**2. Types of metamaterials**

Negative index materials (NIMs) propagate wave in a way where the wave does not parallel the Poynting vector or (energy and phase velocities are anti-parallel). The right-handed vectors of wave vector, magnetic and electric fields (*k*, H &E) respectively, in positive index material (PIM) transforms into left-handed triplet in negative index material, where negative refraction occurs to the propagating light beams [2]. Such a phenomenon was perceived in three systems: left-handed (or double negative) MMs [3], hyperbolic MMs [4] and in photonic crystals near band-gap edge [5].
