Ultrasound transmission through time-varying phononic crystals

Derek W. Wright, Richard S.C. Cobbold

Abstract


The acoustic properties of a photonic crystal is controlled by changing its material properties as a function of time, which affects the acoustic wave scattering within the crystal. An 1D transmission matrix method (TMM) is used to modulate the incident waves within a time-varying photonic crystal at every scattering interface. Acoustic wave propagation within a corrugated tube waveguide is analogous to acoustic wave propagation with a 1D photonic crystal consisting of alternating layers of differing media. The time varying-TMM (TV-TMM) simulation execution times are four to five orders of magnitude faster than the FDTD simulations used for comparison and provide exact solutions at the frequencies of interest. The shapes of the band-gap and band-gap edges are altered, which arises the possibility of changing the band-gap characteristics using material parameter variation as the controlling mechanism.

Keywords


Acoustic properties; Acoustic wave propagation; Acoustic waves; Acoustics; Crystal atomic structure; Crystallography; Elastic waves; Gallium alloys; Numerical analysis; Photonic crystals; Powders; Semiconductor materials; Time varying systems; Underwater acoustics; Wave propagation; 1-D photonic crystals; Alternating layers; Controlling mechanisms; Corrugated tubes; Exact solutions; Execution times; FDTD simulations; Function of times; Gap edges; Incident waves; Material parameters; Material properties; Orders of magnitudes; Phononic crystals; Time varying; Transmission matrix methods

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