Metamaterials are a class of materials with unusual electromagnetic properties. They are artificially engineered to have properties that are not found in nature. Metamaterials can be used to create materials with negative refractive index, which bend light in the opposite direction of conventional materials. They have many potential applications, including cloaking devices that make objects invisible to radar or other forms of detection.
Metamaterials are made from two or more types of material, usually metal and dielectric, arranged in a repeating pattern. The pattern is designed so that the material has a negative refractive index for certain frequencies of light. This means that when light hits the metamaterial, it bends in the opposite direction to what would happen if it hit a normal material with a positive refractive index.
The first metamaterial was created in 2000 bySir John Pendry at Imperial College London. He used Negative Index Materials (NIMs) to create an invisibility cloak. The cloak worked by bending microwaves around the object being cloaked, making it appear as if the microwaves were coming from behind the cloak.
Pendry’s work sparked a great deal of interest in metamaterials and their potential applications. In 2003, David Smith and his team at Duke University created the world’s first 3D NIM structure. This structure was able to deflect visible light, making it invisible to human eyesight.
Since then, there has been rapid progress in the field of metamaterials research. New designs and new methods for creating metamaterials have been developed; these advances have led to new applications for metamaterials being discovered all the time. Some current examples include:
* Metacloaks: Cloaking devices that use metamaterials to make objects invisible to radar or other forms of detection
* Hyperlenses: Devices that can focus waves beyond their diffraction limit
* Acoustic Metamaterials: Materials that can control sound waves
* Thermodynamic Metatools: Tools that can control heat transfer