A tapered core waveguide which may be configured as a spectral component splitter, a spectral component combiner, and various combinations thereof including a reflective mode of operation. The tapered core waveguide has an aperture and cladding, and is dimensioned such that radiant energy admitted into the core via the aperture and having at least two spectral components would be emitted via the cladding at a location dependent on its frequency and/or its polarization, and that a plurality of spectral components injected to the core via the cladding will be mixed and emitted via the aperture.