History
The history of Metamaterials traces back to the second world war when artificial dielectrics in microwave engineering is developed. Yet, there are seminal explorations of artificial materials for manipulating electromagnetic waves at the end of the 19th century. \cite{Ramsay_1958} In 1967, a Russian physicist named Victor Veselago published his seminal work entitled "The Electrodynamics of Substances with Simultaneously Negative Values of ε and μ ".\cite{Veselago_1968} In 1968, it was translated in English. Nowadays, it is considered the beginning of Metamaterials. However, at that time, the experimentation was not conducted until 33 years later due to lack of experimental materials and sufficient computing power. In 2000, a team of UCSD researchers produced and demonstrated metamaterials, which exhibited unusual physical properties that were never produced in nature before. \cite{Smith_2000}These materials obey the physic laws, but behave differently from the materials in nature. That was the time when Metamaterials were shown in front of human race.
Different types of Metameterials
Electromagnetic metamaterials
The Electromagnetic metamaterials are based on the theory of Veselago which states that the materials whose dielectric constant and permeability are both negative have different properties with normal materials. In other word, when a beam of light was shot into this medium,the incident light and refract light occupy the same side of the normal line which is different of the properties of normal materials. Different from normal materials, Electromagnetic metamaterials are divided into different classes, which are negative index, single negative, bandgap, double positive medium, Bi-isotropic and bianisotropic, chiral, and FSS based.