Watching surface waves in phononic crystals

Watching surface waves in phononic crystals.

In this paper, we review results obtained by ultrafast imaging of gigahertz surface acoustic waves in surface phononic crystals with one- and two-dimensional periodicities. By use of quasi-point-source optical excitation, we show how, from a series of images that form a movie of the travelling waves, the dispersion relation of the acoustic modes, their corresponding mode patterns and the positi...

Surface waves in granular phononic crystals.

The existence of surface elastic waves at a mechanically free surface of granular phononic crystals is studied. The granular phononic crystals are made of spherical particles distributed periodically on a simple cubic lattice. It is assumed that the particles are interacting by means of normal, shear, and bending contact rigidities. First, Rayleigh-type surface acoustic waves, where the displac...

Refraction of surface acoustic waves through 2D phononic crystals

We report on the first experimental evidence of negative refraction of surface acoustic waves, through a prism-shaped 2D phononic crystal having a solid matrix. The sample is constituted by a periodic array of air holes drilled in a Si substrate. The experiments are performed using a laser-ultrasonic technique.

Strongly Nonlinear Waves in 3d Phononic Crystals

Three dimensional phononic crystal ("sonic vacuum" without prestress) was assembled from 137 vertical cavities arranged in hexagonal pattern in Silicone matrix filled with stainless steel spheres. This system has unique strongly nonlinear properties with respect to wave propagation inherited from nonlinear Hertz type elastic contact interaction. Trains of strongly nonlinear solitary waves excit...

Plate waves in phononic crystals slabs