Design of a multilayer nano-antenna as a hyperbolic metamaterial with Fano response for optical sensing

In this paper, a nano-antenna with a Fano response is designed based on Heptamer array arrangement of Nano disks. Fano response formation for various arrangements of the nano-disks are investigated and finally, a multi-layer Heptamer structure is suggested and discussed. Moreover, the effect of multi-layers on the Fano response of Heptamer disks for different number of layers is fully studied. The proposed structure shows the hyperbolic metamaterial characteristic for the optical regime, which leads to near-filed performance enhancement. In this structure, polystyrene with refractive index between 1.59 and 2.4 is used as the kerr material to design a reconfigurable optical structure. Generally, in multi-layer structures, the total near field is strengthened up to 130 V/m resulting in a multi-Fano phenomenon. Finally, parametric study has been conducted to choose the best values. The final structure can be used as a sensor for material detection in the optical domain, achieving maximum sensitivity and Figure of Merit (FOM) of 513 nm/RIU and 117 RIU-1, respectively.