Control of acoustic absorption in one-dimensional scattering by resonant scatterers

TLDR

The study examines high‑Q transparent modes generated in a two‑port, one‑dimensional waveguide side‑loaded with isolated moderate‑Q resonators. The authors aim to control strong absorption by tuning the radiation leakage of a few weak‑loss resonators, enabling new wave‑control devices. Experimental results demonstrate that by balancing inherent losses with high‑Q transparent modes, symmetric structures achieve coherent perfect absorption with one‑sided absorption >0.5, while asymmetric structures reach 96% one‑sided absorption in a sub‑wavelength λ/28 sample.

Abstract

We experimentally report perfect acoustic absorption through the interplay of the inherent losses and transparent modes with high Q factor. These modes are generated in a two-port, one-dimensional waveguide, which is side-loaded by isolated resonators of moderate Q factor. In symmetric structures, we show that in the presence of small inherent losses, these modes lead to coherent perfect absorption associated with one-sided absorption slightly larger than 0.5. In asymmetric structures, near perfect one-sided absorption is possible (96%) with a deep sub-wavelength sample (λ/28, where λ is the wavelength of the sound wave in the air). The control of strong absorption by the proper tuning of the radiation leakage of few resonators with weak losses will open possibilities in various wave-control devices.