Phonon propagation dynamics in band-engineered one-dimensional phononic crystal waveguides

TL;DR

This paper investigates how the geometry of one-dimensional phononic crystal waveguides influences phonon propagation, enabling precise control over bandstructure, phonon modes, and transport properties for potential applications in phononic devices.

Contribution

It demonstrates how modifying waveguide width and air hole pitch can engineer phonon bandstructure and mode propagation in 1D phononic crystal waveguides.

Findings

Engineered bandstructure allows control over phonon transmission and bandgaps.

Multiple phonon modes can be sustained and distinguished by their group velocities.

Key geometric parameters enable full control of phonon transport.

Abstract

The phonon propagation dynamics in a phononic crystal waveguide, realized via a suspended one-dimensional membrane array with periodic air holes, is investigated as function of its geometry. The bandstructure of the phononic crystal can be engineered by modifying the characteristics of the phonon standing waves in the waveguide by varying the waveguide width and the pitch of the air holes. This enables the phonon transmission bands, the bandgaps, the velocity and the nonlinear dispersion in the phononic crystal to be controlled. Indeed the engineered bandstructure can also be tuned to sustain multiple phonon modes in a given branch which whilst being spectrally degenerate can be temporally resolved via their differing group velocities. This systematic study reveals the key geometric parameters that enable the phonon transport in phononic crystal waveguides to be fully controlled.