Wave Manipulations by Coherent Perfect Channeling.

We show that through the wave energy conserved and reversible process of coherent interactions of scalar waves in a multi-channel system joint by a common junction, it is possible to generate outgoing waves only in certain channels by controlling the incoming waves. We refer to such processes as coherent perfect channeling (CPC). As two particular examples, we report experimental and theoretical investigations of CPC with two incoming coherent waves in three and four-channel waveguides that are completely channeled into one or two other waveguides mediated by a deep subwavelength dimension scatterer at the common junction. Two such scatterers are discovered, one confirmed by experiments and the other predicted by theory, and their scattering matrices are constructed. Scatterers with other CPC scattering matrices are explored, and preliminary investigations of their properties are conducted. The scattering matrix formulism makes it possible to extend the domain of CPC to other scalar waves, such as electromagnetic waves and quantum wavefunctions.