Emerging frontiers in metamaterials

More than two decades ago, the experimental demonstration of negative refraction in an artificial structure represented a materials science breakthrough of the 21st century. It is not only an exotic phenomenon beyond the common sense, but also opens up some unprecedented capabilities and functionalities (e.g., super-lens). Since then, the concept “Metamaterials” gained considerable attentions, initially in electromagnetic waves and eventually expanded to different fields, such as optics, acoustics, mechanics, as well as technologies like communication, medical equipment, vibration isolation and energy harvesting, to name a few.