Optical (de)multiplexers

An optical demultiplexer/multiplexer, comprising:

• a multimode interference waveguide;
• at least one first coupling waveguide which meets the multimode interference waveguide at at least one first location and a plurality of second coupling waveguides which meet the multimode interference waveguide at a plurality of second locations which are spaced in a direction of transmission in relation to the at least one first location, with the at least one first coupling waveguide and the plurality of second coupling waveguides together with the multimode interference waveguide providing an angled multimode interferometer which operates to demultiplex a first optical signal having optical channels of a plurality of wavelengths and/or polarizations or multiplex optical signals of a plurality of wavelengths and/or polarizations into a first optical signal having optical channels of the plurality of wavelengths and/or polarizations;
• wherein the at least one first coupling waveguide is configured to couple a signal between the at least one first coupling waveguide and the multimode interference waveguide which has a broadened spatial profile, optionally having a substantially flat-top spectral profile.

An optical demultiplexer/multiplexer, comprising:

• a multimode interference waveguide;
• a plurality of first coupling waveguides which meet the multimode interference waveguide at a plurality of first locations and a plurality of second coupling waveguides which meet the multimode interference waveguide at a plurality of second locations which are spaced in a direction of transmission in relation to the first locations, with the first and second coupling waveguides together with the multimode interference waveguide providing an angled multimode interferometer which operates to demultiplex an optical signal having optical channels of a plurality of wavelengths and/or polarizations or multiplex optical signals of a plurality of wavelengths and/or wavelengths into an optical signal having optical channels of the plurality of wavelengths and/or polarizations;
• wherein the first coupling waveguides are configured to receive optical signals having different wavelength and/or polarization components, each comprising optical channels having a plurality of wavelengths and/or polarizations, and provide for a broadened spatial profile, optionally having a substantially flat-top spectral profile, to signals transmitted between the first and second coupling waveguides.

An optical demultiplexer/multiplexer, comprising:

• a multimode interference waveguide, wherein the multimode interference waveguide includes a first reflector at one end in a first direction of transmission which acts to reflect an optical signal or signals in a second direction of transmission which is opposite to the first direction of transmission;
• and
• at least one first coupling waveguide which meets the multimode interference waveguide at at least one first location and a plurality of second coupling waveguides which meet the multimode interference waveguide at a plurality of second locations, with the at least one first coupling waveguide and the plurality of second coupling waveguides together with the multimode interference waveguide providing a first angled multimode interferometer which operates to demultiplex a first optical signal having optical channels of a plurality of wavelengths and/or polarizations or multiplex optical signals of a plurality of wavelengths and/or polarizations into a first optical signal having optical channels of the plurality of wavelengths and/or polarizations.