Evanescent Coupling between Aluminum Pillars

We theoretically investigate, with the help of the finite element method, the interaction between aluminum pillars erected on top of a semi-infinite substrate of silicon in the low frequency range. Our interest is to control and manipulate the propagation of the surface acoustic waves through a linear chain of pillars for frequencies in the [0, 2] GHz range. We show that two pillars can interact together in near field through the excitation of their resonant compressional eigen mode. We will then investigate the resonant modes of a finite linear chain of N pillars, in order to analyze the possibility of propagation along the chain. To reach this objective and to relax the numerical stresses, we have considered a periodicity in the direction perpendicular to the propagation where the lattice parameter is significantly higher to avoid any interaction between two adjacent lines of pillars.