Low loss multilayer frequency selective surface negative index metamaterials for the mid-infrared

In this work, the low-loss negative index metamaterial (NIM) design methodology that uses two cascaded frequency selective surface (FCC) screens are extended to design multilayer FSS metamaterial that can be fabricated without the need for alignment between fabrication layers. A metamaterial structure using five cascaded FSS screens was proposed and optimized by a genetic algorithm (GA) to have an index of refraction of -1 with low absorption and mismatch losses in the mid-IR. Measured dielectric and metallic properties incorporated into the model provide confidence that the periodic finite element boundary integral (PFEBI) predictions are accurate. Extension of the design to six screens indicates that the effective properties are approaching those of a bulk material. Efforts are currently underway to fabricate and test a multilayer FSS NIM.