Propagation of Elastic Waves in a One-Dimensional High Aspect Ratio Nanoridge Phononic Crystal

Abstract

We investigate the propagation of elastic waves in a one-dimensional (1D) phononic crystal constituted by high aspect ratio epoxy nanoridges that have been deposited at the surface of a glass substrate. With the help of the finite element method (FEM), we calculate the dispersion curves of the modes localized at the surface for propagation both parallel and perpendicular to the nanoridges. When the direction of the wave is parallel to the nanoridges, we find that the vibrational states coincide with the Lamb modes of an infinite plate that correspond to one nanoridge. When the direction of wave propagation is perpendicular to the 1D nanoridges, the localized modes inside the nanoridges give rise to flat branches in the band structure that interact with the surface Rayleigh mode, and possibly open narrow band gaps. Filling the nanoridge structure with a viscous liquid produces new modes that propagate along the 1D finite height multilayer array.

Fundamentals, progress and perspectives on high-frequency phononic crystals

“…Simple 1D PnCs are composed of a periodic grating coated on a uniform substrate. This pattern-like surface could confine surface acoustic waves (SAW) [21], enabling their applications in signal processing such as interdigitated transducers [53]. Microlithography is a popular approach to create well-defined micro or nanogratings with an aspect ratio of up to 10 [54].…”

“…Due to the small size, SAW PnCs show advantages for the integration in electronic integrated circuits over bulk wavebased PnCs. The SAW PnCs, with a grating pattern on the surface, possess new zone boundaries, zone folding, and band gaps [53,[128][129][130][131][132]. As the surface corrugations get much shallower than the SAW wavelength, SAWs propagating parallel to the grooves are not disturbed by the presence of the grating [128].…”

Special Issue on Brillouin Scattering and Optomechanics

“…One-dimensional phononic crystals have been studied in this respect, as they allow for rather large amplitude motion and can be fabricated at a scale commensurate with a light wavelength. Gueddida et al [1] considered deeply grooved gratings of nanoridges fabricated in epoxy on a glass substrate. They identified various acoustic phonon modes of the one-dimensional phononic crystal.…”