Dynamics of confined cavity modes in a phononic crystal slab investigated byin situtime-resolved experiments

Abstract

The confinement of elastic waves within a single defect in a phononic crystal slab is investigated both experimentally and theoretically. The structure is formed by a honeycomb lattice of air holes in a silicon plate with one hole missing in its center. The frequencies and polarizations of the localized modes in the first band gap are computed with a finite element method. A noncontact laser ultrasonic technique is used both to excite flexural Lamb waves and to monitor in situ the displacement field within the cavity. We report on the time evolution of confinement, which is distinct according to the symmetry of the eigenmode.

Omnidirectional refractive devices for flexural waves based on graded phononic crystals

“…Thus, propagation properties of flexural waves in plates with periodic arrangements of rigid pins [1,2], holes [3], attached pillars [4,5,6] or point-like spring-mass resonators [7,8,9] attached to them has been investigated by several groups, as well as the resonant properties of complex inclusions [10].…”

Guidance of surface waves in a micron-scale phononic crystal line-defect waveguide

“…This particularly holds for surface acoustic wave (SAW) and Lamb-wave based systems that lie at the basis of a number of applications in the fields of wireless telecommunications or micro-electro-mechanical systems (MEMS). Experimental demonstrations of microscale resonators 12,13 and cavities 14 were recently reported. Phononic waveguiding was also lately considered for Lamb waves in phononic crystal slabs 15 and for SAWs in finite-depth phononic crystals.…”

Active control of the transmission of Lamb waves through an elastic metamaterial

“…They offer the additional advantage of being contactless allowing the application of the external force in any direction. Finally, all-optical techniques such as laser ultrasonics 38 or picosecond time-domain thermoreflectance, 39 could establish the proof of concept of the active control of the transmission of Lamb waves with pillars based metasurfaces.…”