Evanescent Coupling Between Aluminum Pillars
Résumé
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 surface acoustic waves (SAW) along the linear chain of pillars for frequencies in the [0, 2] GHz range. We show that a pair or a chain of pillars can interact together through the excitation of the resonant compressional and bending eigen-modes, depending on the length of the secant line between the two pillars and the angle with respect to the incident surface acoustic wave. The interaction comes from the coupling between the compressional mode with the out-of-plane motion of the Rayleigh wave. Such a coupling can be achieved when the pillars are closed enough from each other to allow the recovery of the evanescent fields.