Three-dimensional metamaterials with a natural bent
Metamaterials, a hot area of research today, are artificial materials engineered with resonant elements to display properties that are not found in natural materials. By organizing materials in a specific way, scientists can build materials with a negative refractivity, for example, which refract light at a reverse angle from normal materials. However, metamaterials up to now have harbored a significant downside. Unlike natural materials, they are two-dimensional and inherently anisotropic, meaning that they are designed to act in a certain direction. By contrast, three-dimensional natural materials typically look the same from all directions. For instance, water in a glass acts as an isotropic material for light, even though the water molecule itself has an asymmetric and anisotropic structure.