The nano loop antenna with Fano resonance and symmetrical formation and reconfigurable characteristic for bio-sensing application
The nanoantenna with Fano response is important for solar cell and bio-sensing application because of the more electric field enhancement. In this paper, we have presented a new structure based on two parallel nano loops and for achieving the Fano response; we have combined this structure with nano-sphere arrays which make a coupling between two nano loops. The Interaction between these nanoparticles is made bright and dark mode and Fano responses. To improve the electric field in this structure, we have implemented a multi-layer graphene under the nanoparticle. We show that by altering the chemical potential from 0.2 to 0.8 eV the maximum electric field has increased more than 20% for 0.6 eV in comparison to the case for 0.2 eV. We have studied the parameters effect on resonances. In addition, the presented antenna is used for biomaterial and we have compared the bare and coated structures which can consider as a figure of merit factor for optical sensing and imaging. Here, we have utilized the graphene layer with the thickness of 2 nm under the nanoparticle as multi-layer graphene. The structure is simulated based on the FIT method by the CST and for the substrate, we are selected SiO2 with the thickness of 80 nm which is a normal substrate for graphene deposition and the Palik mode is considered for gold parts. As a result of the fact, the graphene can be considered for controlling the electric field and the optical nanoantenna for bio-sensing.