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

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). The control of strong absorption by the proper tuning of few resonators with weak losses will open new possibilities in various wave-control devices. PACS numbers: 43.20.Mv, 43.20.Hq,43.20.Fn 1 arXiv:1509.01443v1 [physics.class-ph] 4 Sep 2015One of the most inspiring outcomes in the field of atom optics is the electromagneticallyinduced-transparency (EIT) which results from the coherent interferences between different excitation pathways of the excited states [1]. In the recent years, and after the theoretical revealing of the similarities between atoms driven by optical fields and resonators excited by incident waves, there has been an increasing interest in the implementations of classical analogues of EIT-like spectra. Thus, EIT-like behaviors have been theoretically studied and experimentally observed in plasmonic, photonic and acoustic resonator systems (see [2][3][4][5][6][7][8][9] and references therein). In the lossless case, these open system configurations show

Ultra-thin metamaterial for perfect and quasi-omnidirectional sound absorption

“…One strategy to design these sub-wavelength systems consists of using space-coiling structures [5,6]. Another way is to use sub-wavelength resonators as membranes [4,7] or Helmholtz resonators (HRs) [8,9].Recently, a new type of sub-wavelength metamaterials based on the concept of slow sound propagation have been used to the same purpose. This last type of metamaterials [10][11][12] makes use of its strong dispersion for generating slow-sound conditions inside the material and, therefore, drastically decreasing frequency of the absorption peaks.…”

“…One strategy to design these sub-wavelength systems consists of using space-coiling structures [5,6]. Another way is to use sub-wavelength resonators as membranes [4,7] or Helmholtz resonators (HRs) [8,9].…”

The control of resonance curve using the shape modulation of the scattering region in elastic waveguide

“…A typical feature of Fano resonance appears in the asymmetry of the resonance peak that is detected in the frequency-dependent reflectance in the scattering problem 8 . As a system that is governed by second-order differential equations, acoustic scattering in an air-core has been discussed 9,10 . In contrast with this system, the flexural wave on an elastic plate provides a biharmonic system that is governed by a fourthorder differential equation 11 .…”

Broadband quasi perfect absorption using chirped multi-layer porous materials

“…Perfect absorption (PA) is recently receiving an increasing interest. [1][2][3][4][5][6] Chirped or graded materials are widely used in the wave physics community due to their possibilities to manipulate the wave propagation. These artificial materials are emerging as promising tools for potential applications in several branches of research and technology.…”