Quasi-perfect absorption achieved throughout low frequency range via acoustic meta-surface

Abstract

In this work, we propose a novel design of acoustic meta-surface with coplanar coiled channels and double apertures. Tunable-broadband (30-300 Hz) and quasi-perfect absorption (>0.9) throughout low frequency range can be realized through active control of the channel length and other structural parameters while the whole structural thickness is only ∼1/170 of the operating wavelength. A heat source is introduced in right position of the channel to extend the direct bandwidth of quasi-perfect absorption (>0.9). By appropriately tuning the channel length, the direct quasi-perfect absorption band (>0.9) can be extended by as large as 3 times. The analytical model and the theoretical simulation results are also shown in this paper. Since our design strategy is indeed active control and the heat source is easily applicable, our realization should have a high impact on low frequency noise elimination.