Tapered cavity structures disposed within a stratum may be configured as a spectral component splitters, a spectral component combiners, and various combinations thereof including a reflective mode of operation. The tapered cavities have an aperture at their wider and a tip at the narrower, and are dimensioned such that multi-spectral radiant energy admitted into the cavity via the aperture would depart the tapered cavity via its side periphery at a depth and/or direction dependent on its frequency and/or its polarization, and that a plurality of spectral components admitted to the cavities via the its peripheral side or sides will be mixed and emitted via the aperture. Reflective type structures where portions of radiant energy is selectively absorbed and other portions are reflected are also considered. Differing stratums are disclosed. Applications of the tapered cavities in a stratum are also disclosed.