Perpendicular bowtie and graphene load with Fano resonance for mid infrared application

Graphene single and multi-layer has been recently noticed for making reconfigurable particles. On the other hand, Fano is considered for special properties in the optical regime. In this current work, we are considering a new characteristic shown by graphene in the plasmonic particle. The graphene is used for making asymmetric and quadrupole modes in perpendicular bowtie structures. The quadrupole modes get attention for enhancement of the electric field in comparison with the dipole mode. The SiN substrate with refractive index of 1.98 and the gold metal layer with the Palik optical characteristic are utilized in the design of the proposed Nano-antenna. Simulations are performed by the finite difference time-domain method using CST Microwave Studio and the biasing effect on extinction cross section is being studied for 0–0.3 eV at the mid-infrared domain. We show that how graphene biasing makes a change in plasmonic resonance with dipole mode and convert it to dipole and quadrupole modes where we have Fano resonance. We have revealed that by implementation of the graphene, the dipole mode at 4500 nm for Bowtie structure is converted to quadrupole mode with energy enhancement by chemical potential of 0.3 eV.