Description

Subtitle : Metamaterials offer potential applications in everyday life that might revolutionize acoustic materials. Classical waves, including acoustic waves and electromagnetic waves, are described by conventional wave-propagation functions. Elastic waves were the first waveforms to be understood in condensed matter and have a wide range of applications from industry to defense, from healthcare to entertainment. In 1987, the photonic crystal was proposed to describe the propagation of optical waves in refraction index-modulated periodic structures. Besides, the concept of phononic crystals was conceived with elastic waves propagating in periodic structures modulated with periodic elastic moduli and mass densities. These materials possess a number of important properties, such as band gaps, band edge states7, and the ability to slow the velocity of sound. Furthermore, Metamaterials with subwavelength spatial scales can dramatically change the excitation and propagation of acoustic waves, and thus give rise to subdiffraction-limited resolution and negative index materials. Finally, the metamaterials are a newly emerging field that are important to basic research, and offer potential for applications that might revolutionize acoustic materials.