Scattering of surface acoustic waves by a phononic crystal revealed by heterodyne interferometry

Kimmo Kokkonen (1) , Matti Kaivola (1) , Sarah Benchabane (2) , Abdelkrim Khelif (2) , Vincent Laude (2)

1 Optics and Molecular Materials Laboratory
2 FEMTO-ST - Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174)

Surface acoustic wave propagation within a two-dimensional phononic band gap structure has been studied using a heterodyne laser interferometer. Acoustic waves are launched by interdigital transducers towards a square lattice of holes etched in a piezoelectric medium. Interferometer measurements performed at frequencies lying below, within, and above the expected band gap frequency range provide direct information of the wave interaction with the phononic crystal, revealing anisotropic scattering into higher diffraction orders depending on the apparent grating pitch at the boundary between the phononic crystal and free surface. Furthermore, the measurements also confirm the existence of an elastic band gap, in accordance with previous electrical measurements and theoretical predictions.

Domaines: Acoustique [physics.class-ph]

Kimmo Kokkonen, Matti Kaivola, Sarah Benchabane, Abdelkrim Khelif, Vincent Laude. Scattering of surface acoustic waves by a phononic crystal revealed by heterodyne interferometry. Applied Physics Letters, 2007, 91, pp.083517. ⟨10.1063/1.2768910⟩. ⟨hal-00173880⟩