“…On the other hand, a new class of artificial materials, metallic plates with periodic array of apertures [13][14][15][16][17][18][19][20], drew a great deal of attention recently stimulated by the discovery of extraordinary optical transmission phenomenon [21]. In 2004, Pendry et al demonstrated that metallic plates with slits or square holes support spoof surface plasmon polaritons (SPPs), and when the unit cells are enough subwavelength, such complex systems can be homogenized as plasmonic metamaterials with well-defined equivalent parameters.…”