Optical fishnet metamaterial with negative, zero, positive refractive index and nearly perfect absorption behavior at different frequencies

Metamaterials (MMs) have many novel characteristics with the aid of appropriate structural design. In this study, we report negative refractive index (NRI), zero refractive index (ZRI) and nearly perfect absorption (NPA) characteristics of an optical fishnet structure. Base on the S-parameter retrieval theory, this periodic nano tapered holes fishnet structure that has simultaneously negative permittivity and negative permeability and shows NRI characteristic from 553 THz to 600 THz. The fishnet structure also exhibits a seamless transition between the negative and positive refractive index bands with a zero index at the transition frequency of 600 THz. Moreover, interestingly, a broadband nearly perfect absorption (NPA) characteristic above 95% arises in 650 THz to 700 THz. As mentioned characteristics of NRI, ZRI and NPA above, they are gained from local electromagnetic fields enhancement by the multiple surface plasmon polaritons (SPPs) resonance mechanism.