Band-gap tuning in 2D spatiotemporal phononic crystals

TL;DR

This paper explores how small spatiotemporal modulations in 2D phononic crystals affect elastic wave band gaps, revealing potential for tunable filters and sensors by controlling modulation parameters.

Contribution

It demonstrates that time-varying inclusions in phononic crystals can destroy or preserve band gaps, enabling tunable phononic devices.

Findings

Frequency harmonics appear due to modulation.

Proper tuning can retain some band gaps.

Potential applications in filters and sensors.

Abstract

We investigate the effect of small spatiotemporal modulations in subwavelength-dimensioned phononic crystals with large band gaps, on the frequency spectrum for elastic waves polarized in the plane of periodicity. When the radius of cylinders periodically placed inside a matrix of highly-contrasting elastic properties is time-varying, we find that due to the appearance of frequency harmonics throughout the spectrum, the notion of a band gap is destroyed in general, although with the appropriate tuning of parameters, in particular the modulation frequency, it is possible that some band-gap region is retained, making such systems possible candidates for tunable bandpass filters or phononic isolators, accordingly, and for sensor applications.