WIKIPEDIA dictionary defined the so-called meta-materials as artificial materials engineered to have properties that may not be found in nature. They are assemblies of multiple individual elements fashioned from conventional microscopic materials such as metals or plastics, but usually arranged in pre-designed periodic patterns. During the last two decades, many scientists in different fields have donated a lot of effort to tailor the novel properties of meta-materials, in particular the optical ones. For example, the development of photonic crystals has given us an unprecedented flexibility in designing both linear and nonlinear optical properties, in terms of refractive index and dielectric permittivity, as a function of wavelength, and for different directions and polarizations. [Ref.1]