Related papers: Optimal Sound Absorbing Structures
A coherent perfect absorber is capable of completely absorbing input waves. However, the coherent perfect absorption severely depends on the superposition of the input waves, and the perfect absorption is sensitive to the disorder of the…
In the context of electromagnetic absorption, it is obvious that for an infinite planar periodic structure illuminated by a plane wave, the maximum attainable absorptance, i.e., perfect absorption, is theoretically limited to 100% of the…
We address the question of the optimal broadband absorption of waves in an open, dissipative system. We develop a general framework for absorption induced by multiple overlapping resonances, based on quasi-normal modes and radiative and…
We investigate the acoustic properties of meta-materials that are inspired by sound-absorbing structures. We show that it is possible to construct meta-materials with frequency-dependent effective properties, with large and/or negative…
A microwave ultra-broadband polarization-independent metamaterial absorber is demonstrated. It is composed of a periodic array of metal-dielectric multilayered quadrangular frustum pyramids. These pyramids possess resonant absorption modes…
The aim of this paper is to provide a mathematical and numerical framework for the analysis and design of bubble meta-screens. An acoustic meta-screen is a thin sheet with patterned subwavelength structures, which nevertheless has a…
A metamaterial composed of thin metallic strips as an efficient broadband absorber in the mid-infrared spectrum is investigated. Here the matching between dielectric and geometrical properties of the individual elements is critical to…
The advent of acoustic metamaterials opened up a new frontier in the control of sound transmission. A key limitation, however, is that an acoustic metamaterial based on a single local resonator in the unit cell produces a restricted…
Absorbing airborne noise at frequencies below 300 Hz is a particularly vexing problem due to the absence of natural sound absorbing materials at these frequencies. The prevailing solution for low-frequency sound absorption is the use of…
We suggest to exploit dielectric-metal core-shell nanostructures for efficient resonant and yet broadband absorption of infrared radiation with deeply subwavelength configurations. Realizing that nanostructures would efficiently absorb…
The optical absorption of nanoscale thickness semiconductor films on top of light-trapping structures based on optical interference effects combined with spectrum-splitting structures is theoretically investigated. Nearly perfect absorption…
A new simplified formula is derived for the absorption cross section of small dielectric ellipsoidal particles embedded in lossy media. The new expression leads directly to a closed form solution for the optimal conjugate match with respect…
A procedure for measuring material thickness by means of necessarily-long acoustic wavelengths is examined. The approach utilizes a temporal phase lag caused by the impulse time of wave momentum transferred through a thin layer that is much…
Absorption of surface acoustic waves by a two-dimensional electron gas in a perpendicular magnetic field is considered. The structure of such system at the filling factor $\nu$ close to 1/2 can be understood as a gas of {\em composite…
Modern nanophotonic and meta-optical devices utilize a tremendous number of structural degrees of freedom to enhance light--matter interactions. A fundamental question is how large such enhancements can be. We develop an analytical…
We theoretically and experimentally report sub-wavelength resonant panels for low-frequency quasi-perfect sound absorption including transmission by using the accumulation of cavity resonances due to the slow sound phenomenon. The…
By learning the optimal policy with a double deep Q-learning network, we design ultra-broadband, biomimetic, perfect absorbers with various materials, based the structure of a moths eye. All absorbers achieve over 90% average absorption…
Noise pollution remains a challenging problem requiring the development of novel systems for noise insulation. Extensive work in the field of acoustic metamaterials has led to occurrence of various ventilated structures which, however, are…
We investigate theoretically subwavelength imaging by acoustic metamaterial slabs immersed in the liquid matrix. A near-field subwavelength image formed by evanescent waves is achieved by a designed metamaterial slab with negative mass…
A simple metamaterial-based wide-angle plasmonic absorber is introduced, fabricated, and experimentally characterized using angle-resolved infrared spectroscopy. The metamaterials are prepared by nano-imprint lithography, an attractive…