal positions therealong; wherein the second longitudinal positions and the relative orientations of the waveguides' central longitudinal axes are such that an input optical field distribution, being a lowest order transverse mode of the coupling waveguides and comprising radiation of first and second wavelengths, when introduced into the multimode waveguide via the first coupling waveguide is substantially reproduced at the second longitudinal positions as first and second output optical field distributions of first and second wavelengths respectively, which output distributions are coupled into respective second coupling waveguides, by virtue of modal dispersion and inter-modal interference within the multimode waveguide, characterised in that the coupling waveguides each communicate with a lateral side of the multimode waveguide.