Bloch wave deafness and modal conversion at a phononic crystal boundary

Vincent Laude (1) , Rayisa Moiseyenko (1) , Sarah Benchabane Gaiffe (1) , Nico F Declercq (2)

1 FEMTO-ST - Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174)
2 Georgia Tech Lorraine [Metz]

We investigate modal conversion at the boundary between a homogeneous incident medium and a phononic crystal, with consideration of the impact of symmetry on the excitation of Bloch waves. We give a quantitative criterion for the appearance of deaf Bloch waves, which are antisymmetric with respect to a symmetry axis of the phononic crystal, in the frame of generalized Fresnel formulas for reflection and transmission at the phononic crystal boundary. This criterion is used to index Bloch waves in the complex band structure of the phononic crystal, for directions of incidence along a symmetry axis. We argue that within deaf frequency ranges transmission is multi-exponential, as it is within frequency band gaps.

Domaines: Acoustique [physics.class-ph]; Matériaux; Micro et nanotechnologies/Microélectronique

Vincent Laude, Rayisa Moiseyenko, Sarah Benchabane Gaiffe, Nico F Declercq. Bloch wave deafness and modal conversion at a phononic crystal boundary. AIP Advances, 2011, 1 (4), 041402 (11pp). ⟨hal-02300242⟩