Abstract
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.
Highlights
Strong interaction between two coherent waves can take place when mediated by a suitable scatterer in deep subwavelength dimension, and lead to extraordinary effects
If total wave energy is conserved in the process, the time reversal symmetry is preserved
We first report the experimental demonstration of coherent perfect channeling (CPC) of acoustic waves in the simplest but none-trivial system, namely the three-port T-configuration waveguide system
Summary
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 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. In coherent perfect absorption (CPA) of electromagnetic waves, which was theoretically predicted as the reverse process of lasing[1], the scatterer is an absorber with suitable transmission, reflection, and absorption coefficients[1] It was confirmed experimentally first in a silicon cavity[2], and in dielectric metasurfaces[3]. The logic operations are not ‘perfect’ in that there are always residue reflection in the input channels and spurious scattering waves at the gate junction Such imperfections could be eliminated if by controlled coherent interaction of incoming waves with a suitable scatterer at the junction, outgoing waves are generated only in certain channels, while being totally absent in others. The potential of CPC processes in a wide range of applications, including all-wave logic gates, precision interferometry, highly coherent source arrays, and other coherent perfect manipulation of waves, are discussed
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