This article may be too technical for most readers to understand.(July 2020) |
An acoustic metamaterial, sonic crystal, or phononic crystal is a material designed to control, direct, and manipulate sound waves or phonons in gases, liquids, and solids (crystal lattices). Sound wave control is accomplished through manipulating parameters such as the bulk modulus β, density ρ, and chirality. They can be engineered to either transmit, or trap and amplify sound waves at certain frequencies. In the latter case, the material is an acoustic resonator.
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Continuum mechanics |
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Acoustic metamaterials are used to model and research extremely large-scale acoustic phenomena like seismic waves and earthquakes, but also extremely small-scale phenomena like atoms. The latter is possible due to band gap engineering: acoustic metamaterials can be designed such that they exhibit band gaps for phonons, similar to the existence of band gaps for electrons in solids or electron orbitals in atoms. That has also made the phononic crystal an increasingly widely researched component in quantum technologies and experiments that probe quantum mechanics. Important branches of physics and technology that rely heavily on acoustic metamaterials are negative refractive index material research, and (quantum) optomechanics.