Sound Trapping in an Open Resonator

TL;DR

This paper presents the design and experimental validation of an open acoustic resonator supporting bound states in the continuum (BICs), achieving significantly higher Q-factors than previous structures, with potential for advanced acoustic applications.

Contribution

It introduces a novel open resonator supporting three types of BICs, including a new mirror-symmetry induced BIC, with experimental demonstration of high Q-factors.

Findings

Supported three types of BICs in an open resonator.

Achieved Q-factors up to ten times higher than previous open resonators.

Validated theoretical predictions with experimental results.

Abstract

The ability of extreme sound energy confinement with high-quality factor (Q-factor) resonance is of vital importance for acoustic devices requiring high intensity and hypersensitivity in biological ultrasonics, enhanced collimated sound emission (i.e. sound laser) and high-resolution sensing. However, structures reported so far demonstrated a limited quality factor (Q-factor) of acoustic resonances, up to several tens in an open resonator. The emergence of bound states in the continuum (BIC) makes it possible to realize high-Q factor acoustic modes. Here, we report the theoretical design and experimental demonstration of acoustic BICs supported by a single open resonator. We predicted that such an open acoustic resonator could simultaneously support three types of BICs, including symmetry protected BIC, Friedrich-Wintgen BIC induced by mode interference, as well as a new kind of BIC: mirror-symmetry induced BIC. We also experimentally demonstrated the existence of all three types of BIC with Q-factor up to one order of magnitude greater than the highest Q-factor reported in an open resonator.